diff options
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 10 | ||||
| -rw-r--r-- | arch/x86/kernel/step.c | 13 | ||||
| -rw-r--r-- | include/asm-x86/thread_info.h | 2 |
3 files changed, 24 insertions, 1 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 34e77b16a42a..e37dccce85db 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -1416,6 +1416,16 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs) { long ret = 0; + /* + * If we stepped into a sysenter/syscall insn, it trapped in + * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP. + * If user-mode had set TF itself, then it's still clear from + * do_debug() and we need to set it again to restore the user + * state. If we entered on the slow path, TF was already set. + */ + if (test_thread_flag(TIF_SINGLESTEP)) + regs->flags |= X86_EFLAGS_TF; + /* do the secure computing check first */ secure_computing(regs->orig_ax); diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index 0d2cb363ea75..e8b9863ef8c4 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -108,6 +108,19 @@ static int enable_single_step(struct task_struct *child) unsigned long oflags; /* + * If we stepped into a sysenter/syscall insn, it trapped in + * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP. + * If user-mode had set TF itself, then it's still clear from + * do_debug() and we need to set it again to restore the user + * state so we don't wrongly set TIF_FORCED_TF below. + * If enable_single_step() was used last and that is what + * set TIF_SINGLESTEP, then both TF and TIF_FORCED_TF are + * already set and our bookkeeping is fine. + */ + if (unlikely(test_tsk_thread_flag(child, TIF_SINGLESTEP))) + regs->flags |= X86_EFLAGS_TF; + + /* * Always set TIF_SINGLESTEP - this guarantees that * we single-step system calls etc.. This will also * cause us to set TF when returning to user mode. diff --git a/include/asm-x86/thread_info.h b/include/asm-x86/thread_info.h index b2702a1eeac1..0a8f27d31d0d 100644 --- a/include/asm-x86/thread_info.h +++ b/include/asm-x86/thread_info.h @@ -118,7 +118,7 @@ struct thread_info { /* work to do in syscall_trace_enter() */ #define _TIF_WORK_SYSCALL_ENTRY \ (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | \ - _TIF_SYSCALL_AUDIT | _TIF_SECCOMP) + _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | _TIF_SINGLESTEP) /* work to do in syscall_trace_leave() */ #define _TIF_WORK_SYSCALL_EXIT \ |