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Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 70ac1faa54c0..edfd5efd812f 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -147,6 +147,27 @@ menuconfig ARMV8_DEPRECATED if ARMV8_DEPRECATED +config SWP_EMULATION + bool "Emulate SWP/SWPB instructions" + help + ARMv8 obsoletes the use of A32 SWP/SWPB instructions such that + they are always undefined. Say Y here to enable software + emulation of these instructions for userspace using LDXR/STXR. + + In some older versions of glibc [<=2.8] SWP is used during futex + trylock() operations with the assumption that the code will not + be preempted. This invalid assumption may be more likely to fail + with SWP emulation enabled, leading to deadlock of the user + application. + + NOTE: when accessing uncached shared regions, LDXR/STXR rely + on an external transaction monitoring block called a global + monitor to maintain update atomicity. If your system does not + implement a global monitor, this option can cause programs that + perform SWP operations to uncached memory to deadlock. + + If unsure, say Y + endif endmenu |