diff options
| -rw-r--r-- | arch/arm64/include/asm/mmu.h | 41 | ||||
| -rw-r--r-- | arch/arm64/include/asm/pgtable-prot.h | 4 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 9 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 1 |
5 files changed, 52 insertions, 5 deletions
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 7689c7aa1d77..ac352accb3d9 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -16,6 +16,8 @@ #ifndef __ASM_MMU_H #define __ASM_MMU_H +#include <asm/cputype.h> + #define MMCF_AARCH32 0x1 /* mm context flag for AArch32 executables */ #define USER_ASID_BIT 48 #define USER_ASID_FLAG (UL(1) << USER_ASID_BIT) @@ -44,6 +46,45 @@ static inline bool arm64_kernel_unmapped_at_el0(void) cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0); } +static inline bool arm64_kernel_use_ng_mappings(void) +{ + bool tx1_bug; + + /* What's a kpti? Use global mappings if we don't know. */ + if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) + return false; + + /* + * Note: this function is called before the CPU capabilities have + * been configured, so our early mappings will be global. If we + * later determine that kpti is required, then + * kpti_install_ng_mappings() will make them non-global. + */ + if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + return arm64_kernel_unmapped_at_el0(); + + /* + * KASLR is enabled so we're going to be enabling kpti on non-broken + * CPUs regardless of their susceptibility to Meltdown. Rather + * than force everybody to go through the G -> nG dance later on, + * just put down non-global mappings from the beginning. + */ + if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) { + tx1_bug = false; +#ifndef MODULE + } else if (!static_branch_likely(&arm64_const_caps_ready)) { + extern const struct midr_range cavium_erratum_27456_cpus[]; + + tx1_bug = is_midr_in_range_list(read_cpuid_id(), + cavium_erratum_27456_cpus); +#endif + } else { + tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456); + } + + return !tx1_bug && kaslr_offset() > 0; +} + typedef void (*bp_hardening_cb_t)(void); struct bp_hardening_data { diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index 78b942c1bea4..986e41c4c32b 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -37,8 +37,8 @@ #define _PROT_DEFAULT (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) #define _PROT_SECT_DEFAULT (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) -#define PTE_MAYBE_NG (arm64_kernel_unmapped_at_el0() ? PTE_NG : 0) -#define PMD_MAYBE_NG (arm64_kernel_unmapped_at_el0() ? PMD_SECT_NG : 0) +#define PTE_MAYBE_NG (arm64_kernel_use_ng_mappings() ? PTE_NG : 0) +#define PMD_MAYBE_NG (arm64_kernel_use_ng_mappings() ? PMD_SECT_NG : 0) #define PROT_DEFAULT (_PROT_DEFAULT | PTE_MAYBE_NG) #define PROT_SECT_DEFAULT (_PROT_SECT_DEFAULT | PMD_MAYBE_NG) diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 09ac548c9d44..9950bb0cbd52 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -553,7 +553,7 @@ static const struct midr_range arm64_repeat_tlbi_cpus[] = { #endif #ifdef CONFIG_CAVIUM_ERRATUM_27456 -static const struct midr_range cavium_erratum_27456_cpus[] = { +const struct midr_range cavium_erratum_27456_cpus[] = { /* Cavium ThunderX, T88 pass 1.x - 2.1 */ MIDR_RANGE(MIDR_THUNDERX, 0, 0, 1, 1), /* Cavium ThunderX, T81 pass 1.0 */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 4f272399de89..f6d84e2c92fe 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -983,7 +983,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, /* Useful for KASLR robustness */ if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) - return true; + return kaslr_offset() > 0; /* Don't force KPTI for CPUs that are not vulnerable */ if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) @@ -1003,7 +1003,12 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) static bool kpti_applied = false; int cpu = smp_processor_id(); - if (kpti_applied) + /* + * We don't need to rewrite the page-tables if either we've done + * it already or we have KASLR enabled and therefore have not + * created any global mappings at all. + */ + if (kpti_applied || kaslr_offset() > 0) return; remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings); diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index c7213674cb24..15d79a8e5e5e 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -475,6 +475,7 @@ ENDPROC(__primary_switched) ENTRY(kimage_vaddr) .quad _text - TEXT_OFFSET +EXPORT_SYMBOL(kimage_vaddr) /* * If we're fortunate enough to boot at EL2, ensure that the world is |