[tip:x86/asm] x86/asm: Add unwind hint annotations to sync_core()

[tip-bot for Josh Poimboeuf]

Commit-ID:  76846bf3cb09e98881cb4908385a0e899716b01f
Gitweb:     http://git.kernel.org/tip/76846bf3cb09e98881cb4908385a0e899716b01f
Author:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Tue, 11 Jul 2017 10:33:45 -0500
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 18 Jul 2017 10:57:44 +0200

x86/asm: Add unwind hint annotations to sync_core()

This enables objtool to grok the iret in the middle of a C function.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: live-patching@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/b057be26193c11d2ed3337b2107bc7adcba42c99.1499786555.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/processor.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6a79547..b27dc9b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -22,6 +22,7 @@ struct vm86;
 #include <asm/nops.h>
 #include <asm/special_insns.h>
 #include <asm/fpu/types.h>
+#include <asm/unwind_hints.h>
 
 #include <linux/personality.h>
 #include <linux/cache.h>
@@ -684,6 +685,7 @@ static inline void sync_core(void)
 	unsigned int tmp;
 
 	asm volatile (
+		UNWIND_HINT_SAVE
 		"mov %%ss, %0\n\t"
 		"pushq %q0\n\t"
 		"pushq %%rsp\n\t"
@@ -693,6 +695,7 @@ static inline void sync_core(void)
 		"pushq %q0\n\t"
 		"pushq $1f\n\t"
 		"iretq\n\t"
+		UNWIND_HINT_RESTORE
 		"1:"
 		: "=&r" (tmp), "+r" (__sp) : : "cc", "memory");
 #endif