arch/loongarch/lib/memset.S

Source file repositories/reference/linux-study-clean/arch/loongarch/lib/memset.S

File Facts

System
Linux kernel
Corpus path
arch/loongarch/lib/memset.S
Extension
.S
Size
2530 bytes
Lines
172
Domain
Architecture Layer
Bucket
arch/loongarch
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/export.h>
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/cpu.h>
#include <asm/regdef.h>
#include <asm/unwind_hints.h>

.macro fill_to_64 r0
	bstrins.d \r0, \r0, 15, 8
	bstrins.d \r0, \r0, 31, 16
	bstrins.d \r0, \r0, 63, 32
.endm

.section .noinstr.text, "ax"

SYM_FUNC_START(memset)
	/*
	 * Some CPUs support hardware unaligned access
	 */
	ALTERNATIVE	"b __memset_generic", \
			"b __memset_fast", CPU_FEATURE_UAL
SYM_FUNC_END(memset)
SYM_FUNC_ALIAS(__memset, memset)

EXPORT_SYMBOL(memset)
EXPORT_SYMBOL(__memset)

_ASM_NOKPROBE(memset)
_ASM_NOKPROBE(__memset)

/*
 * void *__memset_generic(void *s, int c, size_t n)
 *
 * a0: s
 * a1: c
 * a2: n
 */
SYM_FUNC_START(__memset_generic)
	move	a3, a0
	beqz	a2, 2f

1:	st.b	a1, a0, 0
	addi.d	a0, a0, 1
	addi.d	a2, a2, -1
	bgt	a2, zero, 1b

2:	move	a0, a3
	jr	ra
SYM_FUNC_END(__memset_generic)
_ASM_NOKPROBE(__memset_generic)

/*
 * void *__memset_fast(void *s, int c, size_t n)
 *
 * a0: s
 * a1: c
 * a2: n
 */
SYM_FUNC_START(__memset_fast)
	/* fill a1 to 64 bits */
	fill_to_64 a1

	sltui	t0, a2, 9
	bnez	t0, .Lsmall

	add.d	a2, a0, a2
	st.d	a1, a0, 0

	/* align up address */

Annotation

Implementation Notes