From 9e2708dfaa93f6532860680b47d3252b2bf35278 Mon Sep 17 00:00:00 2001 From: Taylor R Campbell Date: Wed, 6 Apr 2022 21:15:21 +0000 Subject: [PATCH 47/49] powerpc: Use lwsync, not sync, for mutex_exit. This just needs to be a store-release so that the body of the mutex section happens before releasing the lock. lwsync is a release/acquire barrier (load/store-before-store and load-before-load/store), so issuing lwsync-then-store suffices here. (On booke this will be msync anyway, a full sequential consistency barrier same as classic powerpc sync, so no change to semantics or performance on booke.) --- sys/arch/powerpc/powerpc/lock_stubs.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sys/arch/powerpc/powerpc/lock_stubs.S b/sys/arch/powerpc/powerpc/lock_stubs.S index 62cc593916f1..c6cc52bb7db2 100644 --- a/sys/arch/powerpc/powerpc/lock_stubs.S +++ b/sys/arch/powerpc/powerpc/lock_stubs.S @@ -79,7 +79,7 @@ ENTRY(mutex_enter) * void mutex_exit(kmutex_t *); */ ENTRY(mutex_exit) - SYNC + LWSYNC li %r7,0 1: lptrarx %r10,0,%r3 @@ -163,7 +163,7 @@ ENTRY(rw_tryenter) */ ENTRY(rw_exit) ldptr %r9,RW_OWNER(%r3) - SYNC + LWSYNC andi. %r0,%r9,RW_WRITE_LOCKED bne- 1f