Messages in this thread Patch in this message | | | Date | Sun, 30 Sep 2012 21:41:58 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 1/7] uprobes/x86: Only rep+nop can be emulated correctly |
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__skip_sstep() correctly detects the "nontrivial" nop insns, but since it doesn't update regs->ip we can not really skip "0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0", the probed application is killed by SIGILL'ed handle_swbp().
Remove these additional checks. If we want to implement this correctly we need to know the full insn length to update ->ip.
rep* + nop is fine even without updating ->ip.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- arch/x86/kernel/uprobes.c | 16 ++-------------- 1 files changed, 2 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 9538f00..aafa555 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -651,31 +651,19 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) /* * Skip these instructions as per the currently known x86 ISA. - * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 } + * rep=0x66*; nop=0x90 */ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) { int i; for (i = 0; i < MAX_UINSN_BYTES; i++) { - if ((auprobe->insn[i] == 0x66)) + if (auprobe->insn[i] == 0x66) continue; if (auprobe->insn[i] == 0x90) return true; - if (i == (MAX_UINSN_BYTES - 1)) - break; - - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x1f)) - return true; - - if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x19)) - return true; - - if ((auprobe->insn[i] == 0x87) && (auprobe->insn[i+1] == 0xc0)) - return true; - break; } return false; -- 1.5.5.1
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