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- // 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"
- #ifndef __GENKSYMS__
- #include <trace/hooks/syscall_check.h>
- #endif
- /**
- * 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);
- void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
- struct vm_area_struct *prev)
- {
- struct vm_area_struct *next;
- vma->vm_prev = prev;
- if (prev) {
- next = prev->vm_next;
- prev->vm_next = vma;
- } else {
- next = mm->mmap;
- mm->mmap = vma;
- }
- vma->vm_next = next;
- if (next)
- next->vm_prev = vma;
- }
- void __vma_unlink_list(struct mm_struct *mm, struct vm_area_struct *vma)
- {
- struct vm_area_struct *prev, *next;
- next = vma->vm_next;
- prev = vma->vm_prev;
- if (prev)
- prev->vm_next = next;
- else
- mm->mmap = next;
- if (next)
- next->vm_prev = prev;
- }
- /* 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));
- }
- #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
- }
- #ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
- unsigned long 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;
- }
- EXPORT_SYMBOL_GPL(arch_mmap_rnd);
- 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);
- }
- trace_android_vh_check_mmap_file(file, prot, flag, ret);
- 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.
- *
- * Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
- * __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
- * preferable to the vmalloc fallback, due to visible performance drawbacks.
- *
- * Please note that any use of gfp flags outside of GFP_KERNEL is careful to not
- * fall back to vmalloc.
- *
- * 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;
- /*
- * vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
- * so the given set of flags has to be compatible.
- */
- if ((flags & GFP_KERNEL) != GFP_KERNEL)
- return kmalloc_node(size, flags, node);
- /*
- * 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;
- }
- 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;
- /* Don't even allow crazy sizes */
- if (unlikely(size > INT_MAX)) {
- WARN_ON_ONCE(!(flags & __GFP_NOWARN));
- return NULL;
- }
- return __vmalloc_node(size, 1, flags, 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);
- 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);
- }
- /*
- * Return true if this page is mapped into pagetables.
- * For compound page it returns true if any subpage of compound page is mapped.
- */
- bool page_mapped(struct page *page)
- {
- int i;
- if (likely(!PageCompound(page)))
- return atomic_read(&page->_mapcount) >= 0;
- page = compound_head(page);
- if (atomic_read(compound_mapcount_ptr(page)) >= 0)
- return true;
- if (PageHuge(page))
- return false;
- for (i = 0; i < compound_nr(page); i++) {
- if (atomic_read(&page[i]._mapcount) >= 0)
- return true;
- }
- return false;
- }
- EXPORT_SYMBOL(page_mapped);
- 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)
- {
- struct address_space *mapping;
- page = compound_head(page);
- /* 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 = page->mapping;
- if ((unsigned long)mapping & PAGE_MAPPING_ANON)
- return NULL;
- return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
- }
- EXPORT_SYMBOL(page_mapping);
- /*
- * For file cache pages, return the address_space, otherwise return NULL
- */
- struct address_space *page_mapping_file(struct page *page)
- {
- if (unlikely(PageSwapCache(page)))
- return NULL;
- return page_mapping(page);
- }
- /* 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);
- 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 condtion (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/vm/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:
- 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;
- }
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