MIPS: Allow kernel use of LL/SC to be separate from the presence of LL/SC.

On some CPUs, it is more efficient to disable and enable interrupts in the
kernel rather than use ll/sc for atomic operations.  But if we were to set
cpu_has_llsc to false, we would break the userspace futex interface (in
asm/futex.h).

We separate the two concepts, with a new predicate kernel_uses_llsc, that
lets us disable the kernel's use of ll/sc while still allowing the futex
code to use it.

Also there were a couple of cases in bitops.h where we were using ll/sc
unconditionally even if cpu_has_llsc were false.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 17 insertions, 17 deletions

diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index b1e9e97a9c78..84a383806b2c 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -61,7 +61,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 	unsigned short bit = nr & SZLONG_MASK;
 	unsigned long temp;
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		__asm__ __volatile__(
 		"	.set	mips3					\n"
 		"1:	" __LL "%0, %1			# set_bit	\n"
@@ -72,7 +72,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 		: "=&r" (temp), "=m" (*m)
 		: "ir" (1UL << bit), "m" (*m));
 #ifdef CONFIG_CPU_MIPSR2
-	} else if (__builtin_constant_p(bit)) {
+	} else if (kernel_uses_llsc && __builtin_constant_p(bit)) {
 		__asm__ __volatile__(
 		"1:	" __LL "%0, %1			# set_bit	\n"
 		"	" __INS "%0, %4, %2, 1				\n"
@@ -84,7 +84,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 		: "=&r" (temp), "=m" (*m)
 		: "ir" (bit), "m" (*m), "r" (~0));
 #endif /* CONFIG_CPU_MIPSR2 */
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		__asm__ __volatile__(
 		"	.set	mips3					\n"
 		"1:	" __LL "%0, %1			# set_bit	\n"
@@ -126,7 +126,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 	unsigned short bit = nr & SZLONG_MASK;
 	unsigned long temp;
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		__asm__ __volatile__(
 		"	.set	mips3					\n"
 		"1:	" __LL "%0, %1			# clear_bit	\n"
@@ -137,7 +137,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 		: "=&r" (temp), "=m" (*m)
 		: "ir" (~(1UL << bit)), "m" (*m));
 #ifdef CONFIG_CPU_MIPSR2
-	} else if (__builtin_constant_p(bit)) {
+	} else if (kernel_uses_llsc && __builtin_constant_p(bit)) {
 		__asm__ __volatile__(
 		"1:	" __LL "%0, %1			# clear_bit	\n"
 		"	" __INS "%0, $0, %2, 1				\n"
@@ -149,7 +149,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 		: "=&r" (temp), "=m" (*m)
 		: "ir" (bit), "m" (*m));
 #endif /* CONFIG_CPU_MIPSR2 */
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		__asm__ __volatile__(
 		"	.set	mips3					\n"
 		"1:	" __LL "%0, %1			# clear_bit	\n"
@@ -202,7 +202,7 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
 {
 	unsigned short bit = nr & SZLONG_MASK;
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -215,7 +215,7 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
 		"	.set	mips0				\n"
 		: "=&r" (temp), "=m" (*m)
 		: "ir" (1UL << bit), "m" (*m));
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -260,7 +260,7 @@ static inline int test_and_set_bit(unsigned long nr,
 
 	smp_llsc_mb();
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -275,7 +275,7 @@ static inline int test_and_set_bit(unsigned long nr,
 		: "=&r" (temp), "=m" (*m), "=&r" (res)
 		: "r" (1UL << bit), "m" (*m)
 		: "memory");
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -328,7 +328,7 @@ static inline int test_and_set_bit_lock(unsigned long nr,
 	unsigned short bit = nr & SZLONG_MASK;
 	unsigned long res;
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -343,7 +343,7 @@ static inline int test_and_set_bit_lock(unsigned long nr,
 		: "=&r" (temp), "=m" (*m), "=&r" (res)
 		: "r" (1UL << bit), "m" (*m)
 		: "memory");
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -397,7 +397,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 
 	smp_llsc_mb();
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -414,7 +414,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 		: "r" (1UL << bit), "m" (*m)
 		: "memory");
 #ifdef CONFIG_CPU_MIPSR2
-	} else if (__builtin_constant_p(nr)) {
+	} else if (kernel_uses_llsc && __builtin_constant_p(nr)) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -431,7 +431,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 		: "ir" (bit), "m" (*m)
 		: "memory");
 #endif
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -487,7 +487,7 @@ static inline int test_and_change_bit(unsigned long nr,
 
 	smp_llsc_mb();
 
-	if (cpu_has_llsc && R10000_LLSC_WAR) {
+	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
@@ -502,7 +502,7 @@ static inline int test_and_change_bit(unsigned long nr,
 		: "=&r" (temp), "=m" (*m), "=&r" (res)
 		: "r" (1UL << bit), "m" (*m)
 		: "memory");
-	} else if (cpu_has_llsc) {
+	} else if (kernel_uses_llsc) {
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;