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-rw-r--r--arch/arm64/include/asm/mmu.h40
1 files changed, 38 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 2fcf51231d..65977c7783 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -71,10 +71,46 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
pgprot_t prot, bool page_mappings_only);
extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot);
extern void mark_linear_text_alias_ro(void);
-extern bool kaslr_requires_kpti(void);
+
+/*
+ * This check is triggered during the early boot before the cpufeature
+ * is initialised. Checking the status on the local CPU allows the boot
+ * CPU to detect the need for non-global mappings and thus avoiding a
+ * pagetable re-write after all the CPUs are booted. This check will be
+ * anyway run on individual CPUs, allowing us to get the consistent
+ * state once the SMP CPUs are up and thus make the switch to non-global
+ * mappings if required.
+ */
+static inline bool kaslr_requires_kpti(void)
+{
+ /*
+ * E0PD does a similar job to KPTI so can be used instead
+ * where available.
+ */
+ if (IS_ENABLED(CONFIG_ARM64_E0PD)) {
+ u64 mmfr2 = read_sysreg_s(SYS_ID_AA64MMFR2_EL1);
+ if (cpuid_feature_extract_unsigned_field(mmfr2,
+ ID_AA64MMFR2_EL1_E0PD_SHIFT))
+ return false;
+ }
+
+ /*
+ * Systems affected by Cavium erratum 24756 are incompatible
+ * with KPTI.
+ */
+ if (IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
+ extern const struct midr_range cavium_erratum_27456_cpus[];
+
+ if (is_midr_in_range_list(read_cpuid_id(),
+ cavium_erratum_27456_cpus))
+ return false;
+ }
+
+ return true;
+}
#define INIT_MM_CONTEXT(name) \
- .pgd = init_pg_dir,
+ .pgd = swapper_pg_dir,
#endif /* !__ASSEMBLY__ */
#endif