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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/x86/kernel/kprobes/opt.c
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/kernel/kprobes/opt.c')
-rw-r--r--arch/x86/kernel/kprobes/opt.c555
1 files changed, 555 insertions, 0 deletions
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
new file mode 100644
index 0000000000..517821b483
--- /dev/null
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -0,0 +1,555 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Kernel Probes Jump Optimization (Optprobes)
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ * Copyright (C) Hitachi Ltd., 2012
+ */
+#include <linux/kprobes.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/hardirq.h>
+#include <linux/preempt.h>
+#include <linux/extable.h>
+#include <linux/kdebug.h>
+#include <linux/kallsyms.h>
+#include <linux/kgdb.h>
+#include <linux/ftrace.h>
+#include <linux/objtool.h>
+#include <linux/pgtable.h>
+#include <linux/static_call.h>
+
+#include <asm/text-patching.h>
+#include <asm/cacheflush.h>
+#include <asm/desc.h>
+#include <linux/uaccess.h>
+#include <asm/alternative.h>
+#include <asm/insn.h>
+#include <asm/debugreg.h>
+#include <asm/set_memory.h>
+#include <asm/sections.h>
+#include <asm/nospec-branch.h>
+
+#include "common.h"
+
+unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
+{
+ struct optimized_kprobe *op;
+ struct kprobe *kp;
+ long offs;
+ int i;
+
+ for (i = 0; i < JMP32_INSN_SIZE; i++) {
+ kp = get_kprobe((void *)addr - i);
+ /* This function only handles jump-optimized kprobe */
+ if (kp && kprobe_optimized(kp)) {
+ op = container_of(kp, struct optimized_kprobe, kp);
+ /* If op is optimized or under unoptimizing */
+ if (list_empty(&op->list) || optprobe_queued_unopt(op))
+ goto found;
+ }
+ }
+
+ return addr;
+found:
+ /*
+ * If the kprobe can be optimized, original bytes which can be
+ * overwritten by jump destination address. In this case, original
+ * bytes must be recovered from op->optinsn.copied_insn buffer.
+ */
+ if (copy_from_kernel_nofault(buf, (void *)addr,
+ MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+ return 0UL;
+
+ if (addr == (unsigned long)kp->addr) {
+ buf[0] = kp->opcode;
+ memcpy(buf + 1, op->optinsn.copied_insn, DISP32_SIZE);
+ } else {
+ offs = addr - (unsigned long)kp->addr - 1;
+ memcpy(buf, op->optinsn.copied_insn + offs, DISP32_SIZE - offs);
+ }
+
+ return (unsigned long)buf;
+}
+
+static void synthesize_clac(kprobe_opcode_t *addr)
+{
+ /*
+ * Can't be static_cpu_has() due to how objtool treats this feature bit.
+ * This isn't a fast path anyway.
+ */
+ if (!boot_cpu_has(X86_FEATURE_SMAP))
+ return;
+
+ /* Replace the NOP3 with CLAC */
+ addr[0] = 0x0f;
+ addr[1] = 0x01;
+ addr[2] = 0xca;
+}
+
+/* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */
+static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
+{
+#ifdef CONFIG_X86_64
+ *addr++ = 0x48;
+ *addr++ = 0xbf;
+#else
+ *addr++ = 0xb8;
+#endif
+ *(unsigned long *)addr = val;
+}
+
+asm (
+ ".pushsection .rodata\n"
+ "optprobe_template_func:\n"
+ ".global optprobe_template_entry\n"
+ "optprobe_template_entry:\n"
+#ifdef CONFIG_X86_64
+ " pushq $" __stringify(__KERNEL_DS) "\n"
+ /* Save the 'sp - 8', this will be fixed later. */
+ " pushq %rsp\n"
+ " pushfq\n"
+ ".global optprobe_template_clac\n"
+ "optprobe_template_clac:\n"
+ ASM_NOP3
+ SAVE_REGS_STRING
+ " movq %rsp, %rsi\n"
+ ".global optprobe_template_val\n"
+ "optprobe_template_val:\n"
+ ASM_NOP5
+ ASM_NOP5
+ ".global optprobe_template_call\n"
+ "optprobe_template_call:\n"
+ ASM_NOP5
+ /* Copy 'regs->flags' into 'regs->ss'. */
+ " movq 18*8(%rsp), %rdx\n"
+ " movq %rdx, 20*8(%rsp)\n"
+ RESTORE_REGS_STRING
+ /* Skip 'regs->flags' and 'regs->sp'. */
+ " addq $16, %rsp\n"
+ /* And pop flags register from 'regs->ss'. */
+ " popfq\n"
+#else /* CONFIG_X86_32 */
+ " pushl %ss\n"
+ /* Save the 'sp - 4', this will be fixed later. */
+ " pushl %esp\n"
+ " pushfl\n"
+ ".global optprobe_template_clac\n"
+ "optprobe_template_clac:\n"
+ ASM_NOP3
+ SAVE_REGS_STRING
+ " movl %esp, %edx\n"
+ ".global optprobe_template_val\n"
+ "optprobe_template_val:\n"
+ ASM_NOP5
+ ".global optprobe_template_call\n"
+ "optprobe_template_call:\n"
+ ASM_NOP5
+ /* Copy 'regs->flags' into 'regs->ss'. */
+ " movl 14*4(%esp), %edx\n"
+ " movl %edx, 16*4(%esp)\n"
+ RESTORE_REGS_STRING
+ /* Skip 'regs->flags' and 'regs->sp'. */
+ " addl $8, %esp\n"
+ /* And pop flags register from 'regs->ss'. */
+ " popfl\n"
+#endif
+ ".global optprobe_template_end\n"
+ "optprobe_template_end:\n"
+ ".popsection\n");
+
+void optprobe_template_func(void);
+STACK_FRAME_NON_STANDARD(optprobe_template_func);
+
+#define TMPL_CLAC_IDX \
+ ((long)optprobe_template_clac - (long)optprobe_template_entry)
+#define TMPL_MOVE_IDX \
+ ((long)optprobe_template_val - (long)optprobe_template_entry)
+#define TMPL_CALL_IDX \
+ ((long)optprobe_template_call - (long)optprobe_template_entry)
+#define TMPL_END_IDX \
+ ((long)optprobe_template_end - (long)optprobe_template_entry)
+
+/* Optimized kprobe call back function: called from optinsn */
+static void
+optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
+{
+ /* This is possible if op is under delayed unoptimizing */
+ if (kprobe_disabled(&op->kp))
+ return;
+
+ preempt_disable();
+ if (kprobe_running()) {
+ kprobes_inc_nmissed_count(&op->kp);
+ } else {
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ /* Adjust stack pointer */
+ regs->sp += sizeof(long);
+ /* Save skipped registers */
+ regs->cs = __KERNEL_CS;
+#ifdef CONFIG_X86_32
+ regs->gs = 0;
+#endif
+ regs->ip = (unsigned long)op->kp.addr + INT3_INSN_SIZE;
+ regs->orig_ax = ~0UL;
+
+ __this_cpu_write(current_kprobe, &op->kp);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ opt_pre_handler(&op->kp, regs);
+ __this_cpu_write(current_kprobe, NULL);
+ }
+ preempt_enable();
+}
+NOKPROBE_SYMBOL(optimized_callback);
+
+static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real)
+{
+ struct insn insn;
+ int len = 0, ret;
+
+ while (len < JMP32_INSN_SIZE) {
+ ret = __copy_instruction(dest + len, src + len, real + len, &insn);
+ if (!ret || !can_boost(&insn, src + len))
+ return -EINVAL;
+ len += ret;
+ }
+ /* Check whether the address range is reserved */
+ if (ftrace_text_reserved(src, src + len - 1) ||
+ alternatives_text_reserved(src, src + len - 1) ||
+ jump_label_text_reserved(src, src + len - 1) ||
+ static_call_text_reserved(src, src + len - 1))
+ return -EBUSY;
+
+ return len;
+}
+
+/* Check whether insn is indirect jump */
+static int insn_is_indirect_jump(struct insn *insn)
+{
+ return ((insn->opcode.bytes[0] == 0xff &&
+ (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */
+ insn->opcode.bytes[0] == 0xea); /* Segment based jump */
+}
+
+/* Check whether insn jumps into specified address range */
+static int insn_jump_into_range(struct insn *insn, unsigned long start, int len)
+{
+ unsigned long target = 0;
+
+ switch (insn->opcode.bytes[0]) {
+ case 0xe0: /* loopne */
+ case 0xe1: /* loope */
+ case 0xe2: /* loop */
+ case 0xe3: /* jcxz */
+ case 0xe9: /* near relative jump */
+ case 0xeb: /* short relative jump */
+ break;
+ case 0x0f:
+ if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */
+ break;
+ return 0;
+ default:
+ if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */
+ break;
+ return 0;
+ }
+ target = (unsigned long)insn->next_byte + insn->immediate.value;
+
+ return (start <= target && target <= start + len);
+}
+
+/* Decode whole function to ensure any instructions don't jump into target */
+static int can_optimize(unsigned long paddr)
+{
+ unsigned long addr, size = 0, offset = 0;
+ struct insn insn;
+ kprobe_opcode_t buf[MAX_INSN_SIZE];
+
+ /* Lookup symbol including addr */
+ if (!kallsyms_lookup_size_offset(paddr, &size, &offset))
+ return 0;
+
+ /*
+ * Do not optimize in the entry code due to the unstable
+ * stack handling and registers setup.
+ */
+ if (((paddr >= (unsigned long)__entry_text_start) &&
+ (paddr < (unsigned long)__entry_text_end)))
+ return 0;
+
+ /* Check there is enough space for a relative jump. */
+ if (size - offset < JMP32_INSN_SIZE)
+ return 0;
+
+ /* Decode instructions */
+ addr = paddr - offset;
+ while (addr < paddr - offset + size) { /* Decode until function end */
+ unsigned long recovered_insn;
+ int ret;
+
+ if (search_exception_tables(addr))
+ /*
+ * Since some fixup code will jumps into this function,
+ * we can't optimize kprobe in this function.
+ */
+ return 0;
+ recovered_insn = recover_probed_instruction(buf, addr);
+ if (!recovered_insn)
+ return 0;
+
+ ret = insn_decode_kernel(&insn, (void *)recovered_insn);
+ if (ret < 0)
+ return 0;
+#ifdef CONFIG_KGDB
+ /*
+ * If there is a dynamically installed kgdb sw breakpoint,
+ * this function should not be probed.
+ */
+ if (insn.opcode.bytes[0] == INT3_INSN_OPCODE &&
+ kgdb_has_hit_break(addr))
+ return 0;
+#endif
+ /* Recover address */
+ insn.kaddr = (void *)addr;
+ insn.next_byte = (void *)(addr + insn.length);
+ /*
+ * Check any instructions don't jump into target, indirectly or
+ * directly.
+ *
+ * The indirect case is present to handle a code with jump
+ * tables. When the kernel uses retpolines, the check should in
+ * theory additionally look for jumps to indirect thunks.
+ * However, the kernel built with retpolines or IBT has jump
+ * tables disabled so the check can be skipped altogether.
+ */
+ if (!IS_ENABLED(CONFIG_RETPOLINE) &&
+ !IS_ENABLED(CONFIG_X86_KERNEL_IBT) &&
+ insn_is_indirect_jump(&insn))
+ return 0;
+ if (insn_jump_into_range(&insn, paddr + INT3_INSN_SIZE,
+ DISP32_SIZE))
+ return 0;
+ addr += insn.length;
+ }
+
+ return 1;
+}
+
+/* Check optimized_kprobe can actually be optimized. */
+int arch_check_optimized_kprobe(struct optimized_kprobe *op)
+{
+ int i;
+ struct kprobe *p;
+
+ for (i = 1; i < op->optinsn.size; i++) {
+ p = get_kprobe(op->kp.addr + i);
+ if (p && !kprobe_disarmed(p))
+ return -EEXIST;
+ }
+
+ return 0;
+}
+
+/* Check the addr is within the optimized instructions. */
+int arch_within_optimized_kprobe(struct optimized_kprobe *op,
+ kprobe_opcode_t *addr)
+{
+ return (op->kp.addr <= addr &&
+ op->kp.addr + op->optinsn.size > addr);
+}
+
+/* Free optimized instruction slot */
+static
+void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
+{
+ u8 *slot = op->optinsn.insn;
+ if (slot) {
+ int len = TMPL_END_IDX + op->optinsn.size + JMP32_INSN_SIZE;
+
+ /* Record the perf event before freeing the slot */
+ if (dirty)
+ perf_event_text_poke(slot, slot, len, NULL, 0);
+
+ free_optinsn_slot(slot, dirty);
+ op->optinsn.insn = NULL;
+ op->optinsn.size = 0;
+ }
+}
+
+void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
+{
+ __arch_remove_optimized_kprobe(op, 1);
+}
+
+/*
+ * Copy replacing target instructions
+ * Target instructions MUST be relocatable (checked inside)
+ * This is called when new aggr(opt)probe is allocated or reused.
+ */
+int arch_prepare_optimized_kprobe(struct optimized_kprobe *op,
+ struct kprobe *__unused)
+{
+ u8 *buf = NULL, *slot;
+ int ret, len;
+ long rel;
+
+ if (!can_optimize((unsigned long)op->kp.addr))
+ return -EILSEQ;
+
+ buf = kzalloc(MAX_OPTINSN_SIZE, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ op->optinsn.insn = slot = get_optinsn_slot();
+ if (!slot) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ /*
+ * Verify if the address gap is in 2GB range, because this uses
+ * a relative jump.
+ */
+ rel = (long)slot - (long)op->kp.addr + JMP32_INSN_SIZE;
+ if (abs(rel) > 0x7fffffff) {
+ ret = -ERANGE;
+ goto err;
+ }
+
+ /* Copy arch-dep-instance from template */
+ memcpy(buf, optprobe_template_entry, TMPL_END_IDX);
+
+ /* Copy instructions into the out-of-line buffer */
+ ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr,
+ slot + TMPL_END_IDX);
+ if (ret < 0)
+ goto err;
+ op->optinsn.size = ret;
+ len = TMPL_END_IDX + op->optinsn.size;
+
+ synthesize_clac(buf + TMPL_CLAC_IDX);
+
+ /* Set probe information */
+ synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op);
+
+ /* Set probe function call */
+ synthesize_relcall(buf + TMPL_CALL_IDX,
+ slot + TMPL_CALL_IDX, optimized_callback);
+
+ /* Set returning jmp instruction at the tail of out-of-line buffer */
+ synthesize_reljump(buf + len, slot + len,
+ (u8 *)op->kp.addr + op->optinsn.size);
+ len += JMP32_INSN_SIZE;
+
+ /*
+ * Note len = TMPL_END_IDX + op->optinsn.size + JMP32_INSN_SIZE is also
+ * used in __arch_remove_optimized_kprobe().
+ */
+
+ /* We have to use text_poke() for instruction buffer because it is RO */
+ perf_event_text_poke(slot, NULL, 0, buf, len);
+ text_poke(slot, buf, len);
+
+ ret = 0;
+out:
+ kfree(buf);
+ return ret;
+
+err:
+ __arch_remove_optimized_kprobe(op, 0);
+ goto out;
+}
+
+/*
+ * Replace breakpoints (INT3) with relative jumps (JMP.d32).
+ * Caller must call with locking kprobe_mutex and text_mutex.
+ *
+ * The caller will have installed a regular kprobe and after that issued
+ * syncrhonize_rcu_tasks(), this ensures that the instruction(s) that live in
+ * the 4 bytes after the INT3 are unused and can now be overwritten.
+ */
+void arch_optimize_kprobes(struct list_head *oplist)
+{
+ struct optimized_kprobe *op, *tmp;
+ u8 insn_buff[JMP32_INSN_SIZE];
+
+ list_for_each_entry_safe(op, tmp, oplist, list) {
+ s32 rel = (s32)((long)op->optinsn.insn -
+ ((long)op->kp.addr + JMP32_INSN_SIZE));
+
+ WARN_ON(kprobe_disabled(&op->kp));
+
+ /* Backup instructions which will be replaced by jump address */
+ memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_INSN_SIZE,
+ DISP32_SIZE);
+
+ insn_buff[0] = JMP32_INSN_OPCODE;
+ *(s32 *)(&insn_buff[1]) = rel;
+
+ text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE, NULL);
+
+ list_del_init(&op->list);
+ }
+}
+
+/*
+ * Replace a relative jump (JMP.d32) with a breakpoint (INT3).
+ *
+ * After that, we can restore the 4 bytes after the INT3 to undo what
+ * arch_optimize_kprobes() scribbled. This is safe since those bytes will be
+ * unused once the INT3 lands.
+ */
+void arch_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+ u8 new[JMP32_INSN_SIZE] = { INT3_INSN_OPCODE, };
+ u8 old[JMP32_INSN_SIZE];
+ u8 *addr = op->kp.addr;
+
+ memcpy(old, op->kp.addr, JMP32_INSN_SIZE);
+ memcpy(new + INT3_INSN_SIZE,
+ op->optinsn.copied_insn,
+ JMP32_INSN_SIZE - INT3_INSN_SIZE);
+
+ text_poke(addr, new, INT3_INSN_SIZE);
+ text_poke_sync();
+ text_poke(addr + INT3_INSN_SIZE,
+ new + INT3_INSN_SIZE,
+ JMP32_INSN_SIZE - INT3_INSN_SIZE);
+ text_poke_sync();
+
+ perf_event_text_poke(op->kp.addr, old, JMP32_INSN_SIZE, new, JMP32_INSN_SIZE);
+}
+
+/*
+ * Recover original instructions and breakpoints from relative jumps.
+ * Caller must call with locking kprobe_mutex.
+ */
+extern void arch_unoptimize_kprobes(struct list_head *oplist,
+ struct list_head *done_list)
+{
+ struct optimized_kprobe *op, *tmp;
+
+ list_for_each_entry_safe(op, tmp, oplist, list) {
+ arch_unoptimize_kprobe(op);
+ list_move(&op->list, done_list);
+ }
+}
+
+int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter)
+{
+ struct optimized_kprobe *op;
+
+ if (p->flags & KPROBE_FLAG_OPTIMIZED) {
+ /* This kprobe is really able to run optimized path. */
+ op = container_of(p, struct optimized_kprobe, kp);
+ /* Detour through copied instructions */
+ regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX;
+ if (!reenter)
+ reset_current_kprobe();
+ return 1;
+ }
+ return 0;
+}
+NOKPROBE_SYMBOL(setup_detour_execution);