From: Gage Eads Date: Wed, 3 Apr 2019 19:44:56 +0000 (-0500) Subject: eal/x86: add 128-bit atomic compare exchange X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=640c5f09ef2cb23d300748e220ea5d8fffdbfdd0;p=dpdk.git eal/x86: add 128-bit atomic compare exchange This operation can be used for non-blocking algorithms, such as a non-blocking stack or ring. It is available only for x86_64. Signed-off-by: Gage Eads Reviewed-by: Honnappa Nagarahalli --- diff --git a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h index fd2ec9c537..4b83159269 100644 --- a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h +++ b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h @@ -34,6 +34,7 @@ /* * Inspired from FreeBSD src/sys/amd64/include/atomic.h * Copyright (c) 1998 Doug Rabson + * Copyright (c) 2019 Intel Corporation * All rights reserved. */ @@ -46,6 +47,7 @@ #include #include +#include #include /*------------------------- 64 bit atomic operations -------------------------*/ @@ -208,4 +210,49 @@ static inline void rte_atomic64_clear(rte_atomic64_t *v) } #endif +/*------------------------ 128 bit atomic operations -------------------------*/ + +/** + * 128-bit integer structure. + */ +RTE_STD_C11 +typedef struct { + RTE_STD_C11 + union { + uint64_t val[2]; + __int128 int128; + }; +} __rte_aligned(16) rte_int128_t; + +static inline int __rte_experimental +rte_atomic128_cmp_exchange(rte_int128_t *dst, + rte_int128_t *exp, + const rte_int128_t *src, + unsigned int weak, + int success, + int failure) +{ + RTE_SET_USED(weak); + RTE_SET_USED(success); + RTE_SET_USED(failure); + uint8_t res; + + asm volatile ( + MPLOCKED + "cmpxchg16b %[dst];" + " sete %[res]" + : [dst] "=m" (dst->val[0]), + "=a" (exp->val[0]), + "=d" (exp->val[1]), + [res] "=r" (res) + : "b" (src->val[0]), + "c" (src->val[1]), + "a" (exp->val[0]), + "d" (exp->val[1]), + "m" (dst->val[0]) + : "memory"); + + return res; +} + #endif /* _RTE_ATOMIC_X86_64_H_ */ diff --git a/lib/librte_eal/common/include/generic/rte_atomic.h b/lib/librte_eal/common/include/generic/rte_atomic.h index e917427022..99585436cb 100644 --- a/lib/librte_eal/common/include/generic/rte_atomic.h +++ b/lib/librte_eal/common/include/generic/rte_atomic.h @@ -1079,4 +1079,56 @@ static inline void rte_atomic64_clear(rte_atomic64_t *v) } #endif +/*------------------------ 128 bit atomic operations -------------------------*/ + +#ifdef __DOXYGEN__ + +/** + * An atomic compare and set function used by the mutex functions. + * (Atomically) Equivalent to: + * @code + * if (*dst == *exp) + * *dst = *src + * else + * *exp = *dst + * @endcode + * + * @note This function is currently only available for the x86-64 platform. + * + * @note The success and failure arguments must be one of the __ATOMIC_* values + * defined in the C++11 standard. For details on their behavior, refer to the + * standard. + * + * @param dst + * The destination into which the value will be written. + * @param exp + * Pointer to the expected value. If the operation fails, this memory is + * updated with the actual value. + * @param src + * Pointer to the new value. + * @param weak + * A value of true allows the comparison to spuriously fail and allows the + * 'exp' update to occur non-atomically (i.e. a torn read may occur). + * Implementations may ignore this argument and only implement the strong + * variant. + * @param success + * If successful, the operation's memory behavior conforms to this (or a + * stronger) model. + * @param failure + * If unsuccessful, the operation's memory behavior conforms to this (or a + * stronger) model. This argument cannot be __ATOMIC_RELEASE, + * __ATOMIC_ACQ_REL, or a stronger model than success. + * @return + * Non-zero on success; 0 on failure. + */ +static inline int __rte_experimental +rte_atomic128_cmp_exchange(rte_int128_t *dst, + rte_int128_t *exp, + const rte_int128_t *src, + unsigned int weak, + int success, + int failure); + +#endif /* __DOXYGEN__ */ + #endif /* _RTE_ATOMIC_H_ */