mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-29 23:53:32 +00:00
ee65728e10
so it will be consistent with code mm directory and with Documentation/admin-guide/mm and won't be confused with virtual machines. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Tested-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Acked-by: Wu XiangCheng <bobwxc@email.cn>
1219 lines
30 KiB
C
1219 lines
30 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/compiler.h>
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#include <linux/export.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task_stack.h>
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#include <linux/security.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/mman.h>
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#include <linux/hugetlb.h>
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#include <linux/vmalloc.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/elf.h>
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#include <linux/elf-randomize.h>
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#include <linux/personality.h>
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#include <linux/random.h>
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#include <linux/processor.h>
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#include <linux/sizes.h>
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#include <linux/compat.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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#include "swap.h"
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/**
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* kfree_const - conditionally free memory
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* @x: pointer to the memory
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*
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* Function calls kfree only if @x is not in .rodata section.
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*/
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void kfree_const(const void *x)
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{
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if (!is_kernel_rodata((unsigned long)x))
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kfree(x);
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}
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EXPORT_SYMBOL(kfree_const);
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/**
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* kstrdup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrdup(const char *s, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strlen(s) + 1;
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buf = kmalloc_track_caller(len, gfp);
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if (buf)
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memcpy(buf, s, len);
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return buf;
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}
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EXPORT_SYMBOL(kstrdup);
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/**
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* kstrdup_const - conditionally duplicate an existing const string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Strings allocated by kstrdup_const should be freed by kfree_const and
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* must not be passed to krealloc().
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*
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* Return: source string if it is in .rodata section otherwise
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* fallback to kstrdup.
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*/
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const char *kstrdup_const(const char *s, gfp_t gfp)
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{
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if (is_kernel_rodata((unsigned long)s))
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return s;
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return kstrdup(s, gfp);
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}
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EXPORT_SYMBOL(kstrdup_const);
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/**
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* kstrndup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @max: read at most @max chars from @s
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Use kmemdup_nul() instead if the size is known exactly.
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrndup(const char *s, size_t max, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strnlen(s, max);
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buf = kmalloc_track_caller(len+1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kstrndup);
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/**
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* kmemdup - duplicate region of memory
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*
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* @src: memory region to duplicate
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* @len: memory region length
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* @gfp: GFP mask to use
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*
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* Return: newly allocated copy of @src or %NULL in case of error
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*/
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void *kmemdup(const void *src, size_t len, gfp_t gfp)
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{
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void *p;
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p = kmalloc_track_caller(len, gfp);
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if (p)
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memcpy(p, src, len);
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return p;
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}
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EXPORT_SYMBOL(kmemdup);
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/**
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* kmemdup_nul - Create a NUL-terminated string from unterminated data
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* @s: The data to stringify
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* @len: The size of the data
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s with NUL-termination or %NULL in
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* case of error
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*/
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char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
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{
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char *buf;
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if (!s)
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return NULL;
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buf = kmalloc_track_caller(len + 1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kmemdup_nul);
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/**
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* memdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result is physically
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* contiguous, to be freed by kfree().
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*/
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void *memdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(memdup_user);
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/**
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* vmemdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result may be not
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* physically contiguous. Use kvfree() to free.
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*/
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void *vmemdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kvmalloc(len, GFP_USER);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kvfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(vmemdup_user);
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/**
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* strndup_user - duplicate an existing string from user space
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* @s: The string to duplicate
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* @n: Maximum number of bytes to copy, including the trailing NUL.
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*
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* Return: newly allocated copy of @s or an ERR_PTR() in case of error
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*/
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char *strndup_user(const char __user *s, long n)
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{
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char *p;
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long length;
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length = strnlen_user(s, n);
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if (!length)
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return ERR_PTR(-EFAULT);
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if (length > n)
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return ERR_PTR(-EINVAL);
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p = memdup_user(s, length);
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if (IS_ERR(p))
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return p;
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p[length - 1] = '\0';
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return p;
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}
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EXPORT_SYMBOL(strndup_user);
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/**
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* memdup_user_nul - duplicate memory region from user space and NUL-terminate
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure.
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*/
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void *memdup_user_nul(const void __user *src, size_t len)
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{
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char *p;
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/*
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* Always use GFP_KERNEL, since copy_from_user() can sleep and
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* cause pagefault, which makes it pointless to use GFP_NOFS
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* or GFP_ATOMIC.
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*/
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p = kmalloc_track_caller(len + 1, GFP_KERNEL);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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p[len] = '\0';
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return p;
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}
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EXPORT_SYMBOL(memdup_user_nul);
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void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev)
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{
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struct vm_area_struct *next;
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vma->vm_prev = prev;
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if (prev) {
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next = prev->vm_next;
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prev->vm_next = vma;
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} else {
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next = mm->mmap;
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mm->mmap = vma;
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}
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vma->vm_next = next;
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if (next)
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next->vm_prev = vma;
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}
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void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma)
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{
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struct vm_area_struct *prev, *next;
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next = vma->vm_next;
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prev = vma->vm_prev;
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if (prev)
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prev->vm_next = next;
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else
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mm->mmap = next;
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if (next)
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next->vm_prev = prev;
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}
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/* Check if the vma is being used as a stack by this task */
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int vma_is_stack_for_current(struct vm_area_struct *vma)
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{
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struct task_struct * __maybe_unused t = current;
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return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
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}
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/*
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* Change backing file, only valid to use during initial VMA setup.
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*/
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void vma_set_file(struct vm_area_struct *vma, struct file *file)
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{
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/* Changing an anonymous vma with this is illegal */
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get_file(file);
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swap(vma->vm_file, file);
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fput(file);
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}
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EXPORT_SYMBOL(vma_set_file);
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#ifndef STACK_RND_MASK
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#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
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#endif
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unsigned long randomize_stack_top(unsigned long stack_top)
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{
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unsigned long random_variable = 0;
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if (current->flags & PF_RANDOMIZE) {
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random_variable = get_random_long();
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random_variable &= STACK_RND_MASK;
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random_variable <<= PAGE_SHIFT;
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}
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#ifdef CONFIG_STACK_GROWSUP
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return PAGE_ALIGN(stack_top) + random_variable;
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#else
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return PAGE_ALIGN(stack_top) - random_variable;
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#endif
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}
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/**
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* randomize_page - Generate a random, page aligned address
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* @start: The smallest acceptable address the caller will take.
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* @range: The size of the area, starting at @start, within which the
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* random address must fall.
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*
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* If @start + @range would overflow, @range is capped.
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*
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* NOTE: Historical use of randomize_range, which this replaces, presumed that
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* @start was already page aligned. We now align it regardless.
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*
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* Return: A page aligned address within [start, start + range). On error,
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* @start is returned.
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*/
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unsigned long randomize_page(unsigned long start, unsigned long range)
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{
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if (!PAGE_ALIGNED(start)) {
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range -= PAGE_ALIGN(start) - start;
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start = PAGE_ALIGN(start);
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}
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if (start > ULONG_MAX - range)
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range = ULONG_MAX - start;
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range >>= PAGE_SHIFT;
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if (range == 0)
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return start;
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return start + (get_random_long() % range << PAGE_SHIFT);
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}
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#ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
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unsigned long __weak arch_randomize_brk(struct mm_struct *mm)
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{
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/* Is the current task 32bit ? */
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if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
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return randomize_page(mm->brk, SZ_32M);
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return randomize_page(mm->brk, SZ_1G);
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}
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unsigned long arch_mmap_rnd(void)
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{
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unsigned long rnd;
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
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if (is_compat_task())
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rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
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else
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#endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */
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rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
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return rnd << PAGE_SHIFT;
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}
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static int mmap_is_legacy(struct rlimit *rlim_stack)
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{
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if (current->personality & ADDR_COMPAT_LAYOUT)
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return 1;
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if (rlim_stack->rlim_cur == RLIM_INFINITY)
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return 1;
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return sysctl_legacy_va_layout;
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}
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/*
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* Leave enough space between the mmap area and the stack to honour ulimit in
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* the face of randomisation.
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*/
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#define MIN_GAP (SZ_128M)
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#define MAX_GAP (STACK_TOP / 6 * 5)
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static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
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{
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unsigned long gap = rlim_stack->rlim_cur;
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unsigned long pad = stack_guard_gap;
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/* Account for stack randomization if necessary */
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if (current->flags & PF_RANDOMIZE)
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pad += (STACK_RND_MASK << PAGE_SHIFT);
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/* Values close to RLIM_INFINITY can overflow. */
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if (gap + pad > gap)
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gap += pad;
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if (gap < MIN_GAP)
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gap = MIN_GAP;
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else if (gap > MAX_GAP)
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gap = MAX_GAP;
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return PAGE_ALIGN(STACK_TOP - gap - rnd);
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}
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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unsigned long random_factor = 0UL;
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if (current->flags & PF_RANDOMIZE)
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random_factor = arch_mmap_rnd();
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if (mmap_is_legacy(rlim_stack)) {
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mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
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mm->get_unmapped_area = arch_get_unmapped_area;
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} else {
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mm->mmap_base = mmap_base(random_factor, rlim_stack);
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mm->get_unmapped_area = arch_get_unmapped_area_topdown;
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}
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}
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#elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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mm->mmap_base = TASK_UNMAPPED_BASE;
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mm->get_unmapped_area = arch_get_unmapped_area;
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}
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#endif
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/**
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* __account_locked_vm - account locked pages to an mm's locked_vm
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* @mm: mm to account against
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* @pages: number of pages to account
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* @inc: %true if @pages should be considered positive, %false if not
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* @task: task used to check RLIMIT_MEMLOCK
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* @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
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*
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* Assumes @task and @mm are valid (i.e. at least one reference on each), and
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* that mmap_lock is held as writer.
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*
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* Return:
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* * 0 on success
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* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
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*/
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int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
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struct task_struct *task, bool bypass_rlim)
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{
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unsigned long locked_vm, limit;
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int ret = 0;
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mmap_assert_write_locked(mm);
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locked_vm = mm->locked_vm;
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if (inc) {
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if (!bypass_rlim) {
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limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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if (locked_vm + pages > limit)
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ret = -ENOMEM;
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}
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if (!ret)
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mm->locked_vm = locked_vm + pages;
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} else {
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WARN_ON_ONCE(pages > locked_vm);
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mm->locked_vm = locked_vm - pages;
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}
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pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
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(void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
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locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
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ret ? " - exceeded" : "");
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return ret;
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}
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EXPORT_SYMBOL_GPL(__account_locked_vm);
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/**
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* account_locked_vm - account locked pages to an mm's locked_vm
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* @mm: mm to account against, may be NULL
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* @pages: number of pages to account
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* @inc: %true if @pages should be considered positive, %false if not
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*
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* Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
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*
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* Return:
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* * 0 on success, or if mm is NULL
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* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
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*/
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int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
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{
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int ret;
|
|
|
|
if (pages == 0 || !mm)
|
|
return 0;
|
|
|
|
mmap_write_lock(mm);
|
|
ret = __account_locked_vm(mm, pages, inc, current,
|
|
capable(CAP_IPC_LOCK));
|
|
mmap_write_unlock(mm);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(account_locked_vm);
|
|
|
|
unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flag, unsigned long pgoff)
|
|
{
|
|
unsigned long ret;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long populate;
|
|
LIST_HEAD(uf);
|
|
|
|
ret = security_mmap_file(file, prot, flag);
|
|
if (!ret) {
|
|
if (mmap_write_lock_killable(mm))
|
|
return -EINTR;
|
|
ret = do_mmap(file, addr, len, prot, flag, pgoff, &populate,
|
|
&uf);
|
|
mmap_write_unlock(mm);
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
if (populate)
|
|
mm_populate(ret, populate);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
unsigned long vm_mmap(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flag, unsigned long offset)
|
|
{
|
|
if (unlikely(offset + PAGE_ALIGN(len) < offset))
|
|
return -EINVAL;
|
|
if (unlikely(offset_in_page(offset)))
|
|
return -EINVAL;
|
|
|
|
return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
|
|
}
|
|
EXPORT_SYMBOL(vm_mmap);
|
|
|
|
/**
|
|
* kvmalloc_node - attempt to allocate physically contiguous memory, but upon
|
|
* failure, fall back to non-contiguous (vmalloc) allocation.
|
|
* @size: size of the request.
|
|
* @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
|
|
* @node: numa node to allocate from
|
|
*
|
|
* Uses kmalloc to get the memory but if the allocation fails then falls back
|
|
* to the vmalloc allocator. Use kvfree for freeing the memory.
|
|
*
|
|
* GFP_NOWAIT and GFP_ATOMIC are not supported, neither is the __GFP_NORETRY modifier.
|
|
* __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
|
|
* preferable to the vmalloc fallback, due to visible performance drawbacks.
|
|
*
|
|
* Return: pointer to the allocated memory of %NULL in case of failure
|
|
*/
|
|
void *kvmalloc_node(size_t size, gfp_t flags, int node)
|
|
{
|
|
gfp_t kmalloc_flags = flags;
|
|
void *ret;
|
|
|
|
/*
|
|
* We want to attempt a large physically contiguous block first because
|
|
* it is less likely to fragment multiple larger blocks and therefore
|
|
* contribute to a long term fragmentation less than vmalloc fallback.
|
|
* However make sure that larger requests are not too disruptive - no
|
|
* OOM killer and no allocation failure warnings as we have a fallback.
|
|
*/
|
|
if (size > PAGE_SIZE) {
|
|
kmalloc_flags |= __GFP_NOWARN;
|
|
|
|
if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
|
|
kmalloc_flags |= __GFP_NORETRY;
|
|
|
|
/* nofail semantic is implemented by the vmalloc fallback */
|
|
kmalloc_flags &= ~__GFP_NOFAIL;
|
|
}
|
|
|
|
ret = kmalloc_node(size, kmalloc_flags, node);
|
|
|
|
/*
|
|
* It doesn't really make sense to fallback to vmalloc for sub page
|
|
* requests
|
|
*/
|
|
if (ret || size <= PAGE_SIZE)
|
|
return ret;
|
|
|
|
/* Don't even allow crazy sizes */
|
|
if (unlikely(size > INT_MAX)) {
|
|
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* kvmalloc() can always use VM_ALLOW_HUGE_VMAP,
|
|
* since the callers already cannot assume anything
|
|
* about the resulting pointer, and cannot play
|
|
* protection games.
|
|
*/
|
|
return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
|
|
flags, PAGE_KERNEL, VM_ALLOW_HUGE_VMAP,
|
|
node, __builtin_return_address(0));
|
|
}
|
|
EXPORT_SYMBOL(kvmalloc_node);
|
|
|
|
/**
|
|
* kvfree() - Free memory.
|
|
* @addr: Pointer to allocated memory.
|
|
*
|
|
* kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
|
|
* It is slightly more efficient to use kfree() or vfree() if you are certain
|
|
* that you know which one to use.
|
|
*
|
|
* Context: Either preemptible task context or not-NMI interrupt.
|
|
*/
|
|
void kvfree(const void *addr)
|
|
{
|
|
if (is_vmalloc_addr(addr))
|
|
vfree(addr);
|
|
else
|
|
kfree(addr);
|
|
}
|
|
EXPORT_SYMBOL(kvfree);
|
|
|
|
/**
|
|
* kvfree_sensitive - Free a data object containing sensitive information.
|
|
* @addr: address of the data object to be freed.
|
|
* @len: length of the data object.
|
|
*
|
|
* Use the special memzero_explicit() function to clear the content of a
|
|
* kvmalloc'ed object containing sensitive data to make sure that the
|
|
* compiler won't optimize out the data clearing.
|
|
*/
|
|
void kvfree_sensitive(const void *addr, size_t len)
|
|
{
|
|
if (likely(!ZERO_OR_NULL_PTR(addr))) {
|
|
memzero_explicit((void *)addr, len);
|
|
kvfree(addr);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(kvfree_sensitive);
|
|
|
|
void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
|
|
{
|
|
void *newp;
|
|
|
|
if (oldsize >= newsize)
|
|
return (void *)p;
|
|
newp = kvmalloc(newsize, flags);
|
|
if (!newp)
|
|
return NULL;
|
|
memcpy(newp, p, oldsize);
|
|
kvfree(p);
|
|
return newp;
|
|
}
|
|
EXPORT_SYMBOL(kvrealloc);
|
|
|
|
/**
|
|
* __vmalloc_array - allocate memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
* @flags: the type of memory to allocate (see kmalloc).
|
|
*/
|
|
void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
|
|
{
|
|
size_t bytes;
|
|
|
|
if (unlikely(check_mul_overflow(n, size, &bytes)))
|
|
return NULL;
|
|
return __vmalloc(bytes, flags);
|
|
}
|
|
EXPORT_SYMBOL(__vmalloc_array);
|
|
|
|
/**
|
|
* vmalloc_array - allocate memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
*/
|
|
void *vmalloc_array(size_t n, size_t size)
|
|
{
|
|
return __vmalloc_array(n, size, GFP_KERNEL);
|
|
}
|
|
EXPORT_SYMBOL(vmalloc_array);
|
|
|
|
/**
|
|
* __vcalloc - allocate and zero memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
* @flags: the type of memory to allocate (see kmalloc).
|
|
*/
|
|
void *__vcalloc(size_t n, size_t size, gfp_t flags)
|
|
{
|
|
return __vmalloc_array(n, size, flags | __GFP_ZERO);
|
|
}
|
|
EXPORT_SYMBOL(__vcalloc);
|
|
|
|
/**
|
|
* vcalloc - allocate and zero memory for a virtually contiguous array.
|
|
* @n: number of elements.
|
|
* @size: element size.
|
|
*/
|
|
void *vcalloc(size_t n, size_t size)
|
|
{
|
|
return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
|
|
}
|
|
EXPORT_SYMBOL(vcalloc);
|
|
|
|
/* Neutral page->mapping pointer to address_space or anon_vma or other */
|
|
void *page_rmapping(struct page *page)
|
|
{
|
|
return folio_raw_mapping(page_folio(page));
|
|
}
|
|
|
|
/**
|
|
* folio_mapped - Is this folio mapped into userspace?
|
|
* @folio: The folio.
|
|
*
|
|
* Return: True if any page in this folio is referenced by user page tables.
|
|
*/
|
|
bool folio_mapped(struct folio *folio)
|
|
{
|
|
long i, nr;
|
|
|
|
if (!folio_test_large(folio))
|
|
return atomic_read(&folio->_mapcount) >= 0;
|
|
if (atomic_read(folio_mapcount_ptr(folio)) >= 0)
|
|
return true;
|
|
if (folio_test_hugetlb(folio))
|
|
return false;
|
|
|
|
nr = folio_nr_pages(folio);
|
|
for (i = 0; i < nr; i++) {
|
|
if (atomic_read(&folio_page(folio, i)->_mapcount) >= 0)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL(folio_mapped);
|
|
|
|
struct anon_vma *folio_anon_vma(struct folio *folio)
|
|
{
|
|
unsigned long mapping = (unsigned long)folio->mapping;
|
|
|
|
if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
return NULL;
|
|
return (void *)(mapping - PAGE_MAPPING_ANON);
|
|
}
|
|
|
|
/**
|
|
* folio_mapping - Find the mapping where this folio is stored.
|
|
* @folio: The folio.
|
|
*
|
|
* For folios which are in the page cache, return the mapping that this
|
|
* page belongs to. Folios in the swap cache return the swap mapping
|
|
* this page is stored in (which is different from the mapping for the
|
|
* swap file or swap device where the data is stored).
|
|
*
|
|
* You can call this for folios which aren't in the swap cache or page
|
|
* cache and it will return NULL.
|
|
*/
|
|
struct address_space *folio_mapping(struct folio *folio)
|
|
{
|
|
struct address_space *mapping;
|
|
|
|
/* This happens if someone calls flush_dcache_page on slab page */
|
|
if (unlikely(folio_test_slab(folio)))
|
|
return NULL;
|
|
|
|
if (unlikely(folio_test_swapcache(folio)))
|
|
return swap_address_space(folio_swap_entry(folio));
|
|
|
|
mapping = folio->mapping;
|
|
if ((unsigned long)mapping & PAGE_MAPPING_ANON)
|
|
return NULL;
|
|
|
|
return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
|
|
}
|
|
EXPORT_SYMBOL(folio_mapping);
|
|
|
|
/* Slow path of page_mapcount() for compound pages */
|
|
int __page_mapcount(struct page *page)
|
|
{
|
|
int ret;
|
|
|
|
ret = atomic_read(&page->_mapcount) + 1;
|
|
/*
|
|
* For file THP page->_mapcount contains total number of mapping
|
|
* of the page: no need to look into compound_mapcount.
|
|
*/
|
|
if (!PageAnon(page) && !PageHuge(page))
|
|
return ret;
|
|
page = compound_head(page);
|
|
ret += atomic_read(compound_mapcount_ptr(page)) + 1;
|
|
if (PageDoubleMap(page))
|
|
ret--;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__page_mapcount);
|
|
|
|
/**
|
|
* folio_mapcount() - Calculate the number of mappings of this folio.
|
|
* @folio: The folio.
|
|
*
|
|
* A large folio tracks both how many times the entire folio is mapped,
|
|
* and how many times each individual page in the folio is mapped.
|
|
* This function calculates the total number of times the folio is
|
|
* mapped.
|
|
*
|
|
* Return: The number of times this folio is mapped.
|
|
*/
|
|
int folio_mapcount(struct folio *folio)
|
|
{
|
|
int i, compound, nr, ret;
|
|
|
|
if (likely(!folio_test_large(folio)))
|
|
return atomic_read(&folio->_mapcount) + 1;
|
|
|
|
compound = folio_entire_mapcount(folio);
|
|
nr = folio_nr_pages(folio);
|
|
if (folio_test_hugetlb(folio))
|
|
return compound;
|
|
ret = compound;
|
|
for (i = 0; i < nr; i++)
|
|
ret += atomic_read(&folio_page(folio, i)->_mapcount) + 1;
|
|
/* File pages has compound_mapcount included in _mapcount */
|
|
if (!folio_test_anon(folio))
|
|
return ret - compound * nr;
|
|
if (folio_test_double_map(folio))
|
|
ret -= nr;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* folio_copy - Copy the contents of one folio to another.
|
|
* @dst: Folio to copy to.
|
|
* @src: Folio to copy from.
|
|
*
|
|
* The bytes in the folio represented by @src are copied to @dst.
|
|
* Assumes the caller has validated that @dst is at least as large as @src.
|
|
* Can be called in atomic context for order-0 folios, but if the folio is
|
|
* larger, it may sleep.
|
|
*/
|
|
void folio_copy(struct folio *dst, struct folio *src)
|
|
{
|
|
long i = 0;
|
|
long nr = folio_nr_pages(src);
|
|
|
|
for (;;) {
|
|
copy_highpage(folio_page(dst, i), folio_page(src, i));
|
|
if (++i == nr)
|
|
break;
|
|
cond_resched();
|
|
}
|
|
}
|
|
|
|
int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
|
|
int sysctl_overcommit_ratio __read_mostly = 50;
|
|
unsigned long sysctl_overcommit_kbytes __read_mostly;
|
|
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
|
|
unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
|
|
unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
|
|
|
|
int overcommit_ratio_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_kbytes = 0;
|
|
return ret;
|
|
}
|
|
|
|
static void sync_overcommit_as(struct work_struct *dummy)
|
|
{
|
|
percpu_counter_sync(&vm_committed_as);
|
|
}
|
|
|
|
int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table t;
|
|
int new_policy = -1;
|
|
int ret;
|
|
|
|
/*
|
|
* The deviation of sync_overcommit_as could be big with loose policy
|
|
* like OVERCOMMIT_ALWAYS/OVERCOMMIT_GUESS. When changing policy to
|
|
* strict OVERCOMMIT_NEVER, we need to reduce the deviation to comply
|
|
* with the strict "NEVER", and to avoid possible race condition (even
|
|
* though user usually won't too frequently do the switching to policy
|
|
* OVERCOMMIT_NEVER), the switch is done in the following order:
|
|
* 1. changing the batch
|
|
* 2. sync percpu count on each CPU
|
|
* 3. switch the policy
|
|
*/
|
|
if (write) {
|
|
t = *table;
|
|
t.data = &new_policy;
|
|
ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
|
if (ret || new_policy == -1)
|
|
return ret;
|
|
|
|
mm_compute_batch(new_policy);
|
|
if (new_policy == OVERCOMMIT_NEVER)
|
|
schedule_on_each_cpu(sync_overcommit_as);
|
|
sysctl_overcommit_memory = new_policy;
|
|
} else {
|
|
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
int overcommit_kbytes_handler(struct ctl_table *table, int write, void *buffer,
|
|
size_t *lenp, loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_ratio = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
|
|
*/
|
|
unsigned long vm_commit_limit(void)
|
|
{
|
|
unsigned long allowed;
|
|
|
|
if (sysctl_overcommit_kbytes)
|
|
allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
|
|
else
|
|
allowed = ((totalram_pages() - hugetlb_total_pages())
|
|
* sysctl_overcommit_ratio / 100);
|
|
allowed += total_swap_pages;
|
|
|
|
return allowed;
|
|
}
|
|
|
|
/*
|
|
* Make sure vm_committed_as in one cacheline and not cacheline shared with
|
|
* other variables. It can be updated by several CPUs frequently.
|
|
*/
|
|
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
|
|
|
|
/*
|
|
* The global memory commitment made in the system can be a metric
|
|
* that can be used to drive ballooning decisions when Linux is hosted
|
|
* as a guest. On Hyper-V, the host implements a policy engine for dynamically
|
|
* balancing memory across competing virtual machines that are hosted.
|
|
* Several metrics drive this policy engine including the guest reported
|
|
* memory commitment.
|
|
*
|
|
* The time cost of this is very low for small platforms, and for big
|
|
* platform like a 2S/36C/72T Skylake server, in worst case where
|
|
* vm_committed_as's spinlock is under severe contention, the time cost
|
|
* could be about 30~40 microseconds.
|
|
*/
|
|
unsigned long vm_memory_committed(void)
|
|
{
|
|
return percpu_counter_sum_positive(&vm_committed_as);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vm_memory_committed);
|
|
|
|
/*
|
|
* Check that a process has enough memory to allocate a new virtual
|
|
* mapping. 0 means there is enough memory for the allocation to
|
|
* succeed and -ENOMEM implies there is not.
|
|
*
|
|
* We currently support three overcommit policies, which are set via the
|
|
* vm.overcommit_memory sysctl. See Documentation/mm/overcommit-accounting.rst
|
|
*
|
|
* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
|
|
* Additional code 2002 Jul 20 by Robert Love.
|
|
*
|
|
* cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
|
|
*
|
|
* Note this is a helper function intended to be used by LSMs which
|
|
* wish to use this logic.
|
|
*/
|
|
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
|
|
{
|
|
long allowed;
|
|
|
|
vm_acct_memory(pages);
|
|
|
|
/*
|
|
* Sometimes we want to use more memory than we have
|
|
*/
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
|
|
return 0;
|
|
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
|
|
if (pages > totalram_pages() + total_swap_pages)
|
|
goto error;
|
|
return 0;
|
|
}
|
|
|
|
allowed = vm_commit_limit();
|
|
/*
|
|
* Reserve some for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
/*
|
|
* Don't let a single process grow so big a user can't recover
|
|
*/
|
|
if (mm) {
|
|
long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
allowed -= min_t(long, mm->total_vm / 32, reserve);
|
|
}
|
|
|
|
if (percpu_counter_read_positive(&vm_committed_as) < allowed)
|
|
return 0;
|
|
error:
|
|
vm_unacct_memory(pages);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* get_cmdline() - copy the cmdline value to a buffer.
|
|
* @task: the task whose cmdline value to copy.
|
|
* @buffer: the buffer to copy to.
|
|
* @buflen: the length of the buffer. Larger cmdline values are truncated
|
|
* to this length.
|
|
*
|
|
* Return: the size of the cmdline field copied. Note that the copy does
|
|
* not guarantee an ending NULL byte.
|
|
*/
|
|
int get_cmdline(struct task_struct *task, char *buffer, int buflen)
|
|
{
|
|
int res = 0;
|
|
unsigned int len;
|
|
struct mm_struct *mm = get_task_mm(task);
|
|
unsigned long arg_start, arg_end, env_start, env_end;
|
|
if (!mm)
|
|
goto out;
|
|
if (!mm->arg_end)
|
|
goto out_mm; /* Shh! No looking before we're done */
|
|
|
|
spin_lock(&mm->arg_lock);
|
|
arg_start = mm->arg_start;
|
|
arg_end = mm->arg_end;
|
|
env_start = mm->env_start;
|
|
env_end = mm->env_end;
|
|
spin_unlock(&mm->arg_lock);
|
|
|
|
len = arg_end - arg_start;
|
|
|
|
if (len > buflen)
|
|
len = buflen;
|
|
|
|
res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
|
|
|
|
/*
|
|
* If the nul at the end of args has been overwritten, then
|
|
* assume application is using setproctitle(3).
|
|
*/
|
|
if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
|
|
len = strnlen(buffer, res);
|
|
if (len < res) {
|
|
res = len;
|
|
} else {
|
|
len = env_end - env_start;
|
|
if (len > buflen - res)
|
|
len = buflen - res;
|
|
res += access_process_vm(task, env_start,
|
|
buffer+res, len,
|
|
FOLL_FORCE);
|
|
res = strnlen(buffer, res);
|
|
}
|
|
}
|
|
out_mm:
|
|
mmput(mm);
|
|
out:
|
|
return res;
|
|
}
|
|
|
|
int __weak memcmp_pages(struct page *page1, struct page *page2)
|
|
{
|
|
char *addr1, *addr2;
|
|
int ret;
|
|
|
|
addr1 = kmap_atomic(page1);
|
|
addr2 = kmap_atomic(page2);
|
|
ret = memcmp(addr1, addr2, PAGE_SIZE);
|
|
kunmap_atomic(addr2);
|
|
kunmap_atomic(addr1);
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_PRINTK
|
|
/**
|
|
* mem_dump_obj - Print available provenance information
|
|
* @object: object for which to find provenance information.
|
|
*
|
|
* This function uses pr_cont(), so that the caller is expected to have
|
|
* printed out whatever preamble is appropriate. The provenance information
|
|
* depends on the type of object and on how much debugging is enabled.
|
|
* For example, for a slab-cache object, the slab name is printed, and,
|
|
* if available, the return address and stack trace from the allocation
|
|
* and last free path of that object.
|
|
*/
|
|
void mem_dump_obj(void *object)
|
|
{
|
|
const char *type;
|
|
|
|
if (kmem_valid_obj(object)) {
|
|
kmem_dump_obj(object);
|
|
return;
|
|
}
|
|
|
|
if (vmalloc_dump_obj(object))
|
|
return;
|
|
|
|
if (virt_addr_valid(object))
|
|
type = "non-slab/vmalloc memory";
|
|
else if (object == NULL)
|
|
type = "NULL pointer";
|
|
else if (object == ZERO_SIZE_PTR)
|
|
type = "zero-size pointer";
|
|
else
|
|
type = "non-paged memory";
|
|
|
|
pr_cont(" %s\n", type);
|
|
}
|
|
EXPORT_SYMBOL_GPL(mem_dump_obj);
|
|
#endif
|
|
|
|
/*
|
|
* A driver might set a page logically offline -- PageOffline() -- and
|
|
* turn the page inaccessible in the hypervisor; after that, access to page
|
|
* content can be fatal.
|
|
*
|
|
* Some special PFN walkers -- i.e., /proc/kcore -- read content of random
|
|
* pages after checking PageOffline(); however, these PFN walkers can race
|
|
* with drivers that set PageOffline().
|
|
*
|
|
* page_offline_freeze()/page_offline_thaw() allows for a subsystem to
|
|
* synchronize with such drivers, achieving that a page cannot be set
|
|
* PageOffline() while frozen.
|
|
*
|
|
* page_offline_begin()/page_offline_end() is used by drivers that care about
|
|
* such races when setting a page PageOffline().
|
|
*/
|
|
static DECLARE_RWSEM(page_offline_rwsem);
|
|
|
|
void page_offline_freeze(void)
|
|
{
|
|
down_read(&page_offline_rwsem);
|
|
}
|
|
|
|
void page_offline_thaw(void)
|
|
{
|
|
up_read(&page_offline_rwsem);
|
|
}
|
|
|
|
void page_offline_begin(void)
|
|
{
|
|
down_write(&page_offline_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(page_offline_begin);
|
|
|
|
void page_offline_end(void)
|
|
{
|
|
up_write(&page_offline_rwsem);
|
|
}
|
|
EXPORT_SYMBOL(page_offline_end);
|
|
|
|
#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
|
|
void flush_dcache_folio(struct folio *folio)
|
|
{
|
|
long i, nr = folio_nr_pages(folio);
|
|
|
|
for (i = 0; i < nr; i++)
|
|
flush_dcache_page(folio_page(folio, i));
|
|
}
|
|
EXPORT_SYMBOL(flush_dcache_folio);
|
|
#endif
|