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Commit d2410063 authored by Oleg Nesterov's avatar Oleg Nesterov
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uprobes/x86: Emulate nop's using ops->emulate() 



Finally we can kill the ugly (and very limited) code in __skip_sstep().
Just change branch_setup_xol_ops() to treat "nop" as jmp to the next insn.

Thanks to lib/insn.c, it is clever enough. OPCODE1() == 0x90 includes
"(rep;)+ nop;" at least, and (afaics) much more.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarJim Keniston <jkenisto@us.ibm.com>
parent 7ba6db2d

arch/x86/kernel/uprobes.c

+1 −19
Original line number Diff line number Diff line
@@ -478,6 +478,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) 
	switch (OPCODE1(insn)) {

	case 0xeb:	/* jmp 8 */

	case 0xe9:	/* jmp 32 */

	case 0x90:	/* prefix* + nop; same as jmp with .offs = 0 */

		break;

	default:

		return -ENOSYS;
@@ -710,29 +711,10 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) 
		regs->flags &= ~X86_EFLAGS_TF;

}



/*

 * Skip these instructions as per the currently known x86 ISA.

 * rep=0x66*; nop=0x90

 */

static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)

{

	int i;



	if (auprobe->ops->emulate)

		return auprobe->ops->emulate(auprobe, regs);



	/* TODO: move this code into ->emulate() hook */

	for (i = 0; i < MAX_UINSN_BYTES; i++) {

		if (auprobe->insn[i] == 0x66)

			continue;



		if (auprobe->insn[i] == 0x90) {

			regs->ip += i + 1;

			return true;

		}



		break;

	}

	return false;

}