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x86/asm: Replace "REP; NOP" with PAUSE mnemonic

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Current minimum required version of binutils is 2.25,
which supports PAUSE instruction mnemonic.

Replace "REP; NOP" with this proper mnemonic.

No functional change intended.

Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lore.kernel.org/r/20250418080805.83679-2-ubizjak@gmail.com
This commit is contained in:
Uros Bizjak 2025-04-18 10:07:44 +02:00 committed by Ingo Molnar
parent 42c782fae3
commit d109ff4f0b
3 changed files with 5 additions and 5 deletions
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2
arch/x86/boot/boot.h
View File

@ -34,7 +34,7 @@
extern struct setup_header hdr;
extern struct boot_params boot_params;
#define cpu_relax() asm volatile("rep; nop")
#define cpu_relax() asm volatile("pause")
static inline void io_delay(void)
{

4
arch/x86/include/asm/vdso/processor.h
View File

@ -7,10 +7,10 @@
#ifndef __ASSEMBLER__
/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
/* PAUSE is a good thing to insert into busy-wait loops. */
static __always_inline void rep_nop(void)
{
asm volatile("rep; nop" ::: "memory");
asm volatile("pause" ::: "memory");
}
static __always_inline void cpu_relax(void)

4
arch/x86/kernel/relocate_kernel_64.S
View File

@ -405,7 +405,7 @@ SYM_CODE_START_LOCAL_NOALIGN(pr_char_8250)
inb %dx, %al
testb $XMTRDY, %al
jnz .Lready
rep nop
pause
jmp .Lxmtrdy_loop
.Lready:
@ -426,7 +426,7 @@ SYM_CODE_START_LOCAL_NOALIGN(pr_char_8250_mmio32)
movb (LSR*4)(%rdx), %ah
testb $XMTRDY, %ah
jnz .Lready_mmio
rep nop
pause
jmp .Lxmtrdy_loop_mmio
.Lready_mmio: