arm64: smccc: Save lr before calling __arm_smccc_sve_check()

Commit cfa7ff959a78 ("arm64: smccc: Support SMCCC v1.3 SVE register
saving hint") added a call to __arm_smccc_sve_check() which clobbers the
lr (register x30), causing __arm_smccc_hvc() to return to itself and
crash. Save lr on the stack before calling __arm_smccc_sve_check(). Save
the frame pointer (x29) to complete the frame record, and adjust the
offsets used to access stack parameters.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Fixes: cfa7ff959a78 ("arm64: smccc: Support SMCCC v1.3 SVE register saving hint")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20210721071834.69130-1-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
index d3d37f9..4873811 100644 (file)
--- a/arch/arm64/kernel/smccc-call.S
+++ b/arch/arm64/kernel/smccc-call.S
@@ -32,20 +32,23 @@ SYM_FUNC_END(__arm_smccc_sve_check)
 EXPORT_SYMBOL(__arm_smccc_sve_check)
 
        .macro SMCCC instr
+       stp     x29, x30, [sp, #-16]!
+       mov     x29, sp
 alternative_if ARM64_SVE
        bl      __arm_smccc_sve_check
 alternative_else_nop_endif
        \instr  #0
-       ldr     x4, [sp]
+       ldr     x4, [sp, #16]
        stp     x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
        stp     x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
-       ldr     x4, [sp, #8]
+       ldr     x4, [sp, #24]
        cbz     x4, 1f /* no quirk structure */
        ldr     x9, [x4, #ARM_SMCCC_QUIRK_ID_OFFS]
        cmp     x9, #ARM_SMCCC_QUIRK_QCOM_A6
        b.ne    1f
        str     x6, [x4, ARM_SMCCC_QUIRK_STATE_OFFS]
-1:     ret
+1:     ldp     x29, x30, [sp], #16
+       ret
        .endm
 
 /*