arch/mips/lib/strnlen_user.S

Source file repositories/reference/linux-study-clean/arch/mips/lib/strnlen_user.S

File Facts

System
Linux kernel
Corpus path
arch/mips/lib/strnlen_user.S
Extension
.S
Size
1441 bytes
Lines
65
Domain
Architecture Layer
Bucket
arch/mips
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/asm.h>
#include <asm/asm-offsets.h>
#include <asm/regdef.h>

#define EX(insn,reg,addr,handler)			\
9:	insn	reg, addr;				\
	.section __ex_table,"a";			\
	PTR_WD	9b, handler;				\
	.previous

/*
 * Return the size of a string including the ending NUL character up to a
 * maximum of a1 or 0 in case of error.
 *
 * Note: for performance reasons we deliberately accept that a user may
 *	 make strlen_user and strnlen_user access the first few KSEG0
 *	 bytes.	 There's nothing secret there.	On 64-bit accessing beyond
 *	 the maximum is a tad hairier ...
 */
LEAF(__strnlen_user_asm)
	move		v0, a0
	PTR_ADDU	a1, a0			# stop pointer
1:
#ifdef CONFIG_CPU_DADDI_WORKAROUNDS
	.set		noat
	li		AT, 1
#endif
	beq		v0, a1, 1f		# limit reached?
#ifdef CONFIG_EVA
	.set push
	.set eva
	EX(lbe, t0, (v0), .Lfault)
	.set pop
#else
	EX(lb, t0, (v0), .Lfault)
#endif
	.set		noreorder
	bnez		t0, 1b
1:
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
	 PTR_ADDIU	v0, 1
#else
	 PTR_ADDU	v0, AT
	.set		at
#endif
	.set		reorder
	PTR_SUBU	v0, a0
	jr		ra
	END(__strnlen_user_asm)

.Lfault:
	move		v0, zero
	jr		ra

	EXPORT_SYMBOL(__strnlen_user_asm)

Annotation

Implementation Notes