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-rw-r--r--tools/objtool/check.c4818
1 files changed, 4818 insertions, 0 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
new file mode 100644
index 0000000000..e308d1ba66
--- /dev/null
+++ b/tools/objtool/check.c
@@ -0,0 +1,4818 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+
+#include <objtool/builtin.h>
+#include <objtool/cfi.h>
+#include <objtool/arch.h>
+#include <objtool/check.h>
+#include <objtool/special.h>
+#include <objtool/warn.h>
+#include <objtool/endianness.h>
+
+#include <linux/objtool_types.h>
+#include <linux/hashtable.h>
+#include <linux/kernel.h>
+#include <linux/static_call_types.h>
+
+struct alternative {
+ struct alternative *next;
+ struct instruction *insn;
+ bool skip_orig;
+};
+
+static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
+
+static struct cfi_init_state initial_func_cfi;
+static struct cfi_state init_cfi;
+static struct cfi_state func_cfi;
+static struct cfi_state force_undefined_cfi;
+
+struct instruction *find_insn(struct objtool_file *file,
+ struct section *sec, unsigned long offset)
+{
+ struct instruction *insn;
+
+ hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
+ if (insn->sec == sec && insn->offset == offset)
+ return insn;
+ }
+
+ return NULL;
+}
+
+struct instruction *next_insn_same_sec(struct objtool_file *file,
+ struct instruction *insn)
+{
+ if (insn->idx == INSN_CHUNK_MAX)
+ return find_insn(file, insn->sec, insn->offset + insn->len);
+
+ insn++;
+ if (!insn->len)
+ return NULL;
+
+ return insn;
+}
+
+static struct instruction *next_insn_same_func(struct objtool_file *file,
+ struct instruction *insn)
+{
+ struct instruction *next = next_insn_same_sec(file, insn);
+ struct symbol *func = insn_func(insn);
+
+ if (!func)
+ return NULL;
+
+ if (next && insn_func(next) == func)
+ return next;
+
+ /* Check if we're already in the subfunction: */
+ if (func == func->cfunc)
+ return NULL;
+
+ /* Move to the subfunction: */
+ return find_insn(file, func->cfunc->sec, func->cfunc->offset);
+}
+
+static struct instruction *prev_insn_same_sec(struct objtool_file *file,
+ struct instruction *insn)
+{
+ if (insn->idx == 0) {
+ if (insn->prev_len)
+ return find_insn(file, insn->sec, insn->offset - insn->prev_len);
+ return NULL;
+ }
+
+ return insn - 1;
+}
+
+static struct instruction *prev_insn_same_sym(struct objtool_file *file,
+ struct instruction *insn)
+{
+ struct instruction *prev = prev_insn_same_sec(file, insn);
+
+ if (prev && insn_func(prev) == insn_func(insn))
+ return prev;
+
+ return NULL;
+}
+
+#define for_each_insn(file, insn) \
+ for (struct section *__sec, *__fake = (struct section *)1; \
+ __fake; __fake = NULL) \
+ for_each_sec(file, __sec) \
+ sec_for_each_insn(file, __sec, insn)
+
+#define func_for_each_insn(file, func, insn) \
+ for (insn = find_insn(file, func->sec, func->offset); \
+ insn; \
+ insn = next_insn_same_func(file, insn))
+
+#define sym_for_each_insn(file, sym, insn) \
+ for (insn = find_insn(file, sym->sec, sym->offset); \
+ insn && insn->offset < sym->offset + sym->len; \
+ insn = next_insn_same_sec(file, insn))
+
+#define sym_for_each_insn_continue_reverse(file, sym, insn) \
+ for (insn = prev_insn_same_sec(file, insn); \
+ insn && insn->offset >= sym->offset; \
+ insn = prev_insn_same_sec(file, insn))
+
+#define sec_for_each_insn_from(file, insn) \
+ for (; insn; insn = next_insn_same_sec(file, insn))
+
+#define sec_for_each_insn_continue(file, insn) \
+ for (insn = next_insn_same_sec(file, insn); insn; \
+ insn = next_insn_same_sec(file, insn))
+
+static inline struct symbol *insn_call_dest(struct instruction *insn)
+{
+ if (insn->type == INSN_JUMP_DYNAMIC ||
+ insn->type == INSN_CALL_DYNAMIC)
+ return NULL;
+
+ return insn->_call_dest;
+}
+
+static inline struct reloc *insn_jump_table(struct instruction *insn)
+{
+ if (insn->type == INSN_JUMP_DYNAMIC ||
+ insn->type == INSN_CALL_DYNAMIC)
+ return insn->_jump_table;
+
+ return NULL;
+}
+
+static bool is_jump_table_jump(struct instruction *insn)
+{
+ struct alt_group *alt_group = insn->alt_group;
+
+ if (insn_jump_table(insn))
+ return true;
+
+ /* Retpoline alternative for a jump table? */
+ return alt_group && alt_group->orig_group &&
+ insn_jump_table(alt_group->orig_group->first_insn);
+}
+
+static bool is_sibling_call(struct instruction *insn)
+{
+ /*
+ * Assume only STT_FUNC calls have jump-tables.
+ */
+ if (insn_func(insn)) {
+ /* An indirect jump is either a sibling call or a jump to a table. */
+ if (insn->type == INSN_JUMP_DYNAMIC)
+ return !is_jump_table_jump(insn);
+ }
+
+ /* add_jump_destinations() sets insn_call_dest(insn) for sibling calls. */
+ return (is_static_jump(insn) && insn_call_dest(insn));
+}
+
+/*
+ * This checks to see if the given function is a "noreturn" function.
+ *
+ * For global functions which are outside the scope of this object file, we
+ * have to keep a manual list of them.
+ *
+ * For local functions, we have to detect them manually by simply looking for
+ * the lack of a return instruction.
+ */
+static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
+ int recursion)
+{
+ int i;
+ struct instruction *insn;
+ bool empty = true;
+
+#define NORETURN(func) __stringify(func),
+ static const char * const global_noreturns[] = {
+#include "noreturns.h"
+ };
+#undef NORETURN
+
+ if (!func)
+ return false;
+
+ if (func->bind == STB_GLOBAL || func->bind == STB_WEAK)
+ for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
+ if (!strcmp(func->name, global_noreturns[i]))
+ return true;
+
+ if (func->bind == STB_WEAK)
+ return false;
+
+ if (!func->len)
+ return false;
+
+ insn = find_insn(file, func->sec, func->offset);
+ if (!insn || !insn_func(insn))
+ return false;
+
+ func_for_each_insn(file, func, insn) {
+ empty = false;
+
+ if (insn->type == INSN_RETURN)
+ return false;
+ }
+
+ if (empty)
+ return false;
+
+ /*
+ * A function can have a sibling call instead of a return. In that
+ * case, the function's dead-end status depends on whether the target
+ * of the sibling call returns.
+ */
+ func_for_each_insn(file, func, insn) {
+ if (is_sibling_call(insn)) {
+ struct instruction *dest = insn->jump_dest;
+
+ if (!dest)
+ /* sibling call to another file */
+ return false;
+
+ /* local sibling call */
+ if (recursion == 5) {
+ /*
+ * Infinite recursion: two functions have
+ * sibling calls to each other. This is a very
+ * rare case. It means they aren't dead ends.
+ */
+ return false;
+ }
+
+ return __dead_end_function(file, insn_func(dest), recursion+1);
+ }
+ }
+
+ return true;
+}
+
+static bool dead_end_function(struct objtool_file *file, struct symbol *func)
+{
+ return __dead_end_function(file, func, 0);
+}
+
+static void init_cfi_state(struct cfi_state *cfi)
+{
+ int i;
+
+ for (i = 0; i < CFI_NUM_REGS; i++) {
+ cfi->regs[i].base = CFI_UNDEFINED;
+ cfi->vals[i].base = CFI_UNDEFINED;
+ }
+ cfi->cfa.base = CFI_UNDEFINED;
+ cfi->drap_reg = CFI_UNDEFINED;
+ cfi->drap_offset = -1;
+}
+
+static void init_insn_state(struct objtool_file *file, struct insn_state *state,
+ struct section *sec)
+{
+ memset(state, 0, sizeof(*state));
+ init_cfi_state(&state->cfi);
+
+ /*
+ * We need the full vmlinux for noinstr validation, otherwise we can
+ * not correctly determine insn_call_dest(insn)->sec (external symbols
+ * do not have a section).
+ */
+ if (opts.link && opts.noinstr && sec)
+ state->noinstr = sec->noinstr;
+}
+
+static struct cfi_state *cfi_alloc(void)
+{
+ struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
+ if (!cfi) {
+ WARN("calloc failed");
+ exit(1);
+ }
+ nr_cfi++;
+ return cfi;
+}
+
+static int cfi_bits;
+static struct hlist_head *cfi_hash;
+
+static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
+{
+ return memcmp((void *)cfi1 + sizeof(cfi1->hash),
+ (void *)cfi2 + sizeof(cfi2->hash),
+ sizeof(struct cfi_state) - sizeof(struct hlist_node));
+}
+
+static inline u32 cfi_key(struct cfi_state *cfi)
+{
+ return jhash((void *)cfi + sizeof(cfi->hash),
+ sizeof(*cfi) - sizeof(cfi->hash), 0);
+}
+
+static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
+{
+ struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
+ struct cfi_state *obj;
+
+ hlist_for_each_entry(obj, head, hash) {
+ if (!cficmp(cfi, obj)) {
+ nr_cfi_cache++;
+ return obj;
+ }
+ }
+
+ obj = cfi_alloc();
+ *obj = *cfi;
+ hlist_add_head(&obj->hash, head);
+
+ return obj;
+}
+
+static void cfi_hash_add(struct cfi_state *cfi)
+{
+ struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
+
+ hlist_add_head(&cfi->hash, head);
+}
+
+static void *cfi_hash_alloc(unsigned long size)
+{
+ cfi_bits = max(10, ilog2(size));
+ cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
+ PROT_READ|PROT_WRITE,
+ MAP_PRIVATE|MAP_ANON, -1, 0);
+ if (cfi_hash == (void *)-1L) {
+ WARN("mmap fail cfi_hash");
+ cfi_hash = NULL;
+ } else if (opts.stats) {
+ printf("cfi_bits: %d\n", cfi_bits);
+ }
+
+ return cfi_hash;
+}
+
+static unsigned long nr_insns;
+static unsigned long nr_insns_visited;
+
+/*
+ * Call the arch-specific instruction decoder for all the instructions and add
+ * them to the global instruction list.
+ */
+static int decode_instructions(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *func;
+ unsigned long offset;
+ struct instruction *insn;
+ int ret;
+
+ for_each_sec(file, sec) {
+ struct instruction *insns = NULL;
+ u8 prev_len = 0;
+ u8 idx = 0;
+
+ if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ continue;
+
+ if (strcmp(sec->name, ".altinstr_replacement") &&
+ strcmp(sec->name, ".altinstr_aux") &&
+ strncmp(sec->name, ".discard.", 9))
+ sec->text = true;
+
+ if (!strcmp(sec->name, ".noinstr.text") ||
+ !strcmp(sec->name, ".entry.text") ||
+ !strcmp(sec->name, ".cpuidle.text") ||
+ !strncmp(sec->name, ".text..__x86.", 13))
+ sec->noinstr = true;
+
+ /*
+ * .init.text code is ran before userspace and thus doesn't
+ * strictly need retpolines, except for modules which are
+ * loaded late, they very much do need retpoline in their
+ * .init.text
+ */
+ if (!strcmp(sec->name, ".init.text") && !opts.module)
+ sec->init = true;
+
+ for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
+ if (!insns || idx == INSN_CHUNK_MAX) {
+ insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
+ if (!insns) {
+ WARN("malloc failed");
+ return -1;
+ }
+ idx = 0;
+ } else {
+ idx++;
+ }
+ insn = &insns[idx];
+ insn->idx = idx;
+
+ INIT_LIST_HEAD(&insn->call_node);
+ insn->sec = sec;
+ insn->offset = offset;
+ insn->prev_len = prev_len;
+
+ ret = arch_decode_instruction(file, sec, offset,
+ sec->sh.sh_size - offset,
+ insn);
+ if (ret)
+ return ret;
+
+ prev_len = insn->len;
+
+ /*
+ * By default, "ud2" is a dead end unless otherwise
+ * annotated, because GCC 7 inserts it for certain
+ * divide-by-zero cases.
+ */
+ if (insn->type == INSN_BUG)
+ insn->dead_end = true;
+
+ hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
+ nr_insns++;
+ }
+
+// printf("%s: last chunk used: %d\n", sec->name, (int)idx);
+
+ sec_for_each_sym(sec, func) {
+ if (func->type != STT_NOTYPE && func->type != STT_FUNC)
+ continue;
+
+ if (func->offset == sec->sh.sh_size) {
+ /* Heuristic: likely an "end" symbol */
+ if (func->type == STT_NOTYPE)
+ continue;
+ WARN("%s(): STT_FUNC at end of section",
+ func->name);
+ return -1;
+ }
+
+ if (func->embedded_insn || func->alias != func)
+ continue;
+
+ if (!find_insn(file, sec, func->offset)) {
+ WARN("%s(): can't find starting instruction",
+ func->name);
+ return -1;
+ }
+
+ sym_for_each_insn(file, func, insn) {
+ insn->sym = func;
+ if (func->type == STT_FUNC &&
+ insn->type == INSN_ENDBR &&
+ list_empty(&insn->call_node)) {
+ if (insn->offset == func->offset) {
+ list_add_tail(&insn->call_node, &file->endbr_list);
+ file->nr_endbr++;
+ } else {
+ file->nr_endbr_int++;
+ }
+ }
+ }
+ }
+ }
+
+ if (opts.stats)
+ printf("nr_insns: %lu\n", nr_insns);
+
+ return 0;
+}
+
+/*
+ * Read the pv_ops[] .data table to find the static initialized values.
+ */
+static int add_pv_ops(struct objtool_file *file, const char *symname)
+{
+ struct symbol *sym, *func;
+ unsigned long off, end;
+ struct reloc *reloc;
+ int idx;
+
+ sym = find_symbol_by_name(file->elf, symname);
+ if (!sym)
+ return 0;
+
+ off = sym->offset;
+ end = off + sym->len;
+ for (;;) {
+ reloc = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
+ if (!reloc)
+ break;
+
+ func = reloc->sym;
+ if (func->type == STT_SECTION)
+ func = find_symbol_by_offset(reloc->sym->sec,
+ reloc_addend(reloc));
+
+ idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);
+
+ objtool_pv_add(file, idx, func);
+
+ off = reloc_offset(reloc) + 1;
+ if (off > end)
+ break;
+ }
+
+ return 0;
+}
+
+/*
+ * Allocate and initialize file->pv_ops[].
+ */
+static int init_pv_ops(struct objtool_file *file)
+{
+ static const char *pv_ops_tables[] = {
+ "pv_ops",
+ "xen_cpu_ops",
+ "xen_irq_ops",
+ "xen_mmu_ops",
+ NULL,
+ };
+ const char *pv_ops;
+ struct symbol *sym;
+ int idx, nr;
+
+ if (!opts.noinstr)
+ return 0;
+
+ file->pv_ops = NULL;
+
+ sym = find_symbol_by_name(file->elf, "pv_ops");
+ if (!sym)
+ return 0;
+
+ nr = sym->len / sizeof(unsigned long);
+ file->pv_ops = calloc(sizeof(struct pv_state), nr);
+ if (!file->pv_ops)
+ return -1;
+
+ for (idx = 0; idx < nr; idx++)
+ INIT_LIST_HEAD(&file->pv_ops[idx].targets);
+
+ for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
+ add_pv_ops(file, pv_ops);
+
+ return 0;
+}
+
+static struct instruction *find_last_insn(struct objtool_file *file,
+ struct section *sec)
+{
+ struct instruction *insn = NULL;
+ unsigned int offset;
+ unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
+
+ for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
+ insn = find_insn(file, sec, offset);
+
+ return insn;
+}
+
+/*
+ * Mark "ud2" instructions and manually annotated dead ends.
+ */
+static int add_dead_ends(struct objtool_file *file)
+{
+ struct section *rsec;
+ struct reloc *reloc;
+ struct instruction *insn;
+ s64 addend;
+
+ /*
+ * Check for manually annotated dead ends.
+ */
+ rsec = find_section_by_name(file->elf, ".rela.discard.unreachable");
+ if (!rsec)
+ goto reachable;
+
+ for_each_reloc(rsec, reloc) {
+
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ addend = reloc_addend(reloc);
+
+ insn = find_insn(file, reloc->sym->sec, addend);
+ if (insn)
+ insn = prev_insn_same_sec(file, insn);
+ else if (addend == reloc->sym->sec->sh.sh_size) {
+ insn = find_last_insn(file, reloc->sym->sec);
+ if (!insn) {
+ WARN("can't find unreachable insn at %s+0x%" PRIx64,
+ reloc->sym->sec->name, addend);
+ return -1;
+ }
+ } else {
+ WARN("can't find unreachable insn at %s+0x%" PRIx64,
+ reloc->sym->sec->name, addend);
+ return -1;
+ }
+
+ insn->dead_end = true;
+ }
+
+reachable:
+ /*
+ * These manually annotated reachable checks are needed for GCC 4.4,
+ * where the Linux unreachable() macro isn't supported. In that case
+ * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
+ * not a dead end.
+ */
+ rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ addend = reloc_addend(reloc);
+
+ insn = find_insn(file, reloc->sym->sec, addend);
+ if (insn)
+ insn = prev_insn_same_sec(file, insn);
+ else if (addend == reloc->sym->sec->sh.sh_size) {
+ insn = find_last_insn(file, reloc->sym->sec);
+ if (!insn) {
+ WARN("can't find reachable insn at %s+0x%" PRIx64,
+ reloc->sym->sec->name, addend);
+ return -1;
+ }
+ } else {
+ WARN("can't find reachable insn at %s+0x%" PRIx64,
+ reloc->sym->sec->name, addend);
+ return -1;
+ }
+
+ insn->dead_end = false;
+ }
+
+ return 0;
+}
+
+static int create_static_call_sections(struct objtool_file *file)
+{
+ struct static_call_site *site;
+ struct section *sec;
+ struct instruction *insn;
+ struct symbol *key_sym;
+ char *key_name, *tmp;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".static_call_sites");
+ if (sec) {
+ INIT_LIST_HEAD(&file->static_call_list);
+ WARN("file already has .static_call_sites section, skipping");
+ return 0;
+ }
+
+ if (list_empty(&file->static_call_list))
+ return 0;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->static_call_list, call_node)
+ idx++;
+
+ sec = elf_create_section_pair(file->elf, ".static_call_sites",
+ sizeof(*site), idx, idx * 2);
+ if (!sec)
+ return -1;
+
+ /* Allow modules to modify the low bits of static_call_site::key */
+ sec->sh.sh_flags |= SHF_WRITE;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->static_call_list, call_node) {
+
+ /* populate reloc for 'addr' */
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(*site), idx * 2,
+ insn->sec, insn->offset))
+ return -1;
+
+ /* find key symbol */
+ key_name = strdup(insn_call_dest(insn)->name);
+ if (!key_name) {
+ perror("strdup");
+ return -1;
+ }
+ if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
+ STATIC_CALL_TRAMP_PREFIX_LEN)) {
+ WARN("static_call: trampoline name malformed: %s", key_name);
+ free(key_name);
+ return -1;
+ }
+ tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
+ memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
+
+ key_sym = find_symbol_by_name(file->elf, tmp);
+ if (!key_sym) {
+ if (!opts.module) {
+ WARN("static_call: can't find static_call_key symbol: %s", tmp);
+ free(key_name);
+ return -1;
+ }
+
+ /*
+ * For modules(), the key might not be exported, which
+ * means the module can make static calls but isn't
+ * allowed to change them.
+ *
+ * In that case we temporarily set the key to be the
+ * trampoline address. This is fixed up in
+ * static_call_add_module().
+ */
+ key_sym = insn_call_dest(insn);
+ }
+ free(key_name);
+
+ /* populate reloc for 'key' */
+ if (!elf_init_reloc_data_sym(file->elf, sec,
+ idx * sizeof(*site) + 4,
+ (idx * 2) + 1, key_sym,
+ is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_retpoline_sites_sections(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *sec;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".retpoline_sites");
+ if (sec) {
+ WARN("file already has .retpoline_sites, skipping");
+ return 0;
+ }
+
+ idx = 0;
+ list_for_each_entry(insn, &file->retpoline_call_list, call_node)
+ idx++;
+
+ if (!idx)
+ return 0;
+
+ sec = elf_create_section_pair(file->elf, ".retpoline_sites",
+ sizeof(int), idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
+
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(int), idx,
+ insn->sec, insn->offset))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_return_sites_sections(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *sec;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".return_sites");
+ if (sec) {
+ WARN("file already has .return_sites, skipping");
+ return 0;
+ }
+
+ idx = 0;
+ list_for_each_entry(insn, &file->return_thunk_list, call_node)
+ idx++;
+
+ if (!idx)
+ return 0;
+
+ sec = elf_create_section_pair(file->elf, ".return_sites",
+ sizeof(int), idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->return_thunk_list, call_node) {
+
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(int), idx,
+ insn->sec, insn->offset))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_ibt_endbr_seal_sections(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *sec;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
+ if (sec) {
+ WARN("file already has .ibt_endbr_seal, skipping");
+ return 0;
+ }
+
+ idx = 0;
+ list_for_each_entry(insn, &file->endbr_list, call_node)
+ idx++;
+
+ if (opts.stats) {
+ printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
+ printf("ibt: ENDBR inside functions: %d\n", file->nr_endbr_int);
+ printf("ibt: superfluous ENDBR: %d\n", idx);
+ }
+
+ if (!idx)
+ return 0;
+
+ sec = elf_create_section_pair(file->elf, ".ibt_endbr_seal",
+ sizeof(int), idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->endbr_list, call_node) {
+
+ int *site = (int *)sec->data->d_buf + idx;
+ struct symbol *sym = insn->sym;
+ *site = 0;
+
+ if (opts.module && sym && sym->type == STT_FUNC &&
+ insn->offset == sym->offset &&
+ (!strcmp(sym->name, "init_module") ||
+ !strcmp(sym->name, "cleanup_module")))
+ WARN("%s(): not an indirect call target", sym->name);
+
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(int), idx,
+ insn->sec, insn->offset))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_cfi_sections(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *sym;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".cfi_sites");
+ if (sec) {
+ INIT_LIST_HEAD(&file->call_list);
+ WARN("file already has .cfi_sites section, skipping");
+ return 0;
+ }
+
+ idx = 0;
+ for_each_sym(file, sym) {
+ if (sym->type != STT_FUNC)
+ continue;
+
+ if (strncmp(sym->name, "__cfi_", 6))
+ continue;
+
+ idx++;
+ }
+
+ sec = elf_create_section_pair(file->elf, ".cfi_sites",
+ sizeof(unsigned int), idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ for_each_sym(file, sym) {
+ if (sym->type != STT_FUNC)
+ continue;
+
+ if (strncmp(sym->name, "__cfi_", 6))
+ continue;
+
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(unsigned int), idx,
+ sym->sec, sym->offset))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_mcount_loc_sections(struct objtool_file *file)
+{
+ size_t addr_size = elf_addr_size(file->elf);
+ struct instruction *insn;
+ struct section *sec;
+ int idx;
+
+ sec = find_section_by_name(file->elf, "__mcount_loc");
+ if (sec) {
+ INIT_LIST_HEAD(&file->mcount_loc_list);
+ WARN("file already has __mcount_loc section, skipping");
+ return 0;
+ }
+
+ if (list_empty(&file->mcount_loc_list))
+ return 0;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->mcount_loc_list, call_node)
+ idx++;
+
+ sec = elf_create_section_pair(file->elf, "__mcount_loc", addr_size,
+ idx, idx);
+ if (!sec)
+ return -1;
+
+ sec->sh.sh_addralign = addr_size;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
+
+ struct reloc *reloc;
+
+ reloc = elf_init_reloc_text_sym(file->elf, sec, idx * addr_size, idx,
+ insn->sec, insn->offset);
+ if (!reloc)
+ return -1;
+
+ set_reloc_type(file->elf, reloc, addr_size == 8 ? R_ABS64 : R_ABS32);
+
+ idx++;
+ }
+
+ return 0;
+}
+
+static int create_direct_call_sections(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *sec;
+ int idx;
+
+ sec = find_section_by_name(file->elf, ".call_sites");
+ if (sec) {
+ INIT_LIST_HEAD(&file->call_list);
+ WARN("file already has .call_sites section, skipping");
+ return 0;
+ }
+
+ if (list_empty(&file->call_list))
+ return 0;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->call_list, call_node)
+ idx++;
+
+ sec = elf_create_section_pair(file->elf, ".call_sites",
+ sizeof(unsigned int), idx, idx);
+ if (!sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->call_list, call_node) {
+
+ if (!elf_init_reloc_text_sym(file->elf, sec,
+ idx * sizeof(unsigned int), idx,
+ insn->sec, insn->offset))
+ return -1;
+
+ idx++;
+ }
+
+ return 0;
+}
+
+/*
+ * Warnings shouldn't be reported for ignored functions.
+ */
+static void add_ignores(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *rsec;
+ struct symbol *func;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
+ if (!rsec)
+ return;
+
+ for_each_reloc(rsec, reloc) {
+ switch (reloc->sym->type) {
+ case STT_FUNC:
+ func = reloc->sym;
+ break;
+
+ case STT_SECTION:
+ func = find_func_by_offset(reloc->sym->sec, reloc_addend(reloc));
+ if (!func)
+ continue;
+ break;
+
+ default:
+ WARN("unexpected relocation symbol type in %s: %d",
+ rsec->name, reloc->sym->type);
+ continue;
+ }
+
+ func_for_each_insn(file, func, insn)
+ insn->ignore = true;
+ }
+}
+
+/*
+ * This is a whitelist of functions that is allowed to be called with AC set.
+ * The list is meant to be minimal and only contains compiler instrumentation
+ * ABI and a few functions used to implement *_{to,from}_user() functions.
+ *
+ * These functions must not directly change AC, but may PUSHF/POPF.
+ */
+static const char *uaccess_safe_builtin[] = {
+ /* KASAN */
+ "kasan_report",
+ "kasan_check_range",
+ /* KASAN out-of-line */
+ "__asan_loadN_noabort",
+ "__asan_load1_noabort",
+ "__asan_load2_noabort",
+ "__asan_load4_noabort",
+ "__asan_load8_noabort",
+ "__asan_load16_noabort",
+ "__asan_storeN_noabort",
+ "__asan_store1_noabort",
+ "__asan_store2_noabort",
+ "__asan_store4_noabort",
+ "__asan_store8_noabort",
+ "__asan_store16_noabort",
+ "__kasan_check_read",
+ "__kasan_check_write",
+ /* KASAN in-line */
+ "__asan_report_load_n_noabort",
+ "__asan_report_load1_noabort",
+ "__asan_report_load2_noabort",
+ "__asan_report_load4_noabort",
+ "__asan_report_load8_noabort",
+ "__asan_report_load16_noabort",
+ "__asan_report_store_n_noabort",
+ "__asan_report_store1_noabort",
+ "__asan_report_store2_noabort",
+ "__asan_report_store4_noabort",
+ "__asan_report_store8_noabort",
+ "__asan_report_store16_noabort",
+ /* KCSAN */
+ "__kcsan_check_access",
+ "__kcsan_mb",
+ "__kcsan_wmb",
+ "__kcsan_rmb",
+ "__kcsan_release",
+ "kcsan_found_watchpoint",
+ "kcsan_setup_watchpoint",
+ "kcsan_check_scoped_accesses",
+ "kcsan_disable_current",
+ "kcsan_enable_current_nowarn",
+ /* KCSAN/TSAN */
+ "__tsan_func_entry",
+ "__tsan_func_exit",
+ "__tsan_read_range",
+ "__tsan_write_range",
+ "__tsan_read1",
+ "__tsan_read2",
+ "__tsan_read4",
+ "__tsan_read8",
+ "__tsan_read16",
+ "__tsan_write1",
+ "__tsan_write2",
+ "__tsan_write4",
+ "__tsan_write8",
+ "__tsan_write16",
+ "__tsan_read_write1",
+ "__tsan_read_write2",
+ "__tsan_read_write4",
+ "__tsan_read_write8",
+ "__tsan_read_write16",
+ "__tsan_volatile_read1",
+ "__tsan_volatile_read2",
+ "__tsan_volatile_read4",
+ "__tsan_volatile_read8",
+ "__tsan_volatile_read16",
+ "__tsan_volatile_write1",
+ "__tsan_volatile_write2",
+ "__tsan_volatile_write4",
+ "__tsan_volatile_write8",
+ "__tsan_volatile_write16",
+ "__tsan_atomic8_load",
+ "__tsan_atomic16_load",
+ "__tsan_atomic32_load",
+ "__tsan_atomic64_load",
+ "__tsan_atomic8_store",
+ "__tsan_atomic16_store",
+ "__tsan_atomic32_store",
+ "__tsan_atomic64_store",
+ "__tsan_atomic8_exchange",
+ "__tsan_atomic16_exchange",
+ "__tsan_atomic32_exchange",
+ "__tsan_atomic64_exchange",
+ "__tsan_atomic8_fetch_add",
+ "__tsan_atomic16_fetch_add",
+ "__tsan_atomic32_fetch_add",
+ "__tsan_atomic64_fetch_add",
+ "__tsan_atomic8_fetch_sub",
+ "__tsan_atomic16_fetch_sub",
+ "__tsan_atomic32_fetch_sub",
+ "__tsan_atomic64_fetch_sub",
+ "__tsan_atomic8_fetch_and",
+ "__tsan_atomic16_fetch_and",
+ "__tsan_atomic32_fetch_and",
+ "__tsan_atomic64_fetch_and",
+ "__tsan_atomic8_fetch_or",
+ "__tsan_atomic16_fetch_or",
+ "__tsan_atomic32_fetch_or",
+ "__tsan_atomic64_fetch_or",
+ "__tsan_atomic8_fetch_xor",
+ "__tsan_atomic16_fetch_xor",
+ "__tsan_atomic32_fetch_xor",
+ "__tsan_atomic64_fetch_xor",
+ "__tsan_atomic8_fetch_nand",
+ "__tsan_atomic16_fetch_nand",
+ "__tsan_atomic32_fetch_nand",
+ "__tsan_atomic64_fetch_nand",
+ "__tsan_atomic8_compare_exchange_strong",
+ "__tsan_atomic16_compare_exchange_strong",
+ "__tsan_atomic32_compare_exchange_strong",
+ "__tsan_atomic64_compare_exchange_strong",
+ "__tsan_atomic8_compare_exchange_weak",
+ "__tsan_atomic16_compare_exchange_weak",
+ "__tsan_atomic32_compare_exchange_weak",
+ "__tsan_atomic64_compare_exchange_weak",
+ "__tsan_atomic8_compare_exchange_val",
+ "__tsan_atomic16_compare_exchange_val",
+ "__tsan_atomic32_compare_exchange_val",
+ "__tsan_atomic64_compare_exchange_val",
+ "__tsan_atomic_thread_fence",
+ "__tsan_atomic_signal_fence",
+ "__tsan_unaligned_read16",
+ "__tsan_unaligned_write16",
+ /* KCOV */
+ "write_comp_data",
+ "check_kcov_mode",
+ "__sanitizer_cov_trace_pc",
+ "__sanitizer_cov_trace_const_cmp1",
+ "__sanitizer_cov_trace_const_cmp2",
+ "__sanitizer_cov_trace_const_cmp4",
+ "__sanitizer_cov_trace_const_cmp8",
+ "__sanitizer_cov_trace_cmp1",
+ "__sanitizer_cov_trace_cmp2",
+ "__sanitizer_cov_trace_cmp4",
+ "__sanitizer_cov_trace_cmp8",
+ "__sanitizer_cov_trace_switch",
+ /* KMSAN */
+ "kmsan_copy_to_user",
+ "kmsan_report",
+ "kmsan_unpoison_entry_regs",
+ "kmsan_unpoison_memory",
+ "__msan_chain_origin",
+ "__msan_get_context_state",
+ "__msan_instrument_asm_store",
+ "__msan_metadata_ptr_for_load_1",
+ "__msan_metadata_ptr_for_load_2",
+ "__msan_metadata_ptr_for_load_4",
+ "__msan_metadata_ptr_for_load_8",
+ "__msan_metadata_ptr_for_load_n",
+ "__msan_metadata_ptr_for_store_1",
+ "__msan_metadata_ptr_for_store_2",
+ "__msan_metadata_ptr_for_store_4",
+ "__msan_metadata_ptr_for_store_8",
+ "__msan_metadata_ptr_for_store_n",
+ "__msan_poison_alloca",
+ "__msan_warning",
+ /* UBSAN */
+ "ubsan_type_mismatch_common",
+ "__ubsan_handle_type_mismatch",
+ "__ubsan_handle_type_mismatch_v1",
+ "__ubsan_handle_shift_out_of_bounds",
+ "__ubsan_handle_load_invalid_value",
+ /* STACKLEAK */
+ "stackleak_track_stack",
+ /* misc */
+ "csum_partial_copy_generic",
+ "copy_mc_fragile",
+ "copy_mc_fragile_handle_tail",
+ "copy_mc_enhanced_fast_string",
+ "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
+ "rep_stos_alternative",
+ "rep_movs_alternative",
+ "__copy_user_nocache",
+ NULL
+};
+
+static void add_uaccess_safe(struct objtool_file *file)
+{
+ struct symbol *func;
+ const char **name;
+
+ if (!opts.uaccess)
+ return;
+
+ for (name = uaccess_safe_builtin; *name; name++) {
+ func = find_symbol_by_name(file->elf, *name);
+ if (!func)
+ continue;
+
+ func->uaccess_safe = true;
+ }
+}
+
+/*
+ * FIXME: For now, just ignore any alternatives which add retpolines. This is
+ * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
+ * But it at least allows objtool to understand the control flow *around* the
+ * retpoline.
+ */
+static int add_ignore_alternatives(struct objtool_file *file)
+{
+ struct section *rsec;
+ struct reloc *reloc;
+ struct instruction *insn;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.ignore_alts entry");
+ return -1;
+ }
+
+ insn->ignore_alts = true;
+ }
+
+ return 0;
+}
+
+/*
+ * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
+ * will be added to the .retpoline_sites section.
+ */
+__weak bool arch_is_retpoline(struct symbol *sym)
+{
+ return false;
+}
+
+/*
+ * Symbols that replace INSN_RETURN, every (tail) call to such a symbol
+ * will be added to the .return_sites section.
+ */
+__weak bool arch_is_rethunk(struct symbol *sym)
+{
+ return false;
+}
+
+/*
+ * Symbols that are embedded inside other instructions, because sometimes crazy
+ * code exists. These are mostly ignored for validation purposes.
+ */
+__weak bool arch_is_embedded_insn(struct symbol *sym)
+{
+ return false;
+}
+
+static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
+{
+ struct reloc *reloc;
+
+ if (insn->no_reloc)
+ return NULL;
+
+ if (!file)
+ return NULL;
+
+ reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+ insn->offset, insn->len);
+ if (!reloc) {
+ insn->no_reloc = 1;
+ return NULL;
+ }
+
+ return reloc;
+}
+
+static void remove_insn_ops(struct instruction *insn)
+{
+ struct stack_op *op, *next;
+
+ for (op = insn->stack_ops; op; op = next) {
+ next = op->next;
+ free(op);
+ }
+ insn->stack_ops = NULL;
+}
+
+static void annotate_call_site(struct objtool_file *file,
+ struct instruction *insn, bool sibling)
+{
+ struct reloc *reloc = insn_reloc(file, insn);
+ struct symbol *sym = insn_call_dest(insn);
+
+ if (!sym)
+ sym = reloc->sym;
+
+ /*
+ * Alternative replacement code is just template code which is
+ * sometimes copied to the original instruction. For now, don't
+ * annotate it. (In the future we might consider annotating the
+ * original instruction if/when it ever makes sense to do so.)
+ */
+ if (!strcmp(insn->sec->name, ".altinstr_replacement"))
+ return;
+
+ if (sym->static_call_tramp) {
+ list_add_tail(&insn->call_node, &file->static_call_list);
+ return;
+ }
+
+ if (sym->retpoline_thunk) {
+ list_add_tail(&insn->call_node, &file->retpoline_call_list);
+ return;
+ }
+
+ /*
+ * Many compilers cannot disable KCOV or sanitizer calls with a function
+ * attribute so they need a little help, NOP out any such calls from
+ * noinstr text.
+ */
+ if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
+ if (reloc)
+ set_reloc_type(file->elf, reloc, R_NONE);
+
+ elf_write_insn(file->elf, insn->sec,
+ insn->offset, insn->len,
+ sibling ? arch_ret_insn(insn->len)
+ : arch_nop_insn(insn->len));
+
+ insn->type = sibling ? INSN_RETURN : INSN_NOP;
+
+ if (sibling) {
+ /*
+ * We've replaced the tail-call JMP insn by two new
+ * insn: RET; INT3, except we only have a single struct
+ * insn here. Mark it retpoline_safe to avoid the SLS
+ * warning, instead of adding another insn.
+ */
+ insn->retpoline_safe = true;
+ }
+
+ return;
+ }
+
+ if (opts.mcount && sym->fentry) {
+ if (sibling)
+ WARN_INSN(insn, "tail call to __fentry__ !?!?");
+ if (opts.mnop) {
+ if (reloc)
+ set_reloc_type(file->elf, reloc, R_NONE);
+
+ elf_write_insn(file->elf, insn->sec,
+ insn->offset, insn->len,
+ arch_nop_insn(insn->len));
+
+ insn->type = INSN_NOP;
+ }
+
+ list_add_tail(&insn->call_node, &file->mcount_loc_list);
+ return;
+ }
+
+ if (insn->type == INSN_CALL && !insn->sec->init)
+ list_add_tail(&insn->call_node, &file->call_list);
+
+ if (!sibling && dead_end_function(file, sym))
+ insn->dead_end = true;
+}
+
+static void add_call_dest(struct objtool_file *file, struct instruction *insn,
+ struct symbol *dest, bool sibling)
+{
+ insn->_call_dest = dest;
+ if (!dest)
+ return;
+
+ /*
+ * Whatever stack impact regular CALLs have, should be undone
+ * by the RETURN of the called function.
+ *
+ * Annotated intra-function calls retain the stack_ops but
+ * are converted to JUMP, see read_intra_function_calls().
+ */
+ remove_insn_ops(insn);
+
+ annotate_call_site(file, insn, sibling);
+}
+
+static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
+{
+ /*
+ * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
+ * so convert them accordingly.
+ */
+ switch (insn->type) {
+ case INSN_CALL:
+ insn->type = INSN_CALL_DYNAMIC;
+ break;
+ case INSN_JUMP_UNCONDITIONAL:
+ insn->type = INSN_JUMP_DYNAMIC;
+ break;
+ case INSN_JUMP_CONDITIONAL:
+ insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
+ break;
+ default:
+ return;
+ }
+
+ insn->retpoline_safe = true;
+
+ /*
+ * Whatever stack impact regular CALLs have, should be undone
+ * by the RETURN of the called function.
+ *
+ * Annotated intra-function calls retain the stack_ops but
+ * are converted to JUMP, see read_intra_function_calls().
+ */
+ remove_insn_ops(insn);
+
+ annotate_call_site(file, insn, false);
+}
+
+static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
+{
+ /*
+ * Return thunk tail calls are really just returns in disguise,
+ * so convert them accordingly.
+ */
+ insn->type = INSN_RETURN;
+ insn->retpoline_safe = true;
+
+ if (add)
+ list_add_tail(&insn->call_node, &file->return_thunk_list);
+}
+
+static bool is_first_func_insn(struct objtool_file *file,
+ struct instruction *insn, struct symbol *sym)
+{
+ if (insn->offset == sym->offset)
+ return true;
+
+ /* Allow direct CALL/JMP past ENDBR */
+ if (opts.ibt) {
+ struct instruction *prev = prev_insn_same_sym(file, insn);
+
+ if (prev && prev->type == INSN_ENDBR &&
+ insn->offset == sym->offset + prev->len)
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * A sibling call is a tail-call to another symbol -- to differentiate from a
+ * recursive tail-call which is to the same symbol.
+ */
+static bool jump_is_sibling_call(struct objtool_file *file,
+ struct instruction *from, struct instruction *to)
+{
+ struct symbol *fs = from->sym;
+ struct symbol *ts = to->sym;
+
+ /* Not a sibling call if from/to a symbol hole */
+ if (!fs || !ts)
+ return false;
+
+ /* Not a sibling call if not targeting the start of a symbol. */
+ if (!is_first_func_insn(file, to, ts))
+ return false;
+
+ /* Disallow sibling calls into STT_NOTYPE */
+ if (ts->type == STT_NOTYPE)
+ return false;
+
+ /* Must not be self to be a sibling */
+ return fs->pfunc != ts->pfunc;
+}
+
+/*
+ * Find the destination instructions for all jumps.
+ */
+static int add_jump_destinations(struct objtool_file *file)
+{
+ struct instruction *insn, *jump_dest;
+ struct reloc *reloc;
+ struct section *dest_sec;
+ unsigned long dest_off;
+
+ for_each_insn(file, insn) {
+ if (insn->jump_dest) {
+ /*
+ * handle_group_alt() may have previously set
+ * 'jump_dest' for some alternatives.
+ */
+ continue;
+ }
+ if (!is_static_jump(insn))
+ continue;
+
+ reloc = insn_reloc(file, insn);
+ if (!reloc) {
+ dest_sec = insn->sec;
+ dest_off = arch_jump_destination(insn);
+ } else if (reloc->sym->type == STT_SECTION) {
+ dest_sec = reloc->sym->sec;
+ dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+ } else if (reloc->sym->retpoline_thunk) {
+ add_retpoline_call(file, insn);
+ continue;
+ } else if (reloc->sym->return_thunk) {
+ add_return_call(file, insn, true);
+ continue;
+ } else if (insn_func(insn)) {
+ /*
+ * External sibling call or internal sibling call with
+ * STT_FUNC reloc.
+ */
+ add_call_dest(file, insn, reloc->sym, true);
+ continue;
+ } else if (reloc->sym->sec->idx) {
+ dest_sec = reloc->sym->sec;
+ dest_off = reloc->sym->sym.st_value +
+ arch_dest_reloc_offset(reloc_addend(reloc));
+ } else {
+ /* non-func asm code jumping to another file */
+ continue;
+ }
+
+ jump_dest = find_insn(file, dest_sec, dest_off);
+ if (!jump_dest) {
+ struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
+
+ /*
+ * This is a special case for retbleed_untrain_ret().
+ * It jumps to __x86_return_thunk(), but objtool
+ * can't find the thunk's starting RET
+ * instruction, because the RET is also in the
+ * middle of another instruction. Objtool only
+ * knows about the outer instruction.
+ */
+ if (sym && sym->embedded_insn) {
+ add_return_call(file, insn, false);
+ continue;
+ }
+
+ WARN_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
+ dest_sec->name, dest_off);
+ return -1;
+ }
+
+ /*
+ * Cross-function jump.
+ */
+ if (insn_func(insn) && insn_func(jump_dest) &&
+ insn_func(insn) != insn_func(jump_dest)) {
+
+ /*
+ * For GCC 8+, create parent/child links for any cold
+ * subfunctions. This is _mostly_ redundant with a
+ * similar initialization in read_symbols().
+ *
+ * If a function has aliases, we want the *first* such
+ * function in the symbol table to be the subfunction's
+ * parent. In that case we overwrite the
+ * initialization done in read_symbols().
+ *
+ * However this code can't completely replace the
+ * read_symbols() code because this doesn't detect the
+ * case where the parent function's only reference to a
+ * subfunction is through a jump table.
+ */
+ if (!strstr(insn_func(insn)->name, ".cold") &&
+ strstr(insn_func(jump_dest)->name, ".cold")) {
+ insn_func(insn)->cfunc = insn_func(jump_dest);
+ insn_func(jump_dest)->pfunc = insn_func(insn);
+ }
+ }
+
+ if (jump_is_sibling_call(file, insn, jump_dest)) {
+ /*
+ * Internal sibling call without reloc or with
+ * STT_SECTION reloc.
+ */
+ add_call_dest(file, insn, insn_func(jump_dest), true);
+ continue;
+ }
+
+ insn->jump_dest = jump_dest;
+ }
+
+ return 0;
+}
+
+static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
+{
+ struct symbol *call_dest;
+
+ call_dest = find_func_by_offset(sec, offset);
+ if (!call_dest)
+ call_dest = find_symbol_by_offset(sec, offset);
+
+ return call_dest;
+}
+
+/*
+ * Find the destination instructions for all calls.
+ */
+static int add_call_destinations(struct objtool_file *file)
+{
+ struct instruction *insn;
+ unsigned long dest_off;
+ struct symbol *dest;
+ struct reloc *reloc;
+
+ for_each_insn(file, insn) {
+ if (insn->type != INSN_CALL)
+ continue;
+
+ reloc = insn_reloc(file, insn);
+ if (!reloc) {
+ dest_off = arch_jump_destination(insn);
+ dest = find_call_destination(insn->sec, dest_off);
+
+ add_call_dest(file, insn, dest, false);
+
+ if (insn->ignore)
+ continue;
+
+ if (!insn_call_dest(insn)) {
+ WARN_INSN(insn, "unannotated intra-function call");
+ return -1;
+ }
+
+ if (insn_func(insn) && insn_call_dest(insn)->type != STT_FUNC) {
+ WARN_INSN(insn, "unsupported call to non-function");
+ return -1;
+ }
+
+ } else if (reloc->sym->type == STT_SECTION) {
+ dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+ dest = find_call_destination(reloc->sym->sec, dest_off);
+ if (!dest) {
+ WARN_INSN(insn, "can't find call dest symbol at %s+0x%lx",
+ reloc->sym->sec->name, dest_off);
+ return -1;
+ }
+
+ add_call_dest(file, insn, dest, false);
+
+ } else if (reloc->sym->retpoline_thunk) {
+ add_retpoline_call(file, insn);
+
+ } else
+ add_call_dest(file, insn, reloc->sym, false);
+ }
+
+ return 0;
+}
+
+/*
+ * The .alternatives section requires some extra special care over and above
+ * other special sections because alternatives are patched in place.
+ */
+static int handle_group_alt(struct objtool_file *file,
+ struct special_alt *special_alt,
+ struct instruction *orig_insn,
+ struct instruction **new_insn)
+{
+ struct instruction *last_new_insn = NULL, *insn, *nop = NULL;
+ struct alt_group *orig_alt_group, *new_alt_group;
+ unsigned long dest_off;
+
+ orig_alt_group = orig_insn->alt_group;
+ if (!orig_alt_group) {
+ struct instruction *last_orig_insn = NULL;
+
+ orig_alt_group = malloc(sizeof(*orig_alt_group));
+ if (!orig_alt_group) {
+ WARN("malloc failed");
+ return -1;
+ }
+ orig_alt_group->cfi = calloc(special_alt->orig_len,
+ sizeof(struct cfi_state *));
+ if (!orig_alt_group->cfi) {
+ WARN("calloc failed");
+ return -1;
+ }
+
+ insn = orig_insn;
+ sec_for_each_insn_from(file, insn) {
+ if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
+ break;
+
+ insn->alt_group = orig_alt_group;
+ last_orig_insn = insn;
+ }
+ orig_alt_group->orig_group = NULL;
+ orig_alt_group->first_insn = orig_insn;
+ orig_alt_group->last_insn = last_orig_insn;
+ orig_alt_group->nop = NULL;
+ } else {
+ if (orig_alt_group->last_insn->offset + orig_alt_group->last_insn->len -
+ orig_alt_group->first_insn->offset != special_alt->orig_len) {
+ WARN_INSN(orig_insn, "weirdly overlapping alternative! %ld != %d",
+ orig_alt_group->last_insn->offset +
+ orig_alt_group->last_insn->len -
+ orig_alt_group->first_insn->offset,
+ special_alt->orig_len);
+ return -1;
+ }
+ }
+
+ new_alt_group = malloc(sizeof(*new_alt_group));
+ if (!new_alt_group) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ if (special_alt->new_len < special_alt->orig_len) {
+ /*
+ * Insert a fake nop at the end to make the replacement
+ * alt_group the same size as the original. This is needed to
+ * allow propagate_alt_cfi() to do its magic. When the last
+ * instruction affects the stack, the instruction after it (the
+ * nop) will propagate the new state to the shared CFI array.
+ */
+ nop = malloc(sizeof(*nop));
+ if (!nop) {
+ WARN("malloc failed");
+ return -1;
+ }
+ memset(nop, 0, sizeof(*nop));
+
+ nop->sec = special_alt->new_sec;
+ nop->offset = special_alt->new_off + special_alt->new_len;
+ nop->len = special_alt->orig_len - special_alt->new_len;
+ nop->type = INSN_NOP;
+ nop->sym = orig_insn->sym;
+ nop->alt_group = new_alt_group;
+ nop->ignore = orig_insn->ignore_alts;
+ }
+
+ if (!special_alt->new_len) {
+ *new_insn = nop;
+ goto end;
+ }
+
+ insn = *new_insn;
+ sec_for_each_insn_from(file, insn) {
+ struct reloc *alt_reloc;
+
+ if (insn->offset >= special_alt->new_off + special_alt->new_len)
+ break;
+
+ last_new_insn = insn;
+
+ insn->ignore = orig_insn->ignore_alts;
+ insn->sym = orig_insn->sym;
+ insn->alt_group = new_alt_group;
+
+ /*
+ * Since alternative replacement code is copy/pasted by the
+ * kernel after applying relocations, generally such code can't
+ * have relative-address relocation references to outside the
+ * .altinstr_replacement section, unless the arch's
+ * alternatives code can adjust the relative offsets
+ * accordingly.
+ */
+ alt_reloc = insn_reloc(file, insn);
+ if (alt_reloc && arch_pc_relative_reloc(alt_reloc) &&
+ !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
+
+ WARN_INSN(insn, "unsupported relocation in alternatives section");
+ return -1;
+ }
+
+ if (!is_static_jump(insn))
+ continue;
+
+ if (!insn->immediate)
+ continue;
+
+ dest_off = arch_jump_destination(insn);
+ if (dest_off == special_alt->new_off + special_alt->new_len) {
+ insn->jump_dest = next_insn_same_sec(file, orig_alt_group->last_insn);
+ if (!insn->jump_dest) {
+ WARN_INSN(insn, "can't find alternative jump destination");
+ return -1;
+ }
+ }
+ }
+
+ if (!last_new_insn) {
+ WARN_FUNC("can't find last new alternative instruction",
+ special_alt->new_sec, special_alt->new_off);
+ return -1;
+ }
+
+end:
+ new_alt_group->orig_group = orig_alt_group;
+ new_alt_group->first_insn = *new_insn;
+ new_alt_group->last_insn = last_new_insn;
+ new_alt_group->nop = nop;
+ new_alt_group->cfi = orig_alt_group->cfi;
+ return 0;
+}
+
+/*
+ * A jump table entry can either convert a nop to a jump or a jump to a nop.
+ * If the original instruction is a jump, make the alt entry an effective nop
+ * by just skipping the original instruction.
+ */
+static int handle_jump_alt(struct objtool_file *file,
+ struct special_alt *special_alt,
+ struct instruction *orig_insn,
+ struct instruction **new_insn)
+{
+ if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
+ orig_insn->type != INSN_NOP) {
+
+ WARN_INSN(orig_insn, "unsupported instruction at jump label");
+ return -1;
+ }
+
+ if (opts.hack_jump_label && special_alt->key_addend & 2) {
+ struct reloc *reloc = insn_reloc(file, orig_insn);
+
+ if (reloc)
+ set_reloc_type(file->elf, reloc, R_NONE);
+ elf_write_insn(file->elf, orig_insn->sec,
+ orig_insn->offset, orig_insn->len,
+ arch_nop_insn(orig_insn->len));
+ orig_insn->type = INSN_NOP;
+ }
+
+ if (orig_insn->type == INSN_NOP) {
+ if (orig_insn->len == 2)
+ file->jl_nop_short++;
+ else
+ file->jl_nop_long++;
+
+ return 0;
+ }
+
+ if (orig_insn->len == 2)
+ file->jl_short++;
+ else
+ file->jl_long++;
+
+ *new_insn = next_insn_same_sec(file, orig_insn);
+ return 0;
+}
+
+/*
+ * Read all the special sections which have alternate instructions which can be
+ * patched in or redirected to at runtime. Each instruction having alternate
+ * instruction(s) has them added to its insn->alts list, which will be
+ * traversed in validate_branch().
+ */
+static int add_special_section_alts(struct objtool_file *file)
+{
+ struct list_head special_alts;
+ struct instruction *orig_insn, *new_insn;
+ struct special_alt *special_alt, *tmp;
+ struct alternative *alt;
+ int ret;
+
+ ret = special_get_alts(file->elf, &special_alts);
+ if (ret)
+ return ret;
+
+ list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
+
+ orig_insn = find_insn(file, special_alt->orig_sec,
+ special_alt->orig_off);
+ if (!orig_insn) {
+ WARN_FUNC("special: can't find orig instruction",
+ special_alt->orig_sec, special_alt->orig_off);
+ ret = -1;
+ goto out;
+ }
+
+ new_insn = NULL;
+ if (!special_alt->group || special_alt->new_len) {
+ new_insn = find_insn(file, special_alt->new_sec,
+ special_alt->new_off);
+ if (!new_insn) {
+ WARN_FUNC("special: can't find new instruction",
+ special_alt->new_sec,
+ special_alt->new_off);
+ ret = -1;
+ goto out;
+ }
+ }
+
+ if (special_alt->group) {
+ if (!special_alt->orig_len) {
+ WARN_INSN(orig_insn, "empty alternative entry");
+ continue;
+ }
+
+ ret = handle_group_alt(file, special_alt, orig_insn,
+ &new_insn);
+ if (ret)
+ goto out;
+ } else if (special_alt->jump_or_nop) {
+ ret = handle_jump_alt(file, special_alt, orig_insn,
+ &new_insn);
+ if (ret)
+ goto out;
+ }
+
+ alt = malloc(sizeof(*alt));
+ if (!alt) {
+ WARN("malloc failed");
+ ret = -1;
+ goto out;
+ }
+
+ alt->insn = new_insn;
+ alt->skip_orig = special_alt->skip_orig;
+ orig_insn->ignore_alts |= special_alt->skip_alt;
+ alt->next = orig_insn->alts;
+ orig_insn->alts = alt;
+
+ list_del(&special_alt->list);
+ free(special_alt);
+ }
+
+ if (opts.stats) {
+ printf("jl\\\tNOP\tJMP\n");
+ printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
+ printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
+ }
+
+out:
+ return ret;
+}
+
+static int add_jump_table(struct objtool_file *file, struct instruction *insn,
+ struct reloc *next_table)
+{
+ struct symbol *pfunc = insn_func(insn)->pfunc;
+ struct reloc *table = insn_jump_table(insn);
+ struct instruction *dest_insn;
+ unsigned int prev_offset = 0;
+ struct reloc *reloc = table;
+ struct alternative *alt;
+
+ /*
+ * Each @reloc is a switch table relocation which points to the target
+ * instruction.
+ */
+ for_each_reloc_from(table->sec, reloc) {
+
+ /* Check for the end of the table: */
+ if (reloc != table && reloc == next_table)
+ break;
+
+ /* Make sure the table entries are consecutive: */
+ if (prev_offset && reloc_offset(reloc) != prev_offset + 8)
+ break;
+
+ /* Detect function pointers from contiguous objects: */
+ if (reloc->sym->sec == pfunc->sec &&
+ reloc_addend(reloc) == pfunc->offset)
+ break;
+
+ dest_insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!dest_insn)
+ break;
+
+ /* Make sure the destination is in the same function: */
+ if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)
+ break;
+
+ alt = malloc(sizeof(*alt));
+ if (!alt) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ alt->insn = dest_insn;
+ alt->next = insn->alts;
+ insn->alts = alt;
+ prev_offset = reloc_offset(reloc);
+ }
+
+ if (!prev_offset) {
+ WARN_INSN(insn, "can't find switch jump table");
+ return -1;
+ }
+
+ return 0;
+}
+
+/*
+ * find_jump_table() - Given a dynamic jump, find the switch jump table
+ * associated with it.
+ */
+static struct reloc *find_jump_table(struct objtool_file *file,
+ struct symbol *func,
+ struct instruction *insn)
+{
+ struct reloc *table_reloc;
+ struct instruction *dest_insn, *orig_insn = insn;
+
+ /*
+ * Backward search using the @first_jump_src links, these help avoid
+ * much of the 'in between' code. Which avoids us getting confused by
+ * it.
+ */
+ for (;
+ insn && insn_func(insn) && insn_func(insn)->pfunc == func;
+ insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
+
+ if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
+ break;
+
+ /* allow small jumps within the range */
+ if (insn->type == INSN_JUMP_UNCONDITIONAL &&
+ insn->jump_dest &&
+ (insn->jump_dest->offset <= insn->offset ||
+ insn->jump_dest->offset > orig_insn->offset))
+ break;
+
+ table_reloc = arch_find_switch_table(file, insn);
+ if (!table_reloc)
+ continue;
+ dest_insn = find_insn(file, table_reloc->sym->sec, reloc_addend(table_reloc));
+ if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
+ continue;
+
+ return table_reloc;
+ }
+
+ return NULL;
+}
+
+/*
+ * First pass: Mark the head of each jump table so that in the next pass,
+ * we know when a given jump table ends and the next one starts.
+ */
+static void mark_func_jump_tables(struct objtool_file *file,
+ struct symbol *func)
+{
+ struct instruction *insn, *last = NULL;
+ struct reloc *reloc;
+
+ func_for_each_insn(file, func, insn) {
+ if (!last)
+ last = insn;
+
+ /*
+ * Store back-pointers for unconditional forward jumps such
+ * that find_jump_table() can back-track using those and
+ * avoid some potentially confusing code.
+ */
+ if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
+ insn->offset > last->offset &&
+ insn->jump_dest->offset > insn->offset &&
+ !insn->jump_dest->first_jump_src) {
+
+ insn->jump_dest->first_jump_src = insn;
+ last = insn->jump_dest;
+ }
+
+ if (insn->type != INSN_JUMP_DYNAMIC)
+ continue;
+
+ reloc = find_jump_table(file, func, insn);
+ if (reloc)
+ insn->_jump_table = reloc;
+ }
+}
+
+static int add_func_jump_tables(struct objtool_file *file,
+ struct symbol *func)
+{
+ struct instruction *insn, *insn_t1 = NULL, *insn_t2;
+ int ret = 0;
+
+ func_for_each_insn(file, func, insn) {
+ if (!insn_jump_table(insn))
+ continue;
+
+ if (!insn_t1) {
+ insn_t1 = insn;
+ continue;
+ }
+
+ insn_t2 = insn;
+
+ ret = add_jump_table(file, insn_t1, insn_jump_table(insn_t2));
+ if (ret)
+ return ret;
+
+ insn_t1 = insn_t2;
+ }
+
+ if (insn_t1)
+ ret = add_jump_table(file, insn_t1, NULL);
+
+ return ret;
+}
+
+/*
+ * For some switch statements, gcc generates a jump table in the .rodata
+ * section which contains a list of addresses within the function to jump to.
+ * This finds these jump tables and adds them to the insn->alts lists.
+ */
+static int add_jump_table_alts(struct objtool_file *file)
+{
+ struct symbol *func;
+ int ret;
+
+ if (!file->rodata)
+ return 0;
+
+ for_each_sym(file, func) {
+ if (func->type != STT_FUNC)
+ continue;
+
+ mark_func_jump_tables(file, func);
+ ret = add_func_jump_tables(file, func);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static void set_func_state(struct cfi_state *state)
+{
+ state->cfa = initial_func_cfi.cfa;
+ memcpy(&state->regs, &initial_func_cfi.regs,
+ CFI_NUM_REGS * sizeof(struct cfi_reg));
+ state->stack_size = initial_func_cfi.cfa.offset;
+ state->type = UNWIND_HINT_TYPE_CALL;
+}
+
+static int read_unwind_hints(struct objtool_file *file)
+{
+ struct cfi_state cfi = init_cfi;
+ struct section *sec;
+ struct unwind_hint *hint;
+ struct instruction *insn;
+ struct reloc *reloc;
+ int i;
+
+ sec = find_section_by_name(file->elf, ".discard.unwind_hints");
+ if (!sec)
+ return 0;
+
+ if (!sec->rsec) {
+ WARN("missing .rela.discard.unwind_hints section");
+ return -1;
+ }
+
+ if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
+ WARN("struct unwind_hint size mismatch");
+ return -1;
+ }
+
+ file->hints = true;
+
+ for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
+ hint = (struct unwind_hint *)sec->data->d_buf + i;
+
+ reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
+ if (!reloc) {
+ WARN("can't find reloc for unwind_hints[%d]", i);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("can't find insn for unwind_hints[%d]", i);
+ return -1;
+ }
+
+ insn->hint = true;
+
+ if (hint->type == UNWIND_HINT_TYPE_UNDEFINED) {
+ insn->cfi = &force_undefined_cfi;
+ continue;
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_SAVE) {
+ insn->hint = false;
+ insn->save = true;
+ continue;
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
+ insn->restore = true;
+ continue;
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
+ struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
+
+ if (sym && sym->bind == STB_GLOBAL) {
+ if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
+ WARN_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
+ }
+ }
+ }
+
+ if (hint->type == UNWIND_HINT_TYPE_FUNC) {
+ insn->cfi = &func_cfi;
+ continue;
+ }
+
+ if (insn->cfi)
+ cfi = *(insn->cfi);
+
+ if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
+ WARN_INSN(insn, "unsupported unwind_hint sp base reg %d", hint->sp_reg);
+ return -1;
+ }
+
+ cfi.cfa.offset = bswap_if_needed(file->elf, hint->sp_offset);
+ cfi.type = hint->type;
+ cfi.signal = hint->signal;
+
+ insn->cfi = cfi_hash_find_or_add(&cfi);
+ }
+
+ return 0;
+}
+
+static int read_noendbr_hints(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *rsec;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.noendbr");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ insn = find_insn(file, reloc->sym->sec,
+ reloc->sym->offset + reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.noendbr entry");
+ return -1;
+ }
+
+ insn->noendbr = 1;
+ }
+
+ return 0;
+}
+
+static int read_retpoline_hints(struct objtool_file *file)
+{
+ struct section *rsec;
+ struct instruction *insn;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.retpoline_safe entry");
+ return -1;
+ }
+
+ if (insn->type != INSN_JUMP_DYNAMIC &&
+ insn->type != INSN_CALL_DYNAMIC &&
+ insn->type != INSN_RETURN &&
+ insn->type != INSN_NOP) {
+ WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
+ return -1;
+ }
+
+ insn->retpoline_safe = true;
+ }
+
+ return 0;
+}
+
+static int read_instr_hints(struct objtool_file *file)
+{
+ struct section *rsec;
+ struct instruction *insn;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.instr_end");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.instr_end entry");
+ return -1;
+ }
+
+ insn->instr--;
+ }
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.instr_begin entry");
+ return -1;
+ }
+
+ insn->instr++;
+ }
+
+ return 0;
+}
+
+static int read_validate_unret_hints(struct objtool_file *file)
+{
+ struct section *rsec;
+ struct instruction *insn;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.validate_unret");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s", rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.instr_end entry");
+ return -1;
+ }
+ insn->unret = 1;
+ }
+
+ return 0;
+}
+
+
+static int read_intra_function_calls(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *rsec;
+ struct reloc *reloc;
+
+ rsec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
+ if (!rsec)
+ return 0;
+
+ for_each_reloc(rsec, reloc) {
+ unsigned long dest_off;
+
+ if (reloc->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s",
+ rsec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
+ if (!insn) {
+ WARN("bad .discard.intra_function_call entry");
+ return -1;
+ }
+
+ if (insn->type != INSN_CALL) {
+ WARN_INSN(insn, "intra_function_call not a direct call");
+ return -1;
+ }
+
+ /*
+ * Treat intra-function CALLs as JMPs, but with a stack_op.
+ * See add_call_destinations(), which strips stack_ops from
+ * normal CALLs.
+ */
+ insn->type = INSN_JUMP_UNCONDITIONAL;
+
+ dest_off = arch_jump_destination(insn);
+ insn->jump_dest = find_insn(file, insn->sec, dest_off);
+ if (!insn->jump_dest) {
+ WARN_INSN(insn, "can't find call dest at %s+0x%lx",
+ insn->sec->name, dest_off);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Return true if name matches an instrumentation function, where calls to that
+ * function from noinstr code can safely be removed, but compilers won't do so.
+ */
+static bool is_profiling_func(const char *name)
+{
+ /*
+ * Many compilers cannot disable KCOV with a function attribute.
+ */
+ if (!strncmp(name, "__sanitizer_cov_", 16))
+ return true;
+
+ /*
+ * Some compilers currently do not remove __tsan_func_entry/exit nor
+ * __tsan_atomic_signal_fence (used for barrier instrumentation) with
+ * the __no_sanitize_thread attribute, remove them. Once the kernel's
+ * minimum Clang version is 14.0, this can be removed.
+ */
+ if (!strncmp(name, "__tsan_func_", 12) ||
+ !strcmp(name, "__tsan_atomic_signal_fence"))
+ return true;
+
+ return false;
+}
+
+static int classify_symbols(struct objtool_file *file)
+{
+ struct symbol *func;
+
+ for_each_sym(file, func) {
+ if (func->bind != STB_GLOBAL)
+ continue;
+
+ if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
+ strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
+ func->static_call_tramp = true;
+
+ if (arch_is_retpoline(func))
+ func->retpoline_thunk = true;
+
+ if (arch_is_rethunk(func))
+ func->return_thunk = true;
+
+ if (arch_is_embedded_insn(func))
+ func->embedded_insn = true;
+
+ if (arch_ftrace_match(func->name))
+ func->fentry = true;
+
+ if (is_profiling_func(func->name))
+ func->profiling_func = true;
+ }
+
+ return 0;
+}
+
+static void mark_rodata(struct objtool_file *file)
+{
+ struct section *sec;
+ bool found = false;
+
+ /*
+ * Search for the following rodata sections, each of which can
+ * potentially contain jump tables:
+ *
+ * - .rodata: can contain GCC switch tables
+ * - .rodata.<func>: same, if -fdata-sections is being used
+ * - .rodata..c_jump_table: contains C annotated jump tables
+ *
+ * .rodata.str1.* sections are ignored; they don't contain jump tables.
+ */
+ for_each_sec(file, sec) {
+ if (!strncmp(sec->name, ".rodata", 7) &&
+ !strstr(sec->name, ".str1.")) {
+ sec->rodata = true;
+ found = true;
+ }
+ }
+
+ file->rodata = found;
+}
+
+static int decode_sections(struct objtool_file *file)
+{
+ int ret;
+
+ mark_rodata(file);
+
+ ret = init_pv_ops(file);
+ if (ret)
+ return ret;
+
+ /*
+ * Must be before add_{jump_call}_destination.
+ */
+ ret = classify_symbols(file);
+ if (ret)
+ return ret;
+
+ ret = decode_instructions(file);
+ if (ret)
+ return ret;
+
+ add_ignores(file);
+ add_uaccess_safe(file);
+
+ ret = add_ignore_alternatives(file);
+ if (ret)
+ return ret;
+
+ /*
+ * Must be before read_unwind_hints() since that needs insn->noendbr.
+ */
+ ret = read_noendbr_hints(file);
+ if (ret)
+ return ret;
+
+ /*
+ * Must be before add_jump_destinations(), which depends on 'func'
+ * being set for alternatives, to enable proper sibling call detection.
+ */
+ if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
+ ret = add_special_section_alts(file);
+ if (ret)
+ return ret;
+ }
+
+ ret = add_jump_destinations(file);
+ if (ret)
+ return ret;
+
+ /*
+ * Must be before add_call_destination(); it changes INSN_CALL to
+ * INSN_JUMP.
+ */
+ ret = read_intra_function_calls(file);
+ if (ret)
+ return ret;
+
+ ret = add_call_destinations(file);
+ if (ret)
+ return ret;
+
+ /*
+ * Must be after add_call_destinations() such that it can override
+ * dead_end_function() marks.
+ */
+ ret = add_dead_ends(file);
+ if (ret)
+ return ret;
+
+ ret = add_jump_table_alts(file);
+ if (ret)
+ return ret;
+
+ ret = read_unwind_hints(file);
+ if (ret)
+ return ret;
+
+ ret = read_retpoline_hints(file);
+ if (ret)
+ return ret;
+
+ ret = read_instr_hints(file);
+ if (ret)
+ return ret;
+
+ ret = read_validate_unret_hints(file);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static bool is_special_call(struct instruction *insn)
+{
+ if (insn->type == INSN_CALL) {
+ struct symbol *dest = insn_call_dest(insn);
+
+ if (!dest)
+ return false;
+
+ if (dest->fentry || dest->embedded_insn)
+ return true;
+ }
+
+ return false;
+}
+
+static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
+{
+ struct cfi_state *cfi = &state->cfi;
+ int i;
+
+ if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
+ return true;
+
+ if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
+ return true;
+
+ if (cfi->stack_size != initial_func_cfi.cfa.offset)
+ return true;
+
+ for (i = 0; i < CFI_NUM_REGS; i++) {
+ if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
+ cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
+ return true;
+ }
+
+ return false;
+}
+
+static bool check_reg_frame_pos(const struct cfi_reg *reg,
+ int expected_offset)
+{
+ return reg->base == CFI_CFA &&
+ reg->offset == expected_offset;
+}
+
+static bool has_valid_stack_frame(struct insn_state *state)
+{
+ struct cfi_state *cfi = &state->cfi;
+
+ if (cfi->cfa.base == CFI_BP &&
+ check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
+ check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
+ return true;
+
+ if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
+ return true;
+
+ return false;
+}
+
+static int update_cfi_state_regs(struct instruction *insn,
+ struct cfi_state *cfi,
+ struct stack_op *op)
+{
+ struct cfi_reg *cfa = &cfi->cfa;
+
+ if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
+ return 0;
+
+ /* push */
+ if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
+ cfa->offset += 8;
+
+ /* pop */
+ if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
+ cfa->offset -= 8;
+
+ /* add immediate to sp */
+ if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
+ op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
+ cfa->offset -= op->src.offset;
+
+ return 0;
+}
+
+static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
+{
+ if (arch_callee_saved_reg(reg) &&
+ cfi->regs[reg].base == CFI_UNDEFINED) {
+ cfi->regs[reg].base = base;
+ cfi->regs[reg].offset = offset;
+ }
+}
+
+static void restore_reg(struct cfi_state *cfi, unsigned char reg)
+{
+ cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
+ cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
+}
+
+/*
+ * A note about DRAP stack alignment:
+ *
+ * GCC has the concept of a DRAP register, which is used to help keep track of
+ * the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
+ * register. The typical DRAP pattern is:
+ *
+ * 4c 8d 54 24 08 lea 0x8(%rsp),%r10
+ * 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
+ * 41 ff 72 f8 pushq -0x8(%r10)
+ * 55 push %rbp
+ * 48 89 e5 mov %rsp,%rbp
+ * (more pushes)
+ * 41 52 push %r10
+ * ...
+ * 41 5a pop %r10
+ * (more pops)
+ * 5d pop %rbp
+ * 49 8d 62 f8 lea -0x8(%r10),%rsp
+ * c3 retq
+ *
+ * There are some variations in the epilogues, like:
+ *
+ * 5b pop %rbx
+ * 41 5a pop %r10
+ * 41 5c pop %r12
+ * 41 5d pop %r13
+ * 41 5e pop %r14
+ * c9 leaveq
+ * 49 8d 62 f8 lea -0x8(%r10),%rsp
+ * c3 retq
+ *
+ * and:
+ *
+ * 4c 8b 55 e8 mov -0x18(%rbp),%r10
+ * 48 8b 5d e0 mov -0x20(%rbp),%rbx
+ * 4c 8b 65 f0 mov -0x10(%rbp),%r12
+ * 4c 8b 6d f8 mov -0x8(%rbp),%r13
+ * c9 leaveq
+ * 49 8d 62 f8 lea -0x8(%r10),%rsp
+ * c3 retq
+ *
+ * Sometimes r13 is used as the DRAP register, in which case it's saved and
+ * restored beforehand:
+ *
+ * 41 55 push %r13
+ * 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
+ * 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
+ * ...
+ * 49 8d 65 f0 lea -0x10(%r13),%rsp
+ * 41 5d pop %r13
+ * c3 retq
+ */
+static int update_cfi_state(struct instruction *insn,
+ struct instruction *next_insn,
+ struct cfi_state *cfi, struct stack_op *op)
+{
+ struct cfi_reg *cfa = &cfi->cfa;
+ struct cfi_reg *regs = cfi->regs;
+
+ /* ignore UNWIND_HINT_UNDEFINED regions */
+ if (cfi->force_undefined)
+ return 0;
+
+ /* stack operations don't make sense with an undefined CFA */
+ if (cfa->base == CFI_UNDEFINED) {
+ if (insn_func(insn)) {
+ WARN_INSN(insn, "undefined stack state");
+ return -1;
+ }
+ return 0;
+ }
+
+ if (cfi->type == UNWIND_HINT_TYPE_REGS ||
+ cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
+ return update_cfi_state_regs(insn, cfi, op);
+
+ switch (op->dest.type) {
+
+ case OP_DEST_REG:
+ switch (op->src.type) {
+
+ case OP_SRC_REG:
+ if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
+ cfa->base == CFI_SP &&
+ check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
+
+ /* mov %rsp, %rbp */
+ cfa->base = op->dest.reg;
+ cfi->bp_scratch = false;
+ }
+
+ else if (op->src.reg == CFI_SP &&
+ op->dest.reg == CFI_BP && cfi->drap) {
+
+ /* drap: mov %rsp, %rbp */
+ regs[CFI_BP].base = CFI_BP;
+ regs[CFI_BP].offset = -cfi->stack_size;
+ cfi->bp_scratch = false;
+ }
+
+ else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
+
+ /*
+ * mov %rsp, %reg
+ *
+ * This is needed for the rare case where GCC
+ * does:
+ *
+ * mov %rsp, %rax
+ * ...
+ * mov %rax, %rsp
+ */
+ cfi->vals[op->dest.reg].base = CFI_CFA;
+ cfi->vals[op->dest.reg].offset = -cfi->stack_size;
+ }
+
+ else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
+ (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
+
+ /*
+ * mov %rbp, %rsp
+ *
+ * Restore the original stack pointer (Clang).
+ */
+ cfi->stack_size = -cfi->regs[CFI_BP].offset;
+ }
+
+ else if (op->dest.reg == cfa->base) {
+
+ /* mov %reg, %rsp */
+ if (cfa->base == CFI_SP &&
+ cfi->vals[op->src.reg].base == CFI_CFA) {
+
+ /*
+ * This is needed for the rare case
+ * where GCC does something dumb like:
+ *
+ * lea 0x8(%rsp), %rcx
+ * ...
+ * mov %rcx, %rsp
+ */
+ cfa->offset = -cfi->vals[op->src.reg].offset;
+ cfi->stack_size = cfa->offset;
+
+ } else if (cfa->base == CFI_SP &&
+ cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
+ cfi->vals[op->src.reg].offset == cfa->offset) {
+
+ /*
+ * Stack swizzle:
+ *
+ * 1: mov %rsp, (%[tos])
+ * 2: mov %[tos], %rsp
+ * ...
+ * 3: pop %rsp
+ *
+ * Where:
+ *
+ * 1 - places a pointer to the previous
+ * stack at the Top-of-Stack of the
+ * new stack.
+ *
+ * 2 - switches to the new stack.
+ *
+ * 3 - pops the Top-of-Stack to restore
+ * the original stack.
+ *
+ * Note: we set base to SP_INDIRECT
+ * here and preserve offset. Therefore
+ * when the unwinder reaches ToS it
+ * will dereference SP and then add the
+ * offset to find the next frame, IOW:
+ * (%rsp) + offset.
+ */
+ cfa->base = CFI_SP_INDIRECT;
+
+ } else {
+ cfa->base = CFI_UNDEFINED;
+ cfa->offset = 0;
+ }
+ }
+
+ else if (op->dest.reg == CFI_SP &&
+ cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
+ cfi->vals[op->src.reg].offset == cfa->offset) {
+
+ /*
+ * The same stack swizzle case 2) as above. But
+ * because we can't change cfa->base, case 3)
+ * will become a regular POP. Pretend we're a
+ * PUSH so things don't go unbalanced.
+ */
+ cfi->stack_size += 8;
+ }
+
+
+ break;
+
+ case OP_SRC_ADD:
+ if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
+
+ /* add imm, %rsp */
+ cfi->stack_size -= op->src.offset;
+ if (cfa->base == CFI_SP)
+ cfa->offset -= op->src.offset;
+ break;
+ }
+
+ if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
+
+ /* lea disp(%rbp), %rsp */
+ cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
+ break;
+ }
+
+ if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
+
+ /* drap: lea disp(%rsp), %drap */
+ cfi->drap_reg = op->dest.reg;
+
+ /*
+ * lea disp(%rsp), %reg
+ *
+ * This is needed for the rare case where GCC
+ * does something dumb like:
+ *
+ * lea 0x8(%rsp), %rcx
+ * ...
+ * mov %rcx, %rsp
+ */
+ cfi->vals[op->dest.reg].base = CFI_CFA;
+ cfi->vals[op->dest.reg].offset = \
+ -cfi->stack_size + op->src.offset;
+
+ break;
+ }
+
+ if (cfi->drap && op->dest.reg == CFI_SP &&
+ op->src.reg == cfi->drap_reg) {
+
+ /* drap: lea disp(%drap), %rsp */
+ cfa->base = CFI_SP;
+ cfa->offset = cfi->stack_size = -op->src.offset;
+ cfi->drap_reg = CFI_UNDEFINED;
+ cfi->drap = false;
+ break;
+ }
+
+ if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
+ WARN_INSN(insn, "unsupported stack register modification");
+ return -1;
+ }
+
+ break;
+
+ case OP_SRC_AND:
+ if (op->dest.reg != CFI_SP ||
+ (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
+ (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
+ WARN_INSN(insn, "unsupported stack pointer realignment");
+ return -1;
+ }
+
+ if (cfi->drap_reg != CFI_UNDEFINED) {
+ /* drap: and imm, %rsp */
+ cfa->base = cfi->drap_reg;
+ cfa->offset = cfi->stack_size = 0;
+ cfi->drap = true;
+ }
+
+ /*
+ * Older versions of GCC (4.8ish) realign the stack
+ * without DRAP, with a frame pointer.
+ */
+
+ break;
+
+ case OP_SRC_POP:
+ case OP_SRC_POPF:
+ if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
+
+ /* pop %rsp; # restore from a stack swizzle */
+ cfa->base = CFI_SP;
+ break;
+ }
+
+ if (!cfi->drap && op->dest.reg == cfa->base) {
+
+ /* pop %rbp */
+ cfa->base = CFI_SP;
+ }
+
+ if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
+ op->dest.reg == cfi->drap_reg &&
+ cfi->drap_offset == -cfi->stack_size) {
+
+ /* drap: pop %drap */
+ cfa->base = cfi->drap_reg;
+ cfa->offset = 0;
+ cfi->drap_offset = -1;
+
+ } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
+
+ /* pop %reg */
+ restore_reg(cfi, op->dest.reg);
+ }
+
+ cfi->stack_size -= 8;
+ if (cfa->base == CFI_SP)
+ cfa->offset -= 8;
+
+ break;
+
+ case OP_SRC_REG_INDIRECT:
+ if (!cfi->drap && op->dest.reg == cfa->base &&
+ op->dest.reg == CFI_BP) {
+
+ /* mov disp(%rsp), %rbp */
+ cfa->base = CFI_SP;
+ cfa->offset = cfi->stack_size;
+ }
+
+ if (cfi->drap && op->src.reg == CFI_BP &&
+ op->src.offset == cfi->drap_offset) {
+
+ /* drap: mov disp(%rbp), %drap */
+ cfa->base = cfi->drap_reg;
+ cfa->offset = 0;
+ cfi->drap_offset = -1;
+ }
+
+ if (cfi->drap && op->src.reg == CFI_BP &&
+ op->src.offset == regs[op->dest.reg].offset) {
+
+ /* drap: mov disp(%rbp), %reg */
+ restore_reg(cfi, op->dest.reg);
+
+ } else if (op->src.reg == cfa->base &&
+ op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
+
+ /* mov disp(%rbp), %reg */
+ /* mov disp(%rsp), %reg */
+ restore_reg(cfi, op->dest.reg);
+
+ } else if (op->src.reg == CFI_SP &&
+ op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
+
+ /* mov disp(%rsp), %reg */
+ restore_reg(cfi, op->dest.reg);
+ }
+
+ break;
+
+ default:
+ WARN_INSN(insn, "unknown stack-related instruction");
+ return -1;
+ }
+
+ break;
+
+ case OP_DEST_PUSH:
+ case OP_DEST_PUSHF:
+ cfi->stack_size += 8;
+ if (cfa->base == CFI_SP)
+ cfa->offset += 8;
+
+ if (op->src.type != OP_SRC_REG)
+ break;
+
+ if (cfi->drap) {
+ if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
+
+ /* drap: push %drap */
+ cfa->base = CFI_BP_INDIRECT;
+ cfa->offset = -cfi->stack_size;
+
+ /* save drap so we know when to restore it */
+ cfi->drap_offset = -cfi->stack_size;
+
+ } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
+
+ /* drap: push %rbp */
+ cfi->stack_size = 0;
+
+ } else {
+
+ /* drap: push %reg */
+ save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
+ }
+
+ } else {
+
+ /* push %reg */
+ save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
+ }
+
+ /* detect when asm code uses rbp as a scratch register */
+ if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&
+ cfa->base != CFI_BP)
+ cfi->bp_scratch = true;
+ break;
+
+ case OP_DEST_REG_INDIRECT:
+
+ if (cfi->drap) {
+ if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
+
+ /* drap: mov %drap, disp(%rbp) */
+ cfa->base = CFI_BP_INDIRECT;
+ cfa->offset = op->dest.offset;
+
+ /* save drap offset so we know when to restore it */
+ cfi->drap_offset = op->dest.offset;
+ } else {
+
+ /* drap: mov reg, disp(%rbp) */
+ save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
+ }
+
+ } else if (op->dest.reg == cfa->base) {
+
+ /* mov reg, disp(%rbp) */
+ /* mov reg, disp(%rsp) */
+ save_reg(cfi, op->src.reg, CFI_CFA,
+ op->dest.offset - cfi->cfa.offset);
+
+ } else if (op->dest.reg == CFI_SP) {
+
+ /* mov reg, disp(%rsp) */
+ save_reg(cfi, op->src.reg, CFI_CFA,
+ op->dest.offset - cfi->stack_size);
+
+ } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
+
+ /* mov %rsp, (%reg); # setup a stack swizzle. */
+ cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
+ cfi->vals[op->dest.reg].offset = cfa->offset;
+ }
+
+ break;
+
+ case OP_DEST_MEM:
+ if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
+ WARN_INSN(insn, "unknown stack-related memory operation");
+ return -1;
+ }
+
+ /* pop mem */
+ cfi->stack_size -= 8;
+ if (cfa->base == CFI_SP)
+ cfa->offset -= 8;
+
+ break;
+
+ default:
+ WARN_INSN(insn, "unknown stack-related instruction");
+ return -1;
+ }
+
+ return 0;
+}
+
+/*
+ * The stack layouts of alternatives instructions can sometimes diverge when
+ * they have stack modifications. That's fine as long as the potential stack
+ * layouts don't conflict at any given potential instruction boundary.
+ *
+ * Flatten the CFIs of the different alternative code streams (both original
+ * and replacement) into a single shared CFI array which can be used to detect
+ * conflicts and nicely feed a linear array of ORC entries to the unwinder.
+ */
+static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
+{
+ struct cfi_state **alt_cfi;
+ int group_off;
+
+ if (!insn->alt_group)
+ return 0;
+
+ if (!insn->cfi) {
+ WARN("CFI missing");
+ return -1;
+ }
+
+ alt_cfi = insn->alt_group->cfi;
+ group_off = insn->offset - insn->alt_group->first_insn->offset;
+
+ if (!alt_cfi[group_off]) {
+ alt_cfi[group_off] = insn->cfi;
+ } else {
+ if (cficmp(alt_cfi[group_off], insn->cfi)) {
+ struct alt_group *orig_group = insn->alt_group->orig_group ?: insn->alt_group;
+ struct instruction *orig = orig_group->first_insn;
+ char *where = offstr(insn->sec, insn->offset);
+ WARN_INSN(orig, "stack layout conflict in alternatives: %s", where);
+ free(where);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+static int handle_insn_ops(struct instruction *insn,
+ struct instruction *next_insn,
+ struct insn_state *state)
+{
+ struct stack_op *op;
+
+ for (op = insn->stack_ops; op; op = op->next) {
+
+ if (update_cfi_state(insn, next_insn, &state->cfi, op))
+ return 1;
+
+ if (!insn->alt_group)
+ continue;
+
+ if (op->dest.type == OP_DEST_PUSHF) {
+ if (!state->uaccess_stack) {
+ state->uaccess_stack = 1;
+ } else if (state->uaccess_stack >> 31) {
+ WARN_INSN(insn, "PUSHF stack exhausted");
+ return 1;
+ }
+ state->uaccess_stack <<= 1;
+ state->uaccess_stack |= state->uaccess;
+ }
+
+ if (op->src.type == OP_SRC_POPF) {
+ if (state->uaccess_stack) {
+ state->uaccess = state->uaccess_stack & 1;
+ state->uaccess_stack >>= 1;
+ if (state->uaccess_stack == 1)
+ state->uaccess_stack = 0;
+ }
+ }
+ }
+
+ return 0;
+}
+
+static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
+{
+ struct cfi_state *cfi1 = insn->cfi;
+ int i;
+
+ if (!cfi1) {
+ WARN("CFI missing");
+ return false;
+ }
+
+ if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
+
+ WARN_INSN(insn, "stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
+ cfi1->cfa.base, cfi1->cfa.offset,
+ cfi2->cfa.base, cfi2->cfa.offset);
+
+ } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
+ for (i = 0; i < CFI_NUM_REGS; i++) {
+ if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
+ sizeof(struct cfi_reg)))
+ continue;
+
+ WARN_INSN(insn, "stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
+ i, cfi1->regs[i].base, cfi1->regs[i].offset,
+ i, cfi2->regs[i].base, cfi2->regs[i].offset);
+ break;
+ }
+
+ } else if (cfi1->type != cfi2->type) {
+
+ WARN_INSN(insn, "stack state mismatch: type1=%d type2=%d",
+ cfi1->type, cfi2->type);
+
+ } else if (cfi1->drap != cfi2->drap ||
+ (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
+ (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
+
+ WARN_INSN(insn, "stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
+ cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
+ cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
+
+ } else
+ return true;
+
+ return false;
+}
+
+static inline bool func_uaccess_safe(struct symbol *func)
+{
+ if (func)
+ return func->uaccess_safe;
+
+ return false;
+}
+
+static inline const char *call_dest_name(struct instruction *insn)
+{
+ static char pvname[19];
+ struct reloc *reloc;
+ int idx;
+
+ if (insn_call_dest(insn))
+ return insn_call_dest(insn)->name;
+
+ reloc = insn_reloc(NULL, insn);
+ if (reloc && !strcmp(reloc->sym->name, "pv_ops")) {
+ idx = (reloc_addend(reloc) / sizeof(void *));
+ snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
+ return pvname;
+ }
+
+ return "{dynamic}";
+}
+
+static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
+{
+ struct symbol *target;
+ struct reloc *reloc;
+ int idx;
+
+ reloc = insn_reloc(file, insn);
+ if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
+ return false;
+
+ idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
+
+ if (file->pv_ops[idx].clean)
+ return true;
+
+ file->pv_ops[idx].clean = true;
+
+ list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
+ if (!target->sec->noinstr) {
+ WARN("pv_ops[%d]: %s", idx, target->name);
+ file->pv_ops[idx].clean = false;
+ }
+ }
+
+ return file->pv_ops[idx].clean;
+}
+
+static inline bool noinstr_call_dest(struct objtool_file *file,
+ struct instruction *insn,
+ struct symbol *func)
+{
+ /*
+ * We can't deal with indirect function calls at present;
+ * assume they're instrumented.
+ */
+ if (!func) {
+ if (file->pv_ops)
+ return pv_call_dest(file, insn);
+
+ return false;
+ }
+
+ /*
+ * If the symbol is from a noinstr section; we good.
+ */
+ if (func->sec->noinstr)
+ return true;
+
+ /*
+ * If the symbol is a static_call trampoline, we can't tell.
+ */
+ if (func->static_call_tramp)
+ return true;
+
+ /*
+ * The __ubsan_handle_*() calls are like WARN(), they only happen when
+ * something 'BAD' happened. At the risk of taking the machine down,
+ * let them proceed to get the message out.
+ */
+ if (!strncmp(func->name, "__ubsan_handle_", 15))
+ return true;
+
+ return false;
+}
+
+static int validate_call(struct objtool_file *file,
+ struct instruction *insn,
+ struct insn_state *state)
+{
+ if (state->noinstr && state->instr <= 0 &&
+ !noinstr_call_dest(file, insn, insn_call_dest(insn))) {
+ WARN_INSN(insn, "call to %s() leaves .noinstr.text section", call_dest_name(insn));
+ return 1;
+ }
+
+ if (state->uaccess && !func_uaccess_safe(insn_call_dest(insn))) {
+ WARN_INSN(insn, "call to %s() with UACCESS enabled", call_dest_name(insn));
+ return 1;
+ }
+
+ if (state->df) {
+ WARN_INSN(insn, "call to %s() with DF set", call_dest_name(insn));
+ return 1;
+ }
+
+ return 0;
+}
+
+static int validate_sibling_call(struct objtool_file *file,
+ struct instruction *insn,
+ struct insn_state *state)
+{
+ if (insn_func(insn) && has_modified_stack_frame(insn, state)) {
+ WARN_INSN(insn, "sibling call from callable instruction with modified stack frame");
+ return 1;
+ }
+
+ return validate_call(file, insn, state);
+}
+
+static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
+{
+ if (state->noinstr && state->instr > 0) {
+ WARN_INSN(insn, "return with instrumentation enabled");
+ return 1;
+ }
+
+ if (state->uaccess && !func_uaccess_safe(func)) {
+ WARN_INSN(insn, "return with UACCESS enabled");
+ return 1;
+ }
+
+ if (!state->uaccess && func_uaccess_safe(func)) {
+ WARN_INSN(insn, "return with UACCESS disabled from a UACCESS-safe function");
+ return 1;
+ }
+
+ if (state->df) {
+ WARN_INSN(insn, "return with DF set");
+ return 1;
+ }
+
+ if (func && has_modified_stack_frame(insn, state)) {
+ WARN_INSN(insn, "return with modified stack frame");
+ return 1;
+ }
+
+ if (state->cfi.bp_scratch) {
+ WARN_INSN(insn, "BP used as a scratch register");
+ return 1;
+ }
+
+ return 0;
+}
+
+static struct instruction *next_insn_to_validate(struct objtool_file *file,
+ struct instruction *insn)
+{
+ struct alt_group *alt_group = insn->alt_group;
+
+ /*
+ * Simulate the fact that alternatives are patched in-place. When the
+ * end of a replacement alt_group is reached, redirect objtool flow to
+ * the end of the original alt_group.
+ *
+ * insn->alts->insn -> alt_group->first_insn
+ * ...
+ * alt_group->last_insn
+ * [alt_group->nop] -> next(orig_group->last_insn)
+ */
+ if (alt_group) {
+ if (alt_group->nop) {
+ /* ->nop implies ->orig_group */
+ if (insn == alt_group->last_insn)
+ return alt_group->nop;
+ if (insn == alt_group->nop)
+ goto next_orig;
+ }
+ if (insn == alt_group->last_insn && alt_group->orig_group)
+ goto next_orig;
+ }
+
+ return next_insn_same_sec(file, insn);
+
+next_orig:
+ return next_insn_same_sec(file, alt_group->orig_group->last_insn);
+}
+
+/*
+ * Follow the branch starting at the given instruction, and recursively follow
+ * any other branches (jumps). Meanwhile, track the frame pointer state at
+ * each instruction and validate all the rules described in
+ * tools/objtool/Documentation/objtool.txt.
+ */
+static int validate_branch(struct objtool_file *file, struct symbol *func,
+ struct instruction *insn, struct insn_state state)
+{
+ struct alternative *alt;
+ struct instruction *next_insn, *prev_insn = NULL;
+ struct section *sec;
+ u8 visited;
+ int ret;
+
+ sec = insn->sec;
+
+ while (1) {
+ next_insn = next_insn_to_validate(file, insn);
+
+ if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
+ /* Ignore KCFI type preambles, which always fall through */
+ if (!strncmp(func->name, "__cfi_", 6) ||
+ !strncmp(func->name, "__pfx_", 6))
+ return 0;
+
+ WARN("%s() falls through to next function %s()",
+ func->name, insn_func(insn)->name);
+ return 1;
+ }
+
+ if (func && insn->ignore) {
+ WARN_INSN(insn, "BUG: why am I validating an ignored function?");
+ return 1;
+ }
+
+ visited = VISITED_BRANCH << state.uaccess;
+ if (insn->visited & VISITED_BRANCH_MASK) {
+ if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
+ return 1;
+
+ if (insn->visited & visited)
+ return 0;
+ } else {
+ nr_insns_visited++;
+ }
+
+ if (state.noinstr)
+ state.instr += insn->instr;
+
+ if (insn->hint) {
+ if (insn->restore) {
+ struct instruction *save_insn, *i;
+
+ i = insn;
+ save_insn = NULL;
+
+ sym_for_each_insn_continue_reverse(file, func, i) {
+ if (i->save) {
+ save_insn = i;
+ break;
+ }
+ }
+
+ if (!save_insn) {
+ WARN_INSN(insn, "no corresponding CFI save for CFI restore");
+ return 1;
+ }
+
+ if (!save_insn->visited) {
+ WARN_INSN(insn, "objtool isn't smart enough to handle this CFI save/restore combo");
+ return 1;
+ }
+
+ insn->cfi = save_insn->cfi;
+ nr_cfi_reused++;
+ }
+
+ state.cfi = *insn->cfi;
+ } else {
+ /* XXX track if we actually changed state.cfi */
+
+ if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
+ insn->cfi = prev_insn->cfi;
+ nr_cfi_reused++;
+ } else {
+ insn->cfi = cfi_hash_find_or_add(&state.cfi);
+ }
+ }
+
+ insn->visited |= visited;
+
+ if (propagate_alt_cfi(file, insn))
+ return 1;
+
+ if (!insn->ignore_alts && insn->alts) {
+ bool skip_orig = false;
+
+ for (alt = insn->alts; alt; alt = alt->next) {
+ if (alt->skip_orig)
+ skip_orig = true;
+
+ ret = validate_branch(file, func, alt->insn, state);
+ if (ret) {
+ BT_INSN(insn, "(alt)");
+ return ret;
+ }
+ }
+
+ if (skip_orig)
+ return 0;
+ }
+
+ if (handle_insn_ops(insn, next_insn, &state))
+ return 1;
+
+ switch (insn->type) {
+
+ case INSN_RETURN:
+ return validate_return(func, insn, &state);
+
+ case INSN_CALL:
+ case INSN_CALL_DYNAMIC:
+ ret = validate_call(file, insn, &state);
+ if (ret)
+ return ret;
+
+ if (opts.stackval && func && !is_special_call(insn) &&
+ !has_valid_stack_frame(&state)) {
+ WARN_INSN(insn, "call without frame pointer save/setup");
+ return 1;
+ }
+
+ if (insn->dead_end)
+ return 0;
+
+ break;
+
+ case INSN_JUMP_CONDITIONAL:
+ case INSN_JUMP_UNCONDITIONAL:
+ if (is_sibling_call(insn)) {
+ ret = validate_sibling_call(file, insn, &state);
+ if (ret)
+ return ret;
+
+ } else if (insn->jump_dest) {
+ ret = validate_branch(file, func,
+ insn->jump_dest, state);
+ if (ret) {
+ BT_INSN(insn, "(branch)");
+ return ret;
+ }
+ }
+
+ if (insn->type == INSN_JUMP_UNCONDITIONAL)
+ return 0;
+
+ break;
+
+ case INSN_JUMP_DYNAMIC:
+ case INSN_JUMP_DYNAMIC_CONDITIONAL:
+ if (is_sibling_call(insn)) {
+ ret = validate_sibling_call(file, insn, &state);
+ if (ret)
+ return ret;
+ }
+
+ if (insn->type == INSN_JUMP_DYNAMIC)
+ return 0;
+
+ break;
+
+ case INSN_CONTEXT_SWITCH:
+ if (func && (!next_insn || !next_insn->hint)) {
+ WARN_INSN(insn, "unsupported instruction in callable function");
+ return 1;
+ }
+ return 0;
+
+ case INSN_STAC:
+ if (state.uaccess) {
+ WARN_INSN(insn, "recursive UACCESS enable");
+ return 1;
+ }
+
+ state.uaccess = true;
+ break;
+
+ case INSN_CLAC:
+ if (!state.uaccess && func) {
+ WARN_INSN(insn, "redundant UACCESS disable");
+ return 1;
+ }
+
+ if (func_uaccess_safe(func) && !state.uaccess_stack) {
+ WARN_INSN(insn, "UACCESS-safe disables UACCESS");
+ return 1;
+ }
+
+ state.uaccess = false;
+ break;
+
+ case INSN_STD:
+ if (state.df) {
+ WARN_INSN(insn, "recursive STD");
+ return 1;
+ }
+
+ state.df = true;
+ break;
+
+ case INSN_CLD:
+ if (!state.df && func) {
+ WARN_INSN(insn, "redundant CLD");
+ return 1;
+ }
+
+ state.df = false;
+ break;
+
+ default:
+ break;
+ }
+
+ if (insn->dead_end)
+ return 0;
+
+ if (!next_insn) {
+ if (state.cfi.cfa.base == CFI_UNDEFINED)
+ return 0;
+ WARN("%s: unexpected end of section", sec->name);
+ return 1;
+ }
+
+ prev_insn = insn;
+ insn = next_insn;
+ }
+
+ return 0;
+}
+
+static int validate_unwind_hint(struct objtool_file *file,
+ struct instruction *insn,
+ struct insn_state *state)
+{
+ if (insn->hint && !insn->visited && !insn->ignore) {
+ int ret = validate_branch(file, insn_func(insn), insn, *state);
+ if (ret)
+ BT_INSN(insn, "<=== (hint)");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
+{
+ struct instruction *insn;
+ struct insn_state state;
+ int warnings = 0;
+
+ if (!file->hints)
+ return 0;
+
+ init_insn_state(file, &state, sec);
+
+ if (sec) {
+ sec_for_each_insn(file, sec, insn)
+ warnings += validate_unwind_hint(file, insn, &state);
+ } else {
+ for_each_insn(file, insn)
+ warnings += validate_unwind_hint(file, insn, &state);
+ }
+
+ return warnings;
+}
+
+/*
+ * Validate rethunk entry constraint: must untrain RET before the first RET.
+ *
+ * Follow every branch (intra-function) and ensure VALIDATE_UNRET_END comes
+ * before an actual RET instruction.
+ */
+static int validate_unret(struct objtool_file *file, struct instruction *insn)
+{
+ struct instruction *next, *dest;
+ int ret;
+
+ for (;;) {
+ next = next_insn_to_validate(file, insn);
+
+ if (insn->visited & VISITED_UNRET)
+ return 0;
+
+ insn->visited |= VISITED_UNRET;
+
+ if (!insn->ignore_alts && insn->alts) {
+ struct alternative *alt;
+ bool skip_orig = false;
+
+ for (alt = insn->alts; alt; alt = alt->next) {
+ if (alt->skip_orig)
+ skip_orig = true;
+
+ ret = validate_unret(file, alt->insn);
+ if (ret) {
+ BT_INSN(insn, "(alt)");
+ return ret;
+ }
+ }
+
+ if (skip_orig)
+ return 0;
+ }
+
+ switch (insn->type) {
+
+ case INSN_CALL_DYNAMIC:
+ case INSN_JUMP_DYNAMIC:
+ case INSN_JUMP_DYNAMIC_CONDITIONAL:
+ WARN_INSN(insn, "early indirect call");
+ return 1;
+
+ case INSN_JUMP_UNCONDITIONAL:
+ case INSN_JUMP_CONDITIONAL:
+ if (!is_sibling_call(insn)) {
+ if (!insn->jump_dest) {
+ WARN_INSN(insn, "unresolved jump target after linking?!?");
+ return -1;
+ }
+ ret = validate_unret(file, insn->jump_dest);
+ if (ret) {
+ BT_INSN(insn, "(branch%s)",
+ insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
+ return ret;
+ }
+
+ if (insn->type == INSN_JUMP_UNCONDITIONAL)
+ return 0;
+
+ break;
+ }
+
+ /* fallthrough */
+ case INSN_CALL:
+ dest = find_insn(file, insn_call_dest(insn)->sec,
+ insn_call_dest(insn)->offset);
+ if (!dest) {
+ WARN("Unresolved function after linking!?: %s",
+ insn_call_dest(insn)->name);
+ return -1;
+ }
+
+ ret = validate_unret(file, dest);
+ if (ret) {
+ BT_INSN(insn, "(call)");
+ return ret;
+ }
+ /*
+ * If a call returns without error, it must have seen UNTRAIN_RET.
+ * Therefore any non-error return is a success.
+ */
+ return 0;
+
+ case INSN_RETURN:
+ WARN_INSN(insn, "RET before UNTRAIN");
+ return 1;
+
+ case INSN_NOP:
+ if (insn->retpoline_safe)
+ return 0;
+ break;
+
+ default:
+ break;
+ }
+
+ if (!next) {
+ WARN_INSN(insn, "teh end!");
+ return -1;
+ }
+ insn = next;
+ }
+
+ return 0;
+}
+
+/*
+ * Validate that all branches starting at VALIDATE_UNRET_BEGIN encounter
+ * VALIDATE_UNRET_END before RET.
+ */
+static int validate_unrets(struct objtool_file *file)
+{
+ struct instruction *insn;
+ int ret, warnings = 0;
+
+ for_each_insn(file, insn) {
+ if (!insn->unret)
+ continue;
+
+ ret = validate_unret(file, insn);
+ if (ret < 0) {
+ WARN_INSN(insn, "Failed UNRET validation");
+ return ret;
+ }
+ warnings += ret;
+ }
+
+ return warnings;
+}
+
+static int validate_retpoline(struct objtool_file *file)
+{
+ struct instruction *insn;
+ int warnings = 0;
+
+ for_each_insn(file, insn) {
+ if (insn->type != INSN_JUMP_DYNAMIC &&
+ insn->type != INSN_CALL_DYNAMIC &&
+ insn->type != INSN_RETURN)
+ continue;
+
+ if (insn->retpoline_safe)
+ continue;
+
+ if (insn->sec->init)
+ continue;
+
+ if (insn->type == INSN_RETURN) {
+ if (opts.rethunk) {
+ WARN_INSN(insn, "'naked' return found in RETHUNK build");
+ } else
+ continue;
+ } else {
+ WARN_INSN(insn, "indirect %s found in RETPOLINE build",
+ insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
+ }
+
+ warnings++;
+ }
+
+ return warnings;
+}
+
+static bool is_kasan_insn(struct instruction *insn)
+{
+ return (insn->type == INSN_CALL &&
+ !strcmp(insn_call_dest(insn)->name, "__asan_handle_no_return"));
+}
+
+static bool is_ubsan_insn(struct instruction *insn)
+{
+ return (insn->type == INSN_CALL &&
+ !strcmp(insn_call_dest(insn)->name,
+ "__ubsan_handle_builtin_unreachable"));
+}
+
+static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
+{
+ int i;
+ struct instruction *prev_insn;
+
+ if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
+ return true;
+
+ /*
+ * Ignore alternative replacement instructions. This can happen
+ * when a whitelisted function uses one of the ALTERNATIVE macros.
+ */
+ if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
+ !strcmp(insn->sec->name, ".altinstr_aux"))
+ return true;
+
+ /*
+ * Whole archive runs might encounter dead code from weak symbols.
+ * This is where the linker will have dropped the weak symbol in
+ * favour of a regular symbol, but leaves the code in place.
+ *
+ * In this case we'll find a piece of code (whole function) that is not
+ * covered by a !section symbol. Ignore them.
+ */
+ if (opts.link && !insn_func(insn)) {
+ int size = find_symbol_hole_containing(insn->sec, insn->offset);
+ unsigned long end = insn->offset + size;
+
+ if (!size) /* not a hole */
+ return false;
+
+ if (size < 0) /* hole until the end */
+ return true;
+
+ sec_for_each_insn_continue(file, insn) {
+ /*
+ * If we reach a visited instruction at or before the
+ * end of the hole, ignore the unreachable.
+ */
+ if (insn->visited)
+ return true;
+
+ if (insn->offset >= end)
+ break;
+
+ /*
+ * If this hole jumps to a .cold function, mark it ignore too.
+ */
+ if (insn->jump_dest && insn_func(insn->jump_dest) &&
+ strstr(insn_func(insn->jump_dest)->name, ".cold")) {
+ struct instruction *dest = insn->jump_dest;
+ func_for_each_insn(file, insn_func(dest), dest)
+ dest->ignore = true;
+ }
+ }
+
+ return false;
+ }
+
+ if (!insn_func(insn))
+ return false;
+
+ if (insn_func(insn)->static_call_tramp)
+ return true;
+
+ /*
+ * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
+ * __builtin_unreachable(). The BUG() macro has an unreachable() after
+ * the UD2, which causes GCC's undefined trap logic to emit another UD2
+ * (or occasionally a JMP to UD2).
+ *
+ * It may also insert a UD2 after calling a __noreturn function.
+ */
+ prev_insn = prev_insn_same_sec(file, insn);
+ if (prev_insn->dead_end &&
+ (insn->type == INSN_BUG ||
+ (insn->type == INSN_JUMP_UNCONDITIONAL &&
+ insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
+ return true;
+
+ /*
+ * Check if this (or a subsequent) instruction is related to
+ * CONFIG_UBSAN or CONFIG_KASAN.
+ *
+ * End the search at 5 instructions to avoid going into the weeds.
+ */
+ for (i = 0; i < 5; i++) {
+
+ if (is_kasan_insn(insn) || is_ubsan_insn(insn))
+ return true;
+
+ if (insn->type == INSN_JUMP_UNCONDITIONAL) {
+ if (insn->jump_dest &&
+ insn_func(insn->jump_dest) == insn_func(insn)) {
+ insn = insn->jump_dest;
+ continue;
+ }
+
+ break;
+ }
+
+ if (insn->offset + insn->len >= insn_func(insn)->offset + insn_func(insn)->len)
+ break;
+
+ insn = next_insn_same_sec(file, insn);
+ }
+
+ return false;
+}
+
+static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
+{
+ struct instruction *insn, *prev;
+ struct cfi_state *cfi;
+
+ insn = find_insn(file, func->sec, func->offset);
+ if (!insn)
+ return -1;
+
+ for (prev = prev_insn_same_sec(file, insn);
+ prev;
+ prev = prev_insn_same_sec(file, prev)) {
+ u64 offset;
+
+ if (prev->type != INSN_NOP)
+ return -1;
+
+ offset = func->offset - prev->offset;
+
+ if (offset > opts.prefix)
+ return -1;
+
+ if (offset < opts.prefix)
+ continue;
+
+ elf_create_prefix_symbol(file->elf, func, opts.prefix);
+ break;
+ }
+
+ if (!prev)
+ return -1;
+
+ if (!insn->cfi) {
+ /*
+ * This can happen if stack validation isn't enabled or the
+ * function is annotated with STACK_FRAME_NON_STANDARD.
+ */
+ return 0;
+ }
+
+ /* Propagate insn->cfi to the prefix code */
+ cfi = cfi_hash_find_or_add(insn->cfi);
+ for (; prev != insn; prev = next_insn_same_sec(file, prev))
+ prev->cfi = cfi;
+
+ return 0;
+}
+
+static int add_prefix_symbols(struct objtool_file *file)
+{
+ struct section *sec;
+ struct symbol *func;
+
+ for_each_sec(file, sec) {
+ if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ continue;
+
+ sec_for_each_sym(sec, func) {
+ if (func->type != STT_FUNC)
+ continue;
+
+ add_prefix_symbol(file, func);
+ }
+ }
+
+ return 0;
+}
+
+static int validate_symbol(struct objtool_file *file, struct section *sec,
+ struct symbol *sym, struct insn_state *state)
+{
+ struct instruction *insn;
+ int ret;
+
+ if (!sym->len) {
+ WARN("%s() is missing an ELF size annotation", sym->name);
+ return 1;
+ }
+
+ if (sym->pfunc != sym || sym->alias != sym)
+ return 0;
+
+ insn = find_insn(file, sec, sym->offset);
+ if (!insn || insn->ignore || insn->visited)
+ return 0;
+
+ state->uaccess = sym->uaccess_safe;
+
+ ret = validate_branch(file, insn_func(insn), insn, *state);
+ if (ret)
+ BT_INSN(insn, "<=== (sym)");
+ return ret;
+}
+
+static int validate_section(struct objtool_file *file, struct section *sec)
+{
+ struct insn_state state;
+ struct symbol *func;
+ int warnings = 0;
+
+ sec_for_each_sym(sec, func) {
+ if (func->type != STT_FUNC)
+ continue;
+
+ init_insn_state(file, &state, sec);
+ set_func_state(&state.cfi);
+
+ warnings += validate_symbol(file, sec, func, &state);
+ }
+
+ return warnings;
+}
+
+static int validate_noinstr_sections(struct objtool_file *file)
+{
+ struct section *sec;
+ int warnings = 0;
+
+ sec = find_section_by_name(file->elf, ".noinstr.text");
+ if (sec) {
+ warnings += validate_section(file, sec);
+ warnings += validate_unwind_hints(file, sec);
+ }
+
+ sec = find_section_by_name(file->elf, ".entry.text");
+ if (sec) {
+ warnings += validate_section(file, sec);
+ warnings += validate_unwind_hints(file, sec);
+ }
+
+ sec = find_section_by_name(file->elf, ".cpuidle.text");
+ if (sec) {
+ warnings += validate_section(file, sec);
+ warnings += validate_unwind_hints(file, sec);
+ }
+
+ return warnings;
+}
+
+static int validate_functions(struct objtool_file *file)
+{
+ struct section *sec;
+ int warnings = 0;
+
+ for_each_sec(file, sec) {
+ if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+ continue;
+
+ warnings += validate_section(file, sec);
+ }
+
+ return warnings;
+}
+
+static void mark_endbr_used(struct instruction *insn)
+{
+ if (!list_empty(&insn->call_node))
+ list_del_init(&insn->call_node);
+}
+
+static bool noendbr_range(struct objtool_file *file, struct instruction *insn)
+{
+ struct symbol *sym = find_symbol_containing(insn->sec, insn->offset-1);
+ struct instruction *first;
+
+ if (!sym)
+ return false;
+
+ first = find_insn(file, sym->sec, sym->offset);
+ if (!first)
+ return false;
+
+ if (first->type != INSN_ENDBR && !first->noendbr)
+ return false;
+
+ return insn->offset == sym->offset + sym->len;
+}
+
+static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
+{
+ struct instruction *dest;
+ struct reloc *reloc;
+ unsigned long off;
+ int warnings = 0;
+
+ /*
+ * Looking for function pointer load relocations. Ignore
+ * direct/indirect branches:
+ */
+ switch (insn->type) {
+ case INSN_CALL:
+ case INSN_CALL_DYNAMIC:
+ case INSN_JUMP_CONDITIONAL:
+ case INSN_JUMP_UNCONDITIONAL:
+ case INSN_JUMP_DYNAMIC:
+ case INSN_JUMP_DYNAMIC_CONDITIONAL:
+ case INSN_RETURN:
+ case INSN_NOP:
+ return 0;
+ default:
+ break;
+ }
+
+ for (reloc = insn_reloc(file, insn);
+ reloc;
+ reloc = find_reloc_by_dest_range(file->elf, insn->sec,
+ reloc_offset(reloc) + 1,
+ (insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {
+
+ /*
+ * static_call_update() references the trampoline, which
+ * doesn't have (or need) ENDBR. Skip warning in that case.
+ */
+ if (reloc->sym->static_call_tramp)
+ continue;
+
+ off = reloc->sym->offset;
+ if (reloc_type(reloc) == R_X86_64_PC32 ||
+ reloc_type(reloc) == R_X86_64_PLT32)
+ off += arch_dest_reloc_offset(reloc_addend(reloc));
+ else
+ off += reloc_addend(reloc);
+
+ dest = find_insn(file, reloc->sym->sec, off);
+ if (!dest)
+ continue;
+
+ if (dest->type == INSN_ENDBR) {
+ mark_endbr_used(dest);
+ continue;
+ }
+
+ if (insn_func(dest) && insn_func(insn) &&
+ insn_func(dest)->pfunc == insn_func(insn)->pfunc) {
+ /*
+ * Anything from->to self is either _THIS_IP_ or
+ * IRET-to-self.
+ *
+ * There is no sane way to annotate _THIS_IP_ since the
+ * compiler treats the relocation as a constant and is
+ * happy to fold in offsets, skewing any annotation we
+ * do, leading to vast amounts of false-positives.
+ *
+ * There's also compiler generated _THIS_IP_ through
+ * KCOV and such which we have no hope of annotating.
+ *
+ * As such, blanket accept self-references without
+ * issue.
+ */
+ continue;
+ }
+
+ /*
+ * Accept anything ANNOTATE_NOENDBR.
+ */
+ if (dest->noendbr)
+ continue;
+
+ /*
+ * Accept if this is the instruction after a symbol
+ * that is (no)endbr -- typical code-range usage.
+ */
+ if (noendbr_range(file, dest))
+ continue;
+
+ WARN_INSN(insn, "relocation to !ENDBR: %s", offstr(dest->sec, dest->offset));
+
+ warnings++;
+ }
+
+ return warnings;
+}
+
+static int validate_ibt_data_reloc(struct objtool_file *file,
+ struct reloc *reloc)
+{
+ struct instruction *dest;
+
+ dest = find_insn(file, reloc->sym->sec,
+ reloc->sym->offset + reloc_addend(reloc));
+ if (!dest)
+ return 0;
+
+ if (dest->type == INSN_ENDBR) {
+ mark_endbr_used(dest);
+ return 0;
+ }
+
+ if (dest->noendbr)
+ return 0;
+
+ WARN_FUNC("data relocation to !ENDBR: %s",
+ reloc->sec->base, reloc_offset(reloc),
+ offstr(dest->sec, dest->offset));
+
+ return 1;
+}
+
+/*
+ * Validate IBT rules and remove used ENDBR instructions from the seal list.
+ * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
+ * NOPs) later, in create_ibt_endbr_seal_sections().
+ */
+static int validate_ibt(struct objtool_file *file)
+{
+ struct section *sec;
+ struct reloc *reloc;
+ struct instruction *insn;
+ int warnings = 0;
+
+ for_each_insn(file, insn)
+ warnings += validate_ibt_insn(file, insn);
+
+ for_each_sec(file, sec) {
+
+ /* Already done by validate_ibt_insn() */
+ if (sec->sh.sh_flags & SHF_EXECINSTR)
+ continue;
+
+ if (!sec->rsec)
+ continue;
+
+ /*
+ * These sections can reference text addresses, but not with
+ * the intent to indirect branch to them.
+ */
+ if ((!strncmp(sec->name, ".discard", 8) &&
+ strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
+ !strncmp(sec->name, ".debug", 6) ||
+ !strcmp(sec->name, ".altinstructions") ||
+ !strcmp(sec->name, ".ibt_endbr_seal") ||
+ !strcmp(sec->name, ".orc_unwind_ip") ||
+ !strcmp(sec->name, ".parainstructions") ||
+ !strcmp(sec->name, ".retpoline_sites") ||
+ !strcmp(sec->name, ".smp_locks") ||
+ !strcmp(sec->name, ".static_call_sites") ||
+ !strcmp(sec->name, "_error_injection_whitelist") ||
+ !strcmp(sec->name, "_kprobe_blacklist") ||
+ !strcmp(sec->name, "__bug_table") ||
+ !strcmp(sec->name, "__ex_table") ||
+ !strcmp(sec->name, "__jump_table") ||
+ !strcmp(sec->name, "__mcount_loc") ||
+ !strcmp(sec->name, ".kcfi_traps") ||
+ strstr(sec->name, "__patchable_function_entries"))
+ continue;
+
+ for_each_reloc(sec->rsec, reloc)
+ warnings += validate_ibt_data_reloc(file, reloc);
+ }
+
+ return warnings;
+}
+
+static int validate_sls(struct objtool_file *file)
+{
+ struct instruction *insn, *next_insn;
+ int warnings = 0;
+
+ for_each_insn(file, insn) {
+ next_insn = next_insn_same_sec(file, insn);
+
+ if (insn->retpoline_safe)
+ continue;
+
+ switch (insn->type) {
+ case INSN_RETURN:
+ if (!next_insn || next_insn->type != INSN_TRAP) {
+ WARN_INSN(insn, "missing int3 after ret");
+ warnings++;
+ }
+
+ break;
+ case INSN_JUMP_DYNAMIC:
+ if (!next_insn || next_insn->type != INSN_TRAP) {
+ WARN_INSN(insn, "missing int3 after indirect jump");
+ warnings++;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+
+ return warnings;
+}
+
+static bool ignore_noreturn_call(struct instruction *insn)
+{
+ struct symbol *call_dest = insn_call_dest(insn);
+
+ /*
+ * FIXME: hack, we need a real noreturn solution
+ *
+ * Problem is, exc_double_fault() may or may not return, depending on
+ * whether CONFIG_X86_ESPFIX64 is set. But objtool has no visibility
+ * to the kernel config.
+ *
+ * Other potential ways to fix it:
+ *
+ * - have compiler communicate __noreturn functions somehow
+ * - remove CONFIG_X86_ESPFIX64
+ * - read the .config file
+ * - add a cmdline option
+ * - create a generic objtool annotation format (vs a bunch of custom
+ * formats) and annotate it
+ */
+ if (!strcmp(call_dest->name, "exc_double_fault")) {
+ /* prevent further unreachable warnings for the caller */
+ insn->sym->warned = 1;
+ return true;
+ }
+
+ return false;
+}
+
+static int validate_reachable_instructions(struct objtool_file *file)
+{
+ struct instruction *insn, *prev_insn;
+ struct symbol *call_dest;
+ int warnings = 0;
+
+ if (file->ignore_unreachables)
+ return 0;
+
+ for_each_insn(file, insn) {
+ if (insn->visited || ignore_unreachable_insn(file, insn))
+ continue;
+
+ prev_insn = prev_insn_same_sec(file, insn);
+ if (prev_insn && prev_insn->dead_end) {
+ call_dest = insn_call_dest(prev_insn);
+ if (call_dest && !ignore_noreturn_call(prev_insn)) {
+ WARN_INSN(insn, "%s() is missing a __noreturn annotation",
+ call_dest->name);
+ warnings++;
+ continue;
+ }
+ }
+
+ WARN_INSN(insn, "unreachable instruction");
+ warnings++;
+ }
+
+ return warnings;
+}
+
+/* 'funcs' is a space-separated list of function names */
+static int disas_funcs(const char *funcs)
+{
+ const char *objdump_str, *cross_compile;
+ int size, ret;
+ char *cmd;
+
+ cross_compile = getenv("CROSS_COMPILE");
+
+ objdump_str = "%sobjdump -wdr %s | gawk -M -v _funcs='%s' '"
+ "BEGIN { split(_funcs, funcs); }"
+ "/^$/ { func_match = 0; }"
+ "/<.*>:/ { "
+ "f = gensub(/.*<(.*)>:/, \"\\\\1\", 1);"
+ "for (i in funcs) {"
+ "if (funcs[i] == f) {"
+ "func_match = 1;"
+ "base = strtonum(\"0x\" $1);"
+ "break;"
+ "}"
+ "}"
+ "}"
+ "{"
+ "if (func_match) {"
+ "addr = strtonum(\"0x\" $1);"
+ "printf(\"%%04x \", addr - base);"
+ "print;"
+ "}"
+ "}' 1>&2";
+
+ /* fake snprintf() to calculate the size */
+ size = snprintf(NULL, 0, objdump_str, cross_compile, objname, funcs) + 1;
+ if (size <= 0) {
+ WARN("objdump string size calculation failed");
+ return -1;
+ }
+
+ cmd = malloc(size);
+
+ /* real snprintf() */
+ snprintf(cmd, size, objdump_str, cross_compile, objname, funcs);
+ ret = system(cmd);
+ if (ret) {
+ WARN("disassembly failed: %d", ret);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int disas_warned_funcs(struct objtool_file *file)
+{
+ struct symbol *sym;
+ char *funcs = NULL, *tmp;
+
+ for_each_sym(file, sym) {
+ if (sym->warned) {
+ if (!funcs) {
+ funcs = malloc(strlen(sym->name) + 1);
+ strcpy(funcs, sym->name);
+ } else {
+ tmp = malloc(strlen(funcs) + strlen(sym->name) + 2);
+ sprintf(tmp, "%s %s", funcs, sym->name);
+ free(funcs);
+ funcs = tmp;
+ }
+ }
+ }
+
+ if (funcs)
+ disas_funcs(funcs);
+
+ return 0;
+}
+
+struct insn_chunk {
+ void *addr;
+ struct insn_chunk *next;
+};
+
+/*
+ * Reduce peak RSS usage by freeing insns memory before writing the ELF file,
+ * which can trigger more allocations for .debug_* sections whose data hasn't
+ * been read yet.
+ */
+static void free_insns(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct insn_chunk *chunks = NULL, *chunk;
+
+ for_each_insn(file, insn) {
+ if (!insn->idx) {
+ chunk = malloc(sizeof(*chunk));
+ chunk->addr = insn;
+ chunk->next = chunks;
+ chunks = chunk;
+ }
+ }
+
+ for (chunk = chunks; chunk; chunk = chunk->next)
+ free(chunk->addr);
+}
+
+int check(struct objtool_file *file)
+{
+ int ret, warnings = 0;
+
+ arch_initial_func_cfi_state(&initial_func_cfi);
+ init_cfi_state(&init_cfi);
+ init_cfi_state(&func_cfi);
+ set_func_state(&func_cfi);
+ init_cfi_state(&force_undefined_cfi);
+ force_undefined_cfi.force_undefined = true;
+
+ if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
+ goto out;
+
+ cfi_hash_add(&init_cfi);
+ cfi_hash_add(&func_cfi);
+
+ ret = decode_sections(file);
+ if (ret < 0)
+ goto out;
+
+ warnings += ret;
+
+ if (!nr_insns)
+ goto out;
+
+ if (opts.retpoline) {
+ ret = validate_retpoline(file);
+ if (ret < 0)
+ return ret;
+ warnings += ret;
+ }
+
+ if (opts.stackval || opts.orc || opts.uaccess) {
+ ret = validate_functions(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+
+ ret = validate_unwind_hints(file, NULL);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+
+ if (!warnings) {
+ ret = validate_reachable_instructions(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ } else if (opts.noinstr) {
+ ret = validate_noinstr_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.unret) {
+ /*
+ * Must be after validate_branch() and friends, it plays
+ * further games with insn->visited.
+ */
+ ret = validate_unrets(file);
+ if (ret < 0)
+ return ret;
+ warnings += ret;
+ }
+
+ if (opts.ibt) {
+ ret = validate_ibt(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.sls) {
+ ret = validate_sls(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.static_call) {
+ ret = create_static_call_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.retpoline) {
+ ret = create_retpoline_sites_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.cfi) {
+ ret = create_cfi_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.rethunk) {
+ ret = create_return_sites_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+
+ if (opts.hack_skylake) {
+ ret = create_direct_call_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+ }
+
+ if (opts.mcount) {
+ ret = create_mcount_loc_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.prefix) {
+ ret = add_prefix_symbols(file);
+ if (ret < 0)
+ return ret;
+ warnings += ret;
+ }
+
+ if (opts.ibt) {
+ ret = create_ibt_endbr_seal_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ if (opts.orc && nr_insns) {
+ ret = orc_create(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
+ free_insns(file);
+
+ if (opts.verbose)
+ disas_warned_funcs(file);
+
+ if (opts.stats) {
+ printf("nr_insns_visited: %ld\n", nr_insns_visited);
+ printf("nr_cfi: %ld\n", nr_cfi);
+ printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
+ printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
+ }
+
+out:
+ /*
+ * For now, don't fail the kernel build on fatal warnings. These
+ * errors are still fairly common due to the growing matrix of
+ * supported toolchains and their recent pace of change.
+ */
+ return 0;
+}