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Subject[PATCH 4.19 096/114] arm64: Always enable ssb vulnerability detection
Date
From: Jeremy Linton <jeremy.linton@arm.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@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>
[will: Use IS_ENABLED instead of #ifdef]
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/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
@@ -525,11 +525,7 @@ 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
@@ -239,7 +239,6 @@ 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;
@@ -312,6 +311,11 @@ 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));
@@ -431,7 +435,6 @@ out_printmsg:

return required;
}
-#endif /* CONFIG_ARM64_SSBD */

#ifdef CONFIG_ARM64_ERRATUM_1463225
DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
@@ -710,14 +713,12 @@ const struct arm64_cpu_capabilities arm6
ERRATA_MIDR_RANGE_LIST(arm64_harden_el2_vectors),
},
#endif
-#ifdef CONFIG_ARM64_SSBD
{
.desc = "Speculative Store Bypass Disable",
.capability = ARM64_SSBD,
.type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM,
.matches = has_ssbd_mitigation,
},
-#endif
#ifdef CONFIG_ARM64_ERRATUM_1463225
{
.desc = "ARM erratum 1463225",

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