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1854 lines
45 KiB
1854 lines
45 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/mm/nommu.c |
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* |
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* Replacement code for mm functions to support CPU's that don't |
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* have any form of memory management unit (thus no virtual memory). |
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* |
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* See Documentation/admin-guide/mm/nommu-mmap.rst |
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* |
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* Copyright (c) 2004-2008 David Howells <[email protected]> |
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* Copyright (c) 2000-2003 David McCullough <[email protected]> |
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* Copyright (c) 2000-2001 D Jeff Dionne <[email protected]> |
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* Copyright (c) 2002 Greg Ungerer <[email protected]> |
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* Copyright (c) 2007-2010 Paul Mundt <[email protected]> |
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*/ |
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|
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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|
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#include <linux/export.h> |
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#include <linux/mm.h> |
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#include <linux/sched/mm.h> |
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#include <linux/vmacache.h> |
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#include <linux/mman.h> |
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#include <linux/swap.h> |
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#include <linux/file.h> |
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#include <linux/highmem.h> |
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#include <linux/pagemap.h> |
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#include <linux/slab.h> |
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#include <linux/vmalloc.h> |
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#include <linux/blkdev.h> |
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#include <linux/backing-dev.h> |
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#include <linux/compiler.h> |
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#include <linux/mount.h> |
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#include <linux/personality.h> |
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#include <linux/security.h> |
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#include <linux/syscalls.h> |
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#include <linux/audit.h> |
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#include <linux/printk.h> |
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|
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#include <linux/uaccess.h> |
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#include <asm/tlb.h> |
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#include <asm/tlbflush.h> |
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#include <asm/mmu_context.h> |
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#include "internal.h" |
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|
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void *high_memory; |
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EXPORT_SYMBOL(high_memory); |
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struct page *mem_map; |
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unsigned long max_mapnr; |
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EXPORT_SYMBOL(max_mapnr); |
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unsigned long highest_memmap_pfn; |
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int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; |
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int heap_stack_gap = 0; |
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atomic_long_t mmap_pages_allocated; |
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EXPORT_SYMBOL(mem_map); |
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|
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/* list of mapped, potentially shareable regions */ |
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static struct kmem_cache *vm_region_jar; |
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struct rb_root nommu_region_tree = RB_ROOT; |
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DECLARE_RWSEM(nommu_region_sem); |
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|
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const struct vm_operations_struct generic_file_vm_ops = { |
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}; |
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|
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/* |
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* Return the total memory allocated for this pointer, not |
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* just what the caller asked for. |
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* |
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* Doesn't have to be accurate, i.e. may have races. |
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*/ |
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unsigned int kobjsize(const void *objp) |
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{ |
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struct page *page; |
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|
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/* |
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* If the object we have should not have ksize performed on it, |
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* return size of 0 |
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*/ |
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if (!objp || !virt_addr_valid(objp)) |
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return 0; |
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page = virt_to_head_page(objp); |
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|
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/* |
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* If the allocator sets PageSlab, we know the pointer came from |
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* kmalloc(). |
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*/ |
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if (PageSlab(page)) |
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return ksize(objp); |
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|
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/* |
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* If it's not a compound page, see if we have a matching VMA |
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* region. This test is intentionally done in reverse order, |
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* so if there's no VMA, we still fall through and hand back |
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* PAGE_SIZE for 0-order pages. |
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*/ |
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if (!PageCompound(page)) { |
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struct vm_area_struct *vma; |
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vma = find_vma(current->mm, (unsigned long)objp); |
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if (vma) |
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return vma->vm_end - vma->vm_start; |
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} |
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|
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/* |
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* The ksize() function is only guaranteed to work for pointers |
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* returned by kmalloc(). So handle arbitrary pointers here. |
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*/ |
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return page_size(page); |
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} |
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|
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/** |
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* follow_pfn - look up PFN at a user virtual address |
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* @vma: memory mapping |
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* @address: user virtual address |
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* @pfn: location to store found PFN |
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* |
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* Only IO mappings and raw PFN mappings are allowed. |
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* |
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* Returns zero and the pfn at @pfn on success, -ve otherwise. |
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*/ |
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int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
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unsigned long *pfn) |
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{ |
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if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
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return -EINVAL; |
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|
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*pfn = address >> PAGE_SHIFT; |
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return 0; |
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} |
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EXPORT_SYMBOL(follow_pfn); |
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|
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LIST_HEAD(vmap_area_list); |
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|
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void vfree(const void *addr) |
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{ |
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kfree(addr); |
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} |
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EXPORT_SYMBOL(vfree); |
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void *__vmalloc(unsigned long size, gfp_t gfp_mask) |
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{ |
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/* |
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* You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() |
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* returns only a logical address. |
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*/ |
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return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); |
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} |
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EXPORT_SYMBOL(__vmalloc); |
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void *__vmalloc_node_range(unsigned long size, unsigned long align, |
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unsigned long start, unsigned long end, gfp_t gfp_mask, |
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pgprot_t prot, unsigned long vm_flags, int node, |
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const void *caller) |
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{ |
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return __vmalloc(size, gfp_mask); |
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} |
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void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask, |
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int node, const void *caller) |
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{ |
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return __vmalloc(size, gfp_mask); |
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} |
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static void *__vmalloc_user_flags(unsigned long size, gfp_t flags) |
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{ |
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void *ret; |
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ret = __vmalloc(size, flags); |
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if (ret) { |
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struct vm_area_struct *vma; |
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|
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mmap_write_lock(current->mm); |
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vma = find_vma(current->mm, (unsigned long)ret); |
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if (vma) |
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vma->vm_flags |= VM_USERMAP; |
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mmap_write_unlock(current->mm); |
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} |
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return ret; |
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} |
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void *vmalloc_user(unsigned long size) |
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{ |
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return __vmalloc_user_flags(size, GFP_KERNEL | __GFP_ZERO); |
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} |
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EXPORT_SYMBOL(vmalloc_user); |
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struct page *vmalloc_to_page(const void *addr) |
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{ |
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return virt_to_page(addr); |
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} |
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EXPORT_SYMBOL(vmalloc_to_page); |
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unsigned long vmalloc_to_pfn(const void *addr) |
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{ |
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return page_to_pfn(virt_to_page(addr)); |
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} |
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EXPORT_SYMBOL(vmalloc_to_pfn); |
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|
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long vread(char *buf, char *addr, unsigned long count) |
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{ |
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/* Don't allow overflow */ |
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if ((unsigned long) buf + count < count) |
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count = -(unsigned long) buf; |
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memcpy(buf, addr, count); |
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return count; |
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} |
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long vwrite(char *buf, char *addr, unsigned long count) |
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{ |
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/* Don't allow overflow */ |
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if ((unsigned long) addr + count < count) |
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count = -(unsigned long) addr; |
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|
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memcpy(addr, buf, count); |
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return count; |
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} |
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|
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/* |
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* vmalloc - allocate virtually contiguous memory |
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* |
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* @size: allocation size |
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* |
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* Allocate enough pages to cover @size from the page level |
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* allocator and map them into contiguous kernel virtual space. |
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* |
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* For tight control over page level allocator and protection flags |
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* use __vmalloc() instead. |
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*/ |
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void *vmalloc(unsigned long size) |
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{ |
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return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM); |
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} |
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EXPORT_SYMBOL(vmalloc); |
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|
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/* |
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* vzalloc - allocate virtually contiguous memory with zero fill |
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* |
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* @size: allocation size |
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* |
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* Allocate enough pages to cover @size from the page level |
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* allocator and map them into contiguous kernel virtual space. |
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* The memory allocated is set to zero. |
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* |
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* For tight control over page level allocator and protection flags |
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* use __vmalloc() instead. |
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*/ |
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void *vzalloc(unsigned long size) |
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{ |
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return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO); |
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} |
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EXPORT_SYMBOL(vzalloc); |
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|
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/** |
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* vmalloc_node - allocate memory on a specific node |
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* @size: allocation size |
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* @node: numa node |
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* |
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* Allocate enough pages to cover @size from the page level |
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* allocator and map them into contiguous kernel virtual space. |
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* |
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* For tight control over page level allocator and protection flags |
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* use __vmalloc() instead. |
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*/ |
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void *vmalloc_node(unsigned long size, int node) |
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{ |
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return vmalloc(size); |
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} |
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EXPORT_SYMBOL(vmalloc_node); |
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|
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/** |
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* vzalloc_node - allocate memory on a specific node with zero fill |
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* @size: allocation size |
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* @node: numa node |
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* |
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* Allocate enough pages to cover @size from the page level |
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* allocator and map them into contiguous kernel virtual space. |
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* The memory allocated is set to zero. |
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* |
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* For tight control over page level allocator and protection flags |
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* use __vmalloc() instead. |
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*/ |
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void *vzalloc_node(unsigned long size, int node) |
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{ |
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return vzalloc(size); |
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} |
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EXPORT_SYMBOL(vzalloc_node); |
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|
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/** |
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* vmalloc_32 - allocate virtually contiguous memory (32bit addressable) |
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* @size: allocation size |
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* |
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* Allocate enough 32bit PA addressable pages to cover @size from the |
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* page level allocator and map them into contiguous kernel virtual space. |
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*/ |
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void *vmalloc_32(unsigned long size) |
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{ |
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return __vmalloc(size, GFP_KERNEL); |
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} |
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EXPORT_SYMBOL(vmalloc_32); |
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|
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/** |
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* vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory |
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* @size: allocation size |
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* |
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* The resulting memory area is 32bit addressable and zeroed so it can be |
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* mapped to userspace without leaking data. |
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* |
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* VM_USERMAP is set on the corresponding VMA so that subsequent calls to |
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* remap_vmalloc_range() are permissible. |
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*/ |
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void *vmalloc_32_user(unsigned long size) |
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{ |
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/* |
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* We'll have to sort out the ZONE_DMA bits for 64-bit, |
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* but for now this can simply use vmalloc_user() directly. |
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*/ |
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return vmalloc_user(size); |
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} |
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EXPORT_SYMBOL(vmalloc_32_user); |
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void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) |
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{ |
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BUG(); |
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return NULL; |
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} |
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EXPORT_SYMBOL(vmap); |
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void vunmap(const void *addr) |
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{ |
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BUG(); |
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} |
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EXPORT_SYMBOL(vunmap); |
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void *vm_map_ram(struct page **pages, unsigned int count, int node) |
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{ |
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BUG(); |
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return NULL; |
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} |
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EXPORT_SYMBOL(vm_map_ram); |
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void vm_unmap_ram(const void *mem, unsigned int count) |
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{ |
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BUG(); |
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} |
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EXPORT_SYMBOL(vm_unmap_ram); |
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void vm_unmap_aliases(void) |
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{ |
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} |
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EXPORT_SYMBOL_GPL(vm_unmap_aliases); |
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void free_vm_area(struct vm_struct *area) |
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{ |
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BUG(); |
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} |
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EXPORT_SYMBOL_GPL(free_vm_area); |
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int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
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struct page *page) |
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{ |
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return -EINVAL; |
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} |
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EXPORT_SYMBOL(vm_insert_page); |
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int vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
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unsigned long num) |
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{ |
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return -EINVAL; |
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} |
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EXPORT_SYMBOL(vm_map_pages); |
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int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, |
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unsigned long num) |
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{ |
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return -EINVAL; |
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} |
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EXPORT_SYMBOL(vm_map_pages_zero); |
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|
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/* |
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* sys_brk() for the most part doesn't need the global kernel |
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* lock, except when an application is doing something nasty |
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* like trying to un-brk an area that has already been mapped |
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* to a regular file. in this case, the unmapping will need |
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* to invoke file system routines that need the global lock. |
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*/ |
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SYSCALL_DEFINE1(brk, unsigned long, brk) |
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{ |
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struct mm_struct *mm = current->mm; |
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if (brk < mm->start_brk || brk > mm->context.end_brk) |
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return mm->brk; |
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if (mm->brk == brk) |
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return mm->brk; |
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|
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/* |
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* Always allow shrinking brk |
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*/ |
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if (brk <= mm->brk) { |
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mm->brk = brk; |
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return brk; |
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} |
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|
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/* |
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* Ok, looks good - let it rip. |
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*/ |
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flush_icache_user_range(mm->brk, brk); |
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return mm->brk = brk; |
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} |
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|
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/* |
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* initialise the percpu counter for VM and region record slabs |
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*/ |
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void __init mmap_init(void) |
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{ |
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int ret; |
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ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); |
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VM_BUG_ON(ret); |
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vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT); |
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} |
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|
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/* |
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* validate the region tree |
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* - the caller must hold the region lock |
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*/ |
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#ifdef CONFIG_DEBUG_NOMMU_REGIONS |
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static noinline void validate_nommu_regions(void) |
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{ |
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struct vm_region *region, *last; |
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struct rb_node *p, *lastp; |
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|
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lastp = rb_first(&nommu_region_tree); |
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if (!lastp) |
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return; |
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last = rb_entry(lastp, struct vm_region, vm_rb); |
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BUG_ON(last->vm_end <= last->vm_start); |
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BUG_ON(last->vm_top < last->vm_end); |
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|
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while ((p = rb_next(lastp))) { |
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region = rb_entry(p, struct vm_region, vm_rb); |
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last = rb_entry(lastp, struct vm_region, vm_rb); |
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BUG_ON(region->vm_end <= region->vm_start); |
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BUG_ON(region->vm_top < region->vm_end); |
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BUG_ON(region->vm_start < last->vm_top); |
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lastp = p; |
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} |
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} |
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#else |
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static void validate_nommu_regions(void) |
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{ |
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} |
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#endif |
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|
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/* |
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* add a region into the global tree |
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*/ |
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static void add_nommu_region(struct vm_region *region) |
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{ |
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struct vm_region *pregion; |
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struct rb_node **p, *parent; |
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validate_nommu_regions(); |
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parent = NULL; |
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p = &nommu_region_tree.rb_node; |
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while (*p) { |
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parent = *p; |
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pregion = rb_entry(parent, struct vm_region, vm_rb); |
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if (region->vm_start < pregion->vm_start) |
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p = &(*p)->rb_left; |
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else if (region->vm_start > pregion->vm_start) |
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p = &(*p)->rb_right; |
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else if (pregion == region) |
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return; |
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else |
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BUG(); |
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} |
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rb_link_node(®ion->vm_rb, parent, p); |
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rb_insert_color(®ion->vm_rb, &nommu_region_tree); |
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|
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validate_nommu_regions(); |
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} |
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|
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/* |
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* delete a region from the global tree |
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*/ |
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static void delete_nommu_region(struct vm_region *region) |
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{ |
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BUG_ON(!nommu_region_tree.rb_node); |
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|
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validate_nommu_regions(); |
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rb_erase(®ion->vm_rb, &nommu_region_tree); |
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validate_nommu_regions(); |
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} |
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|
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/* |
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* free a contiguous series of pages |
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*/ |
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static void free_page_series(unsigned long from, unsigned long to) |
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{ |
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for (; from < to; from += PAGE_SIZE) { |
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struct page *page = virt_to_page(from); |
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|
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atomic_long_dec(&mmap_pages_allocated); |
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put_page(page); |
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} |
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} |
|
|
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/* |
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* release a reference to a region |
|
* - the caller must hold the region semaphore for writing, which this releases |
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* - the region may not have been added to the tree yet, in which case vm_top |
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* will equal vm_start |
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*/ |
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static void __put_nommu_region(struct vm_region *region) |
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__releases(nommu_region_sem) |
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{ |
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BUG_ON(!nommu_region_tree.rb_node); |
|
|
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if (--region->vm_usage == 0) { |
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if (region->vm_top > region->vm_start) |
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delete_nommu_region(region); |
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up_write(&nommu_region_sem); |
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|
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if (region->vm_file) |
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fput(region->vm_file); |
|
|
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/* IO memory and memory shared directly out of the pagecache |
|
* from ramfs/tmpfs mustn't be released here */ |
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if (region->vm_flags & VM_MAPPED_COPY) |
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free_page_series(region->vm_start, region->vm_top); |
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kmem_cache_free(vm_region_jar, region); |
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} else { |
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up_write(&nommu_region_sem); |
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} |
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} |
|
|
|
/* |
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* release a reference to a region |
|
*/ |
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static void put_nommu_region(struct vm_region *region) |
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{ |
|
down_write(&nommu_region_sem); |
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__put_nommu_region(region); |
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} |
|
|
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/* |
|
* add a VMA into a process's mm_struct in the appropriate place in the list |
|
* and tree and add to the address space's page tree also if not an anonymous |
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* page |
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* - should be called with mm->mmap_lock held writelocked |
|
*/ |
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static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) |
|
{ |
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struct vm_area_struct *pvma, *prev; |
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struct address_space *mapping; |
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struct rb_node **p, *parent, *rb_prev; |
|
|
|
BUG_ON(!vma->vm_region); |
|
|
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mm->map_count++; |
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vma->vm_mm = mm; |
|
|
|
/* add the VMA to the mapping */ |
|
if (vma->vm_file) { |
|
mapping = vma->vm_file->f_mapping; |
|
|
|
i_mmap_lock_write(mapping); |
|
flush_dcache_mmap_lock(mapping); |
|
vma_interval_tree_insert(vma, &mapping->i_mmap); |
|
flush_dcache_mmap_unlock(mapping); |
|
i_mmap_unlock_write(mapping); |
|
} |
|
|
|
/* add the VMA to the tree */ |
|
parent = rb_prev = NULL; |
|
p = &mm->mm_rb.rb_node; |
|
while (*p) { |
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parent = *p; |
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pvma = rb_entry(parent, struct vm_area_struct, vm_rb); |
|
|
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/* sort by: start addr, end addr, VMA struct addr in that order |
|
* (the latter is necessary as we may get identical VMAs) */ |
|
if (vma->vm_start < pvma->vm_start) |
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p = &(*p)->rb_left; |
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else if (vma->vm_start > pvma->vm_start) { |
|
rb_prev = parent; |
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p = &(*p)->rb_right; |
|
} else if (vma->vm_end < pvma->vm_end) |
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p = &(*p)->rb_left; |
|
else if (vma->vm_end > pvma->vm_end) { |
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rb_prev = parent; |
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p = &(*p)->rb_right; |
|
} else if (vma < pvma) |
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p = &(*p)->rb_left; |
|
else if (vma > pvma) { |
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rb_prev = parent; |
|
p = &(*p)->rb_right; |
|
} else |
|
BUG(); |
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} |
|
|
|
rb_link_node(&vma->vm_rb, parent, p); |
|
rb_insert_color(&vma->vm_rb, &mm->mm_rb); |
|
|
|
/* add VMA to the VMA list also */ |
|
prev = NULL; |
|
if (rb_prev) |
|
prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); |
|
|
|
__vma_link_list(mm, vma, prev); |
|
} |
|
|
|
/* |
|
* delete a VMA from its owning mm_struct and address space |
|
*/ |
|
static void delete_vma_from_mm(struct vm_area_struct *vma) |
|
{ |
|
int i; |
|
struct address_space *mapping; |
|
struct mm_struct *mm = vma->vm_mm; |
|
struct task_struct *curr = current; |
|
|
|
mm->map_count--; |
|
for (i = 0; i < VMACACHE_SIZE; i++) { |
|
/* if the vma is cached, invalidate the entire cache */ |
|
if (curr->vmacache.vmas[i] == vma) { |
|
vmacache_invalidate(mm); |
|
break; |
|
} |
|
} |
|
|
|
/* remove the VMA from the mapping */ |
|
if (vma->vm_file) { |
|
mapping = vma->vm_file->f_mapping; |
|
|
|
i_mmap_lock_write(mapping); |
|
flush_dcache_mmap_lock(mapping); |
|
vma_interval_tree_remove(vma, &mapping->i_mmap); |
|
flush_dcache_mmap_unlock(mapping); |
|
i_mmap_unlock_write(mapping); |
|
} |
|
|
|
/* remove from the MM's tree and list */ |
|
rb_erase(&vma->vm_rb, &mm->mm_rb); |
|
|
|
__vma_unlink_list(mm, vma); |
|
} |
|
|
|
/* |
|
* destroy a VMA record |
|
*/ |
|
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) |
|
{ |
|
if (vma->vm_ops && vma->vm_ops->close) |
|
vma->vm_ops->close(vma); |
|
if (vma->vm_file) |
|
fput(vma->vm_file); |
|
put_nommu_region(vma->vm_region); |
|
vm_area_free(vma); |
|
} |
|
|
|
/* |
|
* look up the first VMA in which addr resides, NULL if none |
|
* - should be called with mm->mmap_lock at least held readlocked |
|
*/ |
|
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
|
{ |
|
struct vm_area_struct *vma; |
|
|
|
/* check the cache first */ |
|
vma = vmacache_find(mm, addr); |
|
if (likely(vma)) |
|
return vma; |
|
|
|
/* trawl the list (there may be multiple mappings in which addr |
|
* resides) */ |
|
for (vma = mm->mmap; vma; vma = vma->vm_next) { |
|
if (vma->vm_start > addr) |
|
return NULL; |
|
if (vma->vm_end > addr) { |
|
vmacache_update(addr, vma); |
|
return vma; |
|
} |
|
} |
|
|
|
return NULL; |
|
} |
|
EXPORT_SYMBOL(find_vma); |
|
|
|
/* |
|
* find a VMA |
|
* - we don't extend stack VMAs under NOMMU conditions |
|
*/ |
|
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) |
|
{ |
|
return find_vma(mm, addr); |
|
} |
|
|
|
/* |
|
* expand a stack to a given address |
|
* - not supported under NOMMU conditions |
|
*/ |
|
int expand_stack(struct vm_area_struct *vma, unsigned long address) |
|
{ |
|
return -ENOMEM; |
|
} |
|
|
|
/* |
|
* look up the first VMA exactly that exactly matches addr |
|
* - should be called with mm->mmap_lock at least held readlocked |
|
*/ |
|
static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, |
|
unsigned long addr, |
|
unsigned long len) |
|
{ |
|
struct vm_area_struct *vma; |
|
unsigned long end = addr + len; |
|
|
|
/* check the cache first */ |
|
vma = vmacache_find_exact(mm, addr, end); |
|
if (vma) |
|
return vma; |
|
|
|
/* trawl the list (there may be multiple mappings in which addr |
|
* resides) */ |
|
for (vma = mm->mmap; vma; vma = vma->vm_next) { |
|
if (vma->vm_start < addr) |
|
continue; |
|
if (vma->vm_start > addr) |
|
return NULL; |
|
if (vma->vm_end == end) { |
|
vmacache_update(addr, vma); |
|
return vma; |
|
} |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
/* |
|
* determine whether a mapping should be permitted and, if so, what sort of |
|
* mapping we're capable of supporting |
|
*/ |
|
static int validate_mmap_request(struct file *file, |
|
unsigned long addr, |
|
unsigned long len, |
|
unsigned long prot, |
|
unsigned long flags, |
|
unsigned long pgoff, |
|
unsigned long *_capabilities) |
|
{ |
|
unsigned long capabilities, rlen; |
|
int ret; |
|
|
|
/* do the simple checks first */ |
|
if (flags & MAP_FIXED) |
|
return -EINVAL; |
|
|
|
if ((flags & MAP_TYPE) != MAP_PRIVATE && |
|
(flags & MAP_TYPE) != MAP_SHARED) |
|
return -EINVAL; |
|
|
|
if (!len) |
|
return -EINVAL; |
|
|
|
/* Careful about overflows.. */ |
|
rlen = PAGE_ALIGN(len); |
|
if (!rlen || rlen > TASK_SIZE) |
|
return -ENOMEM; |
|
|
|
/* offset overflow? */ |
|
if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) |
|
return -EOVERFLOW; |
|
|
|
if (file) { |
|
/* files must support mmap */ |
|
if (!file->f_op->mmap) |
|
return -ENODEV; |
|
|
|
/* work out if what we've got could possibly be shared |
|
* - we support chardevs that provide their own "memory" |
|
* - we support files/blockdevs that are memory backed |
|
*/ |
|
if (file->f_op->mmap_capabilities) { |
|
capabilities = file->f_op->mmap_capabilities(file); |
|
} else { |
|
/* no explicit capabilities set, so assume some |
|
* defaults */ |
|
switch (file_inode(file)->i_mode & S_IFMT) { |
|
case S_IFREG: |
|
case S_IFBLK: |
|
capabilities = NOMMU_MAP_COPY; |
|
break; |
|
|
|
case S_IFCHR: |
|
capabilities = |
|
NOMMU_MAP_DIRECT | |
|
NOMMU_MAP_READ | |
|
NOMMU_MAP_WRITE; |
|
break; |
|
|
|
default: |
|
return -EINVAL; |
|
} |
|
} |
|
|
|
/* eliminate any capabilities that we can't support on this |
|
* device */ |
|
if (!file->f_op->get_unmapped_area) |
|
capabilities &= ~NOMMU_MAP_DIRECT; |
|
if (!(file->f_mode & FMODE_CAN_READ)) |
|
capabilities &= ~NOMMU_MAP_COPY; |
|
|
|
/* The file shall have been opened with read permission. */ |
|
if (!(file->f_mode & FMODE_READ)) |
|
return -EACCES; |
|
|
|
if (flags & MAP_SHARED) { |
|
/* do checks for writing, appending and locking */ |
|
if ((prot & PROT_WRITE) && |
|
!(file->f_mode & FMODE_WRITE)) |
|
return -EACCES; |
|
|
|
if (IS_APPEND(file_inode(file)) && |
|
(file->f_mode & FMODE_WRITE)) |
|
return -EACCES; |
|
|
|
if (locks_verify_locked(file)) |
|
return -EAGAIN; |
|
|
|
if (!(capabilities & NOMMU_MAP_DIRECT)) |
|
return -ENODEV; |
|
|
|
/* we mustn't privatise shared mappings */ |
|
capabilities &= ~NOMMU_MAP_COPY; |
|
} else { |
|
/* we're going to read the file into private memory we |
|
* allocate */ |
|
if (!(capabilities & NOMMU_MAP_COPY)) |
|
return -ENODEV; |
|
|
|
/* we don't permit a private writable mapping to be |
|
* shared with the backing device */ |
|
if (prot & PROT_WRITE) |
|
capabilities &= ~NOMMU_MAP_DIRECT; |
|
} |
|
|
|
if (capabilities & NOMMU_MAP_DIRECT) { |
|
if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) || |
|
((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) || |
|
((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC)) |
|
) { |
|
capabilities &= ~NOMMU_MAP_DIRECT; |
|
if (flags & MAP_SHARED) { |
|
pr_warn("MAP_SHARED not completely supported on !MMU\n"); |
|
return -EINVAL; |
|
} |
|
} |
|
} |
|
|
|
/* handle executable mappings and implied executable |
|
* mappings */ |
|
if (path_noexec(&file->f_path)) { |
|
if (prot & PROT_EXEC) |
|
return -EPERM; |
|
} else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { |
|
/* handle implication of PROT_EXEC by PROT_READ */ |
|
if (current->personality & READ_IMPLIES_EXEC) { |
|
if (capabilities & NOMMU_MAP_EXEC) |
|
prot |= PROT_EXEC; |
|
} |
|
} else if ((prot & PROT_READ) && |
|
(prot & PROT_EXEC) && |
|
!(capabilities & NOMMU_MAP_EXEC) |
|
) { |
|
/* backing file is not executable, try to copy */ |
|
capabilities &= ~NOMMU_MAP_DIRECT; |
|
} |
|
} else { |
|
/* anonymous mappings are always memory backed and can be |
|
* privately mapped |
|
*/ |
|
capabilities = NOMMU_MAP_COPY; |
|
|
|
/* handle PROT_EXEC implication by PROT_READ */ |
|
if ((prot & PROT_READ) && |
|
(current->personality & READ_IMPLIES_EXEC)) |
|
prot |= PROT_EXEC; |
|
} |
|
|
|
/* allow the security API to have its say */ |
|
ret = security_mmap_addr(addr); |
|
if (ret < 0) |
|
return ret; |
|
|
|
/* looks okay */ |
|
*_capabilities = capabilities; |
|
return 0; |
|
} |
|
|
|
/* |
|
* we've determined that we can make the mapping, now translate what we |
|
* now know into VMA flags |
|
*/ |
|
static unsigned long determine_vm_flags(struct file *file, |
|
unsigned long prot, |
|
unsigned long flags, |
|
unsigned long capabilities) |
|
{ |
|
unsigned long vm_flags; |
|
|
|
vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags); |
|
/* vm_flags |= mm->def_flags; */ |
|
|
|
if (!(capabilities & NOMMU_MAP_DIRECT)) { |
|
/* attempt to share read-only copies of mapped file chunks */ |
|
vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
|
if (file && !(prot & PROT_WRITE)) |
|
vm_flags |= VM_MAYSHARE; |
|
} else { |
|
/* overlay a shareable mapping on the backing device or inode |
|
* if possible - used for chardevs, ramfs/tmpfs/shmfs and |
|
* romfs/cramfs */ |
|
vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS); |
|
if (flags & MAP_SHARED) |
|
vm_flags |= VM_SHARED; |
|
} |
|
|
|
/* refuse to let anyone share private mappings with this process if |
|
* it's being traced - otherwise breakpoints set in it may interfere |
|
* with another untraced process |
|
*/ |
|
if ((flags & MAP_PRIVATE) && current->ptrace) |
|
vm_flags &= ~VM_MAYSHARE; |
|
|
|
return vm_flags; |
|
} |
|
|
|
/* |
|
* set up a shared mapping on a file (the driver or filesystem provides and |
|
* pins the storage) |
|
*/ |
|
static int do_mmap_shared_file(struct vm_area_struct *vma) |
|
{ |
|
int ret; |
|
|
|
ret = call_mmap(vma->vm_file, vma); |
|
if (ret == 0) { |
|
vma->vm_region->vm_top = vma->vm_region->vm_end; |
|
return 0; |
|
} |
|
if (ret != -ENOSYS) |
|
return ret; |
|
|
|
/* getting -ENOSYS indicates that direct mmap isn't possible (as |
|
* opposed to tried but failed) so we can only give a suitable error as |
|
* it's not possible to make a private copy if MAP_SHARED was given */ |
|
return -ENODEV; |
|
} |
|
|
|
/* |
|
* set up a private mapping or an anonymous shared mapping |
|
*/ |
|
static int do_mmap_private(struct vm_area_struct *vma, |
|
struct vm_region *region, |
|
unsigned long len, |
|
unsigned long capabilities) |
|
{ |
|
unsigned long total, point; |
|
void *base; |
|
int ret, order; |
|
|
|
/* invoke the file's mapping function so that it can keep track of |
|
* shared mappings on devices or memory |
|
* - VM_MAYSHARE will be set if it may attempt to share |
|
*/ |
|
if (capabilities & NOMMU_MAP_DIRECT) { |
|
ret = call_mmap(vma->vm_file, vma); |
|
if (ret == 0) { |
|
/* shouldn't return success if we're not sharing */ |
|
BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); |
|
vma->vm_region->vm_top = vma->vm_region->vm_end; |
|
return 0; |
|
} |
|
if (ret != -ENOSYS) |
|
return ret; |
|
|
|
/* getting an ENOSYS error indicates that direct mmap isn't |
|
* possible (as opposed to tried but failed) so we'll try to |
|
* make a private copy of the data and map that instead */ |
|
} |
|
|
|
|
|
/* allocate some memory to hold the mapping |
|
* - note that this may not return a page-aligned address if the object |
|
* we're allocating is smaller than a page |
|
*/ |
|
order = get_order(len); |
|
total = 1 << order; |
|
point = len >> PAGE_SHIFT; |
|
|
|
/* we don't want to allocate a power-of-2 sized page set */ |
|
if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) |
|
total = point; |
|
|
|
base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL); |
|
if (!base) |
|
goto enomem; |
|
|
|
atomic_long_add(total, &mmap_pages_allocated); |
|
|
|
region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; |
|
region->vm_start = (unsigned long) base; |
|
region->vm_end = region->vm_start + len; |
|
region->vm_top = region->vm_start + (total << PAGE_SHIFT); |
|
|
|
vma->vm_start = region->vm_start; |
|
vma->vm_end = region->vm_start + len; |
|
|
|
if (vma->vm_file) { |
|
/* read the contents of a file into the copy */ |
|
loff_t fpos; |
|
|
|
fpos = vma->vm_pgoff; |
|
fpos <<= PAGE_SHIFT; |
|
|
|
ret = kernel_read(vma->vm_file, base, len, &fpos); |
|
if (ret < 0) |
|
goto error_free; |
|
|
|
/* clear the last little bit */ |
|
if (ret < len) |
|
memset(base + ret, 0, len - ret); |
|
|
|
} else { |
|
vma_set_anonymous(vma); |
|
} |
|
|
|
return 0; |
|
|
|
error_free: |
|
free_page_series(region->vm_start, region->vm_top); |
|
region->vm_start = vma->vm_start = 0; |
|
region->vm_end = vma->vm_end = 0; |
|
region->vm_top = 0; |
|
return ret; |
|
|
|
enomem: |
|
pr_err("Allocation of length %lu from process %d (%s) failed\n", |
|
len, current->pid, current->comm); |
|
show_free_areas(0, NULL); |
|
return -ENOMEM; |
|
} |
|
|
|
/* |
|
* handle mapping creation for uClinux |
|
*/ |
|
unsigned long do_mmap(struct file *file, |
|
unsigned long addr, |
|
unsigned long len, |
|
unsigned long prot, |
|
unsigned long flags, |
|
unsigned long pgoff, |
|
unsigned long *populate, |
|
struct list_head *uf) |
|
{ |
|
struct vm_area_struct *vma; |
|
struct vm_region *region; |
|
struct rb_node *rb; |
|
vm_flags_t vm_flags; |
|
unsigned long capabilities, result; |
|
int ret; |
|
|
|
*populate = 0; |
|
|
|
/* decide whether we should attempt the mapping, and if so what sort of |
|
* mapping */ |
|
ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, |
|
&capabilities); |
|
if (ret < 0) |
|
return ret; |
|
|
|
/* we ignore the address hint */ |
|
addr = 0; |
|
len = PAGE_ALIGN(len); |
|
|
|
/* we've determined that we can make the mapping, now translate what we |
|
* now know into VMA flags */ |
|
vm_flags = determine_vm_flags(file, prot, flags, capabilities); |
|
|
|
/* we're going to need to record the mapping */ |
|
region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); |
|
if (!region) |
|
goto error_getting_region; |
|
|
|
vma = vm_area_alloc(current->mm); |
|
if (!vma) |
|
goto error_getting_vma; |
|
|
|
region->vm_usage = 1; |
|
region->vm_flags = vm_flags; |
|
region->vm_pgoff = pgoff; |
|
|
|
vma->vm_flags = vm_flags; |
|
vma->vm_pgoff = pgoff; |
|
|
|
if (file) { |
|
region->vm_file = get_file(file); |
|
vma->vm_file = get_file(file); |
|
} |
|
|
|
down_write(&nommu_region_sem); |
|
|
|
/* if we want to share, we need to check for regions created by other |
|
* mmap() calls that overlap with our proposed mapping |
|
* - we can only share with a superset match on most regular files |
|
* - shared mappings on character devices and memory backed files are |
|
* permitted to overlap inexactly as far as we are concerned for in |
|
* these cases, sharing is handled in the driver or filesystem rather |
|
* than here |
|
*/ |
|
if (vm_flags & VM_MAYSHARE) { |
|
struct vm_region *pregion; |
|
unsigned long pglen, rpglen, pgend, rpgend, start; |
|
|
|
pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
|
pgend = pgoff + pglen; |
|
|
|
for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { |
|
pregion = rb_entry(rb, struct vm_region, vm_rb); |
|
|
|
if (!(pregion->vm_flags & VM_MAYSHARE)) |
|
continue; |
|
|
|
/* search for overlapping mappings on the same file */ |
|
if (file_inode(pregion->vm_file) != |
|
file_inode(file)) |
|
continue; |
|
|
|
if (pregion->vm_pgoff >= pgend) |
|
continue; |
|
|
|
rpglen = pregion->vm_end - pregion->vm_start; |
|
rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
|
rpgend = pregion->vm_pgoff + rpglen; |
|
if (pgoff >= rpgend) |
|
continue; |
|
|
|
/* handle inexactly overlapping matches between |
|
* mappings */ |
|
if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && |
|
!(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { |
|
/* new mapping is not a subset of the region */ |
|
if (!(capabilities & NOMMU_MAP_DIRECT)) |
|
goto sharing_violation; |
|
continue; |
|
} |
|
|
|
/* we've found a region we can share */ |
|
pregion->vm_usage++; |
|
vma->vm_region = pregion; |
|
start = pregion->vm_start; |
|
start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; |
|
vma->vm_start = start; |
|
vma->vm_end = start + len; |
|
|
|
if (pregion->vm_flags & VM_MAPPED_COPY) |
|
vma->vm_flags |= VM_MAPPED_COPY; |
|
else { |
|
ret = do_mmap_shared_file(vma); |
|
if (ret < 0) { |
|
vma->vm_region = NULL; |
|
vma->vm_start = 0; |
|
vma->vm_end = 0; |
|
pregion->vm_usage--; |
|
pregion = NULL; |
|
goto error_just_free; |
|
} |
|
} |
|
fput(region->vm_file); |
|
kmem_cache_free(vm_region_jar, region); |
|
region = pregion; |
|
result = start; |
|
goto share; |
|
} |
|
|
|
/* obtain the address at which to make a shared mapping |
|
* - this is the hook for quasi-memory character devices to |
|
* tell us the location of a shared mapping |
|
*/ |
|
if (capabilities & NOMMU_MAP_DIRECT) { |
|
addr = file->f_op->get_unmapped_area(file, addr, len, |
|
pgoff, flags); |
|
if (IS_ERR_VALUE(addr)) { |
|
ret = addr; |
|
if (ret != -ENOSYS) |
|
goto error_just_free; |
|
|
|
/* the driver refused to tell us where to site |
|
* the mapping so we'll have to attempt to copy |
|
* it */ |
|
ret = -ENODEV; |
|
if (!(capabilities & NOMMU_MAP_COPY)) |
|
goto error_just_free; |
|
|
|
capabilities &= ~NOMMU_MAP_DIRECT; |
|
} else { |
|
vma->vm_start = region->vm_start = addr; |
|
vma->vm_end = region->vm_end = addr + len; |
|
} |
|
} |
|
} |
|
|
|
vma->vm_region = region; |
|
|
|
/* set up the mapping |
|
* - the region is filled in if NOMMU_MAP_DIRECT is still set |
|
*/ |
|
if (file && vma->vm_flags & VM_SHARED) |
|
ret = do_mmap_shared_file(vma); |
|
else |
|
ret = do_mmap_private(vma, region, len, capabilities); |
|
if (ret < 0) |
|
goto error_just_free; |
|
add_nommu_region(region); |
|
|
|
/* clear anonymous mappings that don't ask for uninitialized data */ |
|
if (!vma->vm_file && |
|
(!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) || |
|
!(flags & MAP_UNINITIALIZED))) |
|
memset((void *)region->vm_start, 0, |
|
region->vm_end - region->vm_start); |
|
|
|
/* okay... we have a mapping; now we have to register it */ |
|
result = vma->vm_start; |
|
|
|
current->mm->total_vm += len >> PAGE_SHIFT; |
|
|
|
share: |
|
add_vma_to_mm(current->mm, vma); |
|
|
|
/* we flush the region from the icache only when the first executable |
|
* mapping of it is made */ |
|
if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { |
|
flush_icache_user_range(region->vm_start, region->vm_end); |
|
region->vm_icache_flushed = true; |
|
} |
|
|
|
up_write(&nommu_region_sem); |
|
|
|
return result; |
|
|
|
error_just_free: |
|
up_write(&nommu_region_sem); |
|
error: |
|
if (region->vm_file) |
|
fput(region->vm_file); |
|
kmem_cache_free(vm_region_jar, region); |
|
if (vma->vm_file) |
|
fput(vma->vm_file); |
|
vm_area_free(vma); |
|
return ret; |
|
|
|
sharing_violation: |
|
up_write(&nommu_region_sem); |
|
pr_warn("Attempt to share mismatched mappings\n"); |
|
ret = -EINVAL; |
|
goto error; |
|
|
|
error_getting_vma: |
|
kmem_cache_free(vm_region_jar, region); |
|
pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n", |
|
len, current->pid); |
|
show_free_areas(0, NULL); |
|
return -ENOMEM; |
|
|
|
error_getting_region: |
|
pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n", |
|
len, current->pid); |
|
show_free_areas(0, NULL); |
|
return -ENOMEM; |
|
} |
|
|
|
unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, |
|
unsigned long prot, unsigned long flags, |
|
unsigned long fd, unsigned long pgoff) |
|
{ |
|
struct file *file = NULL; |
|
unsigned long retval = -EBADF; |
|
|
|
audit_mmap_fd(fd, flags); |
|
if (!(flags & MAP_ANONYMOUS)) { |
|
file = fget(fd); |
|
if (!file) |
|
goto out; |
|
} |
|
|
|
flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
|
|
|
retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
|
|
|
if (file) |
|
fput(file); |
|
out: |
|
return retval; |
|
} |
|
|
|
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
|
unsigned long, prot, unsigned long, flags, |
|
unsigned long, fd, unsigned long, pgoff) |
|
{ |
|
return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); |
|
} |
|
|
|
#ifdef __ARCH_WANT_SYS_OLD_MMAP |
|
struct mmap_arg_struct { |
|
unsigned long addr; |
|
unsigned long len; |
|
unsigned long prot; |
|
unsigned long flags; |
|
unsigned long fd; |
|
unsigned long offset; |
|
}; |
|
|
|
SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
|
{ |
|
struct mmap_arg_struct a; |
|
|
|
if (copy_from_user(&a, arg, sizeof(a))) |
|
return -EFAULT; |
|
if (offset_in_page(a.offset)) |
|
return -EINVAL; |
|
|
|
return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
|
a.offset >> PAGE_SHIFT); |
|
} |
|
#endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
|
|
|
/* |
|
* split a vma into two pieces at address 'addr', a new vma is allocated either |
|
* for the first part or the tail. |
|
*/ |
|
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, |
|
unsigned long addr, int new_below) |
|
{ |
|
struct vm_area_struct *new; |
|
struct vm_region *region; |
|
unsigned long npages; |
|
|
|
/* we're only permitted to split anonymous regions (these should have |
|
* only a single usage on the region) */ |
|
if (vma->vm_file) |
|
return -ENOMEM; |
|
|
|
if (mm->map_count >= sysctl_max_map_count) |
|
return -ENOMEM; |
|
|
|
region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); |
|
if (!region) |
|
return -ENOMEM; |
|
|
|
new = vm_area_dup(vma); |
|
if (!new) { |
|
kmem_cache_free(vm_region_jar, region); |
|
return -ENOMEM; |
|
} |
|
|
|
/* most fields are the same, copy all, and then fixup */ |
|
*region = *vma->vm_region; |
|
new->vm_region = region; |
|
|
|
npages = (addr - vma->vm_start) >> PAGE_SHIFT; |
|
|
|
if (new_below) { |
|
region->vm_top = region->vm_end = new->vm_end = addr; |
|
} else { |
|
region->vm_start = new->vm_start = addr; |
|
region->vm_pgoff = new->vm_pgoff += npages; |
|
} |
|
|
|
if (new->vm_ops && new->vm_ops->open) |
|
new->vm_ops->open(new); |
|
|
|
delete_vma_from_mm(vma); |
|
down_write(&nommu_region_sem); |
|
delete_nommu_region(vma->vm_region); |
|
if (new_below) { |
|
vma->vm_region->vm_start = vma->vm_start = addr; |
|
vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; |
|
} else { |
|
vma->vm_region->vm_end = vma->vm_end = addr; |
|
vma->vm_region->vm_top = addr; |
|
} |
|
add_nommu_region(vma->vm_region); |
|
add_nommu_region(new->vm_region); |
|
up_write(&nommu_region_sem); |
|
add_vma_to_mm(mm, vma); |
|
add_vma_to_mm(mm, new); |
|
return 0; |
|
} |
|
|
|
/* |
|
* shrink a VMA by removing the specified chunk from either the beginning or |
|
* the end |
|
*/ |
|
static int shrink_vma(struct mm_struct *mm, |
|
struct vm_area_struct *vma, |
|
unsigned long from, unsigned long to) |
|
{ |
|
struct vm_region *region; |
|
|
|
/* adjust the VMA's pointers, which may reposition it in the MM's tree |
|
* and list */ |
|
delete_vma_from_mm(vma); |
|
if (from > vma->vm_start) |
|
vma->vm_end = from; |
|
else |
|
vma->vm_start = to; |
|
add_vma_to_mm(mm, vma); |
|
|
|
/* cut the backing region down to size */ |
|
region = vma->vm_region; |
|
BUG_ON(region->vm_usage != 1); |
|
|
|
down_write(&nommu_region_sem); |
|
delete_nommu_region(region); |
|
if (from > region->vm_start) { |
|
to = region->vm_top; |
|
region->vm_top = region->vm_end = from; |
|
} else { |
|
region->vm_start = to; |
|
} |
|
add_nommu_region(region); |
|
up_write(&nommu_region_sem); |
|
|
|
free_page_series(from, to); |
|
return 0; |
|
} |
|
|
|
/* |
|
* release a mapping |
|
* - under NOMMU conditions the chunk to be unmapped must be backed by a single |
|
* VMA, though it need not cover the whole VMA |
|
*/ |
|
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf) |
|
{ |
|
struct vm_area_struct *vma; |
|
unsigned long end; |
|
int ret; |
|
|
|
len = PAGE_ALIGN(len); |
|
if (len == 0) |
|
return -EINVAL; |
|
|
|
end = start + len; |
|
|
|
/* find the first potentially overlapping VMA */ |
|
vma = find_vma(mm, start); |
|
if (!vma) { |
|
static int limit; |
|
if (limit < 5) { |
|
pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n", |
|
current->pid, current->comm, |
|
start, start + len - 1); |
|
limit++; |
|
} |
|
return -EINVAL; |
|
} |
|
|
|
/* we're allowed to split an anonymous VMA but not a file-backed one */ |
|
if (vma->vm_file) { |
|
do { |
|
if (start > vma->vm_start) |
|
return -EINVAL; |
|
if (end == vma->vm_end) |
|
goto erase_whole_vma; |
|
vma = vma->vm_next; |
|
} while (vma); |
|
return -EINVAL; |
|
} else { |
|
/* the chunk must be a subset of the VMA found */ |
|
if (start == vma->vm_start && end == vma->vm_end) |
|
goto erase_whole_vma; |
|
if (start < vma->vm_start || end > vma->vm_end) |
|
return -EINVAL; |
|
if (offset_in_page(start)) |
|
return -EINVAL; |
|
if (end != vma->vm_end && offset_in_page(end)) |
|
return -EINVAL; |
|
if (start != vma->vm_start && end != vma->vm_end) { |
|
ret = split_vma(mm, vma, start, 1); |
|
if (ret < 0) |
|
return ret; |
|
} |
|
return shrink_vma(mm, vma, start, end); |
|
} |
|
|
|
erase_whole_vma: |
|
delete_vma_from_mm(vma); |
|
delete_vma(mm, vma); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(do_munmap); |
|
|
|
int vm_munmap(unsigned long addr, size_t len) |
|
{ |
|
struct mm_struct *mm = current->mm; |
|
int ret; |
|
|
|
mmap_write_lock(mm); |
|
ret = do_munmap(mm, addr, len, NULL); |
|
mmap_write_unlock(mm); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(vm_munmap); |
|
|
|
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
|
{ |
|
return vm_munmap(addr, len); |
|
} |
|
|
|
/* |
|
* release all the mappings made in a process's VM space |
|
*/ |
|
void exit_mmap(struct mm_struct *mm) |
|
{ |
|
struct vm_area_struct *vma; |
|
|
|
if (!mm) |
|
return; |
|
|
|
mm->total_vm = 0; |
|
|
|
while ((vma = mm->mmap)) { |
|
mm->mmap = vma->vm_next; |
|
delete_vma_from_mm(vma); |
|
delete_vma(mm, vma); |
|
cond_resched(); |
|
} |
|
} |
|
|
|
int vm_brk(unsigned long addr, unsigned long len) |
|
{ |
|
return -ENOMEM; |
|
} |
|
|
|
/* |
|
* expand (or shrink) an existing mapping, potentially moving it at the same |
|
* time (controlled by the MREMAP_MAYMOVE flag and available VM space) |
|
* |
|
* under NOMMU conditions, we only permit changing a mapping's size, and only |
|
* as long as it stays within the region allocated by do_mmap_private() and the |
|
* block is not shareable |
|
* |
|
* MREMAP_FIXED is not supported under NOMMU conditions |
|
*/ |
|
static unsigned long do_mremap(unsigned long addr, |
|
unsigned long old_len, unsigned long new_len, |
|
unsigned long flags, unsigned long new_addr) |
|
{ |
|
struct vm_area_struct *vma; |
|
|
|
/* insanity checks first */ |
|
old_len = PAGE_ALIGN(old_len); |
|
new_len = PAGE_ALIGN(new_len); |
|
if (old_len == 0 || new_len == 0) |
|
return (unsigned long) -EINVAL; |
|
|
|
if (offset_in_page(addr)) |
|
return -EINVAL; |
|
|
|
if (flags & MREMAP_FIXED && new_addr != addr) |
|
return (unsigned long) -EINVAL; |
|
|
|
vma = find_vma_exact(current->mm, addr, old_len); |
|
if (!vma) |
|
return (unsigned long) -EINVAL; |
|
|
|
if (vma->vm_end != vma->vm_start + old_len) |
|
return (unsigned long) -EFAULT; |
|
|
|
if (vma->vm_flags & VM_MAYSHARE) |
|
return (unsigned long) -EPERM; |
|
|
|
if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) |
|
return (unsigned long) -ENOMEM; |
|
|
|
/* all checks complete - do it */ |
|
vma->vm_end = vma->vm_start + new_len; |
|
return vma->vm_start; |
|
} |
|
|
|
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
|
unsigned long, new_len, unsigned long, flags, |
|
unsigned long, new_addr) |
|
{ |
|
unsigned long ret; |
|
|
|
mmap_write_lock(current->mm); |
|
ret = do_mremap(addr, old_len, new_len, flags, new_addr); |
|
mmap_write_unlock(current->mm); |
|
return ret; |
|
} |
|
|
|
struct page *follow_page(struct vm_area_struct *vma, unsigned long address, |
|
unsigned int foll_flags) |
|
{ |
|
return NULL; |
|
} |
|
|
|
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
|
unsigned long pfn, unsigned long size, pgprot_t prot) |
|
{ |
|
if (addr != (pfn << PAGE_SHIFT)) |
|
return -EINVAL; |
|
|
|
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(remap_pfn_range); |
|
|
|
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
|
{ |
|
unsigned long pfn = start >> PAGE_SHIFT; |
|
unsigned long vm_len = vma->vm_end - vma->vm_start; |
|
|
|
pfn += vma->vm_pgoff; |
|
return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
|
} |
|
EXPORT_SYMBOL(vm_iomap_memory); |
|
|
|
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, |
|
unsigned long pgoff) |
|
{ |
|
unsigned int size = vma->vm_end - vma->vm_start; |
|
|
|
if (!(vma->vm_flags & VM_USERMAP)) |
|
return -EINVAL; |
|
|
|
vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); |
|
vma->vm_end = vma->vm_start + size; |
|
|
|
return 0; |
|
} |
|
EXPORT_SYMBOL(remap_vmalloc_range); |
|
|
|
unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, |
|
unsigned long len, unsigned long pgoff, unsigned long flags) |
|
{ |
|
return -ENOMEM; |
|
} |
|
|
|
vm_fault_t filemap_fault(struct vm_fault *vmf) |
|
{ |
|
BUG(); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(filemap_fault); |
|
|
|
vm_fault_t filemap_map_pages(struct vm_fault *vmf, |
|
pgoff_t start_pgoff, pgoff_t end_pgoff) |
|
{ |
|
BUG(); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(filemap_map_pages); |
|
|
|
int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, |
|
int len, unsigned int gup_flags) |
|
{ |
|
struct vm_area_struct *vma; |
|
int write = gup_flags & FOLL_WRITE; |
|
|
|
if (mmap_read_lock_killable(mm)) |
|
return 0; |
|
|
|
/* the access must start within one of the target process's mappings */ |
|
vma = find_vma(mm, addr); |
|
if (vma) { |
|
/* don't overrun this mapping */ |
|
if (addr + len >= vma->vm_end) |
|
len = vma->vm_end - addr; |
|
|
|
/* only read or write mappings where it is permitted */ |
|
if (write && vma->vm_flags & VM_MAYWRITE) |
|
copy_to_user_page(vma, NULL, addr, |
|
(void *) addr, buf, len); |
|
else if (!write && vma->vm_flags & VM_MAYREAD) |
|
copy_from_user_page(vma, NULL, addr, |
|
buf, (void *) addr, len); |
|
else |
|
len = 0; |
|
} else { |
|
len = 0; |
|
} |
|
|
|
mmap_read_unlock(mm); |
|
|
|
return len; |
|
} |
|
|
|
/** |
|
* access_remote_vm - access another process' address space |
|
* @mm: the mm_struct of the target address space |
|
* @addr: start address to access |
|
* @buf: source or destination buffer |
|
* @len: number of bytes to transfer |
|
* @gup_flags: flags modifying lookup behaviour |
|
* |
|
* The caller must hold a reference on @mm. |
|
*/ |
|
int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
|
void *buf, int len, unsigned int gup_flags) |
|
{ |
|
return __access_remote_vm(mm, addr, buf, len, gup_flags); |
|
} |
|
|
|
/* |
|
* Access another process' address space. |
|
* - source/target buffer must be kernel space |
|
*/ |
|
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, |
|
unsigned int gup_flags) |
|
{ |
|
struct mm_struct *mm; |
|
|
|
if (addr + len < addr) |
|
return 0; |
|
|
|
mm = get_task_mm(tsk); |
|
if (!mm) |
|
return 0; |
|
|
|
len = __access_remote_vm(mm, addr, buf, len, gup_flags); |
|
|
|
mmput(mm); |
|
return len; |
|
} |
|
EXPORT_SYMBOL_GPL(access_process_vm); |
|
|
|
/** |
|
* nommu_shrink_inode_mappings - Shrink the shared mappings on an inode |
|
* @inode: The inode to check |
|
* @size: The current filesize of the inode |
|
* @newsize: The proposed filesize of the inode |
|
* |
|
* Check the shared mappings on an inode on behalf of a shrinking truncate to |
|
* make sure that any outstanding VMAs aren't broken and then shrink the |
|
* vm_regions that extend beyond so that do_mmap() doesn't |
|
* automatically grant mappings that are too large. |
|
*/ |
|
int nommu_shrink_inode_mappings(struct inode *inode, size_t size, |
|
size_t newsize) |
|
{ |
|
struct vm_area_struct *vma; |
|
struct vm_region *region; |
|
pgoff_t low, high; |
|
size_t r_size, r_top; |
|
|
|
low = newsize >> PAGE_SHIFT; |
|
high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
|
|
|
down_write(&nommu_region_sem); |
|
i_mmap_lock_read(inode->i_mapping); |
|
|
|
/* search for VMAs that fall within the dead zone */ |
|
vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { |
|
/* found one - only interested if it's shared out of the page |
|
* cache */ |
|
if (vma->vm_flags & VM_SHARED) { |
|
i_mmap_unlock_read(inode->i_mapping); |
|
up_write(&nommu_region_sem); |
|
return -ETXTBSY; /* not quite true, but near enough */ |
|
} |
|
} |
|
|
|
/* reduce any regions that overlap the dead zone - if in existence, |
|
* these will be pointed to by VMAs that don't overlap the dead zone |
|
* |
|
* we don't check for any regions that start beyond the EOF as there |
|
* shouldn't be any |
|
*/ |
|
vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) { |
|
if (!(vma->vm_flags & VM_SHARED)) |
|
continue; |
|
|
|
region = vma->vm_region; |
|
r_size = region->vm_top - region->vm_start; |
|
r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; |
|
|
|
if (r_top > newsize) { |
|
region->vm_top -= r_top - newsize; |
|
if (region->vm_end > region->vm_top) |
|
region->vm_end = region->vm_top; |
|
} |
|
} |
|
|
|
i_mmap_unlock_read(inode->i_mapping); |
|
up_write(&nommu_region_sem); |
|
return 0; |
|
} |
|
|
|
/* |
|
* Initialise sysctl_user_reserve_kbytes. |
|
* |
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* This is intended to prevent a user from starting a single memory hogging |
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* process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
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* mode. |
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* |
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* The default value is min(3% of free memory, 128MB) |
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* 128MB is enough to recover with sshd/login, bash, and top/kill. |
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*/ |
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static int __meminit init_user_reserve(void) |
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{ |
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unsigned long free_kbytes; |
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free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
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sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
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return 0; |
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} |
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subsys_initcall(init_user_reserve); |
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|
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/* |
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* Initialise sysctl_admin_reserve_kbytes. |
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* |
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* The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
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* to log in and kill a memory hogging process. |
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* |
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* Systems with more than 256MB will reserve 8MB, enough to recover |
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* with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
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* only reserve 3% of free pages by default. |
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*/ |
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static int __meminit init_admin_reserve(void) |
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{ |
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unsigned long free_kbytes; |
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free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
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sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
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return 0; |
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} |
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subsys_initcall(init_admin_reserve);
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