Commit bd72baff authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Ingo Molnar
Browse files

x86/runtime-const: Add the RUNTIME_CONST_PTR assembly macro 



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

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarIngo 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
parent fadb6f56

arch/x86/include/asm/runtime-const.h

+13 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/lib/getuser.S

+2 −5
Original line number Diff line number Diff line
@@ -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