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mm/util.c
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#include <linux/mm.h> |
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#include <linux/slab.h> #include <linux/string.h> #include <linux/module.h> |
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#include <linux/err.h> |
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#include <linux/sched.h> |
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#include <asm/uaccess.h> |
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#define CREATE_TRACE_POINTS |
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#include <trace/events/kmem.h> |
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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 * @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; |
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buf = kmalloc_track_caller(len, gfp); |
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if (buf) memcpy(buf, s, len); return buf; } EXPORT_SYMBOL(kstrdup); |
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/** |
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* 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 */ 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); /** |
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* 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; |
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p = kmalloc_track_caller(len, gfp); |
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if (p) memcpy(p, src, len); return p; } EXPORT_SYMBOL(kmemdup); |
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/** |
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* 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); /** |
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* __krealloc - like krealloc() but don't free @p. |
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* @p: object to reallocate memory for. * @new_size: how many bytes of memory are required. * @flags: the type of memory to allocate. * |
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* This function is like krealloc() except it never frees the originally * allocated buffer. Use this if you don't want to free the buffer immediately * like, for example, with RCU. |
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*/ |
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void *__krealloc(const void *p, size_t new_size, gfp_t flags) |
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{ void *ret; |
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size_t ks = 0; |
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if (unlikely(!new_size)) |
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return ZERO_SIZE_PTR; |
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if (p) ks = ksize(p); |
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if (ks >= new_size) return (void *)p; ret = kmalloc_track_caller(new_size, flags); |
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if (ret && p) |
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memcpy(ret, p, ks); |
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return ret; } EXPORT_SYMBOL(__krealloc); /** * krealloc - reallocate memory. The contents will remain unchanged. * @p: object to reallocate memory for. * @new_size: how many bytes of memory are required. * @flags: the type of memory to allocate. * * The contents of the object pointed to are preserved up to the * lesser of the new and old sizes. If @p is %NULL, krealloc() * behaves exactly like kmalloc(). If @size is 0 and @p is not a * %NULL pointer, the object pointed to is freed. */ void *krealloc(const void *p, size_t new_size, gfp_t flags) { void *ret; if (unlikely(!new_size)) { |
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kfree(p); |
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return ZERO_SIZE_PTR; |
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} |
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ret = __krealloc(p, new_size, flags); if (ret && p != ret) kfree(p); |
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return ret; } EXPORT_SYMBOL(krealloc); |
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/** * kzfree - like kfree but zero memory * @p: object to free memory of * * The memory of the object @p points to is zeroed before freed. * If @p is %NULL, kzfree() does nothing. |
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* * Note: this function zeroes the whole allocated buffer which can be a good * deal bigger than the requested buffer size passed to kmalloc(). So be * careful when using this function in performance sensitive code. |
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*/ void kzfree(const void *p) { size_t ks; void *mem = (void *)p; if (unlikely(ZERO_OR_NULL_PTR(mem))) return; ks = ksize(mem); memset(mem, 0, ks); kfree(mem); } EXPORT_SYMBOL(kzfree); |
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/* * strndup_user - duplicate an existing string from user space |
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* @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 = kmalloc(length, GFP_KERNEL); if (!p) return ERR_PTR(-ENOMEM); if (copy_from_user(p, s, length)) { kfree(p); return ERR_PTR(-EFAULT); } p[length - 1] = '\0'; return p; } EXPORT_SYMBOL(strndup_user); |
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#ifndef 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; mm->unmap_area = arch_unmap_area; } #endif |
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/** * 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. * |
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* 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. |
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* * 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. |
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*/ |
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int __attribute__((weak)) get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { struct mm_struct *mm = current->mm; int ret; down_read(&mm->mmap_sem); ret = get_user_pages(current, mm, start, nr_pages, write, 0, pages, NULL); up_read(&mm->mmap_sem); return ret; } EXPORT_SYMBOL_GPL(get_user_pages_fast); |
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/* Tracepoints definitions. */ |
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EXPORT_TRACEPOINT_SYMBOL(kmalloc); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node); EXPORT_TRACEPOINT_SYMBOL(kfree); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); |