diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2019-10-24 14:48:33 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-29 09:17:30 +0100 |
| commit | 5fff7a398c266c8c202a24e573327ba2c1566524 (patch) | |
| tree | 01754ec70552538135cea0015e7724a9b5502c7b | |
| parent | cd91a0fcab932f31f0dcc42f321131974813e567 (diff) | |
arm64/speculation: Support 'mitigations=' cmdline option
[ Upstream commit a111b7c0f20e13b54df2fa959b3dc0bdf1925ae6 ]
Configure arm64 runtime CPU speculation bug mitigations in accordance
with the 'mitigations=' cmdline option. This affects Meltdown, Spectre
v2, and Speculative Store Bypass.
The default behavior is unchanged.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
[will: reorder checks so KASLR implies KPTI and SSBS is affected by cmdline]
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>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 8 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 6 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 8 |
3 files changed, 17 insertions, 5 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 5205740ed39b..b67a6cd08ca1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2389,8 +2389,8 @@ http://repo.or.cz/w/linux-2.6/mini2440.git mitigations= - [X86,PPC,S390] Control optional mitigations for CPU - vulnerabilities. This is a set of curated, + [X86,PPC,S390,ARM64] Control optional mitigations for + CPU vulnerabilities. This is a set of curated, arch-independent options, each of which is an aggregation of existing arch-specific options. @@ -2399,12 +2399,14 @@ improves system performance, but it may also expose users to several CPU vulnerabilities. Equivalent to: nopti [X86,PPC] + kpti=0 [ARM64] nospectre_v1 [PPC] nobp=0 [S390] nospectre_v1 [X86] - nospectre_v2 [X86,PPC,S390] + nospectre_v2 [X86,PPC,S390,ARM64] spectre_v2_user=off [X86] spec_store_bypass_disable=off [X86,PPC] + ssbd=force-off [ARM64] l1tf=off [X86] mds=off [X86] diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index ca718250d5bd..7d15f4cb6393 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -19,6 +19,7 @@ #include <linux/arm-smccc.h> #include <linux/psci.h> #include <linux/types.h> +#include <linux/cpu.h> #include <asm/cpu.h> #include <asm/cputype.h> #include <asm/cpufeature.h> @@ -347,6 +348,9 @@ static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry, WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible()); + if (cpu_mitigations_off()) + ssbd_state = ARM64_SSBD_FORCE_DISABLE; + /* delay setting __ssb_safe until we get a firmware response */ if (is_midr_in_range_list(read_cpuid_id(), entry->midr_range_list)) this_cpu_safe = true; @@ -544,7 +548,7 @@ check_branch_predictor(const struct arm64_cpu_capabilities *entry, int scope) } /* forced off */ - if (__nospectre_v2) { + if (__nospectre_v2 || cpu_mitigations_off()) { pr_info_once("spectrev2 mitigation disabled by command line option\n"); __hardenbp_enab = false; return false; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index b782e98633da..15ce2c8b9ee2 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -24,6 +24,7 @@ #include <linux/stop_machine.h> #include <linux/types.h> #include <linux/mm.h> +#include <linux/cpu.h> #include <asm/cpu.h> #include <asm/cpufeature.h> #include <asm/cpu_ops.h> @@ -841,7 +842,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, MIDR_ALL_VERSIONS(MIDR_CORTEX_A72), MIDR_ALL_VERSIONS(MIDR_CORTEX_A73), }; - char const *str = "command line option"; + char const *str = "kpti command line option"; bool meltdown_safe; meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list); @@ -871,6 +872,11 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, } } + if (cpu_mitigations_off() && !__kpti_forced) { + str = "mitigations=off"; + __kpti_forced = -1; + } + if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) { pr_info_once("kernel page table isolation disabled by kernel configuration\n"); return false; |