| // SPDX-License-Identifier: GPL-2.0-only |
| #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/sched/mm.h> |
| #include <linux/sched/signal.h> |
| #include <linux/sched/task_stack.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 <linux/userfaultfd_k.h> |
| #include <linux/elf.h> |
| #include <linux/elf-randomize.h> |
| #include <linux/personality.h> |
| #include <linux/random.h> |
| #include <linux/processor.h> |
| #include <linux/sizes.h> |
| #include <linux/compat.h> |
| |
| #include <linux/uaccess.h> |
| |
| #include "internal.h" |
| #include "swap.h" |
| |
| /** |
| * 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 |
| * |
| * Return: newly allocated copy of @s or %NULL in case of error |
| */ |
| 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 |
| * |
| * Note: Strings allocated by kstrdup_const should be freed by kfree_const and |
| * must not be passed to krealloc(). |
| * |
| * Return: source string if it is in .rodata section otherwise |
| * fallback to kstrdup. |
| */ |
| 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. |
| * |
| * Return: newly allocated copy of @s or %NULL in case of error |
| */ |
| 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 |
| * |
| * Return: newly allocated copy of @src or %NULL in case of error |
| */ |
| 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 |
| * |
| * Return: newly allocated copy of @s with NUL-termination or %NULL in |
| * case of error |
| */ |
| 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 |
| * |
| * Return: an ERR_PTR() on failure. Result is physically |
| * contiguous, to be freed by kfree(). |
| */ |
| void *memdup_user(const void __user *src, size_t len) |
| { |
| void *p; |
| |
| p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN); |
| 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); |
| |
| /** |
| * vmemdup_user - duplicate memory region from user space |
| * |
| * @src: source address in user space |
| * @len: number of bytes to copy |
| * |
| * Return: an ERR_PTR() on failure. Result may be not |
| * physically contiguous. Use kvfree() to free. |
| */ |
| void *vmemdup_user(const void __user *src, size_t len) |
| { |
| void *p; |
| |
| p = kvmalloc(len, GFP_USER); |
| if (!p) |
| return ERR_PTR(-ENOMEM); |
| |
| if (copy_from_user(p, src, len)) { |
| kvfree(p); |
| return ERR_PTR(-EFAULT); |
| } |
| |
| return p; |
| } |
| EXPORT_SYMBOL(vmemdup_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. |
| * |
| * Return: newly allocated copy of @s or an ERR_PTR() in case of error |
| */ |
| 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); |
| |
| /** |
| * memdup_user_nul - duplicate memory region from user space and NUL-terminate |
| * |
| * @src: source address in user space |
| * @len: number of bytes to copy |
| * |
| * Return: an ERR_PTR() on failure. |
| */ |
| void *memdup_user_nul(const void __user *src, size_t len) |
| { |
| char *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 + 1, GFP_KERNEL); |
| if (!p) |
| return ERR_PTR(-ENOMEM); |
| |
| if (copy_from_user(p, src, len)) { |
| kfree(p); |
| return ERR_PTR(-EFAULT); |
| } |
| p[len] = '\0'; |
| |
| return p; |
| } |
| EXPORT_SYMBOL(memdup_user_nul); |
| |
| /* Check if the vma is being used as a stack by this task */ |
| int vma_is_stack_for_current(struct vm_area_struct *vma) |
| { |
| struct task_struct * __maybe_unused t = current; |
| |
| return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); |
| } |
| |
| /* |
| * Change backing file, only valid to use during initial VMA setup. |
| */ |
| void vma_set_file(struct vm_area_struct *vma, struct file *file) |
| { |
| /* Changing an anonymous vma with this is illegal */ |
| get_file(file); |
| swap(vma->vm_file, file); |
| fput(file); |
| } |
| EXPORT_SYMBOL(vma_set_file); |
| |
| #ifndef STACK_RND_MASK |
| #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */ |
| #endif |
| |
| unsigned long randomize_stack_top(unsigned long stack_top) |
| { |
| unsigned long random_variable = 0; |
| |
| if (current->flags & PF_RANDOMIZE) { |
| random_variable = get_random_long(); |
| random_variable &= STACK_RND_MASK; |
| random_variable <<= PAGE_SHIFT; |
| } |
| #ifdef CONFIG_STACK_GROWSUP |
| return PAGE_ALIGN(stack_top) + random_variable; |
| #else |
| return PAGE_ALIGN(stack_top) - random_variable; |
| #endif |
| } |
| |
| /** |
| * randomize_page - Generate a random, page aligned address |
| * @start: The smallest acceptable address the caller will take. |
| * @range: The size of the area, starting at @start, within which the |
| * random address must fall. |
| * |
| * If @start + @range would overflow, @range is capped. |
| * |
| * NOTE: Historical use of randomize_range, which this replaces, presumed that |
| * @start was already page aligned. We now align it regardless. |
| * |
| * Return: A page aligned address within [start, start + range). On error, |
| * @start is returned. |
| */ |
| unsigned long randomize_page(unsigned long start, unsigned long range) |
| { |
| if (!PAGE_ALIGNED(start)) { |
| range -= PAGE_ALIGN(start) - start; |
| start = PAGE_ALIGN(start); |
| } |
| |
| if (start > ULONG_MAX - range) |
| range = ULONG_MAX - start; |
| |
| range >>= PAGE_SHIFT; |
| |
| if (range == 0) |
| return start; |
| |
| return start + (get_random_long() % range << PAGE_SHIFT); |
| } |
| |
| #ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT |
| unsigned long __weak arch_randomize_brk(struct mm_struct *mm) |
| { |
| /* Is the current task 32bit ? */ |
| if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task()) |
| return randomize_page(mm->brk, SZ_32M); |
| |
| return randomize_page(mm->brk, SZ_1G); |
| } |
| |
| unsigned long arch_mmap_rnd(void) |
| { |
| unsigned long rnd; |
| |
| #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS |
| if (is_compat_task()) |
| rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); |
| else |
| #endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */ |
| rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); |
| |
| return rnd << PAGE_SHIFT; |
| } |
| |
| static int mmap_is_legacy(struct rlimit *rlim_stack) |
| { |
| if (current->personality & ADDR_COMPAT_LAYOUT) |
| return 1; |
| |
| if (rlim_stack->rlim_cur == RLIM_INFINITY) |
| return 1; |
| |
| return sysctl_legacy_va_layout; |
| } |
| |
| /* |
| * Leave enough space between the mmap area and the stack to honour ulimit in |
| * the face of randomisation. |
| */ |
| #define MIN_GAP (SZ_128M) |
| #define MAX_GAP (STACK_TOP / 6 * 5) |
| |
| static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) |
| { |
| unsigned long gap = rlim_stack->rlim_cur; |
| unsigned long pad = stack_guard_gap; |
| |
| /* Account for stack randomization if necessary */ |
| if (current->flags & PF_RANDOMIZE) |
| pad += (STACK_RND_MASK << PAGE_SHIFT); |
| |
| /* Values close to RLIM_INFINITY can overflow. */ |
| if (gap + pad > gap) |
| gap += pad; |
| |
| if (gap < MIN_GAP) |
| gap = MIN_GAP; |
| else if (gap > MAX_GAP) |
| gap = MAX_GAP; |
| |
| return PAGE_ALIGN(STACK_TOP - gap - rnd); |
| } |
| |
| void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) |
| { |
| unsigned long random_factor = 0UL; |
| |
| if (current->flags & PF_RANDOMIZE) |
| random_factor = arch_mmap_rnd(); |
| |
| if (mmap_is_legacy(rlim_stack)) { |
| mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; |
| mm->get_unmapped_area = arch_get_unmapped_area; |
| } else { |
| mm->mmap_base = mmap_base(random_factor, rlim_stack); |
| mm->get_unmapped_area = arch_get_unmapped_area_topdown; |
| } |
| } |
| #elif defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) |
| void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) |
| { |
| mm->mmap_base = TASK_UNMAPPED_BASE; |
| mm->get_unmapped_area = arch_get_unmapped_area; |
| } |
| #endif |
| |
| /** |
| * __account_locked_vm - account locked pages to an mm's locked_vm |
| * @mm: mm to account against |
| * @pages: number of pages to account |
| * @inc: %true if @pages should be considered positive, %false if not |
| * @task: task used to check RLIMIT_MEMLOCK |
| * @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped |
| * |
| * Assumes @task and @mm are valid (i.e. at least one reference on each), and |
| * that mmap_lock is held as writer. |
| * |
| * Return: |
| * * 0 on success |
| * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded. |
| */ |
| int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc, |
| struct task_struct *task, bool bypass_rlim) |
| { |
| unsigned long locked_vm, limit; |
| int ret = 0; |
| |
| mmap_assert_write_locked(mm); |
| |
| locked_vm = mm->locked_vm; |
| if (inc) { |
| if (!bypass_rlim) { |
| limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT; |
| if (locked_vm + pages > limit) |
| ret = -ENOMEM; |
| } |
| if (!ret) |
| mm->locked_vm = locked_vm + pages; |
| } else { |
| WARN_ON_ONCE(pages > locked_vm); |
| mm->locked_vm = locked_vm - pages; |
| } |
| |
| pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid, |
| (void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT, |
| locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK), |
| ret ? " - exceeded" : ""); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(__account_locked_vm); |
| |
| /** |
| * account_locked_vm - account locked pages to an mm's locked_vm |
| * @mm: mm to account against, may be NULL |
| * @pages: number of pages to account |
| * @inc: %true if @pages should be considered positive, %false if not |
| * |
| * Assumes a non-NULL @mm is valid (i.e. at least one reference on it). |
| * |
| * Return: |
| * * 0 on success, or if mm is NULL |
| * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded. |
| */ |
| int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc) |
| { |
| 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; |
| |
| /* non-sleeping allocations are not supported by vmalloc */ |
| if (!gfpflags_allow_blocking(flags)) |
| return NULL; |
| |
| /* 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_FLAGS) |
| return NULL; |
| |
| return mapping; |
| } |
| 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); |
| if (folio_test_hugetlb(folio)) |
| return compound; |
| ret = compound; |
| nr = folio_nr_pages(folio); |
| 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: |
| pr_warn_ratelimited("%s: pid: %d, comm: %s, no enough memory for the allocation\n", |
| __func__, current->pid, current->comm); |
| 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 (is_vmalloc_addr(object)) |
| type = "vmalloc memory"; |
| else 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 |