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 6bc07f0f1202eeb1eaac0b55064acad7f355371a..0ad987d02b722c8dfab8077990ca24fd3b70d732 100644 (file)
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -383,10 +383,6 @@ syscall_exit:
                                        # 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 d92373630963f980fb5471a0d96d903b5d4b18bf..295b5f5c9389d2d0a75bbe4e8e15d7c48638e313 100644 (file)
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -657,12 +657,6 @@ static void do_signal(struct pt_regs *regs)
 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 e53b267662e712681d99b4b5ae6014af9bf790c1..bf87684474f18497e2326d497217ae45b4888df5 100644 (file)
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -487,12 +487,6 @@ static void do_signal(struct pt_regs *regs)
 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 895339d2bc0bae799af368ec10efff5050d5afc3..fb8d3cdf143ec1593d92bd0314bd0aa2267740f8 100644 (file)
--- a/include/asm-x86/thread_info.h
+++ b/include/asm-x86/thread_info.h
@@ -124,7 +124,7 @@ struct thread_info {
 /* 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 @@ struct thread_info {
 
 /* 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                                                        \