arm64: Add skeleton to harden the branch predictor against aliasing attacks

[mirror_ubuntu-artful-kernel.git] / arch / arm64 / include / asm / mmu.h

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 5468c834b072b2a29701a69e0468b0b32cafba4d..6dd83d75b82ab8b9808f8b60b3ac6252344222a8 100644 (file)
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -16,6 +16,12 @@
 #ifndef __ASM_MMU_H
 #define __ASM_MMU_H
 
+#define MMCF_AARCH32   0x1     /* mm context flag for AArch32 executables */
+#define USER_ASID_FLAG (UL(1) << 48)
+#define TTBR_ASID_MASK (UL(0xffff) << 48)
+
+#ifndef __ASSEMBLY__
+
 typedef struct {
        atomic64_t      id;
        void            *vdso;
@@ -29,6 +35,49 @@ typedef struct {
  */
 #define ASID(mm)       ((mm)->context.id.counter & 0xffff)
 
+static inline bool arm64_kernel_unmapped_at_el0(void)
+{
+       return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) &&
+              cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
+}
+
+typedef void (*bp_hardening_cb_t)(void);
+
+struct bp_hardening_data {
+       int                     hyp_vectors_slot;
+       bp_hardening_cb_t       fn;
+};
+
+#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
+extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[];
+
+DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
+
+static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
+{
+       return this_cpu_ptr(&bp_hardening_data);
+}
+
+static inline void arm64_apply_bp_hardening(void)
+{
+       struct bp_hardening_data *d;
+
+       if (!cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR))
+               return;
+
+       d = arm64_get_bp_hardening_data();
+       if (d->fn)
+               d->fn();
+}
+#else
+static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
+{
+       return NULL;
+}
+
+static inline void arm64_apply_bp_hardening(void)      { }
+#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */
+
 extern void paging_init(void);
 extern void bootmem_init(void);
 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
@@ -39,4 +88,5 @@ extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
 extern void mark_linear_text_alias_ro(void);
 
+#endif /* !__ASSEMBLY__ */
 #endif