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