1/*
2 * Xtensa KASAN shadow map initialization
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License.  See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2017 Cadence Design Systems Inc.
9 */
10
11#include <linux/memblock.h>
12#include <linux/init_task.h>
13#include <linux/kasan.h>
14#include <linux/kernel.h>
15#include <asm/initialize_mmu.h>
16#include <asm/tlbflush.h>
17#include <asm/traps.h>
18
19void __init kasan_early_init(void)
20{
21	unsigned long vaddr = KASAN_SHADOW_START;
22	pmd_t *pmd = pmd_off_k(vaddr);
23	int i;
24
25	for (i = 0; i < PTRS_PER_PTE; ++i)
26		set_pte(kasan_early_shadow_pte + i,
27			mk_pte(virt_to_page(kasan_early_shadow_page),
28				PAGE_KERNEL));
29
30	for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
31		BUG_ON(!pmd_none(*pmd));
32		set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
33	}
34	early_trap_init();
35}
36
37static void __init populate(void *start, void *end)
38{
39	unsigned long n_pages = (end - start) / PAGE_SIZE;
40	unsigned long n_pmds = n_pages / PTRS_PER_PTE;
41	unsigned long i, j;
42	unsigned long vaddr = (unsigned long)start;
43	pmd_t *pmd = pmd_off_k(vaddr);
44	pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
45
46	if (!pte)
47		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
48		      __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
49
50	pr_debug("%s: %p - %p\n", __func__, start, end);
51
52	for (i = j = 0; i < n_pmds; ++i) {
53		int k;
54
55		for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
56			phys_addr_t phys =
57				memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
58							  0,
59							  MEMBLOCK_ALLOC_ANYWHERE);
60
61			if (!phys)
62				panic("Failed to allocate page table page\n");
63
64			set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
65		}
66	}
67
68	for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
69		set_pmd(pmd + i, __pmd((unsigned long)pte));
70
71	local_flush_tlb_all();
72	memset(start, 0, end - start);
73}
74
75void __init kasan_init(void)
76{
77	int i;
78
79	BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
80		     (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
81	BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
82
83	/*
84	 * Replace shadow map pages that cover addresses from VMALLOC area
85	 * start to the end of KSEG with clean writable pages.
86	 */
87	populate(kasan_mem_to_shadow((void *)VMALLOC_START),
88		 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
89
90	/*
91	 * Write protect kasan_early_shadow_page and zero-initialize it again.
92	 */
93	for (i = 0; i < PTRS_PER_PTE; ++i)
94		set_pte(kasan_early_shadow_pte + i,
95			mk_pte(virt_to_page(kasan_early_shadow_page),
96				PAGE_KERNEL_RO));
97
98	local_flush_tlb_all();
99	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
100
101	/* At this point kasan is fully initialized. Enable error messages. */
102	current->kasan_depth = 0;
103	pr_info("KernelAddressSanitizer initialized\n");
104}
105