From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Mon, 3 Apr 2017 19:37:34 +0100 Subject: [PATCH v5 01/34] arm64: hyp-stub: Stop pointlessly clobbering lr In-Reply-To: <20170403183807.1620-1-marc.zyngier@arm.com> References: <20170403183807.1620-1-marc.zyngier@arm.com> Message-ID: <20170403183807.1620-2-marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org When entering the kernel hyp stub, we check whether or not we've made it here through an HVC instruction, clobbering lr (aka x30) in the process. This is completely pointless, as HVC is the only way to get here (all traps to EL2 are disabled, no interrupt override is applied). So let's remove this bit of code whose only point is to corrupt a valuable register. Acked-by: Catalin Marinas Signed-off-by: Marc Zyngier --- arch/arm64/kernel/hyp-stub.S | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index d3b5f75e652e..e4215ad06930 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -55,12 +55,6 @@ ENDPROC(__hyp_stub_vectors) .align 11 el1_sync: - mrs x30, esr_el2 - lsr x30, x30, #ESR_ELx_EC_SHIFT - - cmp x30, #ESR_ELx_EC_HVC64 - b.ne 9f // Not an HVC trap - cmp x0, #HVC_GET_VECTORS b.ne 1f mrs x0, vbar_el2 -- 2.11.0