MIPS: Avoid using .set mips0 to restore ISA

We currently have 2 commonly used methods for switching ISA within
assembly code, then restoring the original ISA.

  1) Using a pair of .set push & .set pop directives. For example:

     .set	push
     .set	mips32r2
     <some_insn>
     .set	pop

  2) Using .set mips0 to restore the ISA originally specified on the
     command line. For example:

     .set	mips32r2
     <some_insn>
     .set	mips0

Unfortunately method 2 does not work with nanoMIPS toolchains, where the
assembler rejects the .set mips0 directive like so:

     Error: cannot change ISA from nanoMIPS to mips0

In preparation for supporting nanoMIPS builds, switch all instances of
method 2 in generic non-platform-specific code to use push & pop as in
method 1 instead. The .set push & .set pop is arguably cleaner anyway,
and if nothing else it's good to consistently use one method.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/21037/
Cc: linux-mips@linux-mips.org

1 files changed, 28 insertions, 14 deletions

diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index da1b8718861e..f2a840fb6a9a 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -58,12 +58,13 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 
 	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL "%0, %1			# set_bit	\n"
 		"	or	%0, %2					\n"
 		"	" __SC	"%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "=" GCC_OFF_SMALL_ASM() (*m)
 		: "ir" (1UL << bit), GCC_OFF_SMALL_ASM() (*m));
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
@@ -80,11 +81,12 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 	} else if (kernel_uses_llsc) {
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL "%0, %1		# set_bit	\n"
 			"	or	%0, %2				\n"
 			"	" __SC	"%0, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m)
 			: "ir" (1UL << bit));
 		} while (unlikely(!temp));
@@ -110,12 +112,13 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 
 	if (kernel_uses_llsc && R10000_LLSC_WAR) {
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL "%0, %1			# clear_bit	\n"
 		"	and	%0, %2					\n"
 		"	" __SC "%0, %1					\n"
 		"	beqzl	%0, 1b					\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m)
 		: "ir" (~(1UL << bit)));
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
@@ -132,11 +135,12 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 	} else if (kernel_uses_llsc) {
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL "%0, %1		# clear_bit	\n"
 			"	and	%0, %2				\n"
 			"	" __SC "%0, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m)
 			: "ir" (~(1UL << bit)));
 		} while (unlikely(!temp));
@@ -176,12 +180,13 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
 		unsigned long temp;
 
 		__asm__ __volatile__(
+		"	.set	push				\n"
 		"	.set	arch=r4000			\n"
 		"1:	" __LL "%0, %1		# change_bit	\n"
 		"	xor	%0, %2				\n"
 		"	" __SC	"%0, %1				\n"
 		"	beqzl	%0, 1b				\n"
-		"	.set	mips0				\n"
+		"	.set	pop				\n"
 		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m)
 		: "ir" (1UL << bit));
 	} else if (kernel_uses_llsc) {
@@ -190,11 +195,12 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
 
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL "%0, %1		# change_bit	\n"
 			"	xor	%0, %2				\n"
 			"	" __SC	"%0, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m)
 			: "ir" (1UL << bit));
 		} while (unlikely(!temp));
@@ -223,13 +229,14 @@ static inline int test_and_set_bit(unsigned long nr,
 		unsigned long temp;
 
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL "%0, %1		# test_and_set_bit	\n"
 		"	or	%2, %0, %3				\n"
 		"	" __SC	"%2, %1					\n"
 		"	beqzl	%2, 1b					\n"
 		"	and	%2, %0, %3				\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 		: "r" (1UL << bit)
 		: "memory");
@@ -239,11 +246,12 @@ static inline int test_and_set_bit(unsigned long nr,
 
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL "%0, %1	# test_and_set_bit	\n"
 			"	or	%2, %0, %3			\n"
 			"	" __SC	"%2, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 			: "r" (1UL << bit)
 			: "memory");
@@ -277,13 +285,14 @@ static inline int test_and_set_bit_lock(unsigned long nr,
 		unsigned long temp;
 
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL "%0, %1		# test_and_set_bit	\n"
 		"	or	%2, %0, %3				\n"
 		"	" __SC	"%2, %1					\n"
 		"	beqzl	%2, 1b					\n"
 		"	and	%2, %0, %3				\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "+m" (*m), "=&r" (res)
 		: "r" (1UL << bit)
 		: "memory");
@@ -293,11 +302,12 @@ static inline int test_and_set_bit_lock(unsigned long nr,
 
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL "%0, %1	# test_and_set_bit	\n"
 			"	or	%2, %0, %3			\n"
 			"	" __SC	"%2, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 			: "r" (1UL << bit)
 			: "memory");
@@ -332,6 +342,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 		unsigned long temp;
 
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL	"%0, %1		# test_and_clear_bit	\n"
 		"	or	%2, %0, %3				\n"
@@ -339,7 +350,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 		"	" __SC	"%2, %1					\n"
 		"	beqzl	%2, 1b					\n"
 		"	and	%2, %0, %3				\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 		: "r" (1UL << bit)
 		: "memory");
@@ -365,12 +376,13 @@ static inline int test_and_clear_bit(unsigned long nr,
 
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL	"%0, %1 # test_and_clear_bit	\n"
 			"	or	%2, %0, %3			\n"
 			"	xor	%2, %3				\n"
 			"	" __SC	"%2, %1				\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 			: "r" (1UL << bit)
 			: "memory");
@@ -406,13 +418,14 @@ static inline int test_and_change_bit(unsigned long nr,
 		unsigned long temp;
 
 		__asm__ __volatile__(
+		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
 		"1:	" __LL	"%0, %1		# test_and_change_bit	\n"
 		"	xor	%2, %0, %3				\n"
 		"	" __SC	"%2, %1					\n"
 		"	beqzl	%2, 1b					\n"
 		"	and	%2, %0, %3				\n"
-		"	.set	mips0					\n"
+		"	.set	pop					\n"
 		: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 		: "r" (1UL << bit)
 		: "memory");
@@ -422,11 +435,12 @@ static inline int test_and_change_bit(unsigned long nr,
 
 		do {
 			__asm__ __volatile__(
+			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
 			"	" __LL	"%0, %1 # test_and_change_bit	\n"
 			"	xor	%2, %0, %3			\n"
 			"	" __SC	"\t%2, %1			\n"
-			"	.set	mips0				\n"
+			"	.set	pop				\n"
 			: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
 			: "r" (1UL << bit)
 			: "memory");