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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright IBM Corp. 1999, 2011
*
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
*/
#ifndef __ASM_CMPXCHG_H
#define __ASM_CMPXCHG_H
#include <linux/mmdebug.h>
#include <linux/types.h>
#include <linux/bug.h>
#include <asm/asm.h>
void __cmpxchg_called_with_bad_pointer(void);
static __always_inline u32 __cs_asm(u64 ptr, u32 old, u32 new)
{
asm volatile(
" cs %[old],%[new],%[ptr]\n"
: [old] "+d" (old), [ptr] "+Q" (*(u32 *)ptr)
: [new] "d" (new)
: "memory", "cc");
return old;
}
static __always_inline u64 __csg_asm(u64 ptr, u64 old, u64 new)
{
asm volatile(
" csg %[old],%[new],%[ptr]\n"
: [old] "+d" (old), [ptr] "+QS" (*(u64 *)ptr)
: [new] "d" (new)
: "memory", "cc");
return old;
}
static inline u8 __arch_cmpxchg1(u64 ptr, u8 old, u8 new)
{
union {
u8 b[4];
u32 w;
} old32, new32;
u32 prev;
int i;
i = ptr & 3;
ptr &= ~0x3;
prev = READ_ONCE(*(u32 *)ptr);
do {
old32.w = prev;
if (old32.b[i] != old)
return old32.b[i];
new32.w = old32.w;
new32.b[i] = new;
prev = __cs_asm(ptr, old32.w, new32.w);
} while (prev != old32.w);
return old;
}
static inline u16 __arch_cmpxchg2(u64 ptr, u16 old, u16 new)
{
union {
u16 b[2];
u32 w;
} old32, new32;
u32 prev;
int i;
i = (ptr & 3) >> 1;
ptr &= ~0x3;
prev = READ_ONCE(*(u32 *)ptr);
do {
old32.w = prev;
if (old32.b[i] != old)
return old32.b[i];
new32.w = old32.w;
new32.b[i] = new;
prev = __cs_asm(ptr, old32.w, new32.w);
} while (prev != old32.w);
return old;
}
static __always_inline u64 __arch_cmpxchg(u64 ptr, u64 old, u64 new, int size)
{
switch (size) {
case 1: return __arch_cmpxchg1(ptr, old & 0xff, new & 0xff);
case 2: return __arch_cmpxchg2(ptr, old & 0xffff, new & 0xffff);
case 4: return __cs_asm(ptr, old & 0xffffffff, new & 0xffffffff);
case 8: return __csg_asm(ptr, old, new);
default: __cmpxchg_called_with_bad_pointer();
}
return old;
}
#define arch_cmpxchg(ptr, o, n) \
({ \
(__typeof__(*(ptr)))__arch_cmpxchg((unsigned long)(ptr), \
(unsigned long)(o), \
(unsigned long)(n), \
sizeof(*(ptr))); \
})
#define arch_cmpxchg64 arch_cmpxchg
#define arch_cmpxchg_local arch_cmpxchg
#define arch_cmpxchg64_local arch_cmpxchg
#ifdef __HAVE_ASM_FLAG_OUTPUTS__
#define arch_try_cmpxchg(ptr, oldp, new) \
({ \
__typeof__(ptr) __oldp = (__typeof__(ptr))(oldp); \
__typeof__(*(ptr)) __old = *__oldp; \
__typeof__(*(ptr)) __new = (new); \
__typeof__(*(ptr)) __prev; \
int __cc; \
\
switch (sizeof(*(ptr))) { \
case 1: \
case 2: { \
__prev = arch_cmpxchg((ptr), (__old), (__new)); \
__cc = (__prev != __old); \
if (unlikely(__cc)) \
*__oldp = __prev; \
break; \
} \
case 4: { \
asm volatile( \
" cs %[__old],%[__new],%[__ptr]\n" \
: [__old] "+d" (*__oldp), \
[__ptr] "+Q" (*(ptr)), \
"=@cc" (__cc) \
: [__new] "d" (__new) \
: "memory"); \
break; \
} \
case 8: { \
asm volatile( \
" csg %[__old],%[__new],%[__ptr]\n" \
: [__old] "+d" (*__oldp), \
[__ptr] "+QS" (*(ptr)), \
"=@cc" (__cc) \
: [__new] "d" (__new) \
: "memory"); \
break; \
} \
default: \
__cmpxchg_called_with_bad_pointer(); \
} \
likely(__cc == 0); \
})
#else /* __HAVE_ASM_FLAG_OUTPUTS__ */
#define arch_try_cmpxchg(ptr, oldp, new) \
({ \
__typeof__((ptr)) __oldp = (__typeof__(ptr))(oldp); \
__typeof__(*(ptr)) __old = *__oldp; \
__typeof__(*(ptr)) __new = (new); \
__typeof__(*(ptr)) __prev; \
\
__prev = arch_cmpxchg((ptr), (__old), (__new)); \
if (unlikely(__prev != __old)) \
*__oldp = __prev; \
likely(__prev == __old); \
})
#endif /* __HAVE_ASM_FLAG_OUTPUTS__ */
#define arch_try_cmpxchg64 arch_try_cmpxchg
#define arch_try_cmpxchg_local arch_try_cmpxchg
#define arch_try_cmpxchg64_local arch_try_cmpxchg
void __xchg_called_with_bad_pointer(void);
static inline u8 __arch_xchg1(u64 ptr, u8 x)
{
int shift = (3 ^ (ptr & 3)) << 3;
u32 mask, old, new;
ptr &= ~0x3;
mask = ~(0xff << shift);
old = READ_ONCE(*(u32 *)ptr);
do {
new = old & mask;
new |= x << shift;
} while (!arch_try_cmpxchg((u32 *)ptr, &old, new));
return old >> shift;
}
static inline u16 __arch_xchg2(u64 ptr, u16 x)
{
int shift = (2 ^ (ptr & 2)) << 3;
u32 mask, old, new;
ptr &= ~0x3;
mask = ~(0xffff << shift);
old = READ_ONCE(*(u32 *)ptr);
do {
new = old & mask;
new |= x << shift;
} while (!arch_try_cmpxchg((u32 *)ptr, &old, new));
return old >> shift;
}
static __always_inline u64 __arch_xchg(u64 ptr, u64 x, int size)
{
switch (size) {
case 1:
return __arch_xchg1(ptr, x & 0xff);
case 2:
return __arch_xchg2(ptr, x & 0xffff);
case 4: {
u32 old = READ_ONCE(*(u32 *)ptr);
do {
} while (!arch_try_cmpxchg((u32 *)ptr, &old, x & 0xffffffff));
return old;
}
case 8: {
u64 old = READ_ONCE(*(u64 *)ptr);
do {
} while (!arch_try_cmpxchg((u64 *)ptr, &old, x));
return old;
}
}
__xchg_called_with_bad_pointer();
return x;
}
#define arch_xchg(ptr, x) \
({ \
(__typeof__(*(ptr)))__arch_xchg((unsigned long)(ptr), \
(unsigned long)(x), \
sizeof(*(ptr))); \
})
#define system_has_cmpxchg128() 1
static __always_inline u128 arch_cmpxchg128(volatile u128 *ptr, u128 old, u128 new)
{
asm volatile(
" cdsg %[old],%[new],%[ptr]\n"
: [old] "+d" (old), [ptr] "+QS" (*ptr)
: [new] "d" (new)
: "memory", "cc");
return old;
}
#define arch_cmpxchg128 arch_cmpxchg128
#define arch_cmpxchg128_local arch_cmpxchg128
#ifdef __HAVE_ASM_FLAG_OUTPUTS__
static __always_inline bool arch_try_cmpxchg128(volatile u128 *ptr, u128 *oldp, u128 new)
{
int cc;
asm volatile(
" cdsg %[old],%[new],%[ptr]\n"
: [old] "+d" (*oldp), [ptr] "+QS" (*ptr), "=@cc" (cc)
: [new] "d" (new)
: "memory");
return likely(cc == 0);
}
#define arch_try_cmpxchg128 arch_try_cmpxchg128
#define arch_try_cmpxchg128_local arch_try_cmpxchg128
#endif /* __HAVE_ASM_FLAG_OUTPUTS__ */
#endif /* __ASM_CMPXCHG_H */
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