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![David S. Miller](/assets/img/avatar_default.png)
Such as: fs/ocfs2/file.c: In function ‘ocfs2_file_write_iter’: ./arch/sparc/include/asm/cmpxchg_64.h:55:22: warning: value computed is not used [-Wunused-value] #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) and drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c: In function ‘ixgbevf_xdp_setup’: ./arch/sparc/include/asm/cmpxchg_64.h:55:22: warning: value computed is not used [-Wunused-value] #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) Signed-off-by: David S. Miller <davem@davemloft.net>
208 lines
5.1 KiB
C
208 lines
5.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* 64-bit atomic xchg() and cmpxchg() definitions.
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*
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* Copyright (C) 1996, 1997, 2000 David S. Miller (davem@redhat.com)
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*/
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#ifndef __ARCH_SPARC64_CMPXCHG__
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#define __ARCH_SPARC64_CMPXCHG__
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static inline unsigned long
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__cmpxchg_u32(volatile int *m, int old, int new)
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{
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__asm__ __volatile__("cas [%2], %3, %0"
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: "=&r" (new)
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: "0" (new), "r" (m), "r" (old)
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: "memory");
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return new;
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}
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static inline unsigned long xchg32(__volatile__ unsigned int *m, unsigned int val)
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{
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unsigned long tmp1, tmp2;
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__asm__ __volatile__(
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" mov %0, %1\n"
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"1: lduw [%4], %2\n"
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" cas [%4], %2, %0\n"
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" cmp %2, %0\n"
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" bne,a,pn %%icc, 1b\n"
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" mov %1, %0\n"
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: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
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: "0" (val), "r" (m)
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: "cc", "memory");
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return val;
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}
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static inline unsigned long xchg64(__volatile__ unsigned long *m, unsigned long val)
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{
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unsigned long tmp1, tmp2;
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__asm__ __volatile__(
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" mov %0, %1\n"
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"1: ldx [%4], %2\n"
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" casx [%4], %2, %0\n"
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" cmp %2, %0\n"
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" bne,a,pn %%xcc, 1b\n"
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" mov %1, %0\n"
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: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
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: "0" (val), "r" (m)
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: "cc", "memory");
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return val;
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}
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#define xchg(ptr,x) \
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({ __typeof__(*(ptr)) __ret; \
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__ret = (__typeof__(*(ptr))) \
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__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))); \
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__ret; \
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})
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void __xchg_called_with_bad_pointer(void);
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/*
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* Use 4 byte cas instruction to achieve 2 byte xchg. Main logic
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* here is to get the bit shift of the byte we are interested in.
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* The XOR is handy for reversing the bits for big-endian byte order.
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*/
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static inline unsigned long
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xchg16(__volatile__ unsigned short *m, unsigned short val)
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{
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unsigned long maddr = (unsigned long)m;
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int bit_shift = (((unsigned long)m & 2) ^ 2) << 3;
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unsigned int mask = 0xffff << bit_shift;
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unsigned int *ptr = (unsigned int *) (maddr & ~2);
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unsigned int old32, new32, load32;
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/* Read the old value */
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load32 = *ptr;
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do {
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old32 = load32;
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new32 = (load32 & (~mask)) | val << bit_shift;
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load32 = __cmpxchg_u32(ptr, old32, new32);
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} while (load32 != old32);
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return (load32 & mask) >> bit_shift;
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}
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static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr,
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int size)
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{
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switch (size) {
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case 2:
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return xchg16(ptr, x);
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case 4:
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return xchg32(ptr, x);
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case 8:
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return xchg64(ptr, x);
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}
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__xchg_called_with_bad_pointer();
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return x;
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}
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/*
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* Atomic compare and exchange. Compare OLD with MEM, if identical,
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* store NEW in MEM. Return the initial value in MEM. Success is
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* indicated by comparing RETURN with OLD.
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*/
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#include <asm-generic/cmpxchg-local.h>
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static inline unsigned long
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__cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new)
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{
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__asm__ __volatile__("casx [%2], %3, %0"
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: "=&r" (new)
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: "0" (new), "r" (m), "r" (old)
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: "memory");
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return new;
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}
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/*
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* Use 4 byte cas instruction to achieve 1 byte cmpxchg. Main logic
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* here is to get the bit shift of the byte we are interested in.
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* The XOR is handy for reversing the bits for big-endian byte order
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*/
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static inline unsigned long
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__cmpxchg_u8(volatile unsigned char *m, unsigned char old, unsigned char new)
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{
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unsigned long maddr = (unsigned long)m;
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int bit_shift = (((unsigned long)m & 3) ^ 3) << 3;
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unsigned int mask = 0xff << bit_shift;
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unsigned int *ptr = (unsigned int *) (maddr & ~3);
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unsigned int old32, new32, load;
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unsigned int load32 = *ptr;
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do {
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new32 = (load32 & ~mask) | (new << bit_shift);
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old32 = (load32 & ~mask) | (old << bit_shift);
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load32 = __cmpxchg_u32(ptr, old32, new32);
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if (load32 == old32)
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return old;
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load = (load32 & mask) >> bit_shift;
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} while (load == old);
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return load;
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}
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/* This function doesn't exist, so you'll get a linker error
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if something tries to do an invalid cmpxchg(). */
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void __cmpxchg_called_with_bad_pointer(void);
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static inline unsigned long
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__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
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{
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switch (size) {
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case 1:
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return __cmpxchg_u8(ptr, old, new);
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case 4:
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return __cmpxchg_u32(ptr, old, new);
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case 8:
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return __cmpxchg_u64(ptr, old, new);
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}
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__cmpxchg_called_with_bad_pointer();
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return old;
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}
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#define cmpxchg(ptr,o,n) \
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({ \
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__typeof__(*(ptr)) _o_ = (o); \
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__typeof__(*(ptr)) _n_ = (n); \
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(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
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(unsigned long)_n_, sizeof(*(ptr))); \
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})
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/*
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* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
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* them available.
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*/
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static inline unsigned long __cmpxchg_local(volatile void *ptr,
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unsigned long old,
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unsigned long new, int size)
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{
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switch (size) {
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case 4:
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case 8: return __cmpxchg(ptr, old, new, size);
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default:
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return __cmpxchg_local_generic(ptr, old, new, size);
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}
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return old;
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}
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#define cmpxchg_local(ptr, o, n) \
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((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
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(unsigned long)(n), sizeof(*(ptr))))
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#define cmpxchg64_local(ptr, o, n) \
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({ \
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BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
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cmpxchg_local((ptr), (o), (n)); \
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})
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#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
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#endif /* __ARCH_SPARC64_CMPXCHG__ */
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