diff options
Diffstat (limited to 'arch/arm64/include/asm/atomic_ll_sc.h')
| -rw-r--r-- | arch/arm64/include/asm/atomic_ll_sc.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/atomic_ll_sc.h b/arch/arm64/include/asm/atomic_ll_sc.h index f02d3bf7b9e6..b53f70dd6e10 100644 --- a/arch/arm64/include/asm/atomic_ll_sc.h +++ b/arch/arm64/include/asm/atomic_ll_sc.h @@ -257,6 +257,14 @@ __LL_SC_PREFIX(__cmpxchg_case_##name##sz(volatile void *ptr, \ unsigned long tmp; \ u##sz oldval; \ \ + /* \ + * Sub-word sizes require explicit casting so that the compare \ + * part of the cmpxchg doesn't end up interpreting non-zero \ + * upper bits of the register containing "old". \ + */ \ + if (sz < 32) \ + old = (u##sz)old; \ + \ asm volatile( \ " prfm pstl1strm, %[v]\n" \ "1: ld" #acq "xr" #sfx "\t%" #w "[oldval], %[v]\n" \ |