linux-kernel - [PATCH 4.14 075/119] arm64: Always enable ssb vulnerability detection

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Message-Id: <20191027203341.465064712@linuxfoundation.org>
Date:   Sun, 27 Oct 2019 22:00:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.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 4.14 075/119] arm64: Always enable ssb vulnerability detection

From: Jeremy Linton <jeremy.linton@....com>

[ Upstream commit d42281b6e49510f078ace15a8ea10f71e6262581 ]

Ensure we are always able to detect whether or not the CPU is affected
by SSB, 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>
[will: Use IS_ENABLED instead of #ifdef]
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/include/asm/cpufeature.h |    4 ----
 arch/arm64/kernel/cpu_errata.c      |    9 +++++----
 2 files changed, 5 insertions(+), 8 deletions(-)

--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -493,11 +493,7 @@ static inline int arm64_get_ssbd_state(v
 #endif
 }
 
-#ifdef CONFIG_ARM64_SSBD
 void arm64_set_ssbd_mitigation(bool state);
-#else
-static inline void arm64_set_ssbd_mitigation(bool state) {}
-#endif
 
 #endif /* __ASSEMBLY__ */
 
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -231,7 +231,6 @@ enable_smccc_arch_workaround_1(const str
 }
 #endif	/* CONFIG_HARDEN_BRANCH_PREDICTOR */
 
-#ifdef CONFIG_ARM64_SSBD
 DEFINE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
 
 int ssbd_state __read_mostly = ARM64_SSBD_KERNEL;
@@ -304,6 +303,11 @@ void __init arm64_enable_wa2_handling(st
 
 void arm64_set_ssbd_mitigation(bool state)
 {
+	if (!IS_ENABLED(CONFIG_ARM64_SSBD)) {
+		pr_info_once("SSBD disabled by kernel configuration\n");
+		return;
+	}
+
 	if (this_cpu_has_cap(ARM64_SSBS)) {
 		if (state)
 			asm volatile(SET_PSTATE_SSBS(0));
@@ -423,7 +427,6 @@ out_printmsg:
 
 	return required;
 }
-#endif	/* CONFIG_ARM64_SSBD */
 
 #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max)	\
 	.matches = is_affected_midr_range,			\
@@ -627,14 +630,12 @@ const struct arm64_cpu_capabilities arm6
 		.cpu_enable = enable_smccc_arch_workaround_1,
 	},
 #endif
-#ifdef CONFIG_ARM64_SSBD
 	{
 		.desc = "Speculative Store Bypass Disable",
 		.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
 		.capability = ARM64_SSBD,
 		.matches = has_ssbd_mitigation,
 	},
-#endif
 	{
 	}
 };