Re: [PATCH 06/15] arm64: kvm: Move __smccc_workaround_1_smc to .rodata

Marc Zyngier
2020-05-11T10:05:17Z

On Thu, 30 Apr 2020 15:48:22 +0100
David Brazdil <dbrazdil@google.com> wrote:

> This snippet of assembly is used by cpu_errata.c to overwrite parts of KVM hyp
> vector. It is never directly executed, so move it from .text to .rodata.
>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
> arch/arm64/kvm/hyp/hyp-entry.S | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> index 5986e1d78d3f..7e5f386c5c2d 100644
> --- a/arch/arm64/kvm/hyp/hyp-entry.S
> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> @@ -364,6 +364,11 @@ SYM_CODE_END(__bp_harden_hyp_vecs)
> .popsection
>
> #ifndef __HYPERVISOR__
> + /*
> + * This is not executed directly and is instead copied into the vectors
> + * by install_bp_hardening_cb().
> + */
> + .pushsection .rodata
> SYM_CODE_START(__smccc_workaround_1_smc)

I wonder whether we should keep the SYM_CODE_START() annotation or not.
It feels weird to say "code" in a rodata section, and the alignment
doesn't matter as we copy it in place, as you noticed.

> esb
> sub sp, sp, #(8 * 4)
> @@ -377,5 +382,6 @@ SYM_CODE_START(__smccc_workaround_1_smc)
> 1: .org __smccc_workaround_1_smc + __SMCCC_WORKAROUND_1_SMC_SZ
> .org 1b
> SYM_CODE_END(__smccc_workaround_1_smc)
> + .popsection
> #endif /* __HYPERVISOR__ */
> #endif /* CONFIG_KVM_INDIRECT_VECTORS */

Otherwise, looks good.

Thanks,

M.
--
Jazz is not dead. It just smells funny...