arch/sparc/include/asm/checksum_32.h

Source file repositories/reference/linux-study-clean/arch/sparc/include/asm/checksum_32.h

File Facts

System
Linux kernel
Corpus path
arch/sparc/include/asm/checksum_32.h
Extension
.h
Size
5791 bytes
Lines
211
Domain
Architecture Layer
Bucket
arch/sparc
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 __SPARC_CHECKSUM_H
#define __SPARC_CHECKSUM_H

/*  checksum.h:  IP/UDP/TCP checksum routines on the Sparc.
 *
 *  Copyright(C) 1995 Linus Torvalds
 *  Copyright(C) 1995 Miguel de Icaza
 *  Copyright(C) 1996 David S. Miller
 *  Copyright(C) 1996 Eddie C. Dost
 *  Copyright(C) 1997 Jakub Jelinek
 *
 * derived from:
 *	Alpha checksum c-code
 *      ix86 inline assembly
 *      RFC1071 Computing the Internet Checksum
 */

#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);

/* the same as csum_partial, but copies from fs:src while it
 * checksums
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */

unsigned int __csum_partial_copy_sparc_generic (const unsigned char *, unsigned char *);

static inline __wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len)
{
	register unsigned int ret asm("o0") = (unsigned int)src;
	register char *d asm("o1") = dst;
	register int l asm("g1") = len;

	__asm__ __volatile__ (
		"call __csum_partial_copy_sparc_generic\n\t"
		" mov -1, %%g7\n"
	: "=&r" (ret), "=&r" (d), "=&r" (l)
	: "0" (ret), "1" (d), "2" (l)
	: "o2", "o3", "o4", "o5", "o7",
	  "g2", "g3", "g4", "g5", "g7",
	  "memory", "cc");
	return (__force __wsum)ret;
}

static inline __wsum
csum_and_copy_from_user(const void __user *src, void *dst, int len)
{
	if (unlikely(!access_ok(src, len)))
		return 0;
	return csum_partial_copy_nocheck((__force void *)src, dst, len);
}

static inline __wsum
csum_and_copy_to_user(const void *src, void __user *dst, int len)
{
	if (!access_ok(dst, len))
		return 0;
	return csum_partial_copy_nocheck(src, (__force void *)dst, len);
}

/* ihl is always 5 or greater, almost always is 5, and iph is word aligned
 * the majority of the time.
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
	__sum16 sum;

	/* Note: We must read %2 before we touch %0 for the first time,
	 *       because GCC can legitimately use the same register for
	 *       both operands.
	 */
	__asm__ __volatile__("sub\t%2, 4, %%g4\n\t"
			     "ld\t[%1 + 0x00], %0\n\t"
			     "ld\t[%1 + 0x04], %%g2\n\t"

Annotation

Implementation Notes