diff options
Diffstat (limited to 'drivers/android/binder_alloc.c')
| -rw-r--r-- | drivers/android/binder_alloc.c | 1286 |
1 files changed, 1286 insertions, 0 deletions
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c new file mode 100644 index 000000000..fcbb750b1 --- /dev/null +++ b/drivers/android/binder_alloc.c @@ -0,0 +1,1286 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* binder_alloc.c + * + * Android IPC Subsystem + * + * Copyright (C) 2007-2017 Google, Inc. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/list.h> +#include <linux/sched/mm.h> +#include <linux/module.h> +#include <linux/rtmutex.h> +#include <linux/rbtree.h> +#include <linux/seq_file.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/list_lru.h> +#include <linux/ratelimit.h> +#include <asm/cacheflush.h> +#include <linux/uaccess.h> +#include <linux/highmem.h> +#include <linux/sizes.h> +#include "binder_alloc.h" +#include "binder_trace.h" + +struct list_lru binder_alloc_lru; + +static DEFINE_MUTEX(binder_alloc_mmap_lock); + +enum { + BINDER_DEBUG_USER_ERROR = 1U << 0, + BINDER_DEBUG_OPEN_CLOSE = 1U << 1, + BINDER_DEBUG_BUFFER_ALLOC = 1U << 2, + BINDER_DEBUG_BUFFER_ALLOC_ASYNC = 1U << 3, +}; +static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR; + +module_param_named(debug_mask, binder_alloc_debug_mask, + uint, 0644); + +#define binder_alloc_debug(mask, x...) \ + do { \ + if (binder_alloc_debug_mask & mask) \ + pr_info_ratelimited(x); \ + } while (0) + +static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer) +{ + return list_entry(buffer->entry.next, struct binder_buffer, entry); +} + +static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer) +{ + return list_entry(buffer->entry.prev, struct binder_buffer, entry); +} + +static size_t binder_alloc_buffer_size(struct binder_alloc *alloc, + struct binder_buffer *buffer) +{ + if (list_is_last(&buffer->entry, &alloc->buffers)) + return alloc->buffer + alloc->buffer_size - buffer->user_data; + return binder_buffer_next(buffer)->user_data - buffer->user_data; +} + +static void binder_insert_free_buffer(struct binder_alloc *alloc, + struct binder_buffer *new_buffer) +{ + struct rb_node **p = &alloc->free_buffers.rb_node; + struct rb_node *parent = NULL; + struct binder_buffer *buffer; + size_t buffer_size; + size_t new_buffer_size; + + BUG_ON(!new_buffer->free); + + new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer); + + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: add free buffer, size %zd, at %pK\n", + alloc->pid, new_buffer_size, new_buffer); + + while (*p) { + parent = *p; + buffer = rb_entry(parent, struct binder_buffer, rb_node); + BUG_ON(!buffer->free); + + buffer_size = binder_alloc_buffer_size(alloc, buffer); + + if (new_buffer_size < buffer_size) + p = &parent->rb_left; + else + p = &parent->rb_right; + } + rb_link_node(&new_buffer->rb_node, parent, p); + rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers); +} + +static void binder_insert_allocated_buffer_locked( + struct binder_alloc *alloc, struct binder_buffer *new_buffer) +{ + struct rb_node **p = &alloc->allocated_buffers.rb_node; + struct rb_node *parent = NULL; + struct binder_buffer *buffer; + + BUG_ON(new_buffer->free); + + while (*p) { + parent = *p; + buffer = rb_entry(parent, struct binder_buffer, rb_node); + BUG_ON(buffer->free); + + if (new_buffer->user_data < buffer->user_data) + p = &parent->rb_left; + else if (new_buffer->user_data > buffer->user_data) + p = &parent->rb_right; + else + BUG(); + } + rb_link_node(&new_buffer->rb_node, parent, p); + rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers); +} + +static struct binder_buffer *binder_alloc_prepare_to_free_locked( + struct binder_alloc *alloc, + uintptr_t user_ptr) +{ + struct rb_node *n = alloc->allocated_buffers.rb_node; + struct binder_buffer *buffer; + void __user *uptr; + + uptr = (void __user *)user_ptr; + + while (n) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + BUG_ON(buffer->free); + + if (uptr < buffer->user_data) + n = n->rb_left; + else if (uptr > buffer->user_data) + n = n->rb_right; + else { + /* + * Guard against user threads attempting to + * free the buffer when in use by kernel or + * after it's already been freed. + */ + if (!buffer->allow_user_free) + return ERR_PTR(-EPERM); + buffer->allow_user_free = 0; + return buffer; + } + } + return NULL; +} + +/** + * binder_alloc_prepare_to_free() - get buffer given user ptr + * @alloc: binder_alloc for this proc + * @user_ptr: User pointer to buffer data + * + * Validate userspace pointer to buffer data and return buffer corresponding to + * that user pointer. Search the rb tree for buffer that matches user data + * pointer. + * + * Return: Pointer to buffer or NULL + */ +struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc, + uintptr_t user_ptr) +{ + struct binder_buffer *buffer; + + mutex_lock(&alloc->mutex); + buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr); + mutex_unlock(&alloc->mutex); + return buffer; +} + +static int binder_update_page_range(struct binder_alloc *alloc, int allocate, + void __user *start, void __user *end) +{ + void __user *page_addr; + unsigned long user_page_addr; + struct binder_lru_page *page; + struct vm_area_struct *vma = NULL; + struct mm_struct *mm = NULL; + bool need_mm = false; + + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: %s pages %pK-%pK\n", alloc->pid, + allocate ? "allocate" : "free", start, end); + + if (end <= start) + return 0; + + trace_binder_update_page_range(alloc, allocate, start, end); + + if (allocate == 0) + goto free_range; + + for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) { + page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE]; + if (!page->page_ptr) { + need_mm = true; + break; + } + } + + if (need_mm && mmget_not_zero(alloc->mm)) + mm = alloc->mm; + + if (mm) { + mmap_write_lock(mm); + vma = alloc->vma; + } + + if (!vma && need_mm) { + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "%d: binder_alloc_buf failed to map pages in userspace, no vma\n", + alloc->pid); + goto err_no_vma; + } + + for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) { + int ret; + bool on_lru; + size_t index; + + index = (page_addr - alloc->buffer) / PAGE_SIZE; + page = &alloc->pages[index]; + + if (page->page_ptr) { + trace_binder_alloc_lru_start(alloc, index); + + on_lru = list_lru_del(&binder_alloc_lru, &page->lru); + WARN_ON(!on_lru); + + trace_binder_alloc_lru_end(alloc, index); + continue; + } + + if (WARN_ON(!vma)) + goto err_page_ptr_cleared; + + trace_binder_alloc_page_start(alloc, index); + page->page_ptr = alloc_page(GFP_KERNEL | + __GFP_HIGHMEM | + __GFP_ZERO); + if (!page->page_ptr) { + pr_err("%d: binder_alloc_buf failed for page at %pK\n", + alloc->pid, page_addr); + goto err_alloc_page_failed; + } + page->alloc = alloc; + INIT_LIST_HEAD(&page->lru); + + user_page_addr = (uintptr_t)page_addr; + ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr); + if (ret) { + pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n", + alloc->pid, user_page_addr); + goto err_vm_insert_page_failed; + } + + if (index + 1 > alloc->pages_high) + alloc->pages_high = index + 1; + + trace_binder_alloc_page_end(alloc, index); + } + if (mm) { + mmap_write_unlock(mm); + mmput_async(mm); + } + return 0; + +free_range: + for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) { + bool ret; + size_t index; + + index = (page_addr - alloc->buffer) / PAGE_SIZE; + page = &alloc->pages[index]; + + trace_binder_free_lru_start(alloc, index); + + ret = list_lru_add(&binder_alloc_lru, &page->lru); + WARN_ON(!ret); + + trace_binder_free_lru_end(alloc, index); + if (page_addr == start) + break; + continue; + +err_vm_insert_page_failed: + __free_page(page->page_ptr); + page->page_ptr = NULL; +err_alloc_page_failed: +err_page_ptr_cleared: + if (page_addr == start) + break; + } +err_no_vma: + if (mm) { + mmap_write_unlock(mm); + mmput_async(mm); + } + return vma ? -ENOMEM : -ESRCH; +} + +static inline void binder_alloc_set_vma(struct binder_alloc *alloc, + struct vm_area_struct *vma) +{ + /* pairs with smp_load_acquire in binder_alloc_get_vma() */ + smp_store_release(&alloc->vma, vma); +} + +static inline struct vm_area_struct *binder_alloc_get_vma( + struct binder_alloc *alloc) +{ + /* pairs with smp_store_release in binder_alloc_set_vma() */ + return smp_load_acquire(&alloc->vma); +} + +static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid) +{ + /* + * Find the amount and size of buffers allocated by the current caller; + * The idea is that once we cross the threshold, whoever is responsible + * for the low async space is likely to try to send another async txn, + * and at some point we'll catch them in the act. This is more efficient + * than keeping a map per pid. + */ + struct rb_node *n; + struct binder_buffer *buffer; + size_t total_alloc_size = 0; + size_t num_buffers = 0; + + for (n = rb_first(&alloc->allocated_buffers); n != NULL; + n = rb_next(n)) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + if (buffer->pid != pid) + continue; + if (!buffer->async_transaction) + continue; + total_alloc_size += binder_alloc_buffer_size(alloc, buffer); + num_buffers++; + } + + /* + * Warn if this pid has more than 50 transactions, or more than 50% of + * async space (which is 25% of total buffer size). Oneway spam is only + * detected when the threshold is exceeded. + */ + if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) { + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n", + alloc->pid, pid, num_buffers, total_alloc_size); + if (!alloc->oneway_spam_detected) { + alloc->oneway_spam_detected = true; + return true; + } + } + return false; +} + +static struct binder_buffer *binder_alloc_new_buf_locked( + struct binder_alloc *alloc, + size_t data_size, + size_t offsets_size, + size_t extra_buffers_size, + int is_async, + int pid) +{ + struct rb_node *n = alloc->free_buffers.rb_node; + struct binder_buffer *buffer; + size_t buffer_size; + struct rb_node *best_fit = NULL; + void __user *has_page_addr; + void __user *end_page_addr; + size_t size, data_offsets_size; + int ret; + + /* Check binder_alloc is fully initialized */ + if (!binder_alloc_get_vma(alloc)) { + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "%d: binder_alloc_buf, no vma\n", + alloc->pid); + return ERR_PTR(-ESRCH); + } + + data_offsets_size = ALIGN(data_size, sizeof(void *)) + + ALIGN(offsets_size, sizeof(void *)); + + if (data_offsets_size < data_size || data_offsets_size < offsets_size) { + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: got transaction with invalid size %zd-%zd\n", + alloc->pid, data_size, offsets_size); + return ERR_PTR(-EINVAL); + } + size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *)); + if (size < data_offsets_size || size < extra_buffers_size) { + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: got transaction with invalid extra_buffers_size %zd\n", + alloc->pid, extra_buffers_size); + return ERR_PTR(-EINVAL); + } + + /* Pad 0-size buffers so they get assigned unique addresses */ + size = max(size, sizeof(void *)); + + if (is_async && alloc->free_async_space < size) { + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: binder_alloc_buf size %zd failed, no async space left\n", + alloc->pid, size); + return ERR_PTR(-ENOSPC); + } + + while (n) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + BUG_ON(!buffer->free); + buffer_size = binder_alloc_buffer_size(alloc, buffer); + + if (size < buffer_size) { + best_fit = n; + n = n->rb_left; + } else if (size > buffer_size) + n = n->rb_right; + else { + best_fit = n; + break; + } + } + if (best_fit == NULL) { + size_t allocated_buffers = 0; + size_t largest_alloc_size = 0; + size_t total_alloc_size = 0; + size_t free_buffers = 0; + size_t largest_free_size = 0; + size_t total_free_size = 0; + + for (n = rb_first(&alloc->allocated_buffers); n != NULL; + n = rb_next(n)) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + buffer_size = binder_alloc_buffer_size(alloc, buffer); + allocated_buffers++; + total_alloc_size += buffer_size; + if (buffer_size > largest_alloc_size) + largest_alloc_size = buffer_size; + } + for (n = rb_first(&alloc->free_buffers); n != NULL; + n = rb_next(n)) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + buffer_size = binder_alloc_buffer_size(alloc, buffer); + free_buffers++; + total_free_size += buffer_size; + if (buffer_size > largest_free_size) + largest_free_size = buffer_size; + } + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "%d: binder_alloc_buf size %zd failed, no address space\n", + alloc->pid, size); + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n", + total_alloc_size, allocated_buffers, + largest_alloc_size, total_free_size, + free_buffers, largest_free_size); + return ERR_PTR(-ENOSPC); + } + if (n == NULL) { + buffer = rb_entry(best_fit, struct binder_buffer, rb_node); + buffer_size = binder_alloc_buffer_size(alloc, buffer); + } + + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n", + alloc->pid, size, buffer, buffer_size); + + has_page_addr = (void __user *) + (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK); + WARN_ON(n && buffer_size != size); + end_page_addr = + (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size); + if (end_page_addr > has_page_addr) + end_page_addr = has_page_addr; + ret = binder_update_page_range(alloc, 1, (void __user *) + PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr); + if (ret) + return ERR_PTR(ret); + + if (buffer_size != size) { + struct binder_buffer *new_buffer; + + new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!new_buffer) { + pr_err("%s: %d failed to alloc new buffer struct\n", + __func__, alloc->pid); + goto err_alloc_buf_struct_failed; + } + new_buffer->user_data = (u8 __user *)buffer->user_data + size; + list_add(&new_buffer->entry, &buffer->entry); + new_buffer->free = 1; + binder_insert_free_buffer(alloc, new_buffer); + } + + rb_erase(best_fit, &alloc->free_buffers); + buffer->free = 0; + buffer->allow_user_free = 0; + binder_insert_allocated_buffer_locked(alloc, buffer); + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: binder_alloc_buf size %zd got %pK\n", + alloc->pid, size, buffer); + buffer->data_size = data_size; + buffer->offsets_size = offsets_size; + buffer->async_transaction = is_async; + buffer->extra_buffers_size = extra_buffers_size; + buffer->pid = pid; + buffer->oneway_spam_suspect = false; + if (is_async) { + alloc->free_async_space -= size; + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC, + "%d: binder_alloc_buf size %zd async free %zd\n", + alloc->pid, size, alloc->free_async_space); + if (alloc->free_async_space < alloc->buffer_size / 10) { + /* + * Start detecting spammers once we have less than 20% + * of async space left (which is less than 10% of total + * buffer size). + */ + buffer->oneway_spam_suspect = debug_low_async_space_locked(alloc, pid); + } else { + alloc->oneway_spam_detected = false; + } + } + return buffer; + +err_alloc_buf_struct_failed: + binder_update_page_range(alloc, 0, (void __user *) + PAGE_ALIGN((uintptr_t)buffer->user_data), + end_page_addr); + return ERR_PTR(-ENOMEM); +} + +/** + * binder_alloc_new_buf() - Allocate a new binder buffer + * @alloc: binder_alloc for this proc + * @data_size: size of user data buffer + * @offsets_size: user specified buffer offset + * @extra_buffers_size: size of extra space for meta-data (eg, security context) + * @is_async: buffer for async transaction + * @pid: pid to attribute allocation to (used for debugging) + * + * Allocate a new buffer given the requested sizes. Returns + * the kernel version of the buffer pointer. The size allocated + * is the sum of the three given sizes (each rounded up to + * pointer-sized boundary) + * + * Return: The allocated buffer or %ERR_PTR(-errno) if error + */ +struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc, + size_t data_size, + size_t offsets_size, + size_t extra_buffers_size, + int is_async, + int pid) +{ + struct binder_buffer *buffer; + + mutex_lock(&alloc->mutex); + buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size, + extra_buffers_size, is_async, pid); + mutex_unlock(&alloc->mutex); + return buffer; +} + +static void __user *buffer_start_page(struct binder_buffer *buffer) +{ + return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK); +} + +static void __user *prev_buffer_end_page(struct binder_buffer *buffer) +{ + return (void __user *) + (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK); +} + +static void binder_delete_free_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer) +{ + struct binder_buffer *prev, *next = NULL; + bool to_free = true; + + BUG_ON(alloc->buffers.next == &buffer->entry); + prev = binder_buffer_prev(buffer); + BUG_ON(!prev->free); + if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) { + to_free = false; + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: merge free, buffer %pK share page with %pK\n", + alloc->pid, buffer->user_data, + prev->user_data); + } + + if (!list_is_last(&buffer->entry, &alloc->buffers)) { + next = binder_buffer_next(buffer); + if (buffer_start_page(next) == buffer_start_page(buffer)) { + to_free = false; + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: merge free, buffer %pK share page with %pK\n", + alloc->pid, + buffer->user_data, + next->user_data); + } + } + + if (PAGE_ALIGNED(buffer->user_data)) { + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: merge free, buffer start %pK is page aligned\n", + alloc->pid, buffer->user_data); + to_free = false; + } + + if (to_free) { + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: merge free, buffer %pK do not share page with %pK or %pK\n", + alloc->pid, buffer->user_data, + prev->user_data, + next ? next->user_data : NULL); + binder_update_page_range(alloc, 0, buffer_start_page(buffer), + buffer_start_page(buffer) + PAGE_SIZE); + } + list_del(&buffer->entry); + kfree(buffer); +} + +static void binder_free_buf_locked(struct binder_alloc *alloc, + struct binder_buffer *buffer) +{ + size_t size, buffer_size; + + buffer_size = binder_alloc_buffer_size(alloc, buffer); + + size = ALIGN(buffer->data_size, sizeof(void *)) + + ALIGN(buffer->offsets_size, sizeof(void *)) + + ALIGN(buffer->extra_buffers_size, sizeof(void *)); + + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%d: binder_free_buf %pK size %zd buffer_size %zd\n", + alloc->pid, buffer, size, buffer_size); + + BUG_ON(buffer->free); + BUG_ON(size > buffer_size); + BUG_ON(buffer->transaction != NULL); + BUG_ON(buffer->user_data < alloc->buffer); + BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size); + + if (buffer->async_transaction) { + alloc->free_async_space += buffer_size; + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC, + "%d: binder_free_buf size %zd async free %zd\n", + alloc->pid, size, alloc->free_async_space); + } + + binder_update_page_range(alloc, 0, + (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data), + (void __user *)(((uintptr_t) + buffer->user_data + buffer_size) & PAGE_MASK)); + + rb_erase(&buffer->rb_node, &alloc->allocated_buffers); + buffer->free = 1; + if (!list_is_last(&buffer->entry, &alloc->buffers)) { + struct binder_buffer *next = binder_buffer_next(buffer); + + if (next->free) { + rb_erase(&next->rb_node, &alloc->free_buffers); + binder_delete_free_buffer(alloc, next); + } + } + if (alloc->buffers.next != &buffer->entry) { + struct binder_buffer *prev = binder_buffer_prev(buffer); + + if (prev->free) { + binder_delete_free_buffer(alloc, buffer); + rb_erase(&prev->rb_node, &alloc->free_buffers); + buffer = prev; + } + } + binder_insert_free_buffer(alloc, buffer); +} + +static void binder_alloc_clear_buf(struct binder_alloc *alloc, + struct binder_buffer *buffer); +/** + * binder_alloc_free_buf() - free a binder buffer + * @alloc: binder_alloc for this proc + * @buffer: kernel pointer to buffer + * + * Free the buffer allocated via binder_alloc_new_buf() + */ +void binder_alloc_free_buf(struct binder_alloc *alloc, + struct binder_buffer *buffer) +{ + /* + * We could eliminate the call to binder_alloc_clear_buf() + * from binder_alloc_deferred_release() by moving this to + * binder_free_buf_locked(). However, that could + * increase contention for the alloc mutex if clear_on_free + * is used frequently for large buffers. The mutex is not + * needed for correctness here. + */ + if (buffer->clear_on_free) { + binder_alloc_clear_buf(alloc, buffer); + buffer->clear_on_free = false; + } + mutex_lock(&alloc->mutex); + binder_free_buf_locked(alloc, buffer); + mutex_unlock(&alloc->mutex); +} + +/** + * binder_alloc_mmap_handler() - map virtual address space for proc + * @alloc: alloc structure for this proc + * @vma: vma passed to mmap() + * + * Called by binder_mmap() to initialize the space specified in + * vma for allocating binder buffers + * + * Return: + * 0 = success + * -EBUSY = address space already mapped + * -ENOMEM = failed to map memory to given address space + */ +int binder_alloc_mmap_handler(struct binder_alloc *alloc, + struct vm_area_struct *vma) +{ + int ret; + const char *failure_string; + struct binder_buffer *buffer; + + if (unlikely(vma->vm_mm != alloc->mm)) { + ret = -EINVAL; + failure_string = "invalid vma->vm_mm"; + goto err_invalid_mm; + } + + mutex_lock(&binder_alloc_mmap_lock); + if (alloc->buffer_size) { + ret = -EBUSY; + failure_string = "already mapped"; + goto err_already_mapped; + } + alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start, + SZ_4M); + mutex_unlock(&binder_alloc_mmap_lock); + + alloc->buffer = (void __user *)vma->vm_start; + + alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE, + sizeof(alloc->pages[0]), + GFP_KERNEL); + if (alloc->pages == NULL) { + ret = -ENOMEM; + failure_string = "alloc page array"; + goto err_alloc_pages_failed; + } + + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!buffer) { + ret = -ENOMEM; + failure_string = "alloc buffer struct"; + goto err_alloc_buf_struct_failed; + } + + buffer->user_data = alloc->buffer; + list_add(&buffer->entry, &alloc->buffers); + buffer->free = 1; + binder_insert_free_buffer(alloc, buffer); + alloc->free_async_space = alloc->buffer_size / 2; + + /* Signal binder_alloc is fully initialized */ + binder_alloc_set_vma(alloc, vma); + + return 0; + +err_alloc_buf_struct_failed: + kfree(alloc->pages); + alloc->pages = NULL; +err_alloc_pages_failed: + alloc->buffer = NULL; + mutex_lock(&binder_alloc_mmap_lock); + alloc->buffer_size = 0; +err_already_mapped: + mutex_unlock(&binder_alloc_mmap_lock); +err_invalid_mm: + binder_alloc_debug(BINDER_DEBUG_USER_ERROR, + "%s: %d %lx-%lx %s failed %d\n", __func__, + alloc->pid, vma->vm_start, vma->vm_end, + failure_string, ret); + return ret; +} + + +void binder_alloc_deferred_release(struct binder_alloc *alloc) +{ + struct rb_node *n; + int buffers, page_count; + struct binder_buffer *buffer; + + buffers = 0; + mutex_lock(&alloc->mutex); + BUG_ON(alloc->vma); + + while ((n = rb_first(&alloc->allocated_buffers))) { + buffer = rb_entry(n, struct binder_buffer, rb_node); + + /* Transaction should already have been freed */ + BUG_ON(buffer->transaction); + + if (buffer->clear_on_free) { + binder_alloc_clear_buf(alloc, buffer); + buffer->clear_on_free = false; + } + binder_free_buf_locked(alloc, buffer); + buffers++; + } + + while (!list_empty(&alloc->buffers)) { + buffer = list_first_entry(&alloc->buffers, + struct binder_buffer, entry); + WARN_ON(!buffer->free); + + list_del(&buffer->entry); + WARN_ON_ONCE(!list_empty(&alloc->buffers)); + kfree(buffer); + } + + page_count = 0; + if (alloc->pages) { + int i; + + for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) { + void __user *page_addr; + bool on_lru; + + if (!alloc->pages[i].page_ptr) + continue; + + on_lru = list_lru_del(&binder_alloc_lru, + &alloc->pages[i].lru); + page_addr = alloc->buffer + i * PAGE_SIZE; + binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, + "%s: %d: page %d at %pK %s\n", + __func__, alloc->pid, i, page_addr, + on_lru ? "on lru" : "active"); + __free_page(alloc->pages[i].page_ptr); + page_count++; + } + kfree(alloc->pages); + } + mutex_unlock(&alloc->mutex); + if (alloc->mm) + mmdrop(alloc->mm); + + binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE, + "%s: %d buffers %d, pages %d\n", + __func__, alloc->pid, buffers, page_count); +} + +static void print_binder_buffer(struct seq_file *m, const char *prefix, + struct binder_buffer *buffer) +{ + seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n", + prefix, buffer->debug_id, buffer->user_data, + buffer->data_size, buffer->offsets_size, + buffer->extra_buffers_size, + buffer->transaction ? "active" : "delivered"); +} + +/** + * binder_alloc_print_allocated() - print buffer info + * @m: seq_file for output via seq_printf() + * @alloc: binder_alloc for this proc + * + * Prints information about every buffer associated with + * the binder_alloc state to the given seq_file + */ +void binder_alloc_print_allocated(struct seq_file *m, + struct binder_alloc *alloc) +{ + struct rb_node *n; + + mutex_lock(&alloc->mutex); + for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n)) + print_binder_buffer(m, " buffer", + rb_entry(n, struct binder_buffer, rb_node)); + mutex_unlock(&alloc->mutex); +} + +/** + * binder_alloc_print_pages() - print page usage + * @m: seq_file for output via seq_printf() + * @alloc: binder_alloc for this proc + */ +void binder_alloc_print_pages(struct seq_file *m, + struct binder_alloc *alloc) +{ + struct binder_lru_page *page; + int i; + int active = 0; + int lru = 0; + int free = 0; + + mutex_lock(&alloc->mutex); + /* + * Make sure the binder_alloc is fully initialized, otherwise we might + * read inconsistent state. + */ + if (binder_alloc_get_vma(alloc) != NULL) { + for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) { + page = &alloc->pages[i]; + if (!page->page_ptr) + free++; + else if (list_empty(&page->lru)) + active++; + else + lru++; + } + } + mutex_unlock(&alloc->mutex); + seq_printf(m, " pages: %d:%d:%d\n", active, lru, free); + seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high); +} + +/** + * binder_alloc_get_allocated_count() - return count of buffers + * @alloc: binder_alloc for this proc + * + * Return: count of allocated buffers + */ +int binder_alloc_get_allocated_count(struct binder_alloc *alloc) +{ + struct rb_node *n; + int count = 0; + + mutex_lock(&alloc->mutex); + for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n)) + count++; + mutex_unlock(&alloc->mutex); + return count; +} + + +/** + * binder_alloc_vma_close() - invalidate address space + * @alloc: binder_alloc for this proc + * + * Called from binder_vma_close() when releasing address space. + * Clears alloc->vma to prevent new incoming transactions from + * allocating more buffers. + */ +void binder_alloc_vma_close(struct binder_alloc *alloc) +{ + binder_alloc_set_vma(alloc, NULL); +} + +/** + * binder_alloc_free_page() - shrinker callback to free pages + * @item: item to free + * @lock: lock protecting the item + * @cb_arg: callback argument + * + * Called from list_lru_walk() in binder_shrink_scan() to free + * up pages when the system is under memory pressure. + */ +enum lru_status binder_alloc_free_page(struct list_head *item, + struct list_lru_one *lru, + spinlock_t *lock, + void *cb_arg) + __must_hold(lock) +{ + struct mm_struct *mm = NULL; + struct binder_lru_page *page = container_of(item, + struct binder_lru_page, + lru); + struct binder_alloc *alloc; + uintptr_t page_addr; + size_t index; + struct vm_area_struct *vma; + + alloc = page->alloc; + if (!mutex_trylock(&alloc->mutex)) + goto err_get_alloc_mutex_failed; + + if (!page->page_ptr) + goto err_page_already_freed; + + index = page - alloc->pages; + page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; + + mm = alloc->mm; + if (!mmget_not_zero(mm)) + goto err_mmget; + if (!mmap_read_trylock(mm)) + goto err_mmap_read_lock_failed; + vma = vma_lookup(mm, page_addr); + if (vma && vma != binder_alloc_get_vma(alloc)) + goto err_invalid_vma; + + list_lru_isolate(lru, item); + spin_unlock(lock); + + if (vma) { + trace_binder_unmap_user_start(alloc, index); + + zap_page_range(vma, page_addr, PAGE_SIZE); + + trace_binder_unmap_user_end(alloc, index); + } + mmap_read_unlock(mm); + mmput_async(mm); + + trace_binder_unmap_kernel_start(alloc, index); + + __free_page(page->page_ptr); + page->page_ptr = NULL; + + trace_binder_unmap_kernel_end(alloc, index); + + spin_lock(lock); + mutex_unlock(&alloc->mutex); + return LRU_REMOVED_RETRY; + +err_invalid_vma: + mmap_read_unlock(mm); +err_mmap_read_lock_failed: + mmput_async(mm); +err_mmget: +err_page_already_freed: + mutex_unlock(&alloc->mutex); +err_get_alloc_mutex_failed: + return LRU_SKIP; +} + +static unsigned long +binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +{ + return list_lru_count(&binder_alloc_lru); +} + +static unsigned long +binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + return list_lru_walk(&binder_alloc_lru, binder_alloc_free_page, + NULL, sc->nr_to_scan); +} + +static struct shrinker binder_shrinker = { + .count_objects = binder_shrink_count, + .scan_objects = binder_shrink_scan, + .seeks = DEFAULT_SEEKS, +}; + +/** + * binder_alloc_init() - called by binder_open() for per-proc initialization + * @alloc: binder_alloc for this proc + * + * Called from binder_open() to initialize binder_alloc fields for + * new binder proc + */ +void binder_alloc_init(struct binder_alloc *alloc) +{ + alloc->pid = current->group_leader->pid; + alloc->mm = current->mm; + mmgrab(alloc->mm); + mutex_init(&alloc->mutex); + INIT_LIST_HEAD(&alloc->buffers); +} + +int binder_alloc_shrinker_init(void) +{ + int ret = list_lru_init(&binder_alloc_lru); + + if (ret == 0) { + ret = register_shrinker(&binder_shrinker, "android-binder"); + if (ret) + list_lru_destroy(&binder_alloc_lru); + } + return ret; +} + +void binder_alloc_shrinker_exit(void) +{ + unregister_shrinker(&binder_shrinker); + list_lru_destroy(&binder_alloc_lru); +} + +/** + * check_buffer() - verify that buffer/offset is safe to access + * @alloc: binder_alloc for this proc + * @buffer: binder buffer to be accessed + * @offset: offset into @buffer data + * @bytes: bytes to access from offset + * + * Check that the @offset/@bytes are within the size of the given + * @buffer and that the buffer is currently active and not freeable. + * Offsets must also be multiples of sizeof(u32). The kernel is + * allowed to touch the buffer in two cases: + * + * 1) when the buffer is being created: + * (buffer->free == 0 && buffer->allow_user_free == 0) + * 2) when the buffer is being torn down: + * (buffer->free == 0 && buffer->transaction == NULL). + * + * Return: true if the buffer is safe to access + */ +static inline bool check_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t offset, size_t bytes) +{ + size_t buffer_size = binder_alloc_buffer_size(alloc, buffer); + + return buffer_size >= bytes && + offset <= buffer_size - bytes && + IS_ALIGNED(offset, sizeof(u32)) && + !buffer->free && + (!buffer->allow_user_free || !buffer->transaction); +} + +/** + * binder_alloc_get_page() - get kernel pointer for given buffer offset + * @alloc: binder_alloc for this proc + * @buffer: binder buffer to be accessed + * @buffer_offset: offset into @buffer data + * @pgoffp: address to copy final page offset to + * + * Lookup the struct page corresponding to the address + * at @buffer_offset into @buffer->user_data. If @pgoffp is not + * NULL, the byte-offset into the page is written there. + * + * The caller is responsible to ensure that the offset points + * to a valid address within the @buffer and that @buffer is + * not freeable by the user. Since it can't be freed, we are + * guaranteed that the corresponding elements of @alloc->pages[] + * cannot change. + * + * Return: struct page + */ +static struct page *binder_alloc_get_page(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + pgoff_t *pgoffp) +{ + binder_size_t buffer_space_offset = buffer_offset + + (buffer->user_data - alloc->buffer); + pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK; + size_t index = buffer_space_offset >> PAGE_SHIFT; + struct binder_lru_page *lru_page; + + lru_page = &alloc->pages[index]; + *pgoffp = pgoff; + return lru_page->page_ptr; +} + +/** + * binder_alloc_clear_buf() - zero out buffer + * @alloc: binder_alloc for this proc + * @buffer: binder buffer to be cleared + * + * memset the given buffer to 0 + */ +static void binder_alloc_clear_buf(struct binder_alloc *alloc, + struct binder_buffer *buffer) +{ + size_t bytes = binder_alloc_buffer_size(alloc, buffer); + binder_size_t buffer_offset = 0; + + while (bytes) { + unsigned long size; + struct page *page; + pgoff_t pgoff; + + page = binder_alloc_get_page(alloc, buffer, + buffer_offset, &pgoff); + size = min_t(size_t, bytes, PAGE_SIZE - pgoff); + memset_page(page, pgoff, 0, size); + bytes -= size; + buffer_offset += size; + } +} + +/** + * binder_alloc_copy_user_to_buffer() - copy src user to tgt user + * @alloc: binder_alloc for this proc + * @buffer: binder buffer to be accessed + * @buffer_offset: offset into @buffer data + * @from: userspace pointer to source buffer + * @bytes: bytes to copy + * + * Copy bytes from source userspace to target buffer. + * + * Return: bytes remaining to be copied + */ +unsigned long +binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + const void __user *from, + size_t bytes) +{ + if (!check_buffer(alloc, buffer, buffer_offset, bytes)) + return bytes; + + while (bytes) { + unsigned long size; + unsigned long ret; + struct page *page; + pgoff_t pgoff; + void *kptr; + + page = binder_alloc_get_page(alloc, buffer, + buffer_offset, &pgoff); + size = min_t(size_t, bytes, PAGE_SIZE - pgoff); + kptr = kmap_local_page(page) + pgoff; + ret = copy_from_user(kptr, from, size); + kunmap_local(kptr); + if (ret) + return bytes - size + ret; + bytes -= size; + from += size; + buffer_offset += size; + } + return 0; +} + +static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc, + bool to_buffer, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + void *ptr, + size_t bytes) +{ + /* All copies must be 32-bit aligned and 32-bit size */ + if (!check_buffer(alloc, buffer, buffer_offset, bytes)) + return -EINVAL; + + while (bytes) { + unsigned long size; + struct page *page; + pgoff_t pgoff; + + page = binder_alloc_get_page(alloc, buffer, + buffer_offset, &pgoff); + size = min_t(size_t, bytes, PAGE_SIZE - pgoff); + if (to_buffer) + memcpy_to_page(page, pgoff, ptr, size); + else + memcpy_from_page(ptr, page, pgoff, size); + bytes -= size; + pgoff = 0; + ptr = ptr + size; + buffer_offset += size; + } + return 0; +} + +int binder_alloc_copy_to_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + void *src, + size_t bytes) +{ + return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset, + src, bytes); +} + +int binder_alloc_copy_from_buffer(struct binder_alloc *alloc, + void *dest, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + size_t bytes) +{ + return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset, + dest, bytes); +} + |