[PATCH 3/3] x86: do not save callee-preserved registers around lockdep_sys_exit_thunk

[Denys Vlasenko <dvlasenk@redhat.com>]

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: Linus Torvalds <torvalds@linux-foundation.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ingo Molnar <mingo@kernel.org>
CC: Borislav Petkov <bp@alien8.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Alexei Starovoitov <ast@plumgrid.com>
CC: Will Drewry <wad@chromium.org>
CC: Kees Cook <keescook@chromium.org>
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
---
 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
-- 
1.8.1.4