diff options
Diffstat (limited to 'src/runtime/sys_linux_arm.s')
| -rw-r--r-- | src/runtime/sys_linux_arm.s | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/runtime/sys_linux_arm.s b/src/runtime/sys_linux_arm.s index 50f074a234..b68b81af3e 100644 --- a/src/runtime/sys_linux_arm.s +++ b/src/runtime/sys_linux_arm.s @@ -416,6 +416,22 @@ check: TEXT runtime·casp1(SB),NOSPLIT,$0 B runtime·cas(SB) +// As for cas, memory barriers are complicated on ARM, but the kernel +// provides a user helper. ARMv5 does not support SMP and has no +// memory barrier instruction at all. ARMv6 added SMP support and has +// a memory barrier, but it requires writing to a coprocessor +// register. ARMv7 introduced the DMB instruction, but it's expensive +// even on single-core devices. The kernel helper takes care of all of +// this for us. + +TEXT publicationBarrier<>(SB),NOSPLIT,$0 + // void __kuser_memory_barrier(void); + MOVW $0xffff0fa0, R15 // R15 is hardware PC. + +TEXT ·publicationBarrier(SB),NOSPLIT,$0 + BL publicationBarrier<>(SB) + RET + TEXT runtime·osyield(SB),NOSPLIT,$0 MOVW $SYS_sched_yield, R7 SWI $0 |