1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Extensible Firmware Interface 4 * 5 * Based on Extensible Firmware Interface Specification version 2.4 6 * 7 * Copyright (C) 2013, 2014 Linaro Ltd. 8 */ 9 10 #include <linux/efi.h> 11 #include <linux/init.h> 12 #include <linux/kmemleak.h> 13 #include <linux/screen_info.h> 14 #include <linux/vmalloc.h> 15 16 #include <asm/efi.h> 17 #include <asm/stacktrace.h> 18 #include <asm/vmap_stack.h> 19 20 static bool region_is_misaligned(const efi_memory_desc_t *md) 21 { 22 if (PAGE_SIZE == EFI_PAGE_SIZE) 23 return false; 24 return !PAGE_ALIGNED(md->phys_addr) || 25 !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT); 26 } 27 28 /* 29 * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be 30 * executable, everything else can be mapped with the XN bits 31 * set. Also take the new (optional) RO/XP bits into account. 32 */ 33 static __init ptdesc_t create_mapping_protection(efi_memory_desc_t *md) 34 { 35 u64 attr = md->attribute; 36 u32 type = md->type; 37 38 if (type == EFI_MEMORY_MAPPED_IO) { 39 pgprot_t prot = __pgprot(PROT_DEVICE_nGnRE); 40 41 if (arm64_is_protected_mmio(md->phys_addr, 42 md->num_pages << EFI_PAGE_SHIFT)) 43 prot = pgprot_encrypted(prot); 44 else 45 prot = pgprot_decrypted(prot); 46 return pgprot_val(prot); 47 } 48 49 if (region_is_misaligned(md)) { 50 static bool __initdata code_is_misaligned; 51 52 /* 53 * Regions that are not aligned to the OS page size cannot be 54 * mapped with strict permissions, as those might interfere 55 * with the permissions that are needed by the adjacent 56 * region's mapping. However, if we haven't encountered any 57 * misaligned runtime code regions so far, we can safely use 58 * non-executable permissions for non-code regions. 59 */ 60 code_is_misaligned |= (type == EFI_RUNTIME_SERVICES_CODE); 61 62 return code_is_misaligned ? pgprot_val(PAGE_KERNEL_EXEC) 63 : pgprot_val(PAGE_KERNEL); 64 } 65 66 /* R-- */ 67 if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) == 68 (EFI_MEMORY_XP | EFI_MEMORY_RO)) 69 return pgprot_val(PAGE_KERNEL_RO); 70 71 /* R-X */ 72 if (attr & EFI_MEMORY_RO) 73 return pgprot_val(PAGE_KERNEL_ROX); 74 75 /* RW- */ 76 if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) == 77 EFI_MEMORY_XP) || 78 type != EFI_RUNTIME_SERVICES_CODE) 79 return pgprot_val(PAGE_KERNEL); 80 81 /* RWX */ 82 return pgprot_val(PAGE_KERNEL_EXEC); 83 } 84 85 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) 86 { 87 ptdesc_t prot_val = create_mapping_protection(md); 88 bool page_mappings_only = (md->type == EFI_RUNTIME_SERVICES_CODE || 89 md->type == EFI_RUNTIME_SERVICES_DATA); 90 91 /* 92 * If this region is not aligned to the page size used by the OS, the 93 * mapping will be rounded outwards, and may end up sharing a page 94 * frame with an adjacent runtime memory region. Given that the page 95 * table descriptor covering the shared page will be rewritten when the 96 * adjacent region gets mapped, we must avoid block mappings here so we 97 * don't have to worry about splitting them when that happens. 98 */ 99 if (region_is_misaligned(md)) 100 page_mappings_only = true; 101 102 create_pgd_mapping(mm, md->phys_addr, md->virt_addr, 103 md->num_pages << EFI_PAGE_SHIFT, 104 __pgprot(prot_val | PTE_NG), page_mappings_only); 105 return 0; 106 } 107 108 struct set_perm_data { 109 const efi_memory_desc_t *md; 110 bool has_bti; 111 }; 112 113 static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data) 114 { 115 struct set_perm_data *spd = data; 116 const efi_memory_desc_t *md = spd->md; 117 pte_t pte = __ptep_get(ptep); 118 119 if (md->attribute & EFI_MEMORY_RO) 120 pte = set_pte_bit(pte, __pgprot(PTE_RDONLY)); 121 if (md->attribute & EFI_MEMORY_XP) 122 pte = set_pte_bit(pte, __pgprot(PTE_PXN)); 123 else if (system_supports_bti_kernel() && spd->has_bti) 124 pte = set_pte_bit(pte, __pgprot(PTE_GP)); 125 __set_pte(ptep, pte); 126 return 0; 127 } 128 129 int __init efi_set_mapping_permissions(struct mm_struct *mm, 130 efi_memory_desc_t *md, 131 bool has_bti) 132 { 133 struct set_perm_data data = { md, has_bti }; 134 135 BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE && 136 md->type != EFI_RUNTIME_SERVICES_DATA); 137 138 if (region_is_misaligned(md)) 139 return 0; 140 141 /* 142 * Calling apply_to_page_range() is only safe on regions that are 143 * guaranteed to be mapped down to pages. Since we are only called 144 * for regions that have been mapped using efi_create_mapping() above 145 * (and this is checked by the generic Memory Attributes table parsing 146 * routines), there is no need to check that again here. 147 */ 148 return apply_to_page_range(mm, md->virt_addr, 149 md->num_pages << EFI_PAGE_SHIFT, 150 set_permissions, &data); 151 } 152 153 /* 154 * UpdateCapsule() depends on the system being shutdown via 155 * ResetSystem(). 156 */ 157 bool efi_poweroff_required(void) 158 { 159 return efi_enabled(EFI_RUNTIME_SERVICES); 160 } 161 162 asmlinkage efi_status_t efi_handle_corrupted_x18(efi_status_t s, const char *f) 163 { 164 pr_err_ratelimited(FW_BUG "register x18 corrupted by EFI %s\n", f); 165 return s; 166 } 167 168 static DEFINE_RAW_SPINLOCK(efi_rt_lock); 169 170 void arch_efi_call_virt_setup(void) 171 { 172 efi_virtmap_load(); 173 raw_spin_lock(&efi_rt_lock); 174 __efi_fpsimd_begin(); 175 } 176 177 void arch_efi_call_virt_teardown(void) 178 { 179 __efi_fpsimd_end(); 180 raw_spin_unlock(&efi_rt_lock); 181 efi_virtmap_unload(); 182 } 183 184 asmlinkage u64 *efi_rt_stack_top __ro_after_init; 185 186 asmlinkage efi_status_t __efi_rt_asm_recover(void); 187 188 bool efi_runtime_fixup_exception(struct pt_regs *regs, const char *msg) 189 { 190 /* Check whether the exception occurred while running the firmware */ 191 if (!current_in_efi() || regs->pc >= TASK_SIZE_64) 192 return false; 193 194 pr_err(FW_BUG "Unable to handle %s in EFI runtime service\n", msg); 195 add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK); 196 clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); 197 198 regs->regs[0] = EFI_ABORTED; 199 regs->regs[30] = efi_rt_stack_top[-1]; 200 regs->pc = (u64)__efi_rt_asm_recover; 201 202 if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) 203 regs->regs[18] = efi_rt_stack_top[-2]; 204 205 return true; 206 } 207 208 /* EFI requires 8 KiB of stack space for runtime services */ 209 static_assert(THREAD_SIZE >= SZ_8K); 210 211 static int __init arm64_efi_rt_init(void) 212 { 213 void *p; 214 215 if (!efi_enabled(EFI_RUNTIME_SERVICES)) 216 return 0; 217 218 p = arch_alloc_vmap_stack(THREAD_SIZE, NUMA_NO_NODE); 219 if (!p) { 220 pr_warn("Failed to allocate EFI runtime stack\n"); 221 clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); 222 return -ENOMEM; 223 } 224 225 kmemleak_not_leak(p); 226 efi_rt_stack_top = p + THREAD_SIZE; 227 return 0; 228 } 229 core_initcall(arm64_efi_rt_init); 230