mmap.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
  4 */
  5#include <linux/export.h>
  6#include <linux/hugetlb.h>
  7#include <linux/io.h>
  8#include <linux/kfence.h>
  9#include <linux/memblock.h>
 10#include <linux/mm.h>
 11#include <linux/mman.h>
 12
 13#define SHM_ALIGN_MASK	(SHMLBA - 1)
 14
 15#define COLOUR_ALIGN(addr, pgoff)			\
 16	((((addr) + SHM_ALIGN_MASK) & ~SHM_ALIGN_MASK)	\
 17	 + (((pgoff) << PAGE_SHIFT) & SHM_ALIGN_MASK))
 18
 19enum mmap_allocation_direction {UP, DOWN};
 20
 21static unsigned long arch_get_unmapped_area_common(struct file *filp,
 22	unsigned long addr0, unsigned long len, unsigned long pgoff,
 23	unsigned long flags, enum mmap_allocation_direction dir)
 24{
 25	struct mm_struct *mm = current->mm;
 26	struct vm_area_struct *vma;
 27	unsigned long addr = addr0;
 28	int do_color_align;
 29	struct vm_unmapped_area_info info = {};
 30
 31	if (unlikely(len > TASK_SIZE))
 32		return -ENOMEM;
 33
 34	if (flags & MAP_FIXED) {
 35		/* Even MAP_FIXED mappings must reside within TASK_SIZE */
 36		if (TASK_SIZE - len < addr)
 37			return -EINVAL;
 38
 39		/*
 40		 * We do not accept a shared mapping if it would violate
 41		 * cache aliasing constraints.
 42		 */
 43		if ((flags & MAP_SHARED) &&
 44		    ((addr - (pgoff << PAGE_SHIFT)) & SHM_ALIGN_MASK))
 45			return -EINVAL;
 46		return addr;
 47	}
 48
 49	do_color_align = 0;
 50	if (filp || (flags & MAP_SHARED))
 51		do_color_align = 1;
 52
 53	/* requesting a specific address */
 54	if (addr) {
 55		if (do_color_align)
 56			addr = COLOUR_ALIGN(addr, pgoff);
 57		else
 58			addr = PAGE_ALIGN(addr);
 59
 60		vma = find_vma(mm, addr);
 61		if (TASK_SIZE - len >= addr &&
 62		    (!vma || addr + len <= vm_start_gap(vma)))
 63			return addr;
 64	}
 65
 66	info.length = len;
 67	info.align_offset = pgoff << PAGE_SHIFT;
 68	if (filp && is_file_hugepages(filp))
 69		info.align_mask = huge_page_mask_align(filp);
 70	else
 71		info.align_mask = do_color_align ? (PAGE_MASK & SHM_ALIGN_MASK) : 0;
 72
 73	if (dir == DOWN) {
 74		info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 75		info.low_limit = PAGE_SIZE;
 76		info.high_limit = mm->mmap_base;
 77		addr = vm_unmapped_area(&info);
 78
 79		if (!(addr & ~PAGE_MASK))
 80			return addr;
 81
 82		/*
 83		 * A failed mmap() very likely causes application failure,
 84		 * so fall back to the bottom-up function here. This scenario
 85		 * can happen with large stack limits and large mmap()
 86		 * allocations.
 87		 */
 88	}
 89
 90	info.low_limit = mm->mmap_base;
 91	info.high_limit = TASK_SIZE;
 92	return vm_unmapped_area(&info);
 93}
 94
 95unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
 96	unsigned long len, unsigned long pgoff, unsigned long flags,
 97	vm_flags_t vm_flags)
 98{
 99	return arch_get_unmapped_area_common(filp,
100			addr0, len, pgoff, flags, UP);
101}
102
103/*
104 * There is no need to export this but sched.h declares the function as
105 * extern so making it static here results in an error.
106 */
107unsigned long arch_get_unmapped_area_topdown(struct file *filp,
108	unsigned long addr0, unsigned long len, unsigned long pgoff,
109	unsigned long flags, vm_flags_t vm_flags)
110{
111	return arch_get_unmapped_area_common(filp,
112			addr0, len, pgoff, flags, DOWN);
113}
114
115int __virt_addr_valid(volatile void *kaddr)
116{
117	unsigned long vaddr = (unsigned long)kaddr;
118
119	if (is_kfence_address((void *)kaddr))
120		return 1;
121
122	if ((vaddr < PAGE_OFFSET) || (vaddr >= vm_map_base))
123		return 0;
124
125	return pfn_valid(PFN_DOWN(PHYSADDR(kaddr)));
126}
127EXPORT_SYMBOL_GPL(__virt_addr_valid);
128
129/*
130 * You really shouldn't be using read() or write() on /dev/mem.  This might go
131 * away in the future.
132 */
133int valid_phys_addr_range(phys_addr_t addr, size_t size)
134{
135	/*
136	 * Check whether addr is covered by a memory region without the
137	 * MEMBLOCK_NOMAP attribute, and whether that region covers the
138	 * entire range. In theory, this could lead to false negatives
139	 * if the range is covered by distinct but adjacent memory regions
140	 * that only differ in other attributes. However, few of such
141	 * attributes have been defined, and it is debatable whether it
142	 * follows that /dev/mem read() calls should be able traverse
143	 * such boundaries.
144	 */
145	return memblock_is_region_memory(addr, size) && memblock_is_map_memory(addr);
146}
147
148/*
149 * Do not allow /dev/mem mappings beyond the supported physical range.
150 */
151int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
152{
153	return !(((pfn << PAGE_SHIFT) + size) & ~(GENMASK_ULL(cpu_pabits, 0)));
154}