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![Alexander Kuleshov](/assets/img/avatar_default.png)
linux/mm.h provides offset_in_page() macro. Let's use already predefined macro instead of (addr & ~PAGE_MASK). Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
465 lines
11 KiB
C
465 lines
11 KiB
C
#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/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 <asm/sections.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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static inline int is_kernel_rodata(unsigned long addr)
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{
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return addr >= (unsigned long)__start_rodata &&
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addr < (unsigned long)__end_rodata;
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}
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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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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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* Function returns source string if it is in .rodata section otherwise it
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* fallbacks to kstrdup.
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* Strings allocated by kstrdup_const should be freed by kfree_const.
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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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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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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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* 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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* Returns an ERR_PTR() on failure.
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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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/*
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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, 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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return p;
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}
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EXPORT_SYMBOL(memdup_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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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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void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev, struct rb_node *rb_parent)
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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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mm->mmap = vma;
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if (rb_parent)
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next = rb_entry(rb_parent,
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struct vm_area_struct, vm_rb);
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else
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next = NULL;
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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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/* Check if the vma is being used as a stack by this task */
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static int vm_is_stack_for_task(struct task_struct *t,
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struct vm_area_struct *vma)
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{
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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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* Check if the vma is being used as a stack.
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* If is_group is non-zero, check in the entire thread group or else
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* just check in the current task. Returns the task_struct of the task
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* that the vma is stack for. Must be called under rcu_read_lock().
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*/
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struct task_struct *task_of_stack(struct task_struct *task,
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struct vm_area_struct *vma, bool in_group)
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{
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if (vm_is_stack_for_task(task, vma))
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return task;
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if (in_group) {
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struct task_struct *t;
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for_each_thread(task, t) {
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if (vm_is_stack_for_task(t, vma))
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return t;
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}
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}
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return NULL;
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}
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#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
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void arch_pick_mmap_layout(struct mm_struct *mm)
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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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* Like get_user_pages_fast() except its IRQ-safe in that it won't fall
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* back to the regular GUP.
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* If the architecture not support this function, simply return with no
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* page pinned
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*/
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int __weak __get_user_pages_fast(unsigned long start,
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int nr_pages, int write, struct page **pages)
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{
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return 0;
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}
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EXPORT_SYMBOL_GPL(__get_user_pages_fast);
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/**
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* get_user_pages_fast() - pin user pages in memory
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* @start: starting user address
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* @nr_pages: number of pages from start to pin
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* @write: whether pages will be written to
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* @pages: array that receives pointers to the pages pinned.
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* Should be at least nr_pages long.
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*
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* Returns number of pages pinned. This may be fewer than the number
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* requested. If nr_pages is 0 or negative, returns 0. If no pages
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* were pinned, returns -errno.
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*
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* get_user_pages_fast provides equivalent functionality to get_user_pages,
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* operating on current and current->mm, with force=0 and vma=NULL. However
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* unlike get_user_pages, it must be called without mmap_sem held.
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*
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* get_user_pages_fast may take mmap_sem and page table locks, so no
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* assumptions can be made about lack of locking. get_user_pages_fast is to be
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* implemented in a way that is advantageous (vs get_user_pages()) when the
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* user memory area is already faulted in and present in ptes. However if the
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* pages have to be faulted in, it may turn out to be slightly slower so
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* callers need to carefully consider what to use. On many architectures,
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* get_user_pages_fast simply falls back to get_user_pages.
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*/
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int __weak get_user_pages_fast(unsigned long start,
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int nr_pages, int write, struct page **pages)
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{
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struct mm_struct *mm = current->mm;
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return get_user_pages_unlocked(current, mm, start, nr_pages,
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write, 0, pages);
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}
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EXPORT_SYMBOL_GPL(get_user_pages_fast);
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unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
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unsigned long len, unsigned long prot,
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unsigned long flag, unsigned long pgoff)
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{
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unsigned long ret;
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struct mm_struct *mm = current->mm;
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unsigned long populate;
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ret = security_mmap_file(file, prot, flag);
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if (!ret) {
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down_write(&mm->mmap_sem);
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ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
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&populate);
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up_write(&mm->mmap_sem);
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if (populate)
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mm_populate(ret, populate);
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}
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return ret;
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}
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unsigned long vm_mmap(struct file *file, unsigned long addr,
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unsigned long len, unsigned long prot,
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unsigned long flag, unsigned long offset)
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{
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if (unlikely(offset + PAGE_ALIGN(len) < offset))
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return -EINVAL;
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if (unlikely(offset_in_page(offset)))
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return -EINVAL;
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return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
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}
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EXPORT_SYMBOL(vm_mmap);
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void kvfree(const void *addr)
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{
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if (is_vmalloc_addr(addr))
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vfree(addr);
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else
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kfree(addr);
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}
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EXPORT_SYMBOL(kvfree);
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static inline void *__page_rmapping(struct page *page)
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{
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unsigned long mapping;
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mapping = (unsigned long)page->mapping;
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mapping &= ~PAGE_MAPPING_FLAGS;
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return (void *)mapping;
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}
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/* Neutral page->mapping pointer to address_space or anon_vma or other */
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void *page_rmapping(struct page *page)
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{
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page = compound_head(page);
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return __page_rmapping(page);
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}
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struct anon_vma *page_anon_vma(struct page *page)
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{
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unsigned long mapping;
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page = compound_head(page);
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mapping = (unsigned long)page->mapping;
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if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
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return NULL;
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return __page_rmapping(page);
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}
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struct address_space *page_mapping(struct page *page)
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{
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unsigned long mapping;
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/* This happens if someone calls flush_dcache_page on slab page */
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if (unlikely(PageSlab(page)))
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return NULL;
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if (unlikely(PageSwapCache(page))) {
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swp_entry_t entry;
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entry.val = page_private(page);
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return swap_address_space(entry);
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}
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mapping = (unsigned long)page->mapping;
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if (mapping & PAGE_MAPPING_FLAGS)
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return NULL;
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return page->mapping;
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}
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int overcommit_ratio_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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int ret;
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ret = proc_dointvec(table, write, buffer, lenp, ppos);
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if (ret == 0 && write)
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sysctl_overcommit_kbytes = 0;
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return ret;
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}
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int overcommit_kbytes_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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int ret;
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ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
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if (ret == 0 && write)
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sysctl_overcommit_ratio = 0;
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return ret;
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}
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/*
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* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
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*/
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unsigned long vm_commit_limit(void)
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{
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unsigned long allowed;
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if (sysctl_overcommit_kbytes)
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allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
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else
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allowed = ((totalram_pages - hugetlb_total_pages())
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* sysctl_overcommit_ratio / 100);
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allowed += total_swap_pages;
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return allowed;
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}
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/**
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* get_cmdline() - copy the cmdline value to a buffer.
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* @task: the task whose cmdline value to copy.
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* @buffer: the buffer to copy to.
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* @buflen: the length of the buffer. Larger cmdline values are truncated
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* to this length.
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* Returns the size of the cmdline field copied. Note that the copy does
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* not guarantee an ending NULL byte.
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*/
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int get_cmdline(struct task_struct *task, char *buffer, int buflen)
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{
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int res = 0;
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unsigned int len;
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struct mm_struct *mm = get_task_mm(task);
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if (!mm)
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goto out;
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if (!mm->arg_end)
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goto out_mm; /* Shh! No looking before we're done */
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len = mm->arg_end - mm->arg_start;
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if (len > buflen)
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len = buflen;
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res = access_process_vm(task, mm->arg_start, buffer, len, 0);
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/*
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* If the nul at the end of args has been overwritten, then
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* assume application is using setproctitle(3).
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*/
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if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
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len = strnlen(buffer, res);
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if (len < res) {
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res = len;
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} else {
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len = mm->env_end - mm->env_start;
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if (len > buflen - res)
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len = buflen - res;
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res += access_process_vm(task, mm->env_start,
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buffer+res, len, 0);
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res = strnlen(buffer, res);
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}
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}
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out_mm:
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mmput(mm);
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out:
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return res;
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}
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