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                 if (maddr >= FIXADDR_START)
  48                         return (void *)(kasan_early_shadow_page);
  49
  50                 maddr &= XRANGE_SHADOW_MASK;
  51                 switch (xrange) {
  52                 case XKPRANGE_CC_SEG:
  53                         offset = XKPRANGE_CC_SHADOW_OFFSET;
  54                         break;
  55                 case XKPRANGE_UC_SEG:
  56                         offset = XKPRANGE_UC_SHADOW_OFFSET;
  57                         break;
  58                 case XKVRANGE_VC_SEG:
  59                         offset = XKVRANGE_VC_SHADOW_OFFSET;
  60                         break;
  61                 default:
  62                         WARN_ON(1);
  63                         return NULL;
  64                 }
  65
  66                 return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
  67         }
  68 }
  69
  70 const void *kasan_shadow_to_mem(const void *shadow_addr)
  71 {
  72         unsigned long addr = (unsigned long)shadow_addr;
  73
  74         if (unlikely(addr > KASAN_SHADOW_END) ||
  75                 unlikely(addr < KASAN_SHADOW_START)) {
  76                 WARN_ON(1);
  77                 return NULL;
  78         }
  79
  80         if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
  81                 return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
  82         else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
  83                 return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
  84         else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
  85                 return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
  86         else {
  87                 WARN_ON(1);
  88                 return NULL;
  89         }
  90 }
  91
  92 /*
  93  * Alloc memory for shadow memory page table.
  94  */
  95 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
  96 {
  97         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
  98                                         __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
  99         if (!p)
 100                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
 101                         __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
 102
 103         return __pa(p);
 104 }
 105
 106 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
 107 {
 108         if (__pmd_none(early, READ_ONCE(*pmdp))) {
 109                 phys_addr_t pte_phys = early ?
 110                                 __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
 111                 if (!early)
 112                         memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
 113                 pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
 114         }
 115
 116         return pte_offset_kernel(pmdp, addr);
 117 }
 118
 119 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
 120 {
 121         if (__pud_none(early, READ_ONCE(*pudp))) {
 122                 phys_addr_t pmd_phys = early ?
 123                                 __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
 124                 if (!early)
 125                         memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
 126                 pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
 127         }
 128
 129         return pmd_offset(pudp, addr);
 130 }
 131
 132 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
 133 {
 134         if (__p4d_none(early, READ_ONCE(*p4dp))) {
 135                 phys_addr_t pud_phys = early ?
 136                         __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
 137                 if (!early)
 138                         memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
 139                 p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
 140         }
 141
 142         return pud_offset(p4dp, addr);
 143 }
 144
 145 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 146                                       unsigned long end, int node, bool early)
 147 {
 148         unsigned long next;
 149         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
 150
 151         do {
 152                 phys_addr_t page_phys = early ?
 153                                         __pa_symbol(kasan_early_shadow_page)
 154                                               : kasan_alloc_zeroed_page(node);
 155                 next = addr + PAGE_SIZE;
 156                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 157         } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
 158 }
 159
 160 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 161                                       unsigned long end, int node, bool early)
 162 {
 163         unsigned long next;
 164         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 165
 166         do {
 167                 next = pmd_addr_end(addr, end);
 168                 kasan_pte_populate(pmdp, addr, next, node, early);
 169         } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
 170 }
 171
 172 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 173                                             unsigned long end, int node, bool early)
 174 {
 175         unsigned long next;
 176         pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 177
 178         do {
 179                 next = pud_addr_end(addr, end);
 180                 kasan_pmd_populate(pudp, addr, next, node, early);
 181         } while (pudp++, addr = next, addr != end);
 182 }
 183
 184 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
 185                                             unsigned long end, int node, bool early)
 186 {
 187         unsigned long next;
 188         p4d_t *p4dp = p4d_offset(pgdp, addr);
 189
 190         do {
 191                 next = p4d_addr_end(addr, end);
 192                 kasan_pud_populate(p4dp, addr, next, node, early);
 193         } while (p4dp++, addr = next, addr != end);
 194 }
 195
 196 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 197                                       int node, bool early)
 198 {
 199         unsigned long next;
 200         pgd_t *pgdp;
 201
 202         pgdp = pgd_offset_k(addr);
 203
 204         do {
 205                 next = pgd_addr_end(addr, end);
 206                 kasan_p4d_populate(pgdp, addr, next, node, early);
 207         } while (pgdp++, addr = next, addr != end);
 208
 209 }
 210
 211 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 212 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 213                                       int node)
 214 {
 215         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 216 }
 217
 218 asmlinkage void __init kasan_early_init(void)
 219 {
 220         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
 221         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 222 }
 223
 224 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
 225 {
 226         WRITE_ONCE(*pgdp, pgdval);
 227 }
 228
 229 static void __init clear_pgds(unsigned long start, unsigned long end)
 230 {
 231         /*
 232          * Remove references to kasan page tables from
 233          * swapper_pg_dir. pgd_clear() can't be used
 234          * here because it's nop on 2,3-level pagetable setups
 235          */
 236         for (; start < end; start += PGDIR_SIZE)
 237                 kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
 238 }
 239
 240 void __init kasan_init(void)
 241 {
 242         u64 i;
 243         phys_addr_t pa_start, pa_end;
 244
 245         /*
 246          * PGD was populated as invalid_pmd_table or invalid_pud_table
 247          * in pagetable_init() which depends on how many levels of page
 248          * table you are using, but we had to clean the gpd of kasan
 249          * shadow memory, as the pgd value is none-zero.
 250          * The assertion pgd_none is going to be false and the formal populate
 251          * afterwards is not going to create any new pgd at all.
 252          */
 253         memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
 254         csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
 255         local_flush_tlb_all();
 256
 257         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 258
 259         /* Maps everything to a single page of zeroes */
 260         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
 261
 262         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
 263                                         kasan_mem_to_shadow((void *)KFENCE_AREA_END));
 264
 265         kasan_early_stage = false;
 266
 267         /* Populate the linear mapping */
 268         for_each_mem_range(i, &pa_start, &pa_end) {
 269                 void *start = (void *)phys_to_virt(pa_start);
 270                 void *end   = (void *)phys_to_virt(pa_end);
 271
 272                 if (start >= end)
 273                         break;
 274
 275                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 276                         (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
 277         }
 278
 279         /* Populate modules mapping */
 280         kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
 281                 (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
 282         /*
 283          * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
 284          * should make sure that it maps the zero page read-only.
 285          */
 286         for (i = 0; i < PTRS_PER_PTE; i++)
 287                 set_pte(&kasan_early_shadow_pte[i],
 288                         pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
 289
 290         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 291         csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
 292         local_flush_tlb_all();
 293
 294         /* At this point kasan is fully initialized. Enable error messages */
 295         init_task.kasan_depth = 0;
 296         pr_info("KernelAddressSanitizer initialized.\n");
 297 }