Commit cf3b3baa authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: use "m" constraint instead of "a" in cmpxchg.h assembly 



Use "m" constraint instead of "r" for the address, as "m" allows
compiler to access adjacent locations using base + offset, while "r"
requires updating the base register every time.

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent 812e708a

arch/xtensa/include/asm/cmpxchg.h

+16 −15
Original line number Diff line number Diff line
@@ -43,9 +43,9 @@ __cmpxchg_u32(volatile int *p, int old, int new) 
#elif XCHAL_HAVE_S32C1I

	__asm__ __volatile__(

			"       wsr     %[cmp], scompare1\n"

			"       s32c1i  %[new], %[addr], 0\n"

			: [new] "+a" (new)

			: [addr] "a" (p), [cmp] "a" (old)

			"       s32c1i  %[new], %[mem]\n"

			: [new] "+a" (new), [mem] "+m" (*p)

			: [cmp] "a" (old)

			: "memory"

			);
@@ -53,14 +53,14 @@ __cmpxchg_u32(volatile int *p, int old, int new) 
#else

	__asm__ __volatile__(

			"       rsil    a15, "__stringify(TOPLEVEL)"\n"

			"       l32i    %[old], %[addr], 0\n"

			"       l32i    %[old], %[mem]\n"

			"       bne     %[old], %[cmp], 1f\n"

			"       s32i    %[new], %[addr], 0\n"

			"       s32i    %[new], %[mem]\n"

			"1:\n"

			"       wsr     a15, ps\n"

			"       rsync\n"

			: [old] "=&a" (old)

			: [addr] "a" (p), [cmp] "a" (old), [new] "r" (new)

			: [old] "=&a" (old), [mem] "+m" (*p)

			: [cmp] "a" (old), [new] "r" (new)

			: "a15", "memory");

	return old;

#endif
@@ -143,13 +143,14 @@ static inline unsigned long xchg_u32(volatile int * m, unsigned long val) 
#elif XCHAL_HAVE_S32C1I

	unsigned long tmp, result;

	__asm__ __volatile__(

			"1:     l32i    %[tmp], %[addr], 0\n"

			"1:     l32i    %[tmp], %[mem]\n"

			"       mov     %[result], %[val]\n"

			"       wsr     %[tmp], scompare1\n"

			"       s32c1i  %[result], %[addr], 0\n"

			"       s32c1i  %[result], %[mem]\n"

			"       bne     %[result], %[tmp], 1b\n"

			: [result] "=&a" (result), [tmp] "=&a" (tmp)

			: [addr] "a" (m), [val] "a" (val)

			: [result] "=&a" (result), [tmp] "=&a" (tmp),

			  [mem] "+m" (*m)

			: [val] "a" (val)

			: "memory"

			);

	return result;
@@ -157,12 +158,12 @@ static inline unsigned long xchg_u32(volatile int * m, unsigned long val) 
	unsigned long tmp;

	__asm__ __volatile__(

			"       rsil    a15, "__stringify(TOPLEVEL)"\n"

			"       l32i    %[tmp], %[addr], 0\n"

			"       s32i    %[val], %[addr], 0\n"

			"       l32i    %[tmp], %[mem]\n"

			"       s32i    %[val], %[mem]\n"

			"       wsr     a15, ps\n"

			"       rsync\n"

			: [tmp] "=&a" (tmp)

			: [addr] "a" (m), [val] "a" (val)

			: [tmp] "=&a" (tmp), [mem] "+m" (*m)

			: [val] "a" (val)

			: "a15", "memory");

	return tmp;

#endif