x86/entry: Remove TIF_SINGLESTEP entry work

Now that SYSENTER with TF set puts X86_EFLAGS_TF directly into
regs->flags, we don't need a TIF_SINGLESTEP fixup in the syscall
entry code.  Remove it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2d15f24da52dafc9d2f0b8d76f55544f4779c517.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 1a000f59f04a28cabdf9375fe8c2121547853f30..209ba334e90fd180b9a8b4de8b929d86b98afb8b 100644 (file)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -172,16 +172,6 @@ long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch,
        if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
                BUG_ON(regs != task_pt_regs(current));
 
-       /*
-        * 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 (work & _TIF_SINGLESTEP)
-               regs->flags |= X86_EFLAGS_TF;
-
 #ifdef CONFIG_SECCOMP
        /*
         * Call seccomp_phase2 before running the other hooks so that

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index c0778fcab06d52a8e36a299c6dd730401da408c6..f2e2302c406fb454f3f85353dbf6ecb2e112cb86 100644 (file)
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -137,7 +137,7 @@ 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_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT |     \
+        _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT |       \
         _TIF_NOHZ)
 
 /* work to do on any return to user space */