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 void *kasan_mem_to_shadow(const void *addr)
  39 {
  40         if (!kasan_arch_is_ready()) {
  41                 return (void *)(kasan_early_shadow_page);
  42         } else {
  43                 unsigned long maddr = (unsigned long)addr;
  44                 unsigned long xrange = (maddr >> XRANGE_SHIFT) & 0xffff;
  45                 unsigned long offset = 0;
  46
  47                 maddr &= XRANGE_SHADOW_MASK;
  48                 switch (xrange) {
  49                 case XKPRANGE_CC_SEG:
  50                         offset = XKPRANGE_CC_SHADOW_OFFSET;
  51                         break;
  52                 case XKPRANGE_UC_SEG:
  53                         offset = XKPRANGE_UC_SHADOW_OFFSET;
  54                         break;
  55                 case XKVRANGE_VC_SEG:
  56                         offset = XKVRANGE_VC_SHADOW_OFFSET;
  57                         break;
  58                 default:
  59                         WARN_ON(1);
  60                         return NULL;
  61                 }
  62
  63                 return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
  64         }
  65 }
  66
  67 const void *kasan_shadow_to_mem(const void *shadow_addr)
  68 {
  69         unsigned long addr = (unsigned long)shadow_addr;
  70
  71         if (unlikely(addr > KASAN_SHADOW_END) ||
  72                 unlikely(addr < KASAN_SHADOW_START)) {
  73                 WARN_ON(1);
  74                 return NULL;
  75         }
  76
  77         if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
  78                 return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
  79         else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
  80                 return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
  81         else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
  82                 return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
  83         else {
  84                 WARN_ON(1);
  85                 return NULL;
  86         }
  87 }
  88
  89 /*
  90  * Alloc memory for shadow memory page table.
  91  */
  92 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
  93 {
  94         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
  95                                         __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
  96         if (!p)
  97                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  98                         __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
  99
 100         return __pa(p);
 101 }
 102
 103 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
 104 {
 105         if (__pmd_none(early, READ_ONCE(*pmdp))) {
 106                 phys_addr_t pte_phys = early ?
 107                                 __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
 108                 if (!early)
 109                         memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
 110                 pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
 111         }
 112
 113         return pte_offset_kernel(pmdp, addr);
 114 }
 115
 116 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
 117 {
 118         if (__pud_none(early, READ_ONCE(*pudp))) {
 119                 phys_addr_t pmd_phys = early ?
 120                                 __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
 121                 if (!early)
 122                         memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
 123                 pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
 124         }
 125
 126         return pmd_offset(pudp, addr);
 127 }
 128
 129 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
 130 {
 131         if (__p4d_none(early, READ_ONCE(*p4dp))) {
 132                 phys_addr_t pud_phys = early ?
 133                         __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
 134                 if (!early)
 135                         memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
 136                 p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
 137         }
 138
 139         return pud_offset(p4dp, addr);
 140 }
 141
 142 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 143                                       unsigned long end, int node, bool early)
 144 {
 145         unsigned long next;
 146         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
 147
 148         do {
 149                 phys_addr_t page_phys = early ?
 150                                         __pa_symbol(kasan_early_shadow_page)
 151                                               : kasan_alloc_zeroed_page(node);
 152                 next = addr + PAGE_SIZE;
 153                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 154         } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
 155 }
 156
 157 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 158                                       unsigned long end, int node, bool early)
 159 {
 160         unsigned long next;
 161         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 162
 163         do {
 164                 next = pmd_addr_end(addr, end);
 165                 kasan_pte_populate(pmdp, addr, next, node, early);
 166         } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
 167 }
 168
 169 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 170                                             unsigned long end, int node, bool early)
 171 {
 172         unsigned long next;
 173         pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 174
 175         do {
 176                 next = pud_addr_end(addr, end);
 177                 kasan_pmd_populate(pudp, addr, next, node, early);
 178         } while (pudp++, addr = next, addr != end);
 179 }
 180
 181 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
 182                                             unsigned long end, int node, bool early)
 183 {
 184         unsigned long next;
 185         p4d_t *p4dp = p4d_offset(pgdp, addr);
 186
 187         do {
 188                 next = p4d_addr_end(addr, end);
 189                 kasan_pud_populate(p4dp, addr, next, node, early);
 190         } while (p4dp++, addr = next, addr != end);
 191 }
 192
 193 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 194                                       int node, bool early)
 195 {
 196         unsigned long next;
 197         pgd_t *pgdp;
 198
 199         pgdp = pgd_offset_k(addr);
 200
 201         do {
 202                 next = pgd_addr_end(addr, end);
 203                 kasan_p4d_populate(pgdp, addr, next, node, early);
 204         } while (pgdp++, addr = next, addr != end);
 205
 206 }
 207
 208 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 209 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 210                                       int node)
 211 {
 212         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 213 }
 214
 215 asmlinkage void __init kasan_early_init(void)
 216 {
 217         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
 218         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 219 }
 220
 221 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
 222 {
 223         WRITE_ONCE(*pgdp, pgdval);
 224 }
 225
 226 static void __init clear_pgds(unsigned long start, unsigned long end)
 227 {
 228         /*
 229          * Remove references to kasan page tables from
 230          * swapper_pg_dir. pgd_clear() can't be used
 231          * here because it's nop on 2,3-level pagetable setups
 232          */
 233         for (; start < end; start += PGDIR_SIZE)
 234                 kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
 235 }
 236
 237 void __init kasan_init(void)
 238 {
 239         u64 i;
 240         phys_addr_t pa_start, pa_end;
 241
 242         /*
 243          * PGD was populated as invalid_pmd_table or invalid_pud_table
 244          * in pagetable_init() which depends on how many levels of page
 245          * table you are using, but we had to clean the gpd of kasan
 246          * shadow memory, as the pgd value is none-zero.
 247          * The assertion pgd_none is going to be false and the formal populate
 248          * afterwards is not going to create any new pgd at all.
 249          */
 250         memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
 251         csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
 252         local_flush_tlb_all();
 253
 254         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 255
 256         /* Maps everything to a single page of zeroes */
 257         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
 258
 259         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
 260                                         kasan_mem_to_shadow((void *)KFENCE_AREA_END));
 261
 262         kasan_early_stage = false;
 263
 264         /* Populate the linear mapping */
 265         for_each_mem_range(i, &pa_start, &pa_end) {
 266                 void *start = (void *)phys_to_virt(pa_start);
 267                 void *end   = (void *)phys_to_virt(pa_end);
 268
 269                 if (start >= end)
 270                         break;
 271
 272                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 273                         (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
 274         }
 275
 276         /* Populate modules mapping */
 277         kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
 278                 (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
 279         /*
 280          * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
 281          * should make sure that it maps the zero page read-only.
 282          */
 283         for (i = 0; i < PTRS_PER_PTE; i++)
 284                 set_pte(&kasan_early_shadow_pte[i],
 285                         pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
 286
 287         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 288         csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
 289         local_flush_tlb_all();
 290
 291         /* At this point kasan is fully initialized. Enable error messages */
 292         init_task.kasan_depth = 0;
 293         pr_info("KernelAddressSanitizer initialized.\n");
 294 }