From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Wed, 25 Mar 2015 20:14:28 +0000 (+0100)
Subject: x86/irq/tracing: Do not save callee-preserved registers around lockdep_sys_exit_thunk
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=aa6d9a128b861fe7e9dc37bcc37179837674b739;p=linux-beck.git

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@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1427314468-12763-4-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 19355f34c4a3..9a63eae04e4b 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