252 lines
7.5 KiB
C
252 lines
7.5 KiB
C
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/*
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* This file contains kasan initialization code for ARM64.
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*
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* Copyright (c) 2015 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#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/kernel.h>
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#include <linux/sched/task.h>
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#include <linux/memblock.h>
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#include <linux/start_kernel.h>
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#include <linux/mm.h>
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#include <asm/mmu_context.h>
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#include <asm/kernel-pgtable.h>
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#include <asm/page.h>
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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#include <asm/sections.h>
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#include <asm/tlbflush.h>
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static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
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/*
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* The p*d_populate functions call virt_to_phys implicitly so they can't be used
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* directly on kernel symbols (bm_p*d). All the early functions are called too
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* early to use lm_alias so __p*d_populate functions must be used to populate
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* with the physical address from __pa_symbol.
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*/
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static phys_addr_t __init kasan_alloc_zeroed_page(int node)
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{
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void *p = memblock_virt_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
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__pa(MAX_DMA_ADDRESS),
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MEMBLOCK_ALLOC_KASAN, node);
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return __pa(p);
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}
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static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
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bool early)
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{
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if (pmd_none(READ_ONCE(*pmdp))) {
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phys_addr_t pte_phys = early ?
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__pa_symbol(kasan_early_shadow_pte)
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: kasan_alloc_zeroed_page(node);
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__pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
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}
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return early ? pte_offset_kimg(pmdp, addr)
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: pte_offset_kernel(pmdp, addr);
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}
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static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
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bool early)
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{
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if (pud_none(READ_ONCE(*pudp))) {
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phys_addr_t pmd_phys = early ?
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__pa_symbol(kasan_early_shadow_pmd)
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: kasan_alloc_zeroed_page(node);
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__pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
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}
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return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
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}
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static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
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bool early)
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{
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if (pgd_none(READ_ONCE(*pgdp))) {
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phys_addr_t pud_phys = early ?
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__pa_symbol(kasan_early_shadow_pud)
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: kasan_alloc_zeroed_page(node);
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__pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
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}
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return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
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}
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static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
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unsigned long end, int node, bool early)
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{
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unsigned long next;
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pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
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do {
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phys_addr_t page_phys = early ?
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__pa_symbol(kasan_early_shadow_page)
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: kasan_alloc_zeroed_page(node);
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if (!early)
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memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
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next = addr + PAGE_SIZE;
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set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
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} while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
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}
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static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
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unsigned long end, int node, bool early)
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{
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unsigned long next;
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pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
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do {
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next = pmd_addr_end(addr, end);
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kasan_pte_populate(pmdp, addr, next, node, early);
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} while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
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}
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static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
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unsigned long end, int node, bool early)
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{
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unsigned long next;
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pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
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do {
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next = pud_addr_end(addr, end);
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kasan_pmd_populate(pudp, addr, next, node, early);
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} while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
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}
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static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
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int node, bool early)
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{
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unsigned long next;
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pgd_t *pgdp;
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pgdp = pgd_offset_k(addr);
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do {
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next = pgd_addr_end(addr, end);
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kasan_pud_populate(pgdp, addr, next, node, early);
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} while (pgdp++, addr = next, addr != end);
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}
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/* The early shadow maps everything to a single page of zeroes */
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asmlinkage void __init kasan_early_init(void)
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{
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BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
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KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
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BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
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BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
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kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
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true);
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}
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/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
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static void __init kasan_map_populate(unsigned long start, unsigned long end,
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int node)
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{
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kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
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}
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/*
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* Copy the current shadow region into a new pgdir.
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*/
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void __init kasan_copy_shadow(pgd_t *pgdir)
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{
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pgd_t *pgdp, *pgdp_new, *pgdp_end;
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pgdp = pgd_offset_k(KASAN_SHADOW_START);
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pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
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pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
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do {
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set_pgd(pgdp_new, READ_ONCE(*pgdp));
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} while (pgdp++, pgdp_new++, pgdp != pgdp_end);
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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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/*
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* Remove references to kasan page tables from
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* swapper_pg_dir. pgd_clear() can't be used
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* here because it's nop on 2,3-level pagetable setups
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*/
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for (; start < end; start += PGDIR_SIZE)
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set_pgd(pgd_offset_k(start), __pgd(0));
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}
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void __init kasan_init(void)
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{
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u64 kimg_shadow_start, kimg_shadow_end;
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u64 mod_shadow_start, mod_shadow_end;
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struct memblock_region *reg;
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int i;
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kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
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kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
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mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
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mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
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/*
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* We are going to perform proper setup of shadow memory.
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* At first we should unmap early shadow (clear_pgds() call below).
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* However, instrumented code couldn't execute without shadow memory.
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* tmp_pg_dir used to keep early shadow mapped until full shadow
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* setup will be finished.
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*/
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memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
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dsb(ishst);
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cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
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clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
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kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
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early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
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kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
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(void *)mod_shadow_start);
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kasan_populate_early_shadow((void *)kimg_shadow_end,
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kasan_mem_to_shadow((void *)PAGE_OFFSET));
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if (kimg_shadow_start > mod_shadow_end)
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kasan_populate_early_shadow((void *)mod_shadow_end,
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(void *)kimg_shadow_start);
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for_each_memblock(memory, reg) {
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void *start = (void *)__phys_to_virt(reg->base);
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void *end = (void *)__phys_to_virt(reg->base + reg->size);
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if (start >= end)
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break;
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kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
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(unsigned long)kasan_mem_to_shadow(end),
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early_pfn_to_nid(virt_to_pfn(start)));
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}
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/*
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* KAsan may reuse the contents of kasan_early_shadow_pte directly,
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* so we should make sure that it maps the zero page read-only.
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*/
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for (i = 0; i < PTRS_PER_PTE; i++)
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set_pte(&kasan_early_shadow_pte[i],
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pfn_pte(sym_to_pfn(kasan_early_shadow_page),
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PAGE_KERNEL_RO));
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memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
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cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
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/* At this point kasan is fully initialized. Enable error messages */
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init_task.kasan_depth = 0;
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pr_info("KernelAddressSanitizer initialized\n");
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}
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