Messages in this thread | | | Date | Tue, 2 Mar 2021 21:51:24 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC PATCH 1/1] x86/kprobes: Use int3 instead of debug trap for single-step |
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On Tue, 2 Mar 2021 09:54:43 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Mar 02, 2021 at 09:41:32AM +0100, Peter Zijlstra wrote: > > > Aside of a few nits: > > something like so..
Thanks Peter, I completely agree with that change! Let me update the patch.
> > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -457,13 +457,20 @@ static void kprobe_emulate_call(struct k > } > NOKPROBE_SYMBOL(kprobe_emulate_call); > > -static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) > +static __always_inline > +void __kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs, bool cond) > { > unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > > - ip += p->ainsn.rel32; > + if (cond) > + ip += p->ainsn.rel32; > int3_emulate_jmp(regs, ip); > } > + > +static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) > +{ > + __kprobe_emulate_jmp(p, regs, true); > +} > NOKPROBE_SYMBOL(kprobe_emulate_jmp); > > static const unsigned long jcc_mask[6] = { > @@ -488,10 +495,7 @@ static void kprobe_emulate_jcc(struct kp > if (p->ainsn.jcc.type >= 0xe) > match = match && (regs->flags & X86_EFLAGS_ZF); > } > - if ((match && !invert) || (!match && invert)) > - kprobe_emulate_jmp(p, regs); > - else > - regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > + __kprobe_emulate_jmp(p, regs, (match && !invert) || (!match && invert)); > } > NOKPROBE_SYMBOL(kprobe_emulate_jcc); > > @@ -524,10 +528,7 @@ static void kprobe_emulate_loop(struct k > else if (p->ainsn.loop.type == 1) /* LOOPE */ > match = match && (regs->flags & X86_EFLAGS_ZF); > > - if (match) > - kprobe_emulate_jmp(p, regs); > - else > - regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; > + __kprobe_emulate_jmp(p, regs, match); > } > NOKPROBE_SYMBOL(kprobe_emulate_loop); > > @@ -613,6 +614,12 @@ static int prepare_emulation(struct kpro > else > p->ainsn.rel32 = *(s32 *)&insn->immediate.value; > break; > + case 0x70 ... 0x7f: > + /* 1 byte conditional jump */ > + p->ainsn.emulate_op = kprobe_emulate_jcc; > + p->ainsn.jcc.type = opcode & 0xf; > + p->ainsn.rel32 = *(char *)insn->immediate.bytes; > + break; > case 0x0f: > opcode = insn->opcode.bytes[1]; > if ((opcode & 0xf0) == 0x80) { > @@ -667,12 +674,7 @@ static int prepare_emulation(struct kpro > #endif > break; > default: > - if ((opcode & 0xf0) == 0x70) { > - /* 1 byte conditional jump */ > - p->ainsn.emulate_op = kprobe_emulate_jcc; > - p->ainsn.jcc.type = opcode & 0xf; > - p->ainsn.rel32 = *(char *)insn->immediate.bytes; > - } > + break; > } > p->ainsn.size = insn->length; >
-- Masami Hiramatsu <mhiramat@kernel.org>
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