mem.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  4 */
  5
  6#include <linux/stddef.h>
  7#include <linux/module.h>
  8#include <linux/memblock.h>
  9#include <linux/mm.h>
 10#include <linux/swap.h>
 11#include <linux/slab.h>
 12#include <linux/init.h>
 13#include <asm/sections.h>
 14#include <asm/page.h>
 15#include <asm/pgalloc.h>
 16#include <as-layout.h>
 17#include <init.h>
 18#include <kern.h>
 19#include <kern_util.h>
 20#include <mem_user.h>
 21#include <os.h>
 22#include <um_malloc.h>
 23#include <linux/sched/task.h>
 24#include <linux/kasan.h>
 25
 26#ifdef CONFIG_KASAN
 27void __init kasan_init(void)
 28{
 29	/*
 30	 * kasan_map_memory will map all of the required address space and
 31	 * the host machine will allocate physical memory as necessary.
 32	 */
 33	kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE);
 34	init_task.kasan_depth = 0;
 35	/*
 36	 * Since kasan_init() is called before main(),
 37	 * KASAN is initialized but the enablement is deferred after
 38	 * jump_label_init(). See arch_mm_preinit().
 39	 */
 40}
 41
 42static void (*kasan_init_ptr)(void)
 43__section(".kasan_init") __used
 44= kasan_init;
 45#endif
 46
 47/* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
 48unsigned long *empty_zero_page = NULL;
 49EXPORT_SYMBOL(empty_zero_page);
 50
 51/*
 52 * Initialized during boot, and readonly for initializing page tables
 53 * afterwards
 54 */
 55pgd_t swapper_pg_dir[PTRS_PER_PGD];
 56
 57/* Initialized at boot time, and readonly after that */
 58int kmalloc_ok = 0;
 59
 60/* Used during early boot */
 61static unsigned long brk_end;
 62
 63void __init arch_mm_preinit(void)
 64{
 65	/* Safe to call after jump_label_init(). Enables KASAN. */
 66	kasan_init_generic();
 67
 68	/* clear the zero-page */
 69	memset(empty_zero_page, 0, PAGE_SIZE);
 70
 71	/* Map in the area just after the brk now that kmalloc is about
 72	 * to be turned on.
 73	 */
 74	brk_end = PAGE_ALIGN((unsigned long) sbrk(0));
 75	map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
 76	memblock_free((void *)brk_end, uml_reserved - brk_end);
 77	uml_reserved = brk_end;
 78	min_low_pfn = PFN_UP(__pa(uml_reserved));
 79	max_pfn = max_low_pfn;
 80}
 81
 82void __init mem_init(void)
 83{
 84	kmalloc_ok = 1;
 85}
 86
 87void __init paging_init(void)
 88{
 89	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 90
 91	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 92							       PAGE_SIZE);
 93	if (!empty_zero_page)
 94		panic("%s: Failed to allocate %lu bytes align=%lx\n",
 95		      __func__, PAGE_SIZE, PAGE_SIZE);
 96
 97	max_zone_pfn[ZONE_NORMAL] = high_physmem >> PAGE_SHIFT;
 98	free_area_init(max_zone_pfn);
 99}
100
101/*
102 * This can't do anything because nothing in the kernel image can be freed
103 * since it's not in kernel physical memory.
104 */
105
106void free_initmem(void)
107{
108}
109
110/* Allocate and free page tables. */
111
112pgd_t *pgd_alloc(struct mm_struct *mm)
113{
114	pgd_t *pgd = __pgd_alloc(mm, 0);
115
116	if (pgd)
117		memcpy(pgd + USER_PTRS_PER_PGD,
118		       swapper_pg_dir + USER_PTRS_PER_PGD,
119		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
120
121	return pgd;
122}
123
124void *uml_kmalloc(int size, int flags)
125{
126	return kmalloc(size, flags);
127}
128
129static const pgprot_t protection_map[16] = {
130	[VM_NONE]					= PAGE_NONE,
131	[VM_READ]					= PAGE_READONLY,
132	[VM_WRITE]					= PAGE_COPY,
133	[VM_WRITE | VM_READ]				= PAGE_COPY,
134	[VM_EXEC]					= PAGE_READONLY,
135	[VM_EXEC | VM_READ]				= PAGE_READONLY,
136	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
137	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY,
138	[VM_SHARED]					= PAGE_NONE,
139	[VM_SHARED | VM_READ]				= PAGE_READONLY,
140	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
141	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
142	[VM_SHARED | VM_EXEC]				= PAGE_READONLY,
143	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY,
144	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED,
145	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED
146};
147DECLARE_VM_GET_PAGE_PROT
148
149void mark_rodata_ro(void)
150{
151	unsigned long rodata_start = PFN_ALIGN(__start_rodata);
152	unsigned long rodata_end = PFN_ALIGN(__end_rodata);
153
154	os_protect_memory((void *)rodata_start, rodata_end - rodata_start, 1, 0, 0);
155}