[PATCH v2 31/36] MIPS: syscall: Emit Loongson3 sync workarounds within asm

From: Paul Burton
Date: Tue Oct 01 2019 - 17:54:22 EST


Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
---

Changes in v2: None

arch/mips/kernel/syscall.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index b0e25e913bdb..3ea288ca35f1 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -37,6 +37,7 @@
#include <asm/signal.h>
#include <asm/sim.h>
#include <asm/shmparam.h>
+#include <asm/sync.h>
#include <asm/sysmips.h>
#include <asm/switch_to.h>

@@ -132,12 +133,12 @@ static inline int mips_atomic_set(unsigned long addr, unsigned long new)
[efault] "i" (-EFAULT)
: "memory");
} else if (cpu_has_llsc) {
- loongson_llsc_mb();
__asm__ __volatile__ (
" .set push \n"
" .set "MIPS_ISA_ARCH_LEVEL" \n"
" li %[err], 0 \n"
"1: \n"
+ " " __SYNC(full, loongson3_war) " \n"
user_ll("%[old]", "(%[addr])")
" move %[tmp], %[new] \n"
"2: \n"
--
2.23.0