diff options
Diffstat (limited to 'arch/arm64/mm/mmu.c')
| -rw-r--r-- | arch/arm64/mm/mmu.c | 98 |
1 files changed, 88 insertions, 10 deletions
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index b3d8c3de4149..b8d37eb037fc 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -470,14 +470,6 @@ static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys, mutex_unlock(&fixmap_lock); } -#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 -extern __alias(__create_pgd_mapping_locked) -void create_kpti_ng_temp_pgd(pgd_t *pgdir, phys_addr_t phys, unsigned long virt, - phys_addr_t size, pgprot_t prot, - phys_addr_t (*pgtable_alloc)(enum pgtable_type), - int flags); -#endif - #define INVALID_PHYS_ADDR (-1ULL) static phys_addr_t __pgd_pgtable_alloc(struct mm_struct *mm, gfp_t gfp, @@ -823,7 +815,7 @@ static bool linear_map_requires_bbml2 __initdata; u32 idmap_kpti_bbml2_flag; -void __init init_idmap_kpti_bbml2_flag(void) +static void __init init_idmap_kpti_bbml2_flag(void) { WRITE_ONCE(idmap_kpti_bbml2_flag, 1); /* Must be visible to other CPUs before stop_machine() is called. */ @@ -1135,7 +1127,93 @@ static void __init declare_vma(struct vm_struct *vma, } #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 -static pgprot_t kernel_exec_prot(void) +#define KPTI_NG_TEMP_VA (-(1UL << PMD_SHIFT)) + +static phys_addr_t kpti_ng_temp_alloc __initdata; + +static phys_addr_t __init kpti_ng_pgd_alloc(enum pgtable_type type) +{ + kpti_ng_temp_alloc -= PAGE_SIZE; + return kpti_ng_temp_alloc; +} + +static int __init __kpti_install_ng_mappings(void *__unused) +{ + typedef void (kpti_remap_fn)(int, int, phys_addr_t, unsigned long); + extern kpti_remap_fn idmap_kpti_install_ng_mappings; + kpti_remap_fn *remap_fn; + + int cpu = smp_processor_id(); + int levels = CONFIG_PGTABLE_LEVELS; + int order = order_base_2(levels); + u64 kpti_ng_temp_pgd_pa = 0; + pgd_t *kpti_ng_temp_pgd; + u64 alloc = 0; + + if (levels == 5 && !pgtable_l5_enabled()) + levels = 4; + else if (levels == 4 && !pgtable_l4_enabled()) + levels = 3; + + remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings); + + if (!cpu) { + alloc = __get_free_pages(GFP_ATOMIC | __GFP_ZERO, order); + kpti_ng_temp_pgd = (pgd_t *)(alloc + (levels - 1) * PAGE_SIZE); + kpti_ng_temp_alloc = kpti_ng_temp_pgd_pa = __pa(kpti_ng_temp_pgd); + + // + // Create a minimal page table hierarchy that permits us to map + // the swapper page tables temporarily as we traverse them. + // + // The physical pages are laid out as follows: + // + // +--------+-/-------+-/------ +-/------ +-\\\--------+ + // : PTE[] : | PMD[] : | PUD[] : | P4D[] : ||| PGD[] : + // +--------+-\-------+-\------ +-\------ +-///--------+ + // ^ + // The first page is mapped into this hierarchy at a PMD_SHIFT + // aligned virtual address, so that we can manipulate the PTE + // level entries while the mapping is active. The first entry + // covers the PTE[] page itself, the remaining entries are free + // to be used as a ad-hoc fixmap. + // + __create_pgd_mapping_locked(kpti_ng_temp_pgd, __pa(alloc), + KPTI_NG_TEMP_VA, PAGE_SIZE, PAGE_KERNEL, + kpti_ng_pgd_alloc, 0); + } + + cpu_install_idmap(); + remap_fn(cpu, num_online_cpus(), kpti_ng_temp_pgd_pa, KPTI_NG_TEMP_VA); + cpu_uninstall_idmap(); + + if (!cpu) { + free_pages(alloc, order); + arm64_use_ng_mappings = true; + } + + return 0; +} + +void __init kpti_install_ng_mappings(void) +{ + /* Check whether KPTI is going to be used */ + if (!arm64_kernel_unmapped_at_el0()) + return; + + /* + * 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 (arm64_use_ng_mappings) + return; + + init_idmap_kpti_bbml2_flag(); + stop_machine(__kpti_install_ng_mappings, NULL, cpu_online_mask); +} + +static pgprot_t __init kernel_exec_prot(void) { return rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; } |