arch/loongarch/mm/kasan_init.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2023 Loongson Technology Corporation Limited
   4  */
   5 #define pr_fmt(fmt) "kasan: " fmt
   6 #include <linux/kasan.h>
   7 #include <linux/memblock.h>
   8 #include <linux/sched/task.h>
   9
  10 #include <asm/tlbflush.h>
  11 #include <asm/pgalloc.h>
  12 #include <asm-generic/sections.h>
  13
  14 static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
  15
  16 #ifdef __PAGETABLE_PUD_FOLDED
  17 #define __p4d_none(early, p4d) (0)
  18 #else
  19 #define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
  20 (__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
  21 #endif
  22
  23 #ifdef __PAGETABLE_PMD_FOLDED
  24 #define __pud_none(early, pud) (0)
  25 #else
  26 #define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
  27 (__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
  28 #endif
  29
  30 #define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
  31 (__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
  32
  33 #define __pte_none(early, pte) (early ? pte_none(pte) : \
  34 ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
  35
  36 bool kasan_early_stage = true;
  37
  38 /*
  39  * Alloc memory for shadow memory page table.
  40  */
  41 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
  42 {
  43         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
  44                                         __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
  45         if (!p)
  46                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  47                         __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
  48
  49         return __pa(p);
  50 }
  51
  52 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
  53 {
  54         if (__pmd_none(early, READ_ONCE(*pmdp))) {
  55                 phys_addr_t pte_phys = early ?
  56                                 __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
  57                 if (!early)
  58                         memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
  59                 pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
  60         }
  61
  62         return pte_offset_kernel(pmdp, addr);
  63 }
  64
  65 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
  66 {
  67         if (__pud_none(early, READ_ONCE(*pudp))) {
  68                 phys_addr_t pmd_phys = early ?
  69                                 __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
  70                 if (!early)
  71                         memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
  72                 pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
  73         }
  74
  75         return pmd_offset(pudp, addr);
  76 }
  77
  78 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
  79 {
  80         if (__p4d_none(early, READ_ONCE(*p4dp))) {
  81                 phys_addr_t pud_phys = early ?
  82                         __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
  83                 if (!early)
  84                         memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
  85                 p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
  86         }
  87
  88         return pud_offset(p4dp, addr);
  89 }
  90
  91 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
  92                                       unsigned long end, int node, bool early)
  93 {
  94         unsigned long next;
  95         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
  96
  97         do {
  98                 phys_addr_t page_phys = early ?
  99                                         __pa_symbol(kasan_early_shadow_page)
 100                                               : kasan_alloc_zeroed_page(node);
 101                 next = addr + PAGE_SIZE;
 102                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 103         } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
 104 }
 105
 106 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 107                                       unsigned long end, int node, bool early)
 108 {
 109         unsigned long next;
 110         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 111
 112         do {
 113                 next = pmd_addr_end(addr, end);
 114                 kasan_pte_populate(pmdp, addr, next, node, early);
 115         } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
 116 }
 117
 118 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 119                                             unsigned long end, int node, bool early)
 120 {
 121         unsigned long next;
 122         pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 123
 124         do {
 125                 next = pud_addr_end(addr, end);
 126                 kasan_pmd_populate(pudp, addr, next, node, early);
 127         } while (pudp++, addr = next, addr != end);
 128 }
 129
 130 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
 131                                             unsigned long end, int node, bool early)
 132 {
 133         unsigned long next;
 134         p4d_t *p4dp = p4d_offset(pgdp, addr);
 135
 136         do {
 137                 next = p4d_addr_end(addr, end);
 138                 kasan_pud_populate(p4dp, addr, next, node, early);
 139         } while (p4dp++, addr = next, addr != end);
 140 }
 141
 142 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 143                                       int node, bool early)
 144 {
 145         unsigned long next;
 146         pgd_t *pgdp;
 147
 148         pgdp = pgd_offset_k(addr);
 149
 150         do {
 151                 next = pgd_addr_end(addr, end);
 152                 kasan_p4d_populate(pgdp, addr, next, node, early);
 153         } while (pgdp++, addr = next, addr != end);
 154
 155 }
 156
 157 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 158 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 159                                       int node)
 160 {
 161         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 162 }
 163
 164 asmlinkage void __init kasan_early_init(void)
 165 {
 166         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
 167         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 168 }
 169
 170 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
 171 {
 172         WRITE_ONCE(*pgdp, pgdval);
 173 }
 174
 175 static void __init clear_pgds(unsigned long start, unsigned long end)
 176 {
 177         /*
 178          * Remove references to kasan page tables from
 179          * swapper_pg_dir. pgd_clear() can't be used
 180          * here because it's nop on 2,3-level pagetable setups
 181          */
 182         for (; start < end; start += PGDIR_SIZE)
 183                 kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
 184 }
 185
 186 void __init kasan_init(void)
 187 {
 188         u64 i;
 189         phys_addr_t pa_start, pa_end;
 190
 191         /*
 192          * PGD was populated as invalid_pmd_table or invalid_pud_table
 193          * in pagetable_init() which depends on how many levels of page
 194          * table you are using, but we had to clean the gpd of kasan
 195          * shadow memory, as the pgd value is none-zero.
 196          * The assertion pgd_none is going to be false and the formal populate
 197          * afterwards is not going to create any new pgd at all.
 198          */
 199         memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
 200         csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
 201         local_flush_tlb_all();
 202
 203         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 204
 205         /* Maps everything to a single page of zeroes */
 206         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
 207
 208         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
 209                                         kasan_mem_to_shadow((void *)KFENCE_AREA_END));
 210
 211         kasan_early_stage = false;
 212
 213         /* Populate the linear mapping */
 214         for_each_mem_range(i, &pa_start, &pa_end) {
 215                 void *start = (void *)phys_to_virt(pa_start);
 216                 void *end   = (void *)phys_to_virt(pa_end);
 217
 218                 if (start >= end)
 219                         break;
 220
 221                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 222                         (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
 223         }
 224
 225         /* Populate modules mapping */
 226         kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
 227                 (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
 228         /*
 229          * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
 230          * should make sure that it maps the zero page read-only.
 231          */
 232         for (i = 0; i < PTRS_PER_PTE; i++)
 233                 set_pte(&kasan_early_shadow_pte[i],
 234                         pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
 235
 236         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 237         csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
 238         local_flush_tlb_all();
 239
 240         /* At this point kasan is fully initialized. Enable error messages */
 241         init_task.kasan_depth = 0;
 242         pr_info("KernelAddressSanitizer initialized.\n");
 243 }