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authorRalf Baechle <ralf@linux-mips.org>2006-09-28 01:45:21 +0100
committerRalf Baechle <ralf@linux-mips.org>2007-02-13 22:40:50 +0000
commitf65e4fa8e0c6022ad58dc88d1b11b12589ed7f9f (patch)
tree2405e012e079693e0fcfde9ff981c549d6c68a21 /include/asm-mips/system.h
parent509cb37e173d4e39cec47238397e91b718730794 (diff)
[MIPS] Improve branch prediction in ll/sc atomic operations.
Now that finally all supported versions of binutils have functioning support for .subsection use .subsection to tweak the branch prediction I did not modify the R10000 errata variants because it seems unclear if this will invalidate the workaround which actually relies on the cheesy prediction of branch likely to cause a misspredict if the sc was successful. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'include/asm-mips/system.h')
-rw-r--r--include/asm-mips/system.h20
1 files changed, 16 insertions, 4 deletions
diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h
index 5e1289c85ed9..597a3743f6a1 100644
--- a/include/asm-mips/system.h
+++ b/include/asm-mips/system.h
@@ -110,7 +110,10 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
" move %2, %z4 \n"
" .set mips3 \n"
" sc %2, %1 \n"
- " beqz %2, 1b \n"
+ " beqz %2, 2f \n"
+ " .subsection 2 \n"
+ "2: b 1b \n"
+ " .previous \n"
" .set mips0 \n"
: "=&r" (retval), "=m" (*m), "=&r" (dummy)
: "R" (*m), "Jr" (val)
@@ -155,7 +158,10 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
"1: lld %0, %3 # xchg_u64 \n"
" move %2, %z4 \n"
" scd %2, %1 \n"
- " beqz %2, 1b \n"
+ " beqz %2, 2f \n"
+ " .subsection 2 \n"
+ "2: b 1b \n"
+ " .previous \n"
" .set mips0 \n"
: "=&r" (retval), "=m" (*m), "=&r" (dummy)
: "R" (*m), "Jr" (val)
@@ -232,8 +238,11 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,
" move $1, %z4 \n"
" .set mips3 \n"
" sc $1, %1 \n"
- " beqz $1, 1b \n"
+ " beqz $1, 3f \n"
"2: \n"
+ " .subsection 2 \n"
+ "3: b 1b \n"
+ " .previous \n"
" .set pop \n"
: "=&r" (retval), "=R" (*m)
: "R" (*m), "Jr" (old), "Jr" (new)
@@ -283,8 +292,11 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old,
" bne %0, %z3, 2f \n"
" move $1, %z4 \n"
" scd $1, %1 \n"
- " beqz $1, 1b \n"
+ " beqz $1, 3f \n"
"2: \n"
+ " .subsection 2 \n"
+ "3: b 1b \n"
+ " .previous \n"
" .set pop \n"
: "=&r" (retval), "=R" (*m)
: "R" (*m), "Jr" (old), "Jr" (new)