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Message-Id: <20180215151717.154641972@linuxfoundation.org>
Date: Thu, 15 Feb 2018 16:16:10 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Shanker Donthineni <shankerd@...eaurora.org>,
Will Deacon <will.deacon@....com>,
Catalin Marinas <catalin.marinas@....com>
Subject: [PATCH 4.15 070/202] [Variant 2/Spectre-v2] arm64: Implement branch predictor hardening for Falkor
4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shanker Donthineni <shankerd@...eaurora.org>
Commit ec82b567a74f upstream.
Falkor is susceptible to branch predictor aliasing and can
theoretically be attacked by malicious code. This patch
implements a mitigation for these attacks, preventing any
malicious entries from affecting other victim contexts.
Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
[will: fix label name when !CONFIG_KVM and remove references to MIDR_FALKOR]
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/arm64/include/asm/cpucaps.h | 3 +-
arch/arm64/include/asm/kvm_asm.h | 2 +
arch/arm64/kernel/bpi.S | 8 +++++++
arch/arm64/kernel/cpu_errata.c | 40 +++++++++++++++++++++++++++++++++++++--
arch/arm64/kvm/hyp/entry.S | 12 +++++++++++
arch/arm64/kvm/hyp/switch.c | 8 +++++++
6 files changed, 70 insertions(+), 3 deletions(-)
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -43,7 +43,8 @@
#define ARM64_SVE 22
#define ARM64_UNMAP_KERNEL_AT_EL0 23
#define ARM64_HARDEN_BRANCH_PREDICTOR 24
+#define ARM64_HARDEN_BP_POST_GUEST_EXIT 25
-#define ARM64_NCAPS 25
+#define ARM64_NCAPS 26
#endif /* __ASM_CPUCAPS_H */
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -68,6 +68,8 @@ extern u32 __kvm_get_mdcr_el2(void);
extern u32 __init_stage2_translation(void);
+extern void __qcom_hyp_sanitize_btac_predictors(void);
+
#endif
#endif /* __ARM_KVM_ASM_H__ */
--- a/arch/arm64/kernel/bpi.S
+++ b/arch/arm64/kernel/bpi.S
@@ -77,3 +77,11 @@ ENTRY(__psci_hyp_bp_inval_start)
ldp x0, x1, [sp, #(16 * 8)]
add sp, sp, #(8 * 18)
ENTRY(__psci_hyp_bp_inval_end)
+
+ENTRY(__qcom_hyp_sanitize_link_stack_start)
+ stp x29, x30, [sp, #-16]!
+ .rept 16
+ bl . + 4
+ .endr
+ ldp x29, x30, [sp], #16
+ENTRY(__qcom_hyp_sanitize_link_stack_end)
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -68,6 +68,8 @@ DEFINE_PER_CPU_READ_MOSTLY(struct bp_har
#ifdef CONFIG_KVM
extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[];
+extern char __qcom_hyp_sanitize_link_stack_start[];
+extern char __qcom_hyp_sanitize_link_stack_end[];
static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start,
const char *hyp_vecs_end)
@@ -110,8 +112,10 @@ static void __install_bp_hardening_cb(bp
spin_unlock(&bp_lock);
}
#else
-#define __psci_hyp_bp_inval_start NULL
-#define __psci_hyp_bp_inval_end NULL
+#define __psci_hyp_bp_inval_start NULL
+#define __psci_hyp_bp_inval_end NULL
+#define __qcom_hyp_sanitize_link_stack_start NULL
+#define __qcom_hyp_sanitize_link_stack_end NULL
static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
const char *hyp_vecs_start,
@@ -152,6 +156,29 @@ static int enable_psci_bp_hardening(void
return 0;
}
+
+static void qcom_link_stack_sanitization(void)
+{
+ u64 tmp;
+
+ asm volatile("mov %0, x30 \n"
+ ".rept 16 \n"
+ "bl . + 4 \n"
+ ".endr \n"
+ "mov x30, %0 \n"
+ : "=&r" (tmp));
+}
+
+static int qcom_enable_link_stack_sanitization(void *data)
+{
+ const struct arm64_cpu_capabilities *entry = data;
+
+ install_bp_hardening_cb(entry, qcom_link_stack_sanitization,
+ __qcom_hyp_sanitize_link_stack_start,
+ __qcom_hyp_sanitize_link_stack_end);
+
+ return 0;
+}
#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */
#define MIDR_RANGE(model, min, max) \
@@ -323,6 +350,15 @@ const struct arm64_cpu_capabilities arm6
MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
.enable = enable_psci_bp_hardening,
},
+ {
+ .capability = ARM64_HARDEN_BRANCH_PREDICTOR,
+ MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
+ .enable = qcom_enable_link_stack_sanitization,
+ },
+ {
+ .capability = ARM64_HARDEN_BP_POST_GUEST_EXIT,
+ MIDR_ALL_VERSIONS(MIDR_QCOM_FALKOR_V1),
+ },
#endif
{
}
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -196,3 +196,15 @@ alternative_endif
eret
ENDPROC(__fpsimd_guest_restore)
+
+ENTRY(__qcom_hyp_sanitize_btac_predictors)
+ /**
+ * Call SMC64 with Silicon provider serviceID 23<<8 (0xc2001700)
+ * 0xC2000000-0xC200FFFF: assigned to SiP Service Calls
+ * b15-b0: contains SiP functionID
+ */
+ movz x0, #0x1700
+ movk x0, #0xc200, lsl #16
+ smc #0
+ ret
+ENDPROC(__qcom_hyp_sanitize_btac_predictors)
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -393,6 +393,14 @@ again:
/* 0 falls through to be handled out of EL2 */
}
+ if (cpus_have_const_cap(ARM64_HARDEN_BP_POST_GUEST_EXIT)) {
+ u32 midr = read_cpuid_id();
+
+ /* Apply BTAC predictors mitigation to all Falkor chips */
+ if ((midr & MIDR_CPU_MODEL_MASK) == MIDR_QCOM_FALKOR_V1)
+ __qcom_hyp_sanitize_btac_predictors();
+ }
+
fp_enabled = __fpsimd_enabled();
__sysreg_save_guest_state(guest_ctxt);
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