diff options
Diffstat (limited to 'mm/util.c')
| -rw-r--r-- | mm/util.c | 418 |
1 files changed, 397 insertions, 21 deletions
diff --git a/mm/util.c b/mm/util.c index 8f18683825b..d5ea733c508 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1,9 +1,24 @@ +#include <linux/mm.h> #include <linux/slab.h> #include <linux/string.h> -#include <linux/module.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/uaccess.h> +#include "internal.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/kmem.h> + /** * kstrdup - allocate space for and copy an existing string * @s: the string to duplicate @@ -68,6 +83,75 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) EXPORT_SYMBOL(kmemdup); /** + * 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); + +static __always_inline void *__do_krealloc(const void *p, size_t new_size, + gfp_t flags) +{ + void *ret; + size_t ks = 0; + + if (p) + ks = ksize(p); + + if (ks >= new_size) + return (void *)p; + + ret = kmalloc_track_caller(new_size, flags); + if (ret && p) + memcpy(ret, p, ks); + + return ret; +} + +/** + * __krealloc - like krealloc() but don't free @p. + * @p: object to reallocate memory for. + * @new_size: how many bytes of memory are required. + * @flags: the type of memory to allocate. + * + * 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. + */ +void *__krealloc(const void *p, size_t new_size, gfp_t flags) +{ + if (unlikely(!new_size)) + return ZERO_SIZE_PTR; + + return __do_krealloc(p, new_size, flags); + +} +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. @@ -75,34 +159,50 @@ EXPORT_SYMBOL(kmemdup); * * 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 + * behaves exactly like kmalloc(). If @new_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; - size_t ks = 0; if (unlikely(!new_size)) { kfree(p); return ZERO_SIZE_PTR; } - if (p) - ks = ksize(p); - - if (ks >= new_size) - return (void *)p; - - ret = kmalloc_track_caller(new_size, flags); - if (ret && p) { - memcpy(ret, p, ks); + ret = __do_krealloc(p, new_size, flags); + if (ret && p != ret) kfree(p); - } + return ret; } EXPORT_SYMBOL(krealloc); +/** + * 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. + * + * 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. + */ +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); + /* * strndup_user - duplicate an existing string from user space * @s: The string to duplicate @@ -121,18 +221,294 @@ char *strndup_user(const char __user *s, long n) if (length > n) return ERR_PTR(-EINVAL); - p = kmalloc(length, GFP_KERNEL); - - if (!p) - return ERR_PTR(-ENOMEM); + p = memdup_user(s, length); - if (copy_from_user(p, s, length)) { - kfree(p); - return ERR_PTR(-EFAULT); - } + 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 */ +static int vm_is_stack_for_task(struct task_struct *t, + struct vm_area_struct *vma) +{ + return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); +} + +/* + * Check if the vma is being used as a stack. + * If is_group is non-zero, check in the entire thread group or else + * just check in the current task. Returns the pid of the task that + * the vma is stack for. + */ +pid_t vm_is_stack(struct task_struct *task, + struct vm_area_struct *vma, int in_group) +{ + pid_t ret = 0; + + if (vm_is_stack_for_task(task, vma)) + return task->pid; + + if (in_group) { + struct task_struct *t; + rcu_read_lock(); + if (!pid_alive(task)) + goto done; + + t = task; + do { + if (vm_is_stack_for_task(t, vma)) { + ret = t->pid; + goto done; + } + } while_each_thread(task, t); +done: + rcu_read_unlock(); + } + + return ret; +} + +#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; + 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); + +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 & ~PAGE_MASK)) + 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); + +struct address_space *page_mapping(struct page *page) +{ + struct address_space *mapping = page->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); + mapping = swap_address_space(entry); + } else if ((unsigned long)mapping & PAGE_MAPPING_ANON) + mapping = NULL; + return 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); + if (!mm) + goto out; + if (!mm->arg_end) + goto out_mm; /* Shh! No looking before we're done */ + + len = mm->arg_end - mm->arg_start; + + if (len > buflen) + len = buflen; + + res = access_process_vm(task, mm->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 = mm->env_end - mm->env_start; + if (len > buflen - res) + len = buflen - res; + res += access_process_vm(task, mm->env_start, + buffer+res, len, 0); + res = strnlen(buffer, res); + } + } +out_mm: + mmput(mm); +out: + return res; +} + +/* Tracepoints definitions. */ +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); |