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