From 9c5f225f1a2c67c57ff5dfbe0589de20c5706a16 Mon Sep 17 00:00:00 2001 From: David Wilder Date: Wed, 22 Aug 2007 13:51:44 +0200 Subject: [S390] kprobes: fix instruction length calculation Placing a kprobe on "bc" instruction (s390/s390x) can cause an oops. The instruction length is encoded into the first two bits of the s390 instruction. Kprobe is incorrectly computing the instruction length. The instruction length is used for determining what type of "fix-up" is needed for conditional branch instruction. The problem can bee seen by placing a kprobe on a "bc" instruction that will not branch. The results is that Kprobe incorrectly computes the new instruction pointer (psw.addr) after single stepping the instruction. The problem is corrected with this patch. Signed-off-by: David Wilder Signed-off-by: Martin Schwidefsky Signed-off-by: Heiko Carstens --- arch/s390/kernel/kprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c index 358d2bbbc481..e40373d9fbce 100644 --- a/arch/s390/kernel/kprobes.c +++ b/arch/s390/kernel/kprobes.c @@ -85,7 +85,7 @@ void __kprobes get_instruction_type(struct arch_specific_insn *ainsn) ainsn->reg = (*ainsn->insn & 0xf0) >> 4; /* save the instruction length (pop 5-5) in bytes */ - switch (*(__u8 *) (ainsn->insn) >> 4) { + switch (*(__u8 *) (ainsn->insn) >> 6) { case 0: ainsn->ilen = 2; break; -- cgit v1.2.3