Re: [PATCH -tip] x86/asm: Use %a instead of %c(%%rip) in rip_rel_ptr()
From: H. Peter Anvin
Date: Sun May 04 2025 - 22:59:40 EST
On 5/4/25 11:43, Uros Bizjak wrote:
The "a" asm operand modifier substitutes a memory reference, with the
actual operand treated as address. For x86_64, when a symbol is
provided, the "a" modifier emits "sym(%rip)" instead of "sym".
No functional changes intended.
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
arch/x86/include/asm/asm.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index f963848024a5..d7610b99b8d8 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -116,7 +116,7 @@
#ifndef __ASSEMBLER__
static __always_inline __pure void *rip_rel_ptr(void *p)
{
- asm("leaq %c1(%%rip), %0" : "=r"(p) : "i"(p));
+ asm("leaq %a1, %0" : "=r"(p) : "i"(p));
return p;
}
Also, this function really should be __attribute_const__ rather than __pure.
Acked-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>