[tip:x86/asm] x86/irq/tracing: Do not save callee-preserved registers around lockdep_sys_exit_thunk

[tip-bot for Denys Vlasenko]

Commit-ID:  aa6d9a128b861fe7e9dc37bcc37179837674b739
Gitweb:     http://git.kernel.org/tip/aa6d9a128b861fe7e9dc37bcc37179837674b739
Author:     Denys Vlasenko <dvlasenk@xxxxxxxxxx>
AuthorDate: Wed, 25 Mar 2015 21:14:28 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 27 Mar 2015 10:01:49 +0100

x86/irq/tracing: Do not save callee-preserved registers around lockdep_sys_exit_thunk

Internally, lockdep_sys_exit_thunk saves callee-clobbered
registers, and calls a C function, lockdep_sys_exit. Thus,
callee-preserved registers won't be mangled, there is no need to
save them.

Patch was run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Will Drewry <wad@xxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1427314468-12763-4-git-send-email-dvlasenk@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/irqflags.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 19355f3..9a63eae 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -179,9 +179,7 @@ static inline int arch_irqs_disabled(void)
 #    define LOCKDEP_SYS_EXIT_IRQ \
 	TRACE_IRQS_ON; \
 	sti; \
-	SAVE_EXTRA_REGS; \
 	call lockdep_sys_exit_thunk; \
-	RESTORE_EXTRA_REGS; \
 	cli; \
 	TRACE_IRQS_OFF;
 #  else
--
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