diff options
Diffstat (limited to 'libc/sysdeps/linux/mips/bits/atomic.h')
| -rw-r--r-- | libc/sysdeps/linux/mips/bits/atomic.h | 90 |
1 files changed, 58 insertions, 32 deletions
diff --git a/libc/sysdeps/linux/mips/bits/atomic.h b/libc/sysdeps/linux/mips/bits/atomic.h index 4f73cc261..3fab82955 100644 --- a/libc/sysdeps/linux/mips/bits/atomic.h +++ b/libc/sysdeps/linux/mips/bits/atomic.h @@ -49,6 +49,32 @@ typedef uintmax_t uatomic_max_t; # define MIPS_SYNC sync #endif +/* Certain revisions of the R10000 Processor need an LL/SC Workaround + enabled. Revisions before 3.0 misbehave on atomic operations, and + Revs 2.6 and lower deadlock after several seconds due to other errata. + + To quote the R10K Errata: + Workaround: The basic idea is to inhibit the four instructions + from simultaneously becoming active in R10000. Padding all + ll/sc sequences with nops or changing the looping branch in the + routines to a branch likely (which is always predicted taken + by R10000) will work. The nops should go after the loop, and the + number of them should be 28. This number could be decremented for + each additional instruction in the ll/sc loop such as the lock + modifier(s) between the ll and sc, the looping branch and its + delay slot. For typical short routines with one ll/sc loop, any + instructions after the loop could also count as a decrement. The + nop workaround pollutes the cache more but would be a few cycles + faster if all the code is in the cache and the looping branch + is predicted not taken. */ + + +#ifdef _MIPS_ARCH_R10000 +#define R10K_BEQZ_INSN "beqzl" +#else +#define R10K_BEQZ_INSN "beqz" +#endif + #define MIPS_SYNC_STR_2(X) #X #define MIPS_SYNC_STR_1(X) MIPS_SYNC_STR_2(X) #define MIPS_SYNC_STR MIPS_SYNC_STR_1(MIPS_SYNC) @@ -69,16 +95,16 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\t" \ - "ll %0,%4\n\t" \ + "ll %0,%5\n\t" \ "move %1,$0\n\t" \ - "bne %0,%2,2f\n\t" \ - "move %1,%3\n\t" \ - "sc %1,%4\n\t" \ - "beqz %1,1b\n" \ + "bne %0,%3,2f\n\t" \ + "move %1,%4\n\t" \ + "sc %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (oldval), "r" (newval), "m" (*mem) \ : "memory") @@ -93,16 +119,16 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\t" \ - "lld %0,%4\n\t" \ + "lld %0,%5\n\t" \ "move %1,$0\n\t" \ - "bne %0,%2,2f\n\t" \ - "move %1,%3\n\t" \ - "scd %1,%4\n\t" \ - "beqz %1,1b\n" \ + "bne %0,%3,2f\n\t" \ + "move %1,%4\n\t" \ + "scd %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (oldval), "r" (newval), "m" (*mem) \ : "memory") #endif @@ -189,14 +215,14 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\t" \ - "ll %0,%3\n\t" \ - "move %1,%2\n\t" \ - "sc %1,%3\n\t" \ - "beqz %1,1b\n" \ + "ll %0,%4\n\t" \ + "move %1,%3\n\t" \ + "sc %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (newval), "m" (*mem) \ : "memory"); \ __prev; }) @@ -213,14 +239,14 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\n" \ - "lld %0,%3\n\t" \ - "move %1,%2\n\t" \ - "scd %1,%3\n\t" \ - "beqz %1,1b\n" \ + "lld %0,%4\n\t" \ + "move %1,%3\n\t" \ + "scd %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (newval), "m" (*mem) \ : "memory"); \ __prev; }) @@ -248,14 +274,14 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\t" \ - "ll %0,%3\n\t" \ - "addu %1,%0,%2\n\t" \ - "sc %1,%3\n\t" \ - "beqz %1,1b\n" \ + "ll %0,%4\n\t" \ + "addu %1,%0,%3\n\t" \ + "sc %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (value), "m" (*mem) \ : "memory"); \ __prev; }) @@ -272,14 +298,14 @@ typedef uintmax_t uatomic_max_t; MIPS_PUSH_MIPS2 \ rel "\n" \ "1:\t" \ - "lld %0,%3\n\t" \ - "daddu %1,%0,%2\n\t" \ - "scd %1,%3\n\t" \ - "beqz %1,1b\n" \ + "lld %0,%4\n\t" \ + "daddu %1,%0,%3\n\t" \ + "scd %1,%2\n\t" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ - : "=&r" (__prev), "=&r" (__cmp) \ + : "=&r" (__prev), "=&r" (__cmp), "=m" (*mem) \ : "r" (value), "m" (*mem) \ : "memory"); \ __prev; }) |