x86/signals: Propagate RF EFLAGS bit through the signal restore call

While porting Vince's perf overflow tests I found perf event
breakpoint overflow does not work properly.

I found the x86 RF EFLAG bit not being set when returning
from debug exception after triggering signal handler. Which
is exactly what you get when you set perf breakpoint overflow
SIGIO handler.

This patch and the next two patches fix the underlying bugs.

This patch adds the RF EFLAGS bit to be restored on return from
signal from the original register context before the signal was
entered.

This will prevent the RF flag to disappear when returning
from exception due to the signal handler being executed.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Originally-Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1367421944-19082-2-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index cf1a471a18a2f7dc1178810fc80d8c3b6462c46a..bccfca68430ec1bb130feb6a87a37385b8b7b6af 100644 (file)
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -34,8 +34,6 @@
 #include <asm/sys_ia32.h>
 #include <asm/smap.h>
 
-#define FIX_EFLAGS     __FIX_EFLAGS
-
 int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
 {
        int err = 0;

diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index beff97f7df3790d04dfba1906fe657b1d024e579..7a958164088c10a61aeed98f6353152ebad83ff5 100644 (file)
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -7,10 +7,10 @@
 
 #include <asm/processor-flags.h>
 
-#define __FIX_EFLAGS   (X86_EFLAGS_AC | X86_EFLAGS_OF | \
+#define FIX_EFLAGS     (X86_EFLAGS_AC | X86_EFLAGS_OF | \
                         X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
                         X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
-                        X86_EFLAGS_CF)
+                        X86_EFLAGS_CF | X86_EFLAGS_RF)
 
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
 

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 69562992e457456eaa4a861de85f6faf4eba8278..9df4c0b5ecac54afac6f0d4f9d30c51973290ecb 100644 (file)
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -43,12 +43,6 @@
 
 #include <asm/sigframe.h>
 
-#ifdef CONFIG_X86_32
-# define FIX_EFLAGS    (__FIX_EFLAGS | X86_EFLAGS_RF)
-#else
-# define FIX_EFLAGS    __FIX_EFLAGS
-#endif
-
 #define COPY(x)                        do {                    \
        get_user_ex(regs->x, &sc->x);                   \
 } while (0)