Re: [Xen-devel] [PATCH v4 04/16] livepatch: Initial ARM64 support.

[Julien Grall <julien.grall@xxxxxxx>]

Hi Konrad,

On 16/09/2016 18:38, Konrad Rzeszutek Wilk wrote:
> diff --git a/xen/arch/arm/arm64/livepatch.c b/xen/arch/arm/arm64/livepatch.c
> new file mode 100644
> index 0000000..49eb69b
> --- /dev/null
> +++ b/xen/arch/arm/arm64/livepatch.c
[...]

> +int arch_livepatch_perform_rela(struct livepatch_elf *elf,
> +                                const struct livepatch_elf_sec *base,
> +                                const struct livepatch_elf_sec *rela)
> +{
[...]

> +
> +        /* MOVW instruction relocations. */
> +        case R_AARCH64_MOVW_UABS_G0_NC:
> +            overflow_check = false;
Can you add a comment here to mention the fall-through?

> +
> +        case R_AARCH64_MOVW_UABS_G0:
> +            ovf = reloc_insn_movw(RELOC_OP_ABS, dest, val, 0,
> +                                  AARCH64_INSN_IMM_MOVKZ);
> +            break;
> +
> +        case R_AARCH64_MOVW_UABS_G1_NC:
> +            overflow_check = false;
Ditto.

> +
> +        case R_AARCH64_MOVW_UABS_G1:
> +            ovf = reloc_insn_movw(RELOC_OP_ABS, dest, val, 16,
> +                                  AARCH64_INSN_IMM_MOVKZ);
> +            break;
> +
> +        case R_AARCH64_MOVW_UABS_G2_NC:
> +            overflow_check = false;
Ditto.

> +
> +        case R_AARCH64_MOVW_UABS_G2:
> +            ovf = reloc_insn_movw(RELOC_OP_ABS, dest, val, 32,
> +                                  AARCH64_INSN_IMM_MOVKZ);
> +            break;
[...]

> +        /* Instructions. */
> +        case R_AARCH64_ADR_PREL_LO21:
> +            ovf = reloc_insn_imm(RELOC_OP_PREL, dest, val, 0, 21,
> +                                 AARCH64_INSN_IMM_ADR);
> +            break;
> +
> +        case R_AARCH64_ADR_PREL_PG_HI21_NC:
> +            overflow_check = false;
Ditto.

> +        case R_AARCH64_ADR_PREL_PG_HI21:
> +            ovf = reloc_insn_imm(RELOC_OP_PAGE, dest, val, 12, 21,
> +                                 AARCH64_INSN_IMM_ADR);
> +            break;
[...]

> diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c
> index 755f596..b4b4b6c 100644
> --- a/xen/arch/arm/livepatch.c
> +++ b/xen/arch/arm/livepatch.c
[...]

>  void arch_livepatch_revive(void)
>  {
> +    /*
> +     * Nuke the instruction cache. Data cache has been cleaned before in
> +     * arch_livepatch_apply_jmp.
I think you forgot to clean text region from the payload. Without that, 
you may receive a crash if you have a separate cache for data and 
instruction.
> +     */
> +    invalidate_icache();
> +
> +    if ( vmap_of_xen_text )
> +        vunmap(vmap_of_xen_text);
> +
> +    vmap_of_xen_text = NULL;
>  }
Regards,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel