arch/arm64/lib/copy_to_user.S

Source file repositories/reference/linux-study-clean/arch/arm64/lib/copy_to_user.S

File Facts

System
Linux kernel
Corpus path
arch/arm64/lib/copy_to_user.S
Extension
.S
Size
1693 bytes
Lines
84
Domain
Architecture Layer
Bucket
arch/arm64
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/linkage.h>

#include <asm/asm-uaccess.h>
#include <asm/assembler.h>
#include <asm/cache.h>

/*
 * Copy to user space from a kernel buffer (alignment handled by the hardware)
 *
 * Parameters:
 *	x0 - to
 *	x1 - from
 *	x2 - n
 * Returns:
 *	x0 - bytes not copied
 */
	.macro ldrb1 reg, ptr, val
	ldrb  \reg, [\ptr], \val
	.endm

	.macro strb1 reg, ptr, val
	user_ldst 9998f, sttrb, \reg, \ptr, \val
	.endm

	.macro ldrh1 reg, ptr, val
	ldrh  \reg, [\ptr], \val
	.endm

	.macro strh1 reg, ptr, val
	user_ldst 9997f, sttrh, \reg, \ptr, \val
	.endm

	.macro ldr1 reg, ptr, val
	ldr \reg, [\ptr], \val
	.endm

	.macro str1 reg, ptr, val
	user_ldst 9997f, sttr, \reg, \ptr, \val
	.endm

	.macro ldp1 reg1, reg2, ptr, val
	ldp \reg1, \reg2, [\ptr], \val
	.endm

	.macro stp1 reg1, reg2, ptr, val
	user_stp 9997f, \reg1, \reg2, \ptr, \val
	.endm

	.macro cpy1 dst, src, count
	.arch_extension mops
	USER_CPY(9997f, 1, cpyfpwt [\dst]!, [\src]!, \count!)
	USER_CPY(9996f, 1, cpyfmwt [\dst]!, [\src]!, \count!)
	USER_CPY(9996f, 1, cpyfewt [\dst]!, [\src]!, \count!)
	.endm

end	.req	x5
srcin	.req	x15
SYM_FUNC_START(__arch_copy_to_user)
	add	end, x0, x2
	mov	srcin, x1
#include "copy_template.S"
	mov	x0, #0
	ret

	// Exception fixups
9996:	b.cs	9997f
	// Registers are in Option A format
	add	dst, dst, count
9997:	cmp	dst, dstin
	b.ne	9998f

Annotation

Implementation Notes