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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/openrisc/include/asm/cmpxchg.h | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/openrisc/include/asm/cmpxchg.h')
-rw-r--r-- | arch/openrisc/include/asm/cmpxchg.h | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/arch/openrisc/include/asm/cmpxchg.h b/arch/openrisc/include/asm/cmpxchg.h new file mode 100644 index 000000000..79fd16162 --- /dev/null +++ b/arch/openrisc/include/asm/cmpxchg.h @@ -0,0 +1,171 @@ +/* + * 1,2 and 4 byte cmpxchg and xchg implementations for OpenRISC. + * + * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> + * Copyright (C) 2017 Stafford Horne <shorne@gmail.com> + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + * + * Note: + * The portable implementations of 1 and 2 byte xchg and cmpxchg using a 4 + * byte cmpxchg is sourced heavily from the sh and mips implementations. + */ + +#ifndef __ASM_OPENRISC_CMPXCHG_H +#define __ASM_OPENRISC_CMPXCHG_H + +#include <linux/bits.h> +#include <linux/compiler.h> +#include <linux/types.h> + +#define __HAVE_ARCH_CMPXCHG 1 + +static inline unsigned long cmpxchg_u32(volatile void *ptr, + unsigned long old, unsigned long new) +{ + __asm__ __volatile__( + "1: l.lwa %0, 0(%1) \n" + " l.sfeq %0, %2 \n" + " l.bnf 2f \n" + " l.nop \n" + " l.swa 0(%1), %3 \n" + " l.bnf 1b \n" + " l.nop \n" + "2: \n" + : "=&r"(old) + : "r"(ptr), "r"(old), "r"(new) + : "cc", "memory"); + + return old; +} + +static inline unsigned long xchg_u32(volatile void *ptr, + unsigned long val) +{ + __asm__ __volatile__( + "1: l.lwa %0, 0(%1) \n" + " l.swa 0(%1), %2 \n" + " l.bnf 1b \n" + " l.nop \n" + : "=&r"(val) + : "r"(ptr), "r"(val) + : "cc", "memory"); + + return val; +} + +static inline u32 cmpxchg_small(volatile void *ptr, u32 old, u32 new, + int size) +{ + int off = (unsigned long)ptr % sizeof(u32); + volatile u32 *p = ptr - off; +#ifdef __BIG_ENDIAN + int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE; +#else + int bitoff = off * BITS_PER_BYTE; +#endif + u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff; + u32 load32, old32, new32; + u32 ret; + + load32 = READ_ONCE(*p); + + while (true) { + ret = (load32 & bitmask) >> bitoff; + if (old != ret) + return ret; + + old32 = (load32 & ~bitmask) | (old << bitoff); + new32 = (load32 & ~bitmask) | (new << bitoff); + + /* Do 32 bit cmpxchg */ + load32 = cmpxchg_u32(p, old32, new32); + if (load32 == old32) + return old; + } +} + +/* xchg */ + +static inline u32 xchg_small(volatile void *ptr, u32 x, int size) +{ + int off = (unsigned long)ptr % sizeof(u32); + volatile u32 *p = ptr - off; +#ifdef __BIG_ENDIAN + int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE; +#else + int bitoff = off * BITS_PER_BYTE; +#endif + u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff; + u32 oldv, newv; + u32 ret; + + do { + oldv = READ_ONCE(*p); + ret = (oldv & bitmask) >> bitoff; + newv = (oldv & ~bitmask) | (x << bitoff); + } while (cmpxchg_u32(p, oldv, newv) != oldv); + + return ret; +} + +/* + * This function doesn't exist, so you'll get a linker error + * if something tries to do an invalid cmpxchg(). + */ +extern unsigned long __cmpxchg_called_with_bad_pointer(void) + __compiletime_error("Bad argument size for cmpxchg"); + +static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, + unsigned long new, int size) +{ + switch (size) { + case 1: + case 2: + return cmpxchg_small(ptr, old, new, size); + case 4: + return cmpxchg_u32(ptr, old, new); + default: + return __cmpxchg_called_with_bad_pointer(); + } +} + +#define arch_cmpxchg(ptr, o, n) \ + ({ \ + (__typeof__(*(ptr))) __cmpxchg((ptr), \ + (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr))); \ + }) + +/* + * This function doesn't exist, so you'll get a linker error if + * something tries to do an invalidly-sized xchg(). + */ +extern unsigned long __xchg_called_with_bad_pointer(void) + __compiletime_error("Bad argument size for xchg"); + +static inline unsigned long __xchg(volatile void *ptr, unsigned long with, + int size) +{ + switch (size) { + case 1: + case 2: + return xchg_small(ptr, with, size); + case 4: + return xchg_u32(ptr, with); + default: + return __xchg_called_with_bad_pointer(); + } +} + +#define arch_xchg(ptr, with) \ + ({ \ + (__typeof__(*(ptr))) __xchg((ptr), \ + (unsigned long)(with), \ + sizeof(*(ptr))); \ + }) + +#endif /* __ASM_OPENRISC_CMPXCHG_H */ |