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Date: Mon, 18 Oct 2021 22:17:08 -0700
From: Max Filippov <jcmvbkbc@...il.com>
To: linux-xtensa@...ux-xtensa.org
Cc: Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH 02/10] xtensa: use a14 instead of a15 in inline assembly
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@...il.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
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