diff options
Diffstat (limited to 'arch/arm64/kernel/probes/kprobes.c')
-rw-r--r-- | arch/arm64/kernel/probes/kprobes.c | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index d9dfa82c1f18..c9e4d0720285 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -44,13 +44,28 @@ post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); static void __kprobes arch_prepare_ss_slot(struct kprobe *p) { kprobe_opcode_t *addr = p->ainsn.api.insn; - void *addrs[] = {addr, addr + 1}; - u32 insns[] = {p->opcode, BRK64_OPCODE_KPROBES_SS}; - /* prepare insn slot */ - aarch64_insn_patch_text(addrs, insns, 2); - - flush_icache_range((uintptr_t)addr, (uintptr_t)(addr + MAX_INSN_SIZE)); + /* + * Prepare insn slot, Mark Rutland points out it depends on a coupe of + * subtleties: + * + * - That the I-cache maintenance for these instructions is complete + * *before* the kprobe BRK is written (and aarch64_insn_patch_text_nosync() + * ensures this, but just omits causing a Context-Synchronization-Event + * on all CPUS). + * + * - That the kprobe BRK results in an exception (and consequently a + * Context-Synchronoization-Event), which ensures that the CPU will + * fetch thesingle-step slot instructions *after* this, ensuring that + * the new instructions are used + * + * It supposes to place ISB after patching to guarantee I-cache maintenance + * is observed on all CPUS, however, single-step slot is installed in + * the BRK exception handler, so it is unnecessary to generate + * Contex-Synchronization-Event via ISB again. + */ + aarch64_insn_patch_text_nosync(addr, p->opcode); + aarch64_insn_patch_text_nosync(addr + 1, BRK64_OPCODE_KPROBES_SS); /* * Needs restoring of return address after stepping xol. @@ -335,7 +350,7 @@ static void __kprobes kprobe_handler(struct pt_regs *regs) } static int __kprobes -kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned int esr) +kprobe_breakpoint_ss_handler(struct pt_regs *regs, unsigned long esr) { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); unsigned long addr = instruction_pointer(regs); @@ -359,7 +374,7 @@ static struct break_hook kprobes_break_ss_hook = { }; static int __kprobes -kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) +kprobe_breakpoint_handler(struct pt_regs *regs, unsigned long esr) { kprobe_handler(regs); return DBG_HOOK_HANDLED; |