linux-kernel - [PATCH 4.19 099/114] arm64: Always enable spectre-v2 vulnerability detection

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Date:   Thu, 10 Oct 2019 10:36:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeremy Linton <jeremy.linton@....com>,
        Andre Przywara <andre.przywara@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: [PATCH 4.19 099/114] arm64: Always enable spectre-v2 vulnerability detection

From: Jeremy Linton <jeremy.linton@....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@....com>
Reviewed-by: Andre Przywara <andre.przywara@....com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Tested-by: Stefan Wahren <stefan.wahren@...e.com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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",