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authorVladimir Murzin <vladimir.murzin@arm.com>2016-09-01 15:35:59 +0200
committerWill Deacon <will.deacon@arm.com>2016-09-01 21:22:47 +0200
commit563cada03db9cb5df19b20290b65c4e5e1d21358 (patch)
tree494a916076f45e93bac2aa361e17fc0e4dd5770d /arch/arm64/kernel/entry.S
parentarm64: debug: convert OS lock CPU hotplug notifier to new infrastructure (diff)
downloadlinux-563cada03db9cb5df19b20290b65c4e5e1d21358.tar.xz
linux-563cada03db9cb5df19b20290b65c4e5e1d21358.zip
arm64: kernel: do not need to reset UAO on exception entry
Commit e19a6ee2460b ("arm64: kernel: Save and restore UAO and addr_limit on exception entry") states that exception handler inherits the original PSTATE.UAO value, so UAO needes to be reset explicitly. However, ARM 8.2 Extension documentation says: PSTATE.UAO is copied to SPSR_ELx.UAO and is then set to 0 on an exception taken from AArch64 to AArch64 so hardware already does the right thing. Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com> Acked-by: James Morse <james.morse@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
-rw-r--r--arch/arm64/kernel/entry.S2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 6a64182822e5..6880dcc3b465 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -104,7 +104,7 @@
str x20, [sp, #S_ORIG_ADDR_LIMIT]
mov x20, #TASK_SIZE_64
str x20, [tsk, #TI_ADDR_LIMIT]
- ALTERNATIVE(nop, SET_PSTATE_UAO(0), ARM64_HAS_UAO, CONFIG_ARM64_UAO)
+ /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */
.endif /* \el == 0 */
mrs x22, elr_el1
mrs x23, spsr_el1