1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/module.h> 3 #include <linux/kernel.h> 4 #include <linux/slab.h> 5 #include <linux/mm_types.h> 6 #include <linux/pgtable.h> 7 8 #include <asm/cputype.h> 9 #include <asm/idmap.h> 10 #include <asm/hwcap.h> 11 #include <asm/pgalloc.h> 12 #include <asm/sections.h> 13 #include <asm/system_info.h> 14 15 /* 16 * Note: accesses outside of the kernel image and the identity map area 17 * are not supported on any CPU using the idmap tables as its current 18 * page tables. 19 */ 20 pgd_t *idmap_pgd __ro_after_init; 21 long long arch_phys_to_idmap_offset __ro_after_init; 22 23 #ifdef CONFIG_ARM_LPAE 24 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end, 25 unsigned long prot) 26 { 27 pmd_t *pmd; 28 unsigned long next; 29 30 if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) { 31 pmd = pmd_alloc_one(&init_mm, addr); 32 if (!pmd) { 33 pr_warn("Failed to allocate identity pmd.\n"); 34 return; 35 } 36 /* 37 * Copy the original PMD to ensure that the PMD entries for 38 * the kernel image are preserved. 39 */ 40 if (!pud_none(*pud)) 41 memcpy(pmd, pmd_offset(pud, 0), 42 PTRS_PER_PMD * sizeof(pmd_t)); 43 pud_populate(&init_mm, pud, pmd); 44 pmd += pmd_index(addr); 45 } else 46 pmd = pmd_offset(pud, addr); 47 48 do { 49 next = pmd_addr_end(addr, end); 50 *pmd = __pmd((addr & PMD_MASK) | prot); 51 flush_pmd_entry(pmd); 52 } while (pmd++, addr = next, addr != end); 53 } 54 #else /* !CONFIG_ARM_LPAE */ 55 static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end, 56 unsigned long prot) 57 { 58 pmd_t *pmd = pmd_offset(pud, addr); 59 60 addr = (addr & PMD_MASK) | prot; 61 pmd[0] = __pmd(addr); 62 addr += SECTION_SIZE; 63 pmd[1] = __pmd(addr); 64 flush_pmd_entry(pmd); 65 } 66 #endif /* CONFIG_ARM_LPAE */ 67 68 static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end, 69 unsigned long prot) 70 { 71 p4d_t *p4d = p4d_offset(pgd, addr); 72 pud_t *pud = pud_offset(p4d, addr); 73 unsigned long next; 74 75 do { 76 next = pud_addr_end(addr, end); 77 idmap_add_pmd(pud, addr, next, prot); 78 } while (pud++, addr = next, addr != end); 79 } 80 81 static void identity_mapping_add(pgd_t *pgd, const char *text_start, 82 const char *text_end, unsigned long prot) 83 { 84 unsigned long addr, end; 85 unsigned long next; 86 87 addr = virt_to_idmap(text_start); 88 end = virt_to_idmap(text_end); 89 pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end); 90 91 prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF; 92 93 if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family()) 94 prot |= PMD_BIT4; 95 96 pgd += pgd_index(addr); 97 do { 98 next = pgd_addr_end(addr, end); 99 idmap_add_pud(pgd, addr, next, prot); 100 } while (pgd++, addr = next, addr != end); 101 } 102 103 extern char __idmap_text_start[], __idmap_text_end[]; 104 105 static int __init init_static_idmap(void) 106 { 107 idmap_pgd = pgd_alloc(&init_mm); 108 if (!idmap_pgd) 109 return -ENOMEM; 110 111 identity_mapping_add(idmap_pgd, __idmap_text_start, 112 __idmap_text_end, 0); 113 114 /* Flush L1 for the hardware to see this page table content */ 115 if (!(elf_hwcap & HWCAP_LPAE)) 116 flush_cache_louis(); 117 118 return 0; 119 } 120 early_initcall(init_static_idmap); 121 122 /* 123 * In order to soft-boot, we need to switch to a 1:1 mapping for the 124 * cpu_reset functions. This will then ensure that we have predictable 125 * results when turning off the mmu. 126 */ 127 void setup_mm_for_reboot(void) 128 { 129 /* Switch to the identity mapping. */ 130 cpu_switch_mm(idmap_pgd, &init_mm); 131 local_flush_bp_all(); 132 133 #ifdef CONFIG_CPU_HAS_ASID 134 /* 135 * We don't have a clean ASID for the identity mapping, which 136 * may clash with virtual addresses of the previous page tables 137 * and therefore potentially in the TLB. 138 */ 139 local_flush_tlb_all(); 140 #endif 141 } 142