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- #include <linux/mm.h>
- #include <linux/slab.h>
- #include <linux/string.h>
- #include <linux/compiler.h>
- #include <linux/export.h>
- #include <linux/err.h>
- #include <linux/sched.h>
- #include <linux/security.h>
- #include <linux/swap.h>
- #include <linux/swapops.h>
- #include <linux/mman.h>
- #include <linux/hugetlb.h>
- #include <linux/vmalloc.h>
- #include <asm/sections.h>
- #include <asm/uaccess.h>
- #include "internal.h"
- static inline int is_kernel_rodata(unsigned long addr)
- {
- return addr >= (unsigned long)__start_rodata &&
- addr < (unsigned long)__end_rodata;
- }
- /**
- * kfree_const - conditionally free memory
- * @x: pointer to the memory
- *
- * Function calls kfree only if @x is not in .rodata section.
- */
- void kfree_const(const void *x)
- {
- if (!is_kernel_rodata((unsigned long)x))
- kfree(x);
- }
- EXPORT_SYMBOL(kfree_const);
- /**
- * kstrdup - allocate space for and copy an existing string
- * @s: the string to duplicate
- * @gfp: the GFP mask used in the kmalloc() call when allocating memory
- */
- char *kstrdup(const char *s, gfp_t gfp)
- {
- size_t len;
- char *buf;
- if (!s)
- return NULL;
- len = strlen(s) + 1;
- buf = kmalloc_track_caller(len, gfp);
- if (buf)
- memcpy(buf, s, len);
- return buf;
- }
- EXPORT_SYMBOL(kstrdup);
- /**
- * kstrdup_const - conditionally duplicate an existing const string
- * @s: the string to duplicate
- * @gfp: the GFP mask used in the kmalloc() call when allocating memory
- *
- * Function returns source string if it is in .rodata section otherwise it
- * fallbacks to kstrdup.
- * Strings allocated by kstrdup_const should be freed by kfree_const.
- */
- const char *kstrdup_const(const char *s, gfp_t gfp)
- {
- if (is_kernel_rodata((unsigned long)s))
- return s;
- return kstrdup(s, gfp);
- }
- EXPORT_SYMBOL(kstrdup_const);
- /**
- * kstrndup - allocate space for and copy an existing string
- * @s: the string to duplicate
- * @max: read at most @max chars from @s
- * @gfp: the GFP mask used in the kmalloc() call when allocating memory
- *
- * Note: Use kmemdup_nul() instead if the size is known exactly.
- */
- char *kstrndup(const char *s, size_t max, gfp_t gfp)
- {
- size_t len;
- char *buf;
- if (!s)
- return NULL;
- len = strnlen(s, max);
- buf = kmalloc_track_caller(len+1, gfp);
- if (buf) {
- memcpy(buf, s, len);
- buf[len] = '\0';
- }
- return buf;
- }
- EXPORT_SYMBOL(kstrndup);
- /**
- * kmemdup - duplicate region of memory
- *
- * @src: memory region to duplicate
- * @len: memory region length
- * @gfp: GFP mask to use
- */
- void *kmemdup(const void *src, size_t len, gfp_t gfp)
- {
- void *p;
- p = kmalloc_track_caller(len, gfp);
- if (p)
- memcpy(p, src, len);
- return p;
- }
- EXPORT_SYMBOL(kmemdup);
- /**
- * kmemdup_nul - Create a NUL-terminated string from unterminated data
- * @s: The data to stringify
- * @len: The size of the data
- * @gfp: the GFP mask used in the kmalloc() call when allocating memory
- */
- char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
- {
- char *buf;
- if (!s)
- return NULL;
- buf = kmalloc_track_caller(len + 1, gfp);
- if (buf) {
- memcpy(buf, s, len);
- buf[len] = '\0';
- }
- return buf;
- }
- EXPORT_SYMBOL(kmemdup_nul);
- /**
- * memdup_user - duplicate memory region from user space
- *
- * @src: source address in user space
- * @len: number of bytes to copy
- *
- * Returns an ERR_PTR() on failure.
- */
- void *memdup_user(const void __user *src, size_t len)
- {
- void *p;
- /*
- * Always use GFP_KERNEL, since copy_from_user() can sleep and
- * cause pagefault, which makes it pointless to use GFP_NOFS
- * or GFP_ATOMIC.
- */
- p = kmalloc_track_caller(len, GFP_KERNEL);
- if (!p)
- return ERR_PTR(-ENOMEM);
- if (copy_from_user(p, src, len)) {
- kfree(p);
- return ERR_PTR(-EFAULT);
- }
- return p;
- }
- EXPORT_SYMBOL(memdup_user);
- /*
- * strndup_user - duplicate an existing string from user space
- * @s: The string to duplicate
- * @n: Maximum number of bytes to copy, including the trailing NUL.
- */
- char *strndup_user(const char __user *s, long n)
- {
- char *p;
- long length;
- length = strnlen_user(s, n);
- if (!length)
- return ERR_PTR(-EFAULT);
- if (length > n)
- return ERR_PTR(-EINVAL);
- p = memdup_user(s, length);
- if (IS_ERR(p))
- return p;
- p[length - 1] = '\0';
- return p;
- }
- EXPORT_SYMBOL(strndup_user);
- void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
- struct vm_area_struct *prev, struct rb_node *rb_parent)
- {
- struct vm_area_struct *next;
- vma->vm_prev = prev;
- if (prev) {
- next = prev->vm_next;
- prev->vm_next = vma;
- } else {
- mm->mmap = vma;
- if (rb_parent)
- next = rb_entry(rb_parent,
- struct vm_area_struct, vm_rb);
- else
- next = NULL;
- }
- vma->vm_next = next;
- if (next)
- next->vm_prev = vma;
- }
- /* Check if the vma is being used as a stack by this task */
- int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t)
- {
- return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
- }
- #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
- void arch_pick_mmap_layout(struct mm_struct *mm)
- {
- mm->mmap_base = TASK_UNMAPPED_BASE;
- mm->get_unmapped_area = arch_get_unmapped_area;
- }
- #endif
- /*
- * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
- * back to the regular GUP.
- * If the architecture not support this function, simply return with no
- * page pinned
- */
- int __weak __get_user_pages_fast(unsigned long start,
- int nr_pages, int write, struct page **pages)
- {
- return 0;
- }
- EXPORT_SYMBOL_GPL(__get_user_pages_fast);
- /**
- * get_user_pages_fast() - pin user pages in memory
- * @start: starting user address
- * @nr_pages: number of pages from start to pin
- * @write: whether pages will be written to
- * @pages: array that receives pointers to the pages pinned.
- * Should be at least nr_pages long.
- *
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno.
- *
- * get_user_pages_fast provides equivalent functionality to get_user_pages,
- * operating on current and current->mm, with force=0 and vma=NULL. However
- * unlike get_user_pages, it must be called without mmap_sem held.
- *
- * get_user_pages_fast may take mmap_sem and page table locks, so no
- * assumptions can be made about lack of locking. get_user_pages_fast is to be
- * implemented in a way that is advantageous (vs get_user_pages()) when the
- * user memory area is already faulted in and present in ptes. However if the
- * pages have to be faulted in, it may turn out to be slightly slower so
- * callers need to carefully consider what to use. On many architectures,
- * get_user_pages_fast simply falls back to get_user_pages.
- */
- int __weak get_user_pages_fast(unsigned long start,
- int nr_pages, int write, struct page **pages)
- {
- struct mm_struct *mm = current->mm;
- return get_user_pages_unlocked(current, mm, start, nr_pages,
- pages, write ? FOLL_WRITE : 0);
- }
- EXPORT_SYMBOL_GPL(get_user_pages_fast);
- 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;
- ret = security_mmap_file(file, prot, flag);
- if (!ret) {
- down_write(&mm->mmap_sem);
- ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
- &populate);
- up_write(&mm->mmap_sem);
- 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);
- void kvfree(const void *addr)
- {
- if (is_vmalloc_addr(addr))
- vfree(addr);
- else
- kfree(addr);
- }
- EXPORT_SYMBOL(kvfree);
- static inline void *__page_rmapping(struct page *page)
- {
- unsigned long mapping;
- mapping = (unsigned long)page->mapping;
- mapping &= ~PAGE_MAPPING_FLAGS;
- return (void *)mapping;
- }
- /* Neutral page->mapping pointer to address_space or anon_vma or other */
- void *page_rmapping(struct page *page)
- {
- page = compound_head(page);
- return __page_rmapping(page);
- }
- struct anon_vma *page_anon_vma(struct page *page)
- {
- unsigned long mapping;
- page = compound_head(page);
- mapping = (unsigned long)page->mapping;
- if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
- return NULL;
- return __page_rmapping(page);
- }
- struct address_space *page_mapping(struct page *page)
- {
- unsigned long mapping;
- /* This happens if someone calls flush_dcache_page on slab page */
- if (unlikely(PageSlab(page)))
- return NULL;
- if (unlikely(PageSwapCache(page))) {
- swp_entry_t entry;
- entry.val = page_private(page);
- return swap_address_space(entry);
- }
- mapping = (unsigned long)page->mapping;
- if (mapping & PAGE_MAPPING_FLAGS)
- return NULL;
- return page->mapping;
- }
- int overcommit_ratio_handler(struct ctl_table *table, int write,
- void __user *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;
- }
- int overcommit_kbytes_handler(struct ctl_table *table, int write,
- void __user *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;
- }
- /**
- * 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.
- * Returns 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 */
- down_read(&mm->mmap_sem);
- arg_start = mm->arg_start;
- arg_end = mm->arg_end;
- env_start = mm->env_start;
- env_end = mm->env_end;
- up_read(&mm->mmap_sem);
- len = arg_end - arg_start;
- if (len > buflen)
- len = buflen;
- res = access_process_vm(task, arg_start, buffer, len, 0);
- /*
- * 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, 0);
- res = strnlen(buffer, res);
- }
- }
- out_mm:
- mmput(mm);
- out:
- return res;
- }
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