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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: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
This commit is contained in:
Oleg Nesterov 2014-04-05 21:06:10 +02:00
parent 7ba6db2d68
commit d241006354
1 changed files with 1 additions and 19 deletions
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20
arch/x86/kernel/uprobes.c
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@ -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;
}