x86 ptrace: unify TIF_SINGLESTEP
This unifies the treatment of TIF_SINGLESTEP on i386 and x86_64.
The bit is now excluded from _TIF_WORK_MASK on i386 as it has been
on x86_64. This means the do_notify_resume() path using it is never
used, so TIF_SINGLESTEP is not cleared on returning to user mode.
Both now leave TIF_SINGLESTEP set when returning to user, so that
it's already set on an int $0x80 system call entry. This removes
the need for testing TF on the system_call path. Doing it this way
fixes the regression for PTRACE_SINGLESTEP into a sigreturn syscall,
introduced by commit 1e2e99f0e4aa6363e8515ed17011c210c8f1b52a.
The clear_TF_reenable case that sets TIF_SINGLESTEP can only happen
on a non-exception kernel entry, i.e. sysenter/syscall instruction.
That will always get to the syscall exit tracing path.
Signed-off-by: Roland McGrath <roland@redhat.com>
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 6bc07f0..0ad987d 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -383,10 +383,6 @@
# setting need_resched or sigpending
# between sampling and the iret
TRACE_IRQS_OFF
- testl $X86_EFLAGS_TF,PT_EFLAGS(%esp) # If tracing set singlestep flag on exit
- jz no_singlestep
- orl $_TIF_SINGLESTEP,TI_flags(%ebp)
-no_singlestep:
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx # current->work
jne syscall_exit_work
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index d923736..295b5f5 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -657,12 +657,6 @@
void
do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
{
- /* Pending single-step? */
- if (thread_info_flags & _TIF_SINGLESTEP) {
- regs->flags |= X86_EFLAGS_TF;
- clear_thread_flag(TIF_SINGLESTEP);
- }
-
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index e53b267..bf87684 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -487,12 +487,6 @@
void do_notify_resume(struct pt_regs *regs, void *unused,
__u32 thread_info_flags)
{
- /* Pending single-step? */
- if (thread_info_flags & _TIF_SINGLESTEP) {
- regs->flags |= X86_EFLAGS_TF;
- clear_thread_flag(TIF_SINGLESTEP);
- }
-
#ifdef CONFIG_X86_MCE
/* notify userspace of pending MCEs */
if (thread_info_flags & _TIF_MCE_NOTIFY)
diff --git a/include/asm-x86/thread_info.h b/include/asm-x86/thread_info.h
index 895339d..fb8d3cd 100644
--- a/include/asm-x86/thread_info.h
+++ b/include/asm-x86/thread_info.h
@@ -124,7 +124,7 @@
/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
(0x0000FFFF & \
- ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP| \
+ ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \
_TIF_SECCOMP|_TIF_SYSCALL_EMU))
/* work to do on any return to user space */
@@ -132,7 +132,7 @@
/* Only used for 64 bit */
#define _TIF_DO_NOTIFY_MASK \
- (_TIF_SIGPENDING|_TIF_SINGLESTEP|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED)
+ (_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_HRTICK_RESCHED)
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW \