@@ -, +, @@ --- ChangeLog.mips | 4 ++++ sysdeps/mips/bits/atomic.h | 38 ++++++++++++++++++++++++++++++++------ 2 files changed, 36 insertions(+), 6 deletions(-) --- a/sysdeps/mips/bits/atomic.h +++ a/sysdeps/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) @@ -74,7 +100,7 @@ typedef uintmax_t uatomic_max_t; "bne %0,%3,2f\n\t" \ "move %1,%4\n\t" \ "sc %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ @@ -98,7 +124,7 @@ typedef uintmax_t uatomic_max_t; "bne %0,%3,2f\n\t" \ "move %1,%4\n\t" \ "scd %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ @@ -192,7 +218,7 @@ typedef uintmax_t uatomic_max_t; "ll %0,%4\n\t" \ "move %1,%3\n\t" \ "sc %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ @@ -216,7 +242,7 @@ typedef uintmax_t uatomic_max_t; "lld %0,%4\n\t" \ "move %1,%3\n\t" \ "scd %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ @@ -251,7 +277,7 @@ typedef uintmax_t uatomic_max_t; "ll %0,%4\n\t" \ "addu %1,%0,%3\n\t" \ "sc %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ @@ -275,7 +301,7 @@ typedef uintmax_t uatomic_max_t; "lld %0,%4\n\t" \ "daddu %1,%0,%3\n\t" \ "scd %1,%2\n\t" \ - "beqz %1,1b\n" \ + R10K_BEQZ_INSN" %1,1b\n" \ acq "\n\t" \ ".set pop\n" \ "2:\n\t" \ --