244 строки
6.1 KiB
C
244 строки
6.1 KiB
C
#define pr_fmt(fmt) "kasan: " fmt
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#include <linux/bootmem.h>
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#include <linux/kasan.h>
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#include <linux/kdebug.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/vmalloc.h>
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#include <asm/tlbflush.h>
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#include <asm/sections.h>
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extern pgd_t early_level4_pgt[PTRS_PER_PGD];
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extern struct range pfn_mapped[E820_X_MAX];
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static pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
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static pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
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static pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
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/*
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* This page used as early shadow. We don't use empty_zero_page
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* at early stages, stack instrumentation could write some garbage
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* to this page.
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* Latter we reuse it as zero shadow for large ranges of memory
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* that allowed to access, but not instrumented by kasan
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* (vmalloc/vmemmap ...).
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*/
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static unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
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static int __init map_range(struct range *range)
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{
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unsigned long start;
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unsigned long end;
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start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
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end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
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/*
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* end + 1 here is intentional. We check several shadow bytes in advance
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* to slightly speed up fastpath. In some rare cases we could cross
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* boundary of mapped shadow, so we just map some more here.
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*/
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return vmemmap_populate(start, end + 1, NUMA_NO_NODE);
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}
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static void __init clear_pgds(unsigned long start,
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unsigned long end)
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{
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for (; start < end; start += PGDIR_SIZE)
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pgd_clear(pgd_offset_k(start));
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}
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static void __init kasan_map_early_shadow(pgd_t *pgd)
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{
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int i;
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unsigned long start = KASAN_SHADOW_START;
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unsigned long end = KASAN_SHADOW_END;
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for (i = pgd_index(start); start < end; i++) {
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pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud)
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| _KERNPG_TABLE);
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start += PGDIR_SIZE;
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}
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}
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static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
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unsigned long end)
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{
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pte_t *pte = pte_offset_kernel(pmd, addr);
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while (addr + PAGE_SIZE <= end) {
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WARN_ON(!pte_none(*pte));
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set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
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| __PAGE_KERNEL_RO));
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addr += PAGE_SIZE;
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pte = pte_offset_kernel(pmd, addr);
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}
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return 0;
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}
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static int __init zero_pmd_populate(pud_t *pud, unsigned long addr,
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unsigned long end)
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{
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int ret = 0;
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pmd_t *pmd = pmd_offset(pud, addr);
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while (IS_ALIGNED(addr, PMD_SIZE) && addr + PMD_SIZE <= end) {
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WARN_ON(!pmd_none(*pmd));
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set_pmd(pmd, __pmd(__pa_nodebug(kasan_zero_pte)
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| _KERNPG_TABLE));
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addr += PMD_SIZE;
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pmd = pmd_offset(pud, addr);
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}
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if (addr < end) {
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if (pmd_none(*pmd)) {
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void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
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if (!p)
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return -ENOMEM;
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set_pmd(pmd, __pmd(__pa_nodebug(p) | _KERNPG_TABLE));
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}
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ret = zero_pte_populate(pmd, addr, end);
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}
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return ret;
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}
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static int __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
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unsigned long end)
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{
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int ret = 0;
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pud_t *pud = pud_offset(pgd, addr);
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while (IS_ALIGNED(addr, PUD_SIZE) && addr + PUD_SIZE <= end) {
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WARN_ON(!pud_none(*pud));
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set_pud(pud, __pud(__pa_nodebug(kasan_zero_pmd)
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| _KERNPG_TABLE));
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addr += PUD_SIZE;
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pud = pud_offset(pgd, addr);
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}
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if (addr < end) {
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if (pud_none(*pud)) {
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void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
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if (!p)
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return -ENOMEM;
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set_pud(pud, __pud(__pa_nodebug(p) | _KERNPG_TABLE));
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}
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ret = zero_pmd_populate(pud, addr, end);
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}
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return ret;
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}
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static int __init zero_pgd_populate(unsigned long addr, unsigned long end)
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{
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int ret = 0;
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pgd_t *pgd = pgd_offset_k(addr);
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while (IS_ALIGNED(addr, PGDIR_SIZE) && addr + PGDIR_SIZE <= end) {
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WARN_ON(!pgd_none(*pgd));
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set_pgd(pgd, __pgd(__pa_nodebug(kasan_zero_pud)
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| _KERNPG_TABLE));
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addr += PGDIR_SIZE;
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pgd = pgd_offset_k(addr);
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}
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if (addr < end) {
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if (pgd_none(*pgd)) {
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void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
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if (!p)
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return -ENOMEM;
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set_pgd(pgd, __pgd(__pa_nodebug(p) | _KERNPG_TABLE));
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}
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ret = zero_pud_populate(pgd, addr, end);
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}
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return ret;
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}
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static void __init populate_zero_shadow(const void *start, const void *end)
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{
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if (zero_pgd_populate((unsigned long)start, (unsigned long)end))
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panic("kasan: unable to map zero shadow!");
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}
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#ifdef CONFIG_KASAN_INLINE
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static int kasan_die_handler(struct notifier_block *self,
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unsigned long val,
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void *data)
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{
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if (val == DIE_GPF) {
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pr_emerg("CONFIG_KASAN_INLINE enabled");
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pr_emerg("GPF could be caused by NULL-ptr deref or user memory access");
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}
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return NOTIFY_OK;
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}
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static struct notifier_block kasan_die_notifier = {
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.notifier_call = kasan_die_handler,
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};
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#endif
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void __init kasan_early_init(void)
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{
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int i;
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pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
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pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
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pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
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for (i = 0; i < PTRS_PER_PTE; i++)
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kasan_zero_pte[i] = __pte(pte_val);
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for (i = 0; i < PTRS_PER_PMD; i++)
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kasan_zero_pmd[i] = __pmd(pmd_val);
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for (i = 0; i < PTRS_PER_PUD; i++)
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kasan_zero_pud[i] = __pud(pud_val);
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kasan_map_early_shadow(early_level4_pgt);
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kasan_map_early_shadow(init_level4_pgt);
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}
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void __init kasan_init(void)
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{
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int i;
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#ifdef CONFIG_KASAN_INLINE
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register_die_notifier(&kasan_die_notifier);
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#endif
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memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt));
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load_cr3(early_level4_pgt);
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__flush_tlb_all();
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clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
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populate_zero_shadow((void *)KASAN_SHADOW_START,
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kasan_mem_to_shadow((void *)PAGE_OFFSET));
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for (i = 0; i < E820_X_MAX; i++) {
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if (pfn_mapped[i].end == 0)
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break;
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if (map_range(&pfn_mapped[i]))
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panic("kasan: unable to allocate shadow!");
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}
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populate_zero_shadow(kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
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kasan_mem_to_shadow((void *)__START_KERNEL_map));
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vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
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(unsigned long)kasan_mem_to_shadow(_end),
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NUMA_NO_NODE);
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populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
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(void *)KASAN_SHADOW_END);
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memset(kasan_zero_page, 0, PAGE_SIZE);
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load_cr3(init_level4_pgt);
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__flush_tlb_all();
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init_task.kasan_depth = 0;
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pr_info("Kernel address sanitizer initialized\n");
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}
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