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Subject[PATCH 4.19 099/114] arm64: Always enable spectre-v2 vulnerability detection
Date
From: Jeremy Linton <jeremy.linton@arm.com>

[ Upstream commit 8c1e3d2bb44cbb998cb28ff9a18f105fee7f1eb3 ]

Ensure we are always able to detect whether or not the CPU is affected
by Spectre-v2, so that we can later advertise this to userspace.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kernel/cpu_errata.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -87,7 +87,6 @@ cpu_enable_trap_ctr_access(const struct

atomic_t arm64_el2_vector_last_slot = ATOMIC_INIT(-1);

-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>

@@ -225,11 +224,11 @@ static int detect_harden_bp_fw(void)
((midr & MIDR_CPU_MODEL_MASK) == MIDR_QCOM_FALKOR_V1))
cb = qcom_link_stack_sanitization;

- install_bp_hardening_cb(cb, smccc_start, smccc_end);
+ if (IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR))
+ install_bp_hardening_cb(cb, smccc_start, smccc_end);

return 1;
}
-#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */

DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);

@@ -513,7 +512,6 @@ multi_entry_cap_cpu_enable(const struct
caps->cpu_enable(caps);
}

-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
/*
* List of CPUs that do not need any Spectre-v2 mitigation at all.
*/
@@ -545,6 +543,12 @@ check_branch_predictor(const struct arm6
if (!need_wa)
return false;

+ if (!IS_ENABLED(CONFIG_HARDEN_BRANCH_PREDICTOR)) {
+ pr_warn_once("spectrev2 mitigation disabled by kernel configuration\n");
+ __hardenbp_enab = false;
+ return false;
+ }
+
/* forced off */
if (__nospectre_v2) {
pr_info_once("spectrev2 mitigation disabled by command line option\n");
@@ -556,7 +560,6 @@ check_branch_predictor(const struct arm6

return (need_wa > 0);
}
-#endif

#ifdef CONFIG_HARDEN_EL2_VECTORS

@@ -715,13 +718,11 @@ const struct arm64_cpu_capabilities arm6
ERRATA_MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
},
#endif
-#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
{
.capability = ARM64_HARDEN_BRANCH_PREDICTOR,
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
.matches = check_branch_predictor,
},
-#endif
#ifdef CONFIG_HARDEN_EL2_VECTORS
{
.desc = "EL2 vector hardening",

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