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Date: Wed, 24 Nov 2021 11:50:01 +0800
From: Huang Pei <huangpei@...ngson.cn>
To: netdev@...r.kernel.org, ambrosehua@...il.com
Cc: linux-arch@...r.kernel.org
Subject: [PATCH 1/4] MIPS: rework local_t operation on MIPS64
+. use "daddu/dsubu" for long int on MIPS64 instead of "addu/subu"
+. remove "asm/war.h" since R10000_LLSC_WAR became a config option
+. clean up
Suggested-by: "Maciej W. Rozycki" <macro@...am.me.uk>
Signed-off-by: Huang Pei <huangpei@...ngson.cn>
---
arch/mips/include/asm/asm.h | 18 ++++++++++
arch/mips/include/asm/local.h | 62 +++++++++--------------------------
2 files changed, 33 insertions(+), 47 deletions(-)
diff --git a/arch/mips/include/asm/asm.h b/arch/mips/include/asm/asm.h
index 2f8ce94ebaaf..f3302b13d3e0 100644
--- a/arch/mips/include/asm/asm.h
+++ b/arch/mips/include/asm/asm.h
@@ -19,6 +19,7 @@
#include <asm/sgidefs.h>
#include <asm/asm-eva.h>
+#include <asm/isa-rev.h>
#ifndef __VDSO__
/*
@@ -211,6 +212,8 @@ symbol = value
#define LONG_SUB sub
#define LONG_SUBU subu
#define LONG_L lw
+#define LONG_LL ll
+#define LONG_SC sc
#define LONG_S sw
#define LONG_SP swp
#define LONG_SLL sll
@@ -236,6 +239,8 @@ symbol = value
#define LONG_SUB dsub
#define LONG_SUBU dsubu
#define LONG_L ld
+#define LONG_LL lld
+#define LONG_SC scd
#define LONG_S sd
#define LONG_SP sdp
#define LONG_SLL dsll
@@ -320,6 +325,19 @@ symbol = value
#define SSNOP sll zero, zero, 1
+/*
+ * Using a branch-likely instruction to check the result of an sc instruction
+ * works around a bug present in R10000 CPUs prior to revision 3.0 that could
+ * cause ll-sc sequences to execute non-atomically.
+ */
+#ifdef CONFIG_WAR_R10000_LLSC
+# define SC_BEQZ beqzl
+#elif MIPS_ISA_REV >= 6
+# define SC_BEQZ beqzc
+#else
+# define SC_BEQZ beqz
+#endif
+
#ifdef CONFIG_SGI_IP28
/* Inhibit speculative stores to volatile (e.g.DMA) or invalid addresses. */
#include <asm/cacheops.h>
diff --git a/arch/mips/include/asm/local.h b/arch/mips/include/asm/local.h
index ecda7295ddcd..c1e109357110 100644
--- a/arch/mips/include/asm/local.h
+++ b/arch/mips/include/asm/local.h
@@ -7,7 +7,7 @@
#include <linux/atomic.h>
#include <asm/cmpxchg.h>
#include <asm/compiler.h>
-#include <asm/war.h>
+#include <asm/asm.h>
typedef struct
{
@@ -31,34 +31,18 @@ static __inline__ long local_add_return(long i, local_t * l)
{
unsigned long result;
- if (kernel_uses_llsc && IS_ENABLED(CONFIG_WAR_R10000_LLSC)) {
- unsigned long temp;
-
- __asm__ __volatile__(
- " .set push \n"
- " .set arch=r4000 \n"
- __SYNC(full, loongson3_war) " \n"
- "1:" __LL "%1, %2 # local_add_return \n"
- " addu %0, %1, %3 \n"
- __SC "%0, %2 \n"
- " beqzl %0, 1b \n"
- " addu %0, %1, %3 \n"
- " .set pop \n"
- : "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
- : "Ir" (i), "m" (l->a.counter)
- : "memory");
- } else if (kernel_uses_llsc) {
+ if (kernel_uses_llsc) {
unsigned long temp;
__asm__ __volatile__(
" .set push \n"
" .set "MIPS_ISA_ARCH_LEVEL" \n"
- __SYNC(full, loongson3_war) " \n"
- "1:" __LL "%1, %2 # local_add_return \n"
- " addu %0, %1, %3 \n"
- __SC "%0, %2 \n"
- " beqz %0, 1b \n"
- " addu %0, %1, %3 \n"
+ __SYNC(full, loongson3_war) " \n"
+ "1:" __stringify(LONG_LL) " %1, %2 \n"
+ " "__stringify(LONG_ADDU) " %0, %1, %3 \n"
+ " "__stringify(LONG_SC) " %0, %2 \n"
+ " "__stringify(SC_BEQZ) " %0, 1b \n"
+ " "__stringify(LONG_ADDU) " %0, %1, %3 \n"
" .set pop \n"
: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
: "Ir" (i), "m" (l->a.counter)
@@ -80,34 +64,18 @@ static __inline__ long local_sub_return(long i, local_t * l)
{
unsigned long result;
- if (kernel_uses_llsc && IS_ENABLED(CONFIG_WAR_R10000_LLSC)) {
- unsigned long temp;
-
- __asm__ __volatile__(
- " .set push \n"
- " .set arch=r4000 \n"
- __SYNC(full, loongson3_war) " \n"
- "1:" __LL "%1, %2 # local_sub_return \n"
- " subu %0, %1, %3 \n"
- __SC "%0, %2 \n"
- " beqzl %0, 1b \n"
- " subu %0, %1, %3 \n"
- " .set pop \n"
- : "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
- : "Ir" (i), "m" (l->a.counter)
- : "memory");
- } else if (kernel_uses_llsc) {
+ if (kernel_uses_llsc) {
unsigned long temp;
__asm__ __volatile__(
" .set push \n"
" .set "MIPS_ISA_ARCH_LEVEL" \n"
- __SYNC(full, loongson3_war) " \n"
- "1:" __LL "%1, %2 # local_sub_return \n"
- " subu %0, %1, %3 \n"
- __SC "%0, %2 \n"
- " beqz %0, 1b \n"
- " subu %0, %1, %3 \n"
+ __SYNC(full, loongson3_war) " \n"
+ "1:" __stringify(LONG_LL) " %1, %2 \n"
+ " "__stringify(LONG_SUBU) " %0, %1, %3 \n"
+ " "__stringify(LONG_SC) " %0, %2 \n"
+ " "__stringify(SC_BEQZ) " %0, 1b \n"
+ " "__stringify(LONG_SUBU) " %0, %1, %3 \n"
" .set pop \n"
: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
: "Ir" (i), "m" (l->a.counter)
--
2.20.1
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