From 0b9e2cac8a56e197d0a9e06268db4c8652d23dd5 Mon Sep 17 00:00:00 2001 From: Prasanna S Panchamukhi <prasanna@in.ibm.com> Date: Thu, 5 May 2005 16:15:40 -0700 Subject: [PATCH] [PATCH] Kprobes: Incorrect handling of probes on ret/lret instruction Kprobes could not handle the insertion of a probe on the ret/lret instruction and used to oops after single stepping since kprobes was modifying eip/rip incorrectly. Adjustment of eip/rip is not required after single stepping in case of ret/lret instruction, because eip/rip points to the correct location after execution of the ret/lret instruction. This patch fixes the above problem. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> --- arch/i386/kernel/kprobes.c | 7 +++++++ arch/x86_64/kernel/kprobes.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index 671681659243..59ff9b455069 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -217,6 +217,13 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs) *tos &= ~(TF_MASK | IF_MASK); *tos |= kprobe_old_eflags; break; + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + regs->eflags &= ~TF_MASK; + /* eip is already adjusted, no more changes required*/ + return; case 0xe8: /* call relative - Fix return addr */ *tos = orig_eip + (*tos - copy_eip); break; diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index 4f2a852299b6..f77f8a0ff187 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -355,6 +355,13 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs) *tos &= ~(TF_MASK | IF_MASK); *tos |= kprobe_old_rflags; break; + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + regs->eflags &= ~TF_MASK; + /* rip is already adjusted, no more changes required*/ + return; case 0xe8: /* call relative - Fix return addr */ *tos = orig_rip + (*tos - copy_rip); break; -- GitLab