arm64: hyp-stub: Stop pointlessly clobbering lr

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 <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S
index d3b5f75..e4215ad 100644 (file)
--- 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