linux-kernel - [tip: x86/asm] x86/asm: Remove %P operand modifier from altinstr asm templates

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Date: Tue, 19 Mar 2024 12:31:41 -0000
From: "tip-bot2 for Uros Bizjak" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>, Ingo Molnar <mingo@...nel.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Josh Poimboeuf <jpoimboe@...hat.com>, Ard Biesheuvel <ardb@...nel.org>,
 "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/asm] x86/asm: Remove %P operand modifier from altinstr asm
 templates

The following commit has been merged into the x86/asm branch of tip:

Commit-ID:     a3ff53167cef2b5c6c8948246172d6f9279f037f
Gitweb:        https://git.kernel.org/tip/a3ff53167cef2b5c6c8948246172d6f9279f037f
Author:        Uros Bizjak <ubizjak@...il.com>
AuthorDate:    Tue, 19 Mar 2024 11:40:12 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 19 Mar 2024 13:15:34 +01:00

x86/asm: Remove %P operand modifier from altinstr asm templates

The "P" asm operand modifier is a x86 target-specific modifier.

For x86_64, when used with a symbol reference, the "%P" modifier
emits "sym" instead of "sym(%rip)". This property is currently
used to prevent %RIP-relative addressing in .altinstr sections.

%RIP-relative addresses are nowadays correctly handled in .altinstr
sections, so remove %P operand modifier from altinstr asm templates.

Also note that unlike GCC, clang emits %rip-relative symbol
reference with "P" asm operand modifier, so the patch also unifies
symbol handling with both compilers.

No functional changes intended.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Link: https://lore.kernel.org/r/20240319104418.284519-2-ubizjak@gmail.com
---
 arch/x86/include/asm/apic.h          | 2 +-
 arch/x86/include/asm/processor.h     | 6 +++---
 arch/x86/include/asm/special_insns.h | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 94ce0f7..fa2e424 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -91,7 +91,7 @@ static inline void native_apic_mem_write(u32 reg, u32 v)
 {
 	volatile u32 *addr = (volatile u32 *)(APIC_BASE + reg);
 
-	alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP,
+	alternative_io("movl %0, %1", "xchgl %0, %1", X86_BUG_11AP,
 		       ASM_OUTPUT2("=r" (v), "=m" (*addr)),
 		       ASM_OUTPUT2("0" (v), "m" (*addr)));
 }
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 811548f..438c0c8 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -587,7 +587,7 @@ extern char			ignore_fpu_irq;
 # define BASE_PREFETCH		""
 # define ARCH_HAS_PREFETCH
 #else
-# define BASE_PREFETCH		"prefetcht0 %P1"
+# define BASE_PREFETCH		"prefetcht0 %1"
 #endif
 
 /*
@@ -598,7 +598,7 @@ extern char			ignore_fpu_irq;
  */
 static inline void prefetch(const void *x)
 {
-	alternative_input(BASE_PREFETCH, "prefetchnta %P1",
+	alternative_input(BASE_PREFETCH, "prefetchnta %1",
 			  X86_FEATURE_XMM,
 			  "m" (*(const char *)x));
 }
@@ -610,7 +610,7 @@ static inline void prefetch(const void *x)
  */
 static __always_inline void prefetchw(const void *x)
 {
-	alternative_input(BASE_PREFETCH, "prefetchw %P1",
+	alternative_input(BASE_PREFETCH, "prefetchw %1",
 			  X86_FEATURE_3DNOWPREFETCH,
 			  "m" (*(const char *)x));
 }
diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 2e9fc5c..0ee2ba5 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -182,8 +182,8 @@ static __always_inline void clflush(volatile void *__p)
 
 static inline void clflushopt(volatile void *__p)
 {
-	alternative_io(".byte 0x3e; clflush %P0",
-		       ".byte 0x66; clflush %P0",
+	alternative_io(".byte 0x3e; clflush %0",
+		       ".byte 0x66; clflush %0",
 		       X86_FEATURE_CLFLUSHOPT,
 		       "+m" (*(volatile char __force *)__p));
 }