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lib: Support atomic swap instructions

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If compiler supports riscv atomic instructions, we should
use them instead of legacy gcc built-in macros
__sync_lock_test_and_set in atomic exchange functions.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
This commit is contained in:
Atish Patra 2019-08-29 15:19:12 -07:00 • committed by Anup Patel
parent 2e5cc9051b
commit 6bd1512024
1 changed files with 36 additions and 18 deletions
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54
lib/sbi/riscv_atomic.c
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@ -50,6 +50,39 @@ long atomic_sub_return(atomic_t *atom, long value)
return ret - value;
}
#define __axchg(ptr, new, size) \
({ \
__typeof__(ptr) __ptr = (ptr); \
__typeof__(new) __new = (new); \
__typeof__(*(ptr)) __ret; \
switch (size) { \
case 4: \
__asm__ __volatile__ ( \
" amoswap.w.aqrl %0, %2, %1\n" \
: "=r" (__ret), "+A" (*__ptr) \
: "r" (__new) \
: "memory"); \
break; \
case 8: \
__asm__ __volatile__ ( \
" amoswap.d.aqrl %0, %2, %1\n" \
: "=r" (__ret), "+A" (*__ptr) \
: "r" (__new) \
: "memory"); \
break; \
default: \
break; \
} \
__ret; \
})
#define axchg(ptr, x) \
({ \
__typeof__(*(ptr)) _x_ = (x); \
(__typeof__(*(ptr))) __xchg((ptr), _x_, sizeof(*(ptr))); \
})
#define __xchg(ptr, new, size) \
({ \
__typeof__(ptr) __ptr = (ptr); \
@ -148,12 +181,7 @@ long arch_atomic_xchg(atomic_t *atom, long newval)
{
/* Atomically set new value and return old value. */
#ifdef __riscv_atomic
/*
* The name of GCC built-in macro __sync_lock_test_and_set()
* is misleading. A more appropriate name for GCC built-in
* macro would be __sync_val_exchange().
*/
return __sync_lock_test_and_set(&atom->counter, newval);
return axchg(&atom->counter, newval);
#else
return xchg(&atom->counter, newval);
#endif
@ -164,12 +192,7 @@ unsigned int atomic_raw_xchg_uint(volatile unsigned int *ptr,
{
/* Atomically set new value and return old value. */
#ifdef __riscv_atomic
/*
* The name of GCC built-in macro __sync_lock_test_and_set()
* is misleading. A more appropriate name for GCC built-in
* macro would be __sync_val_exchange().
*/
return __sync_lock_test_and_set(ptr, newval);
return axchg(ptr, newval);
#else
return xchg(ptr, newval);
#endif
@ -180,12 +203,7 @@ unsigned long atomic_raw_xchg_ulong(volatile unsigned long *ptr,
{
/* Atomically set new value and return old value. */
#ifdef __riscv_atomic
/*
* The name of GCC built-in macro __sync_lock_test_and_set()
* is misleading. A more appropriate name for GCC built-in
* macro would be __sync_val_exchange().
*/
return __sync_lock_test_and_set(ptr, newval);
return axchg(ptr, newval);
#else
return xchg(ptr, newval);
#endif