linux_dsm_epyc7002/arch/x86/include/asm/string_64.h
Dan Williams 60622d6822 x86/asm/memcpy_mcsafe: Return bytes remaining
Machine check safe memory copies are currently deployed in the pmem
driver whenever reading from persistent memory media, so that -EIO is
returned rather than triggering a kernel panic. While this protects most
pmem accesses, it is not complete in the filesystem-dax case. When
filesystem-dax is enabled reads may bypass the block layer and the
driver via dax_iomap_actor() and its usage of copy_to_iter().

In preparation for creating a copy_to_iter() variant that can handle
machine checks, teach memcpy_mcsafe() to return the number of bytes
remaining rather than -EFAULT when an exception occurs.

Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539238119.31796.14318473522414462886.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 08:32:42 +02:00

158 lines
4.0 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_STRING_64_H
#define _ASM_X86_STRING_64_H
#ifdef __KERNEL__
#include <linux/jump_label.h>
/* Written 2002 by Andi Kleen */
/* Only used for special circumstances. Stolen from i386/string.h */
static __always_inline void *__inline_memcpy(void *to, const void *from, size_t n)
{
unsigned long d0, d1, d2;
asm volatile("rep ; movsl\n\t"
"testb $2,%b4\n\t"
"je 1f\n\t"
"movsw\n"
"1:\ttestb $1,%b4\n\t"
"je 2f\n\t"
"movsb\n"
"2:"
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
: "0" (n / 4), "q" (n), "1" ((long)to), "2" ((long)from)
: "memory");
return to;
}
/* Even with __builtin_ the compiler may decide to use the out of line
function. */
#define __HAVE_ARCH_MEMCPY 1
extern void *memcpy(void *to, const void *from, size_t len);
extern void *__memcpy(void *to, const void *from, size_t len);
#ifndef CONFIG_FORTIFY_SOURCE
#if (__GNUC__ == 4 && __GNUC_MINOR__ < 3) || __GNUC__ < 4
#define memcpy(dst, src, len) \
({ \
size_t __len = (len); \
void *__ret; \
if (__builtin_constant_p(len) && __len >= 64) \
__ret = __memcpy((dst), (src), __len); \
else \
__ret = __builtin_memcpy((dst), (src), __len); \
__ret; \
})
#endif
#endif /* !CONFIG_FORTIFY_SOURCE */
#define __HAVE_ARCH_MEMSET
void *memset(void *s, int c, size_t n);
void *__memset(void *s, int c, size_t n);
#define __HAVE_ARCH_MEMSET16
static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
{
long d0, d1;
asm volatile("rep\n\t"
"stosw"
: "=&c" (d0), "=&D" (d1)
: "a" (v), "1" (s), "0" (n)
: "memory");
return s;
}
#define __HAVE_ARCH_MEMSET32
static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
{
long d0, d1;
asm volatile("rep\n\t"
"stosl"
: "=&c" (d0), "=&D" (d1)
: "a" (v), "1" (s), "0" (n)
: "memory");
return s;
}
#define __HAVE_ARCH_MEMSET64
static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
{
long d0, d1;
asm volatile("rep\n\t"
"stosq"
: "=&c" (d0), "=&D" (d1)
: "a" (v), "1" (s), "0" (n)
: "memory");
return s;
}
#define __HAVE_ARCH_MEMMOVE
void *memmove(void *dest, const void *src, size_t count);
void *__memmove(void *dest, const void *src, size_t count);
int memcmp(const void *cs, const void *ct, size_t count);
size_t strlen(const char *s);
char *strcpy(char *dest, const char *src);
char *strcat(char *dest, const char *src);
int strcmp(const char *cs, const char *ct);
#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
/*
* For files that not instrumented (e.g. mm/slub.c) we
* should use not instrumented version of mem* functions.
*/
#undef memcpy
#define memcpy(dst, src, len) __memcpy(dst, src, len)
#define memmove(dst, src, len) __memmove(dst, src, len)
#define memset(s, c, n) __memset(s, c, n)
#ifndef __NO_FORTIFY
#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
#endif
#endif
#define __HAVE_ARCH_MEMCPY_MCSAFE 1
__must_check unsigned long __memcpy_mcsafe(void *dst, const void *src,
size_t cnt);
DECLARE_STATIC_KEY_FALSE(mcsafe_key);
/**
* memcpy_mcsafe - copy memory with indication if a machine check happened
*
* @dst: destination address
* @src: source address
* @cnt: number of bytes to copy
*
* Low level memory copy function that catches machine checks
* We only call into the "safe" function on systems that can
* actually do machine check recovery. Everyone else can just
* use memcpy().
*
* Return 0 for success, or number of bytes not copied if there was an
* exception.
*/
static __always_inline __must_check unsigned long
memcpy_mcsafe(void *dst, const void *src, size_t cnt)
{
#ifdef CONFIG_X86_MCE
if (static_branch_unlikely(&mcsafe_key))
return __memcpy_mcsafe(dst, src, cnt);
else
#endif
memcpy(dst, src, cnt);
return 0;
}
#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
#define __HAVE_ARCH_MEMCPY_FLUSHCACHE 1
void memcpy_flushcache(void *dst, const void *src, size_t cnt);
#endif
#endif /* __KERNEL__ */
#endif /* _ASM_X86_STRING_64_H */