arch/mips/include/asm/checksum.h

Source file repositories/reference/linux-study-clean/arch/mips/include/asm/checksum.h

File Facts

System
Linux kernel
Corpus path
arch/mips/include/asm/checksum.h
Extension
.h
Size
5791 bytes
Lines
254
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: implementation source
Status
source 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

#ifndef _ASM_CHECKSUM_H
#define _ASM_CHECKSUM_H

#ifdef CONFIG_GENERIC_CSUM
#include <asm-generic/checksum.h>
#else

#include <linux/in6.h>

#include <linux/uaccess.h>

/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
__wsum csum_partial(const void *buff, int len, __wsum sum);

__wsum __csum_partial_copy_from_user(const void __user *src, void *dst, int len);
__wsum __csum_partial_copy_to_user(const void *src, void __user *dst, int len);

#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
static inline
__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
{
	might_fault();
	if (!access_ok(src, len))
		return 0;
	return __csum_partial_copy_from_user(src, dst, len);
}

/*
 * Copy and checksum to user
 */
#define HAVE_CSUM_COPY_USER
static inline
__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
{
	might_fault();
	if (!access_ok(dst, len))
		return 0;
	return __csum_partial_copy_to_user(src, dst, len);
}

/*
 * the same as csum_partial, but copies from user space (but on MIPS
 * we have just one address space, so this is identical to the above)
 */
#define _HAVE_ARCH_CSUM_AND_COPY
__wsum __csum_partial_copy_nocheck(const void *src, void *dst, int len);
static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
{
	return __csum_partial_copy_nocheck(src, dst, len);
}

/*
 *	Fold a partial checksum without adding pseudo headers
 */
static inline __sum16 csum_fold(__wsum csum)
{
	u32 sum = (__force u32)csum;

	sum += (sum << 16);
	csum = (__force __wsum)(sum < (__force u32)csum);
	sum >>= 16;
	sum += (__force u32)csum;

	return (__force __sum16)~sum;
}
#define csum_fold csum_fold

/*
 *	This is a version of ip_compute_csum() optimized for IP headers,
 *	which always checksum on 4 octet boundaries.
 *
 *	By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
 *	Arnt Gulbrandsen.
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
	const unsigned int *word = iph;
	const unsigned int *stop = word + ihl;
	unsigned int csum;

Annotation

Implementation Notes