linux-kernel - [PATCH RESEND 2/2] locking/atomic/x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64

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Message-ID: <20241103160954.3329-2-ubizjak@gmail.com>
Date: Sun,  3 Nov 2024 17:09:32 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Mark Rutland <mark.rutland@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jan Beulich <JBeulich@...e.com>
Subject: [PATCH RESEND 2/2] locking/atomic/x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu()

x86_32 __arch_{,try_}cmpxchg64_emu()() macros use CALL instruction
inside asm statement. Use ALT_OUTPUT_SP() macro to add required
dependence on %esp register.

Fixes: 79e1dd05d1a2 ("x86: Provide an alternative() based cmpxchg64()")
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Cc: Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Jan Beulich <JBeulich@...e.com>
---
 arch/x86/include/asm/cmpxchg_32.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/cmpxchg_32.h b/arch/x86/include/asm/cmpxchg_32.h
index 62cef2113ca7..fd1282a783dd 100644
--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -94,7 +94,7 @@ static __always_inline bool __try_cmpxchg64_local(volatile u64 *ptr, u64 *oldp,
 	asm volatile(ALTERNATIVE(_lock_loc				\
 				 "call cmpxchg8b_emu",			\
 				 _lock "cmpxchg8b %a[ptr]", X86_FEATURE_CX8) \
-		     : "+a" (o.low), "+d" (o.high)			\
+		     : ALT_OUTPUT_SP("+a" (o.low), "+d" (o.high))	\
 		     : "b" (n.low), "c" (n.high), [ptr] "S" (_ptr)	\
 		     : "memory");					\
 									\
@@ -123,8 +123,8 @@ static __always_inline u64 arch_cmpxchg64_local(volatile u64 *ptr, u64 old, u64
 				 "call cmpxchg8b_emu",			\
 				 _lock "cmpxchg8b %a[ptr]", X86_FEATURE_CX8) \
 		     CC_SET(e)						\
-		     : CC_OUT(e) (ret),					\
-		       "+a" (o.low), "+d" (o.high)			\
+		     : ALT_OUTPUT_SP(CC_OUT(e) (ret),			\
+				     "+a" (o.low), "+d" (o.high))	\
 		     : "b" (n.low), "c" (n.high), [ptr] "S" (_ptr)	\
 		     : "memory");					\
 									\
-- 
2.42.0