Messages in this thread Patch in this message | | | From | Adrian Hunter <> | Subject | [PATCH V7 05/15] perf/x86: Add perf text poke events for kprobes | Date | Tue, 12 May 2020 15:19:12 +0300 |
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Add perf text poke events for kprobes. That includes:
- the replaced instruction(s) which are executed out-of-line i.e. arch_copy_kprobe() and arch_remove_kprobe()
- the INT3 that activates the kprobe i.e. arch_arm_kprobe() and arch_disarm_kprobe()
- optimised kprobe function i.e. arch_prepare_optimized_kprobe() and __arch_remove_optimized_kprobe()
- optimised kprobe i.e. arch_optimize_kprobes() and arch_unoptimize_kprobe()
Resulting in 8 possible text_poke events:
0: NULL -> probe.ainsn.insn (if ainsn.boostable && !kp.post_handler) arch_copy_kprobe()
1: old0 -> INT3 arch_arm_kprobe()
// boosted kprobe active
2: NULL -> optprobe_trampoline arch_prepare_optimized_kprobe()
3: INT3,old1,old2,old3,old4 -> JMP32 arch_optimize_kprobes()
// optprobe active
4: JMP32 -> INT3,old1,old2,old3,old4
// optprobe disabled and kprobe active (this sometimes goes back to 3) arch_unoptimize_kprobe()
5: optprobe_trampoline -> NULL arch_remove_optimized_kprobe()
// boosted kprobe active
6: INT3 -> old0 arch_disarm_kprobe()
7: probe.ainsn.insn -> NULL (if ainsn.boostable && !kp.post_handler) arch_remove_kprobe()
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/x86/include/asm/kprobes.h | 2 ++ arch/x86/kernel/kprobes/core.c | 15 +++++++++++++- arch/x86/kernel/kprobes/opt.c | 38 +++++++++++++++++++++++++++++----- 3 files changed, 49 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h index 073eb7ad2f56..143bc9abe99c 100644 --- a/arch/x86/include/asm/kprobes.h +++ b/arch/x86/include/asm/kprobes.h @@ -66,6 +66,8 @@ struct arch_specific_insn { */ bool boostable; bool if_modifier; + /* Number of bytes of text poked */ + int tp_len; }; struct arch_optimized_insn { diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 4d7022a740ab..6d8b58c84cbc 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -33,6 +33,7 @@ #include <linux/hardirq.h> #include <linux/preempt.h> #include <linux/sched/debug.h> +#include <linux/perf_event.h> #include <linux/extable.h> #include <linux/kdebug.h> #include <linux/kallsyms.h> @@ -471,6 +472,9 @@ static int arch_copy_kprobe(struct kprobe *p) /* Also, displacement change doesn't affect the first byte */ p->opcode = buf[0]; + p->ainsn.tp_len = len; + perf_event_text_poke(p->ainsn.insn, NULL, 0, buf, len); + /* OK, write back the instruction(s) into ROX insn buffer */ text_poke(p->ainsn.insn, buf, len); @@ -502,12 +506,18 @@ int arch_prepare_kprobe(struct kprobe *p) void arch_arm_kprobe(struct kprobe *p) { - text_poke(p->addr, ((unsigned char []){INT3_INSN_OPCODE}), 1); + u8 int3 = INT3_INSN_OPCODE; + + text_poke(p->addr, &int3, 1); text_poke_sync(); + perf_event_text_poke(p->addr, &p->opcode, 1, &int3, 1); } void arch_disarm_kprobe(struct kprobe *p) { + u8 int3 = INT3_INSN_OPCODE; + + perf_event_text_poke(p->addr, &int3, 1, &p->opcode, 1); text_poke(p->addr, &p->opcode, 1); text_poke_sync(); } @@ -515,6 +525,9 @@ void arch_disarm_kprobe(struct kprobe *p) void arch_remove_kprobe(struct kprobe *p) { if (p->ainsn.insn) { + /* Record the perf event before freeing the slot */ + perf_event_text_poke(p->ainsn.insn, p->ainsn.insn, + p->ainsn.tp_len, NULL, 0); free_insn_slot(p->ainsn.insn, p->ainsn.boostable); p->ainsn.insn = NULL; } diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index ea13f6888284..f86be31d37cc 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -6,6 +6,7 @@ * 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> @@ -354,8 +355,15 @@ int arch_within_optimized_kprobe(struct optimized_kprobe *op, static void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty) { - if (op->optinsn.insn) { - free_optinsn_slot(op->optinsn.insn, 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; } @@ -426,8 +434,15 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, (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); @@ -479,10 +494,23 @@ void arch_optimize_kprobes(struct list_head *oplist) */ void arch_unoptimize_kprobe(struct optimized_kprobe *op) { - arch_arm_kprobe(&op->kp); - text_poke(op->kp.addr + INT3_INSN_SIZE, - op->optinsn.copied_insn, DISP32_SIZE); + 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); } /* -- 2.17.1
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