Subject: [PATCH v4 5/5] arm64/kernel: enable A53 erratum #8434319 handling at runtime

From: [email-masked] (Will Deacon)
Date: Thu, 8 Mar 2018 13:45:12 +0000

On Tue, Mar 06, 2018 at 05:15:35PM +0000, Ard Biesheuvel wrote:
> Omit patching of ADRP instruction at module load time if the current
> CPUs are not susceptible to the erratum.

[...]

> diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c
> index 534bf1d47119..1a583ccace00 100644
> --- a/arch/arm64/kernel/module-plts.c
> +++ b/arch/arm64/kernel/module-plts.c
> @@ -158,7 +158,8 @@ static unsigned int count_plts(Elf64_Sym *syms, Elf64_Rela *rela, int num,
>  			break;
>  		case R_AARCH64_ADR_PREL_PG_HI21_NC:
>  		case R_AARCH64_ADR_PREL_PG_HI21:
> -			if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_843419))
> +			if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_843419) ||
> +			    !cpus_have_const_cap(ARM64_WORKAROUND_843419))
>  				break;
>  
>  			/*
> diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
> index 89217704944e..47b40aaa1a5d 100644
> --- a/arch/arm64/kernel/module.c
> +++ b/arch/arm64/kernel/module.c
> @@ -201,6 +201,7 @@ static int reloc_insn_imm(enum aarch64_reloc_op op, __le32 *place, u64 val,
>  static int reloc_insn_adrp(struct module *mod, __le32 *place, u64 val)
>  {
>  	if (!IS_ENABLED(CONFIG_ARM64_ERRATUM_843419) ||
> +	    !cpus_have_const_cap(ARM64_WORKAROUND_843419) ||

Mind if I drop the IS_ENABLED check here and in the hunk above? The
const_cap check along should be sufficient, no?

Will