From 4ffbd55d9346b6a8ba391c6df9a0f692c4b61ace Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 13 Aug 2021 13:58:47 -0400
Subject: [PATCH] Add RISC-V spinlock support in s_lock.h.
Like the ARM case, just use gcc's __sync_lock_test_and_set();
that will compile into AMOSWAP.W.AQ which does what we need.
At some point it might be worth doing some work on atomic ops
for RISC-V, but this should be enough for a creditable port.
Back-patch to all supported branches, just in case somebody
wants to try them on RISC-V.
Marek Szuba
Discussion: https://postgr.es/m/dea97b6d-f55f-1f6d-9109-504aa7dfa421@gentoo.org
---
src/include/storage/s_lock.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index 254c40d477..dccbd299ce 100644
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -314,6 +314,7 @@ tas(volatile slock_t *lock)
#endif /* __INTEL_COMPILER */
#endif /* __ia64__ || __ia64 */
+
/*
* On ARM and ARM64, we use __sync_lock_test_and_set(int *, int) if available.
*
@@ -340,6 +341,29 @@ tas(volatile slock_t *lock)
#endif /* __arm__ || __arm || __aarch64__ || __aarch64 */
+/*
+ * RISC-V likewise uses __sync_lock_test_and_set(int *, int) if available.
+ */
+#if defined(__riscv)
+#ifdef HAVE_GCC__SYNC_INT32_TAS
+#define HAS_TEST_AND_SET
+
+#define TAS(lock) tas(lock)
+
+typedef int slock_t;
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+ return __sync_lock_test_and_set(lock, 1);
+}
+
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+#endif /* HAVE_GCC__SYNC_INT32_TAS */
+#endif /* __riscv */
+
+
/* S/390 and S/390x Linux (32- and 64-bit zSeries) */
#if defined(__s390__) || defined(__s390x__)
#define HAS_TEST_AND_SET
--
2.24.1