init_book3s_64.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * KASAN for 64-bit Book3S powerpc
  4 *
  5 * Copyright 2019-2022, Daniel Axtens, IBM Corporation.
  6 */
  7
  8/*
  9 * ppc64 turns on virtual memory late in boot, after calling into generic code
 10 * like the device-tree parser, so it uses this in conjunction with a hook in
 11 * outline mode to avoid invalid access early in boot.
 12 */
 13
 14#define DISABLE_BRANCH_PROFILING
 15
 16#include <linux/kasan.h>
 17#include <linux/printk.h>
 18#include <linux/sched/task.h>
 19#include <linux/memblock.h>
 20#include <asm/pgalloc.h>
 21
 22static void __init kasan_init_phys_region(void *start, void *end)
 23{
 24	unsigned long k_start, k_end, k_cur;
 25	void *va;
 26
 27	if (start >= end)
 28		return;
 29
 30	k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
 31	k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
 32
 33	va = memblock_alloc_or_panic(k_end - k_start, PAGE_SIZE);
 34	for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
 35		map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
 36}
 37
 38void __init kasan_init(void)
 39{
 40	/*
 41	 * We want to do the following things:
 42	 *  1) Map real memory into the shadow for all physical memblocks
 43	 *     This takes us from c000... to c008...
 44	 *  2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC
 45	 *     will manage this for us.
 46	 *     This takes us from c008... to c00a...
 47	 *  3) Map the 'early shadow'/zero page over iomap and vmemmap space.
 48	 *     This takes us up to where we start at c00e...
 49	 */
 50
 51	void *k_start = kasan_mem_to_shadow((void *)RADIX_VMALLOC_END);
 52	void *k_end = kasan_mem_to_shadow((void *)RADIX_VMEMMAP_END);
 53	phys_addr_t start, end;
 54	u64 i;
 55	pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
 56
 57	if (!early_radix_enabled()) {
 58		pr_warn("KASAN not enabled as it requires radix!");
 59		return;
 60	}
 61
 62	for_each_mem_range(i, &start, &end)
 63		kasan_init_phys_region(phys_to_virt(start), phys_to_virt(end));
 64
 65	for (i = 0; i < PTRS_PER_PTE; i++)
 66		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
 67			     &kasan_early_shadow_pte[i], zero_pte, 0);
 68
 69	for (i = 0; i < PTRS_PER_PMD; i++)
 70		pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
 71				    kasan_early_shadow_pte);
 72
 73	for (i = 0; i < PTRS_PER_PUD; i++)
 74		pud_populate(&init_mm, &kasan_early_shadow_pud[i],
 75			     kasan_early_shadow_pmd);
 76
 77	/* map the early shadow over the iomap and vmemmap space */
 78	kasan_populate_early_shadow(k_start, k_end);
 79
 80	/* mark early shadow region as RO and wipe it */
 81	zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
 82	for (i = 0; i < PTRS_PER_PTE; i++)
 83		__set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
 84			     &kasan_early_shadow_pte[i], zero_pte, 0);
 85
 86	/*
 87	 * clear_page relies on some cache info that hasn't been set up yet.
 88	 * It ends up looping ~forever and blows up other data.
 89	 * Use memset instead.
 90	 */
 91	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 92
 93	/* Enable error messages */
 94	init_task.kasan_depth = 0;
 95	kasan_init_generic();
 96}
 97
 98void __init kasan_early_init(void) { }
 99
100void __init kasan_late_init(void) { }