Messages in this thread | | | Subject | Re: [PATCH v5 07/17] arm64: add basic pointer authentication support | From | Suzuki K Poulose <> | Date | Thu, 11 Oct 2018 17:00:04 +0100 |
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Hi Kristina,
On 05/10/18 09:47, Kristina Martsenko wrote: > From: Mark Rutland <mark.rutland@arm.com> > > This patch adds basic support for pointer authentication, allowing > userspace to make use of APIAKey. The kernel maintains an APIAKey value > for each process (shared by all threads within), which is initialised to > a random value at exec() time. > > To describe that address authentication instructions are available, the > ID_AA64ISAR0.{APA,API} fields are exposed to userspace. A new hwcap, > APIA, is added to describe that the kernel manages APIAKey. > > Instructions using other keys (APIBKey, APDAKey, APDBKey) are disabled, > and will behave as NOPs. These may be made use of in future patches. > > No support is added for the generic key (APGAKey), though this cannot be > trapped or made to behave as a NOP. Its presence is not advertised with > a hwcap. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > [kristina: init keys in arch_bprm_mm_init; add AA64ISAR1.API HWCAP_CAP; use sysreg_clear_set] > Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> > Tested-by: Adam Wallis <awallis@codeaurora.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Will Deacon <will.deacon@arm.com>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index 0dd171c7d71e..3157685aa56a 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -1040,6 +1040,11 @@ static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused) > } > > #ifdef CONFIG_ARM64_PTR_AUTH > +static void cpu_enable_address_auth(struct arm64_cpu_capabilities const *cap) > +{ > + sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_ENIA); > +} > + > static bool has_address_auth(const struct arm64_cpu_capabilities *entry, > int __unused) > { > @@ -1267,6 +1272,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { > .capability = ARM64_HAS_ADDRESS_AUTH, > .type = ARM64_CPUCAP_SYSTEM_FEATURE, > .matches = has_address_auth, > + .cpu_enable = cpu_enable_address_auth, > }, > #endif /* CONFIG_ARM64_PTR_AUTH */ > {}, > @@ -1314,6 +1320,10 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = { > #ifdef CONFIG_ARM64_SVE > HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, HWCAP_SVE), > #endif > +#ifdef CONFIG_ARM64_PTR_AUTH > + HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_APA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_APIA), > + HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_API_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_APIA),
This is a bit problematic. If all the CPUs have just the IMPDEF algorithm available, we could fail to match the first entry (APA) for a late secondary CPU and thus thus fail the CPU from booting. I guess we need a custom entry which reuses the has_address_auth() as the matches().
Rest looks fine to me.
Suzuki
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