diff options
Diffstat (limited to 'arch/arm64/kernel/cpufeature.c')
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 476fb5caa361..9bc9847072b6 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -23,6 +23,7 @@ #include <linux/sort.h> #include <linux/stop_machine.h> #include <linux/types.h> +#include <linux/mm.h> #include <asm/cpu.h> #include <asm/cpufeature.h> #include <asm/cpu_ops.h> @@ -46,6 +47,7 @@ unsigned int compat_elf_hwcap2 __read_mostly; #endif DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); +EXPORT_SYMBOL(cpu_hwcaps); #define __ARM64_FTR_BITS(SIGNED, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \ { \ @@ -654,6 +656,39 @@ static bool runs_at_el2(const struct arm64_cpu_capabilities *entry) return is_kernel_in_hyp_mode(); } +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ + +static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry) +{ + /* Forced on command line? */ + if (__kpti_forced) { + pr_info_once("kernel page table isolation forced %s by command line option\n", + __kpti_forced > 0 ? "ON" : "OFF"); + return __kpti_forced > 0; + } + + /* Useful for KASLR robustness */ + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + return true; + + return false; +} + +static int __init parse_kpti(char *str) +{ + bool enabled; + int ret = strtobool(str, &enabled); + + if (ret) + return ret; + + __kpti_forced = enabled ? 1 : -1; + return 0; +} +__setup("kpti=", parse_kpti); +#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ + static const struct arm64_cpu_capabilities arm64_features[] = { { .desc = "GIC system register CPU interface", @@ -711,6 +746,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .capability = ARM64_HAS_VIRT_HOST_EXTN, .matches = runs_at_el2, }, +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 + { + .capability = ARM64_UNMAP_KERNEL_AT_EL0, + .matches = unmap_kernel_at_el0, + }, +#endif {}, }; |