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authorRalf Baechle <ralf@linux-mips.org>2010-10-29 19:08:24 +0100
committerRalf Baechle <ralf@linux-mips.org>2010-10-29 19:08:24 +0100
commit7837314d141c661c70bc13c5050694413ecfe14a (patch)
treede137b1d2945d2490bc1dcdf6d76eac6006f7ab0 /arch/mips/include/asm/atomic.h
parent18cb657ca1bafe635f368346a1676fb04c512edf (diff)
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MIPS: Get rid of branches to .subsections.
It was a nice optimization - on paper at least. In practice it results in branches that may exceed the maximum legal range for a branch. We can fight that problem with -ffunction-sections but -ffunction-sections again is incompatible with -pg used by the function tracer. By rewriting the loop around all simple LL/SC blocks to C we reduce the amount of inline assembler and at the same time allow GCC to often fill the branch delay slots with something sensible or whatever else clever optimization it may have up in its sleeve. With this optimization gone we also no longer need -ffunction-sections, so drop it. This optimization was originally introduced in 2.6.21, commit 5999eca25c1fd4b9b9aca7833b04d10fe4bc877d (linux-mips.org) rsp. f65e4fa8e0c6022ad58dc88d1b11b12589ed7f9f (kernel.org). Original fix for the issues which caused me to pull this optimization by Paul Gortmaker <paul.gortmaker@windriver.com>. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm/atomic.h')
-rw-r--r--arch/mips/include/asm/atomic.h208
1 files changed, 96 insertions, 112 deletions
diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index 47d87da379f..4a02fe891ab 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -64,18 +64,16 @@ static __inline__ void atomic_add(int i, atomic_t * v)
} else if (kernel_uses_llsc) {
int temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: ll %0, %1 # atomic_add \n"
- " addu %0, %2 \n"
- " sc %0, %1 \n"
- " beqz %0, 2f \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter));
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " ll %0, %1 # atomic_add \n"
+ " addu %0, %2 \n"
+ " sc %0, %1 \n"
+ " .set mips0 \n"
+ : "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter));
+ } while (unlikely(!temp));
} else {
unsigned long flags;
@@ -109,18 +107,16 @@ static __inline__ void atomic_sub(int i, atomic_t * v)
} else if (kernel_uses_llsc) {
int temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: ll %0, %1 # atomic_sub \n"
- " subu %0, %2 \n"
- " sc %0, %1 \n"
- " beqz %0, 2f \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter));
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " ll %0, %1 # atomic_sub \n"
+ " subu %0, %2 \n"
+ " sc %0, %1 \n"
+ " .set mips0 \n"
+ : "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter));
+ } while (unlikely(!temp));
} else {
unsigned long flags;
@@ -156,20 +152,19 @@ static __inline__ int atomic_add_return(int i, atomic_t * v)
} else if (kernel_uses_llsc) {
int temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: ll %1, %2 # atomic_add_return \n"
- " addu %0, %1, %3 \n"
- " sc %0, %2 \n"
- " beqz %0, 2f \n"
- " addu %0, %1, %3 \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (result), "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter)
- : "memory");
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " ll %1, %2 # atomic_add_return \n"
+ " addu %0, %1, %3 \n"
+ " sc %0, %2 \n"
+ " .set mips0 \n"
+ : "=&r" (result), "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter)
+ : "memory");
+ } while (unlikely(!result));
+
+ result = temp + i;
} else {
unsigned long flags;
@@ -205,23 +200,24 @@ static __inline__ int atomic_sub_return(int i, atomic_t * v)
: "=&r" (result), "=&r" (temp), "=m" (v->counter)
: "Ir" (i), "m" (v->counter)
: "memory");
+
+ result = temp - i;
} else if (kernel_uses_llsc) {
int temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: ll %1, %2 # atomic_sub_return \n"
- " subu %0, %1, %3 \n"
- " sc %0, %2 \n"
- " beqz %0, 2f \n"
- " subu %0, %1, %3 \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (result), "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter)
- : "memory");
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " ll %1, %2 # atomic_sub_return \n"
+ " subu %0, %1, %3 \n"
+ " sc %0, %2 \n"
+ " .set mips0 \n"
+ : "=&r" (result), "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter)
+ : "memory");
+ } while (unlikely(!result));
+
+ result = temp - i;
} else {
unsigned long flags;
@@ -279,12 +275,9 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
" bltz %0, 1f \n"
" sc %0, %2 \n"
" .set noreorder \n"
- " beqz %0, 2f \n"
+ " beqz %0, 1b \n"
" subu %0, %1, %3 \n"
" .set reorder \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
"1: \n"
" .set mips0 \n"
: "=&r" (result), "=&r" (temp), "=m" (v->counter)
@@ -443,18 +436,16 @@ static __inline__ void atomic64_add(long i, atomic64_t * v)
} else if (kernel_uses_llsc) {
long temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: lld %0, %1 # atomic64_add \n"
- " daddu %0, %2 \n"
- " scd %0, %1 \n"
- " beqz %0, 2f \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter));
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " lld %0, %1 # atomic64_add \n"
+ " daddu %0, %2 \n"
+ " scd %0, %1 \n"
+ " .set mips0 \n"
+ : "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter));
+ } while (unlikely(!temp));
} else {
unsigned long flags;
@@ -488,18 +479,16 @@ static __inline__ void atomic64_sub(long i, atomic64_t * v)
} else if (kernel_uses_llsc) {
long temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: lld %0, %1 # atomic64_sub \n"
- " dsubu %0, %2 \n"
- " scd %0, %1 \n"
- " beqz %0, 2f \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter));
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " lld %0, %1 # atomic64_sub \n"
+ " dsubu %0, %2 \n"
+ " scd %0, %1 \n"
+ " .set mips0 \n"
+ : "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter));
+ } while (unlikely(!temp));
} else {
unsigned long flags;
@@ -535,20 +524,19 @@ static __inline__ long atomic64_add_return(long i, atomic64_t * v)
} else if (kernel_uses_llsc) {
long temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: lld %1, %2 # atomic64_add_return \n"
- " daddu %0, %1, %3 \n"
- " scd %0, %2 \n"
- " beqz %0, 2f \n"
- " daddu %0, %1, %3 \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (result), "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter)
- : "memory");
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " lld %1, %2 # atomic64_add_return \n"
+ " daddu %0, %1, %3 \n"
+ " scd %0, %2 \n"
+ " .set mips0 \n"
+ : "=&r" (result), "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter)
+ : "memory");
+ } while (unlikely(!result));
+
+ result = temp + i;
} else {
unsigned long flags;
@@ -587,20 +575,19 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t * v)
} else if (kernel_uses_llsc) {
long temp;
- __asm__ __volatile__(
- " .set mips3 \n"
- "1: lld %1, %2 # atomic64_sub_return \n"
- " dsubu %0, %1, %3 \n"
- " scd %0, %2 \n"
- " beqz %0, 2f \n"
- " dsubu %0, %1, %3 \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
- " .set mips0 \n"
- : "=&r" (result), "=&r" (temp), "=m" (v->counter)
- : "Ir" (i), "m" (v->counter)
- : "memory");
+ do {
+ __asm__ __volatile__(
+ " .set mips3 \n"
+ " lld %1, %2 # atomic64_sub_return \n"
+ " dsubu %0, %1, %3 \n"
+ " scd %0, %2 \n"
+ " .set mips0 \n"
+ : "=&r" (result), "=&r" (temp), "=m" (v->counter)
+ : "Ir" (i), "m" (v->counter)
+ : "memory");
+ } while (unlikely(!result));
+
+ result = temp - i;
} else {
unsigned long flags;
@@ -658,12 +645,9 @@ static __inline__ long atomic64_sub_if_positive(long i, atomic64_t * v)
" bltz %0, 1f \n"
" scd %0, %2 \n"
" .set noreorder \n"
- " beqz %0, 2f \n"
+ " beqz %0, 1b \n"
" dsubu %0, %1, %3 \n"
" .set reorder \n"
- " .subsection 2 \n"
- "2: b 1b \n"
- " .previous \n"
"1: \n"
" .set mips0 \n"
: "=&r" (result), "=&r" (temp), "=m" (v->counter)