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#define pr_fmt(fmt) "kasan: " fmt
#include <linux/bootmem.h>
#include <linux/kasan.h>
#include <linux/kdebug.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/vmalloc.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];
static int __init map_range(struct range *range)
{
unsigned long start;
unsigned long end;
start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
/*
* end + 1 here is intentional. We check several shadow bytes in advance
* to slightly speed up fastpath. In some rare cases we could cross
* boundary of mapped shadow, so we just map some more here.
*/
return vmemmap_populate(start, end + 1, NUMA_NO_NODE);
}
static void __init clear_pgds(unsigned long start,
unsigned long end)
{
pgd_t *pgd;
for (; start < end; start += PGDIR_SIZE) {
pgd = pgd_offset_k(start);
/*
* With folded p4d, pgd_clear() is nop, use p4d_clear()
* instead.
*/
if (CONFIG_PGTABLE_LEVELS < 5)
p4d_clear(p4d_offset(pgd, start));
else
pgd_clear(pgd);
}
}
static void __init kasan_map_early_shadow(pgd_t *pgd)
{
int i;
unsigned long start = KASAN_SHADOW_START;
unsigned long end = KASAN_SHADOW_END;
for (i = pgd_index(start); start < end; i++) {
pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud)
| _KERNPG_TABLE);
start += PGDIR_SIZE;
}
}
#ifdef CONFIG_KASAN_INLINE
static int kasan_die_handler(struct notifier_block *self,
unsigned long val,
void *data)
{
if (val == DIE_GPF) {
pr_emerg("CONFIG_KASAN_INLINE enabled\n");
pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
}
return NOTIFY_OK;
}
static struct notifier_block kasan_die_notifier = {
.notifier_call = kasan_die_handler,
};
#endif
void __init kasan_early_init(void)
{
int i;
pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
for (i = 0; i < PTRS_PER_PTE; i++)
kasan_zero_pte[i] = __pte(pte_val);
for (i = 0; i < PTRS_PER_PMD; i++)
kasan_zero_pmd[i] = __pmd(pmd_val);
for (i = 0; i < PTRS_PER_PUD; i++)
kasan_zero_pud[i] = __pud(pud_val);
kasan_map_early_shadow(early_level4_pgt);
kasan_map_early_shadow(init_level4_pgt);
}
void __init kasan_init(void)
{
int i;
#ifdef CONFIG_KASAN_INLINE
register_die_notifier(&kasan_die_notifier);
#endif
memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt));
load_cr3(early_level4_pgt);
__flush_tlb_all();
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
kasan_mem_to_shadow((void *)PAGE_OFFSET));
for (i = 0; i < E820_X_MAX; i++) {
if (pfn_mapped[i].end == 0)
break;
if (map_range(&pfn_mapped[i]))
panic("kasan: unable to allocate shadow!");
}
kasan_populate_zero_shadow(
kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
kasan_mem_to_shadow((void *)__START_KERNEL_map));
vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
(unsigned long)kasan_mem_to_shadow(_end),
NUMA_NO_NODE);
kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
(void *)KASAN_SHADOW_END);
load_cr3(init_level4_pgt);
__flush_tlb_all();
/*
* kasan_zero_page has been used as early shadow memory, thus it may
* contain some garbage. Now we can clear and write protect it, since
* after the TLB flush no one should write to it.
*/
memset(kasan_zero_page, 0, PAGE_SIZE);
for (i = 0; i < PTRS_PER_PTE; i++) {
pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
set_pte(&kasan_zero_pte[i], pte);
}
/* Flush TLBs again to be sure that write protection applied. */
__flush_tlb_all();
init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
}
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