From: Vladimir Murzin Date: Thu, 1 Sep 2016 13:35:59 +0000 (+0100) Subject: arm64: kernel: do not need to reset UAO on exception entry X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=563cada03db9cb5df19b20290b65c4e5e1d21358;p=linux-beck.git 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 Acked-by: James Morse Signed-off-by: Will Deacon --- 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