From: Prasanna S Panchamukhi 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 Signed-off-by: Andrew Morton --- 25-akpm/arch/i386/kernel/kprobes.c | 7 +++++++ 25-akpm/arch/x86_64/kernel/kprobes.c | 7 +++++++ 2 files changed, 14 insertions(+) diff -puN arch/i386/kernel/kprobes.c~kprobes-incorrect-handling-of-probes-on-ret-lret-instruction arch/i386/kernel/kprobes.c --- 25/arch/i386/kernel/kprobes.c~kprobes-incorrect-handling-of-probes-on-ret-lret-instruction 2005-04-01 00:49:09.000000000 -0800 +++ 25-akpm/arch/i386/kernel/kprobes.c 2005-04-01 00:49:09.000000000 -0800 @@ -217,6 +217,13 @@ static void resume_execution(struct kpro *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 -puN arch/x86_64/kernel/kprobes.c~kprobes-incorrect-handling-of-probes-on-ret-lret-instruction arch/x86_64/kernel/kprobes.c --- 25/arch/x86_64/kernel/kprobes.c~kprobes-incorrect-handling-of-probes-on-ret-lret-instruction 2005-04-01 00:49:09.000000000 -0800 +++ 25-akpm/arch/x86_64/kernel/kprobes.c 2005-04-01 00:49:09.000000000 -0800 @@ -355,6 +355,13 @@ static void resume_execution(struct kpro *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; _