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From:   Max Filippov <jcmvbkbc@gmail.com>
To:     linux-xtensa@linux-xtensa.org
Cc:     Chris Zankel <chris@zankel.net>, linux-kernel@vger.kernel.org,
        Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH 02/10] xtensa: use a14 instead of a15 in inline assembly
Date:   Mon, 18 Oct 2021 22:17:08 -0700
Message-Id: <20211019051716.4173-3-jcmvbkbc@gmail.com>
In-Reply-To: <20211019051716.4173-1-jcmvbkbc@gmail.com>
References: <20211019051716.4173-1-jcmvbkbc@gmail.com>
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a15 is a frame pointer in the call0 xtensa ABI, don't use it explicitly
in the inline assembly. Use a14 instead, as it has the same properties
as a15 w.r.t. window overflow.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/include/asm/atomic.h  | 26 +++++++++++++-------------
 arch/xtensa/include/asm/cmpxchg.h | 16 ++++++++--------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/arch/xtensa/include/asm/atomic.h b/arch/xtensa/include/asm/atomic.h
index 4361fe4247e3..52da614f953c 100644
--- a/arch/xtensa/include/asm/atomic.h
+++ b/arch/xtensa/include/asm/atomic.h
@@ -25,15 +25,15 @@
  *
  * Locking interrupts looks like this:
  *
- *    rsil a15, TOPLEVEL
+ *    rsil a14, TOPLEVEL
  *    <code>
- *    wsr  a15, PS
+ *    wsr  a14, PS
  *    rsync
  *
- * Note that a15 is used here because the register allocation
+ * Note that a14 is used here because the register allocation
  * done by the compiler is not guaranteed and a window overflow
  * may not occur between the rsil and wsr instructions. By using
- * a15 in the rsil, the machine is guaranteed to be in a state
+ * a14 in the rsil, the machine is guaranteed to be in a state
  * where no register reference will cause an overflow.
  */
 
@@ -185,15 +185,15 @@ static inline void arch_atomic_##op(int i, atomic_t * v)		\
 	unsigned int vval;						\
 									\
 	__asm__ __volatile__(						\
-			"       rsil    a15, "__stringify(TOPLEVEL)"\n"	\
+			"       rsil    a14, "__stringify(TOPLEVEL)"\n"	\
 			"       l32i    %[result], %[mem]\n"		\
 			"       " #op " %[result], %[result], %[i]\n"	\
 			"       s32i    %[result], %[mem]\n"		\
-			"       wsr     a15, ps\n"			\
+			"       wsr     a14, ps\n"			\
 			"       rsync\n"				\
 			: [result] "=&a" (vval), [mem] "+m" (*v)	\
 			: [i] "a" (i)					\
-			: "a15", "memory"				\
+			: "a14", "memory"				\
 			);						\
 }									\
 
@@ -203,15 +203,15 @@ static inline int arch_atomic_##op##_return(int i, atomic_t * v)	\
 	unsigned int vval;						\
 									\
 	__asm__ __volatile__(						\
-			"       rsil    a15,"__stringify(TOPLEVEL)"\n"	\
+			"       rsil    a14,"__stringify(TOPLEVEL)"\n"	\
 			"       l32i    %[result], %[mem]\n"		\
 			"       " #op " %[result], %[result], %[i]\n"	\
 			"       s32i    %[result], %[mem]\n"		\
-			"       wsr     a15, ps\n"			\
+			"       wsr     a14, ps\n"			\
 			"       rsync\n"				\
 			: [result] "=&a" (vval), [mem] "+m" (*v)	\
 			: [i] "a" (i)					\
-			: "a15", "memory"				\
+			: "a14", "memory"				\
 			);						\
 									\
 	return vval;							\
@@ -223,16 +223,16 @@ static inline int arch_atomic_fetch_##op(int i, atomic_t * v)		\
 	unsigned int tmp, vval;						\
 									\
 	__asm__ __volatile__(						\
-			"       rsil    a15,"__stringify(TOPLEVEL)"\n"	\
+			"       rsil    a14,"__stringify(TOPLEVEL)"\n"	\
 			"       l32i    %[result], %[mem]\n"		\
 			"       " #op " %[tmp], %[result], %[i]\n"	\
 			"       s32i    %[tmp], %[mem]\n"		\
-			"       wsr     a15, ps\n"			\
+			"       wsr     a14, ps\n"			\
 			"       rsync\n"				\
 			: [result] "=&a" (vval), [tmp] "=&a" (tmp),	\
 			  [mem] "+m" (*v)				\
 			: [i] "a" (i)					\
-			: "a15", "memory"				\
+			: "a14", "memory"				\
 			);						\
 									\
 	return vval;							\
diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h
index 3699e2818efb..eb87810357ad 100644
--- a/arch/xtensa/include/asm/cmpxchg.h
+++ b/arch/xtensa/include/asm/cmpxchg.h
@@ -52,16 +52,16 @@ __cmpxchg_u32(volatile int *p, int old, int new)
 	return new;
 #else
 	__asm__ __volatile__(
-			"       rsil    a15, "__stringify(TOPLEVEL)"\n"
+			"       rsil    a14, "__stringify(TOPLEVEL)"\n"
 			"       l32i    %[old], %[mem]\n"
 			"       bne     %[old], %[cmp], 1f\n"
 			"       s32i    %[new], %[mem]\n"
 			"1:\n"
-			"       wsr     a15, ps\n"
+			"       wsr     a14, ps\n"
 			"       rsync\n"
 			: [old] "=&a" (old), [mem] "+m" (*p)
 			: [cmp] "a" (old), [new] "r" (new)
-			: "a15", "memory");
+			: "a14", "memory");
 	return old;
 #endif
 }
@@ -116,10 +116,10 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr,
 /*
  * xchg_u32
  *
- * Note that a15 is used here because the register allocation
+ * Note that a14 is used here because the register allocation
  * done by the compiler is not guaranteed and a window overflow
  * may not occur between the rsil and wsr instructions. By using
- * a15 in the rsil, the machine is guaranteed to be in a state
+ * a14 in the rsil, the machine is guaranteed to be in a state
  * where no register reference will cause an overflow.
  */
 
@@ -157,14 +157,14 @@ static inline unsigned long xchg_u32(volatile int * m, unsigned long val)
 #else
 	unsigned long tmp;
 	__asm__ __volatile__(
-			"       rsil    a15, "__stringify(TOPLEVEL)"\n"
+			"       rsil    a14, "__stringify(TOPLEVEL)"\n"
 			"       l32i    %[tmp], %[mem]\n"
 			"       s32i    %[val], %[mem]\n"
-			"       wsr     a15, ps\n"
+			"       wsr     a14, ps\n"
 			"       rsync\n"
 			: [tmp] "=&a" (tmp), [mem] "+m" (*m)
 			: [val] "a" (val)
-			: "a15", "memory");
+			: "a14", "memory");
 	return tmp;
 #endif
 }
-- 
2.20.1