From: Will Deacon <will.deacon@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, ard.biesheuvel@linaro.org,
marc.zyngier@arm.com, lorenzo.pieralisi@arm.com,
christoffer.dall@linaro.org, linux-kernel@vger.kernel.org,
shankerd@codeaurora.org, jnair@caviumnetworks.com,
Will Deacon <will.deacon@arm.com>
Subject: [PATCH v3 03/13] arm64: Take into account ID_AA64PFR0_EL1.CSV3
Date: Mon, 8 Jan 2018 17:32:28 +0000 [thread overview]
Message-ID: <1515432758-26440-4-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1515432758-26440-1-git-send-email-will.deacon@arm.com>
For non-KASLR kernels where the KPTI behaviour has not been overridden
on the command line we can use ID_AA64PFR0_EL1.CSV3 to determine whether
or not we should unmap the kernel whilst running at EL0.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/sysreg.h | 1 +
arch/arm64/kernel/cpufeature.c | 8 +++++++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 08cc88574659..ae519bbd3f9e 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -437,6 +437,7 @@
#define ID_AA64ISAR1_DPB_SHIFT 0
/* id_aa64pfr0 */
+#define ID_AA64PFR0_CSV3_SHIFT 60
#define ID_AA64PFR0_SVE_SHIFT 32
#define ID_AA64PFR0_GIC_SHIFT 24
#define ID_AA64PFR0_ASIMD_SHIFT 20
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9f0545dfe497..d723fc071f39 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -145,6 +145,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
+ ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI),
@@ -851,6 +852,8 @@ static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */
static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
int __unused)
{
+ u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
+
/* Forced on command line? */
if (__kpti_forced) {
pr_info_once("kernel page table isolation forced %s by command line option\n",
@@ -862,7 +865,9 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
return true;
- return false;
+ /* Defer to CPU feature registers */
+ return !cpuid_feature_extract_unsigned_field(pfr0,
+ ID_AA64PFR0_CSV3_SHIFT);
}
static int __init parse_kpti(char *str)
@@ -967,6 +972,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
},
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
{
+ .desc = "Kernel page table isolation (KPTI)",
.capability = ARM64_UNMAP_KERNEL_AT_EL0,
.def_scope = SCOPE_SYSTEM,
.matches = unmap_kernel_at_el0,
--
2.1.4
next prev parent reply other threads:[~2018-01-08 17:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 17:32 [PATCH v3 00/13] arm64 kpti hardening and variant 2 workarounds Will Deacon
2018-01-08 17:32 ` [PATCH v3 01/13] arm64: use RET instruction for exiting the trampoline Will Deacon
2018-01-08 17:32 ` [PATCH v3 02/13] arm64: Kconfig: Reword UNMAP_KERNEL_AT_EL0 kconfig entry Will Deacon
2018-01-09 17:17 ` Christoph Hellwig
2018-01-10 19:26 ` Will Deacon
2018-01-08 17:32 ` Will Deacon [this message]
2018-01-08 17:32 ` [PATCH v3 04/13] arm64: cpufeature: Pass capability structure to ->enable callback Will Deacon
2018-01-08 17:32 ` [PATCH v3 05/13] drivers/firmware: Expose psci_get_version through psci_ops structure Will Deacon
2018-01-08 17:32 ` [PATCH v3 06/13] arm64: Move post_ttbr_update_workaround to C code Will Deacon
2018-01-08 17:32 ` [PATCH v3 07/13] arm64: Add skeleton to harden the branch predictor against aliasing attacks Will Deacon
2018-01-09 12:55 ` Philippe Ombredanne
2018-01-08 17:32 ` [PATCH v3 08/13] arm64: KVM: Use per-CPU vector when BP hardening is enabled Will Deacon
2018-01-08 17:32 ` [PATCH v3 09/13] arm64: KVM: Make PSCI_VERSION a fast path Will Deacon
2018-01-08 17:32 ` [PATCH v3 10/13] arm64: cputype: Add missing MIDR values for Cortex-A72 and Cortex-A75 Will Deacon
2018-01-08 17:32 ` [PATCH v3 11/13] arm64: Implement branch predictor hardening for affected Cortex-A CPUs Will Deacon
2018-01-09 16:12 ` Suzuki K Poulose
2018-01-15 11:51 ` Marc Zyngier
2018-01-15 18:01 ` Catalin Marinas
2018-01-08 17:32 ` [PATCH v3 12/13] arm64: Implement branch predictor hardening for Falkor Will Deacon
2018-01-12 17:58 ` Shanker Donthineni
2018-01-08 17:32 ` [PATCH v3 13/13] arm64: cputype: Add MIDR values for Cavium ThunderX2 CPUs Will Deacon
2018-01-08 18:53 ` [PATCH v3 00/13] arm64 kpti hardening and variant 2 workarounds Catalin Marinas
2018-01-09 14:07 ` Matthias Brugger
2018-01-12 15:58 ` Catalin Marinas
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