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4c9a938001
- Use "+" constraint modifier,
simplify inputs and output lists,
delete dummy variables with meaningless names,
"&" only makes sense in complex assembly creating constraints on
intermediate registers. But 1 instruction assemblies don't have
inner body so to speak.
- Write "rep stos*" on one line:
Rep prefix is integral part of x86 instruction. I'm not sure why
people separate "rep" with newline.
Uros Bizjak adds context: "some archaic assemblers rejected 'rep
insn' on one line. I have checked that the minimum required
binutils-2.25 assembles this without problems."
- Use __auto_type for maximum copy pasta experience,
- Reformat a bit to make everything looks nicer.
Note that "memory" clobber is too much if "n" is known at compile time.
However,
"=m" (*(T(*)[n])s)
doesn't work because -Wvla even if "n" is compile time constant:
if (BCP(n)) {
rep stos
: "=m" (*(T(*)[n])s)
} else {
rep stosw
: "memory"
}
The above doesn't work.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20240314165715.31831-1-adobriyan@gmail.com
105 lines
2.5 KiB
C
105 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_STRING_64_H
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#define _ASM_X86_STRING_64_H
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#ifdef __KERNEL__
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#include <linux/jump_label.h>
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/* Written 2002 by Andi Kleen */
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/* Even with __builtin_ the compiler may decide to use the out of line
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function. */
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#if defined(__SANITIZE_MEMORY__) && defined(__NO_FORTIFY)
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#include <linux/kmsan_string.h>
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#endif
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#define __HAVE_ARCH_MEMCPY 1
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extern void *memcpy(void *to, const void *from, size_t len);
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extern void *__memcpy(void *to, const void *from, size_t len);
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#define __HAVE_ARCH_MEMSET
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void *memset(void *s, int c, size_t n);
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void *__memset(void *s, int c, size_t n);
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/*
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* KMSAN needs to instrument as much code as possible. Use C versions of
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* memsetXX() from lib/string.c under KMSAN.
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*/
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#if !defined(CONFIG_KMSAN)
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#define __HAVE_ARCH_MEMSET16
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static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
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{
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const __auto_type s0 = s;
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asm volatile (
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"rep stosw"
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: "+D" (s), "+c" (n)
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: "a" (v)
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: "memory"
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);
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return s0;
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}
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#define __HAVE_ARCH_MEMSET32
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static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
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{
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const __auto_type s0 = s;
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asm volatile (
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"rep stosl"
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: "+D" (s), "+c" (n)
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: "a" (v)
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: "memory"
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);
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return s0;
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}
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#define __HAVE_ARCH_MEMSET64
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static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
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{
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const __auto_type s0 = s;
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asm volatile (
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"rep stosq"
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: "+D" (s), "+c" (n)
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: "a" (v)
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: "memory"
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);
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return s0;
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}
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#endif
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#define __HAVE_ARCH_MEMMOVE
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void *memmove(void *dest, const void *src, size_t count);
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void *__memmove(void *dest, const void *src, size_t count);
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int memcmp(const void *cs, const void *ct, size_t count);
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size_t strlen(const char *s);
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char *strcpy(char *dest, const char *src);
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char *strcat(char *dest, const char *src);
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int strcmp(const char *cs, const char *ct);
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#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
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#define __HAVE_ARCH_MEMCPY_FLUSHCACHE 1
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void __memcpy_flushcache(void *dst, const void *src, size_t cnt);
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static __always_inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
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{
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if (__builtin_constant_p(cnt)) {
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switch (cnt) {
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case 4:
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asm ("movntil %1, %0" : "=m"(*(u32 *)dst) : "r"(*(u32 *)src));
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return;
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case 8:
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asm ("movntiq %1, %0" : "=m"(*(u64 *)dst) : "r"(*(u64 *)src));
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return;
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case 16:
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asm ("movntiq %1, %0" : "=m"(*(u64 *)dst) : "r"(*(u64 *)src));
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asm ("movntiq %1, %0" : "=m"(*(u64 *)(dst + 8)) : "r"(*(u64 *)(src + 8)));
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return;
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}
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}
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__memcpy_flushcache(dst, src, cnt);
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}
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#endif
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#endif /* __KERNEL__ */
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#endif /* _ASM_X86_STRING_64_H */
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