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-rw-r--r--arch/loongarch/kernel/unwind_orc.c528
1 files changed, 528 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/unwind_orc.c b/arch/loongarch/kernel/unwind_orc.c
new file mode 100644
index 0000000000..b257228763
--- /dev/null
+++ b/arch/loongarch/kernel/unwind_orc.c
@@ -0,0 +1,528 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/objtool.h>
+#include <linux/module.h>
+#include <linux/sort.h>
+#include <asm/exception.h>
+#include <asm/orc_header.h>
+#include <asm/orc_lookup.h>
+#include <asm/orc_types.h>
+#include <asm/ptrace.h>
+#include <asm/setup.h>
+#include <asm/stacktrace.h>
+#include <asm/tlb.h>
+#include <asm/unwind.h>
+
+ORC_HEADER;
+
+#define orc_warn(fmt, ...) \
+ printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__)
+
+extern int __start_orc_unwind_ip[];
+extern int __stop_orc_unwind_ip[];
+extern struct orc_entry __start_orc_unwind[];
+extern struct orc_entry __stop_orc_unwind[];
+
+static bool orc_init __ro_after_init;
+static unsigned int lookup_num_blocks __ro_after_init;
+
+/* Fake frame pointer entry -- used as a fallback for generated code */
+static struct orc_entry orc_fp_entry = {
+ .sp_reg = ORC_REG_FP,
+ .sp_offset = 16,
+ .fp_reg = ORC_REG_PREV_SP,
+ .fp_offset = -16,
+ .ra_reg = ORC_REG_PREV_SP,
+ .ra_offset = -8,
+ .type = ORC_TYPE_CALL
+};
+
+/*
+ * If we crash with IP==0, the last successfully executed instruction
+ * was probably an indirect function call with a NULL function pointer,
+ * and we don't have unwind information for NULL.
+ * This hardcoded ORC entry for IP==0 allows us to unwind from a NULL function
+ * pointer into its parent and then continue normally from there.
+ */
+static struct orc_entry orc_null_entry = {
+ .sp_reg = ORC_REG_SP,
+ .sp_offset = sizeof(long),
+ .fp_reg = ORC_REG_UNDEFINED,
+ .type = ORC_TYPE_CALL
+};
+
+static inline unsigned long orc_ip(const int *ip)
+{
+ return (unsigned long)ip + *ip;
+}
+
+static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
+ unsigned int num_entries, unsigned long ip)
+{
+ int *first = ip_table;
+ int *mid = first, *found = first;
+ int *last = ip_table + num_entries - 1;
+
+ if (!num_entries)
+ return NULL;
+
+ /*
+ * Do a binary range search to find the rightmost duplicate of a given
+ * starting address. Some entries are section terminators which are
+ * "weak" entries for ensuring there are no gaps. They should be
+ * ignored when they conflict with a real entry.
+ */
+ while (first <= last) {
+ mid = first + ((last - first) / 2);
+
+ if (orc_ip(mid) <= ip) {
+ found = mid;
+ first = mid + 1;
+ } else
+ last = mid - 1;
+ }
+
+ return u_table + (found - ip_table);
+}
+
+#ifdef CONFIG_MODULES
+static struct orc_entry *orc_module_find(unsigned long ip)
+{
+ struct module *mod;
+
+ mod = __module_address(ip);
+ if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip)
+ return NULL;
+
+ return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, mod->arch.num_orcs, ip);
+}
+#else
+static struct orc_entry *orc_module_find(unsigned long ip)
+{
+ return NULL;
+}
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+static struct orc_entry *orc_find(unsigned long ip);
+
+/*
+ * Ftrace dynamic trampolines do not have orc entries of their own.
+ * But they are copies of the ftrace entries that are static and
+ * defined in ftrace_*.S, which do have orc entries.
+ *
+ * If the unwinder comes across a ftrace trampoline, then find the
+ * ftrace function that was used to create it, and use that ftrace
+ * function's orc entry, as the placement of the return code in
+ * the stack will be identical.
+ */
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+ struct ftrace_ops *ops;
+ unsigned long tramp_addr, offset;
+
+ ops = ftrace_ops_trampoline(ip);
+ if (!ops)
+ return NULL;
+
+ /* Set tramp_addr to the start of the code copied by the trampoline */
+ if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
+ tramp_addr = (unsigned long)ftrace_regs_caller;
+ else
+ tramp_addr = (unsigned long)ftrace_caller;
+
+ /* Now place tramp_addr to the location within the trampoline ip is at */
+ offset = ip - ops->trampoline;
+ tramp_addr += offset;
+
+ /* Prevent unlikely recursion */
+ if (ip == tramp_addr)
+ return NULL;
+
+ return orc_find(tramp_addr);
+}
+#else
+static struct orc_entry *orc_ftrace_find(unsigned long ip)
+{
+ return NULL;
+}
+#endif
+
+static struct orc_entry *orc_find(unsigned long ip)
+{
+ static struct orc_entry *orc;
+
+ if (ip == 0)
+ return &orc_null_entry;
+
+ /* For non-init vmlinux addresses, use the fast lookup table: */
+ if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) {
+ unsigned int idx, start, stop;
+
+ idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE;
+
+ if (unlikely((idx >= lookup_num_blocks-1))) {
+ orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%pB\n",
+ idx, lookup_num_blocks, (void *)ip);
+ return NULL;
+ }
+
+ start = orc_lookup[idx];
+ stop = orc_lookup[idx + 1] + 1;
+
+ if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) ||
+ (__start_orc_unwind + stop > __stop_orc_unwind))) {
+ orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%pB\n",
+ idx, lookup_num_blocks, start, stop, (void *)ip);
+ return NULL;
+ }
+
+ return __orc_find(__start_orc_unwind_ip + start,
+ __start_orc_unwind + start, stop - start, ip);
+ }
+
+ /* vmlinux .init slow lookup: */
+ if (is_kernel_inittext(ip))
+ return __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
+ __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);
+
+ /* Module lookup: */
+ orc = orc_module_find(ip);
+ if (orc)
+ return orc;
+
+ return orc_ftrace_find(ip);
+}
+
+#ifdef CONFIG_MODULES
+
+static DEFINE_MUTEX(sort_mutex);
+static int *cur_orc_ip_table = __start_orc_unwind_ip;
+static struct orc_entry *cur_orc_table = __start_orc_unwind;
+
+static void orc_sort_swap(void *_a, void *_b, int size)
+{
+ int delta = _b - _a;
+ int *a = _a, *b = _b, tmp;
+ struct orc_entry *orc_a, *orc_b;
+
+ /* Swap the .orc_unwind_ip entries: */
+ tmp = *a;
+ *a = *b + delta;
+ *b = tmp - delta;
+
+ /* Swap the corresponding .orc_unwind entries: */
+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
+ orc_b = cur_orc_table + (b - cur_orc_ip_table);
+ swap(*orc_a, *orc_b);
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+ const int *a = _a, *b = _b;
+ unsigned long a_val = orc_ip(a);
+ unsigned long b_val = orc_ip(b);
+ struct orc_entry *orc_a;
+
+ if (a_val > b_val)
+ return 1;
+ if (a_val < b_val)
+ return -1;
+
+ /*
+ * The "weak" section terminator entries need to always be first
+ * to ensure the lookup code skips them in favor of real entries.
+ * These terminator entries exist to handle any gaps created by
+ * whitelisted .o files which didn't get objtool generation.
+ */
+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
+
+ return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
+}
+
+void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
+ void *_orc, size_t orc_size)
+{
+ int *orc_ip = _orc_ip;
+ struct orc_entry *orc = _orc;
+ unsigned int num_entries = orc_ip_size / sizeof(int);
+
+ WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 ||
+ orc_size % sizeof(*orc) != 0 ||
+ num_entries != orc_size / sizeof(*orc));
+
+ /*
+ * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
+ * associate an .orc_unwind_ip table entry with its corresponding
+ * .orc_unwind entry so they can both be swapped.
+ */
+ mutex_lock(&sort_mutex);
+ cur_orc_ip_table = orc_ip;
+ cur_orc_table = orc;
+ sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
+ mutex_unlock(&sort_mutex);
+
+ mod->arch.orc_unwind_ip = orc_ip;
+ mod->arch.orc_unwind = orc;
+ mod->arch.num_orcs = num_entries;
+}
+#endif
+
+void __init unwind_init(void)
+{
+ int i;
+ size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
+ size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
+ size_t num_entries = orc_ip_size / sizeof(int);
+ struct orc_entry *orc;
+
+ if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
+ orc_size % sizeof(struct orc_entry) != 0 ||
+ num_entries != orc_size / sizeof(struct orc_entry)) {
+ orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n");
+ return;
+ }
+
+ /*
+ * Note, the orc_unwind and orc_unwind_ip tables were already
+ * sorted at build time via the 'sorttable' tool.
+ * It's ready for binary search straight away, no need to sort it.
+ */
+
+ /* Initialize the fast lookup table: */
+ lookup_num_blocks = orc_lookup_end - orc_lookup;
+ for (i = 0; i < lookup_num_blocks-1; i++) {
+ orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
+ num_entries, LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
+ if (!orc) {
+ orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
+ return;
+ }
+
+ orc_lookup[i] = orc - __start_orc_unwind;
+ }
+
+ /* Initialize the ending block: */
+ orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, LOOKUP_STOP_IP);
+ if (!orc) {
+ orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n");
+ return;
+ }
+ orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
+
+ orc_init = true;
+}
+
+static inline bool on_stack(struct stack_info *info, unsigned long addr, size_t len)
+{
+ unsigned long begin = info->begin;
+ unsigned long end = info->end;
+
+ return (info->type != STACK_TYPE_UNKNOWN &&
+ addr >= begin && addr < end && addr + len > begin && addr + len <= end);
+}
+
+static bool stack_access_ok(struct unwind_state *state, unsigned long addr, size_t len)
+{
+ struct stack_info *info = &state->stack_info;
+
+ if (on_stack(info, addr, len))
+ return true;
+
+ return !get_stack_info(addr, state->task, info) && on_stack(info, addr, len);
+}
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+ return __unwind_get_return_address(state);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs)
+{
+ __unwind_start(state, task, regs);
+ state->type = UNWINDER_ORC;
+ if (!unwind_done(state) && !__kernel_text_address(state->pc))
+ unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+static bool is_entry_func(unsigned long addr)
+{
+ extern u32 kernel_entry;
+ extern u32 kernel_entry_end;
+
+ return addr >= (unsigned long)&kernel_entry && addr < (unsigned long)&kernel_entry_end;
+}
+
+static inline unsigned long bt_address(unsigned long ra)
+{
+ extern unsigned long eentry;
+
+ if (__kernel_text_address(ra))
+ return ra;
+
+ if (__module_text_address(ra))
+ return ra;
+
+ if (ra >= eentry && ra < eentry + EXCCODE_INT_END * VECSIZE) {
+ unsigned long func;
+ unsigned long type = (ra - eentry) / VECSIZE;
+ unsigned long offset = (ra - eentry) % VECSIZE;
+
+ switch (type) {
+ case 0 ... EXCCODE_INT_START - 1:
+ func = (unsigned long)exception_table[type];
+ break;
+ case EXCCODE_INT_START ... EXCCODE_INT_END:
+ func = (unsigned long)handle_vint;
+ break;
+ default:
+ func = (unsigned long)handle_reserved;
+ break;
+ }
+
+ return func + offset;
+ }
+
+ return ra;
+}
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ unsigned long *p, pc;
+ struct pt_regs *regs;
+ struct orc_entry *orc;
+ struct stack_info *info = &state->stack_info;
+
+ if (unwind_done(state))
+ return false;
+
+ /* Don't let modules unload while we're reading their ORC data. */
+ preempt_disable();
+
+ if (is_entry_func(state->pc))
+ goto end;
+
+ orc = orc_find(state->pc);
+ if (!orc) {
+ /*
+ * As a fallback, try to assume this code uses a frame pointer.
+ * This is useful for generated code, like BPF, which ORC
+ * doesn't know about. This is just a guess, so the rest of
+ * the unwind is no longer considered reliable.
+ */
+ orc = &orc_fp_entry;
+ state->error = true;
+ } else {
+ if (orc->type == ORC_TYPE_UNDEFINED)
+ goto err;
+
+ if (orc->type == ORC_TYPE_END_OF_STACK)
+ goto end;
+ }
+
+ switch (orc->sp_reg) {
+ case ORC_REG_SP:
+ if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
+ orc->type = ORC_TYPE_REGS;
+ else
+ state->sp = state->sp + orc->sp_offset;
+ break;
+ case ORC_REG_FP:
+ state->sp = state->fp;
+ break;
+ default:
+ orc_warn("unknown SP base reg %d at %pB\n", orc->sp_reg, (void *)state->pc);
+ goto err;
+ }
+
+ switch (orc->fp_reg) {
+ case ORC_REG_PREV_SP:
+ p = (unsigned long *)(state->sp + orc->fp_offset);
+ if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
+ goto err;
+
+ state->fp = *p;
+ break;
+ case ORC_REG_UNDEFINED:
+ /* Nothing. */
+ break;
+ default:
+ orc_warn("unknown FP base reg %d at %pB\n", orc->fp_reg, (void *)state->pc);
+ goto err;
+ }
+
+ switch (orc->type) {
+ case ORC_TYPE_CALL:
+ if (orc->ra_reg == ORC_REG_PREV_SP) {
+ p = (unsigned long *)(state->sp + orc->ra_offset);
+ if (!stack_access_ok(state, (unsigned long)p, sizeof(unsigned long)))
+ goto err;
+
+ pc = unwind_graph_addr(state, *p, state->sp);
+ pc -= LOONGARCH_INSN_SIZE;
+ } else if (orc->ra_reg == ORC_REG_UNDEFINED) {
+ if (!state->ra || state->ra == state->pc)
+ goto err;
+
+ pc = unwind_graph_addr(state, state->ra, state->sp);
+ pc -= LOONGARCH_INSN_SIZE;
+ state->ra = 0;
+ } else {
+ orc_warn("unknown ra base reg %d at %pB\n", orc->ra_reg, (void *)state->pc);
+ goto err;
+ }
+ break;
+ case ORC_TYPE_REGS:
+ if (info->type == STACK_TYPE_IRQ && state->sp == info->end)
+ regs = (struct pt_regs *)info->next_sp;
+ else
+ regs = (struct pt_regs *)state->sp;
+
+ if (!stack_access_ok(state, (unsigned long)regs, sizeof(*regs)))
+ goto err;
+
+ if ((info->end == (unsigned long)regs + sizeof(*regs)) &&
+ !regs->regs[3] && !regs->regs[1])
+ goto end;
+
+ if (user_mode(regs))
+ goto end;
+
+ pc = regs->csr_era;
+ if (!__kernel_text_address(pc))
+ goto err;
+
+ state->sp = regs->regs[3];
+ state->ra = regs->regs[1];
+ state->fp = regs->regs[22];
+ get_stack_info(state->sp, state->task, info);
+
+ break;
+ default:
+ orc_warn("unknown .orc_unwind entry type %d at %pB\n", orc->type, (void *)state->pc);
+ goto err;
+ }
+
+ state->pc = bt_address(pc);
+ if (!state->pc) {
+ pr_err("cannot find unwind pc at %pK\n", (void *)pc);
+ goto err;
+ }
+
+ if (!__kernel_text_address(state->pc))
+ goto err;
+
+ preempt_enable();
+ return true;
+
+err:
+ state->error = true;
+
+end:
+ preempt_enable();
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-11 22:01:22 +0000