On Tue, 2 Mar 2021 09:54:43 +0100
Peter Zijlstra <pet...@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 <mhira...@kernel.org>
