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[RFC,V2,10/10] arm64: uprobes: check conditions before simulating instructions

Message ID 350cf38eb8b9008d14a51ef7e0f8099644c8b97f.1434598237.git.panand@redhat.com
State New
Headers show

Commit Message

Pratyush Anand June 18, 2015, 3:58 a.m. UTC 
From: Steve Capper <steve.capper@linaro.org>

Currently uprobes just simulates any instruction that it can't in
place execute. This can lead to unpredictable behaviour if the
execution condition fails and the instruction wouldn't otherwise
have been executed.

This patch adds the condition check

Signed-off-by: Steve Capper <steve.capper@linaro.org>
---
 arch/arm64/kernel/uprobes.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
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Patch

diff --git a/arch/arm64/kernel/uprobes.c b/arch/arm64/kernel/uprobes.c
index 2cc9114deac2..a6d12b81e9ae 100644
--- a/arch/arm64/kernel/uprobes.c
+++ b/arch/arm64/kernel/uprobes.c
@@ -119,15 +119,22 @@  bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
 	kprobe_opcode_t insn;
 	unsigned long addr;
+	struct arch_specific_insn *ainsn;
 
 	if (!auprobe->simulate)
 		return false;
 
 	insn = *(kprobe_opcode_t *)(&auprobe->insn[0]);
 	addr = instruction_pointer(regs);
+	ainsn = &auprobe->ainsn;
+
+	if (ainsn->handler) {
+		if (!ainsn->check_condn || ainsn->check_condn(insn, ainsn, regs))
+			ainsn->handler(insn, addr, regs);
+		else
+			instruction_pointer_set(regs, instruction_pointer(regs) + 4);
+	}
 
-	if (auprobe->ainsn.handler)
-		auprobe->ainsn.handler(insn, addr, regs);
 
 	return true;
 }