From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Thu, 8 Mar 2018 13:48:21 +0000 Subject: [PATCH v4 5/5] arm64/kernel: enable A53 erratum #8434319 handling at runtime In-Reply-To: References: <20180306171535.25681-1-ard.biesheuvel@linaro.org> <20180306171535.25681-6-ard.biesheuvel@linaro.org> <20180308134512.GA18452@arm.com> Message-ID: <20180308134820.GB18452@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Mar 08, 2018 at 01:47:26PM +0000, Ard Biesheuvel wrote: > On 8 March 2018 at 13:46, Ard Biesheuvel wrote: > > On 8 March 2018 at 13:45, Will Deacon wrote: > >> 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? > >> > > > > Without the IS_ENABLED() check, the code will always be present in the > > object file. > > > > I have no strong preference either way, though. > > Ehm, strike that. You will probably hit a linker error if you drop it, > because some dependent functions are #ifdef'ed out if the erratum > workaround is disabled. Ah, ok then. Thanks for the quick response. Will