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x86/runtime-const: Add the RUNTIME_CONST_PTR assembly macro

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Add an assembly macro to refer runtime cost. It hides linker magic and
makes assembly more readable.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250304153342.2016569-1-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2025-03-04 17:33:42 +02:00 committed by Ingo Molnar
parent fadb6f569b
commit bd72baff22
2 changed files with 15 additions and 5 deletions
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13
arch/x86/include/asm/runtime-const.h
View File

@ -2,6 +2,18 @@
#ifndef _ASM_RUNTIME_CONST_H
#define _ASM_RUNTIME_CONST_H
#ifdef __ASSEMBLY__
.macro RUNTIME_CONST_PTR sym reg
movq $0x0123456789abcdef, %\reg
1:
.pushsection runtime_ptr_\sym, "a"
.long 1b - 8 - .
.popsection
.endm
#else /* __ASSEMBLY__ */
#define runtime_const_ptr(sym) ({ \
typeof(sym) __ret; \
asm_inline("mov %1,%0\n1:\n" \
@ -58,4 +70,5 @@ static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
}
}
#endif /* __ASSEMBLY__ */
#endif

7
arch/x86/lib/getuser.S
View File

@ -35,16 +35,13 @@
#include <asm/thread_info.h>
#include <asm/asm.h>
#include <asm/smap.h>
#include <asm/runtime-const.h>
#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC
.macro check_range size:req
.if IS_ENABLED(CONFIG_X86_64)
movq $0x0123456789abcdef,%rdx
1:
.pushsection runtime_ptr_USER_PTR_MAX,"a"
.long 1b - 8 - .
.popsection
RUNTIME_CONST_PTR USER_PTR_MAX, rdx
cmp %rdx, %rax
cmova %rdx, %rax
.else