1 // SPDX-License-Identifier: GPL-2.0-only 2 /* binder_alloc.c 3 * 4 * Android IPC Subsystem 5 * 6 * Copyright (C) 2007-2017 Google, Inc. 7 */ 8 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 11 #include <linux/list.h> 12 #include <linux/sched/mm.h> 13 #include <linux/module.h> 14 #include <linux/rtmutex.h> 15 #include <linux/rbtree.h> 16 #include <linux/seq_file.h> 17 #include <linux/vmalloc.h> 18 #include <linux/slab.h> 19 #include <linux/sched.h> 20 #include <linux/list_lru.h> 21 #include <linux/ratelimit.h> 22 #include <asm/cacheflush.h> 23 #include <linux/uaccess.h> 24 #include <linux/highmem.h> 25 #include <linux/sizes.h> 26 #include "binder_alloc.h" 27 #include "binder_trace.h" 28 29 struct list_lru binder_alloc_lru; 30 31 static DEFINE_MUTEX(binder_alloc_mmap_lock); 32 33 enum { 34 BINDER_DEBUG_USER_ERROR = 1U << 0, 35 BINDER_DEBUG_OPEN_CLOSE = 1U << 1, 36 BINDER_DEBUG_BUFFER_ALLOC = 1U << 2, 37 BINDER_DEBUG_BUFFER_ALLOC_ASYNC = 1U << 3, 38 }; 39 static uint32_t binder_alloc_debug_mask = BINDER_DEBUG_USER_ERROR; 40 41 module_param_named(debug_mask, binder_alloc_debug_mask, 42 uint, 0644); 43 44 #define binder_alloc_debug(mask, x...) \ 45 do { \ 46 if (binder_alloc_debug_mask & mask) \ 47 pr_info_ratelimited(x); \ 48 } while (0) 49 50 static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer) 51 { 52 return list_entry(buffer->entry.next, struct binder_buffer, entry); 53 } 54 55 static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer) 56 { 57 return list_entry(buffer->entry.prev, struct binder_buffer, entry); 58 } 59 60 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc, 61 struct binder_buffer *buffer) 62 { 63 if (list_is_last(&buffer->entry, &alloc->buffers)) 64 return alloc->buffer + alloc->buffer_size - buffer->user_data; 65 return binder_buffer_next(buffer)->user_data - buffer->user_data; 66 } 67 68 static void binder_insert_free_buffer(struct binder_alloc *alloc, 69 struct binder_buffer *new_buffer) 70 { 71 struct rb_node **p = &alloc->free_buffers.rb_node; 72 struct rb_node *parent = NULL; 73 struct binder_buffer *buffer; 74 size_t buffer_size; 75 size_t new_buffer_size; 76 77 BUG_ON(!new_buffer->free); 78 79 new_buffer_size = binder_alloc_buffer_size(alloc, new_buffer); 80 81 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 82 "%d: add free buffer, size %zd, at %pK\n", 83 alloc->pid, new_buffer_size, new_buffer); 84 85 while (*p) { 86 parent = *p; 87 buffer = rb_entry(parent, struct binder_buffer, rb_node); 88 BUG_ON(!buffer->free); 89 90 buffer_size = binder_alloc_buffer_size(alloc, buffer); 91 92 if (new_buffer_size < buffer_size) 93 p = &parent->rb_left; 94 else 95 p = &parent->rb_right; 96 } 97 rb_link_node(&new_buffer->rb_node, parent, p); 98 rb_insert_color(&new_buffer->rb_node, &alloc->free_buffers); 99 } 100 101 static void binder_insert_allocated_buffer_locked( 102 struct binder_alloc *alloc, struct binder_buffer *new_buffer) 103 { 104 struct rb_node **p = &alloc->allocated_buffers.rb_node; 105 struct rb_node *parent = NULL; 106 struct binder_buffer *buffer; 107 108 BUG_ON(new_buffer->free); 109 110 while (*p) { 111 parent = *p; 112 buffer = rb_entry(parent, struct binder_buffer, rb_node); 113 BUG_ON(buffer->free); 114 115 if (new_buffer->user_data < buffer->user_data) 116 p = &parent->rb_left; 117 else if (new_buffer->user_data > buffer->user_data) 118 p = &parent->rb_right; 119 else 120 BUG(); 121 } 122 rb_link_node(&new_buffer->rb_node, parent, p); 123 rb_insert_color(&new_buffer->rb_node, &alloc->allocated_buffers); 124 } 125 126 static struct binder_buffer *binder_alloc_prepare_to_free_locked( 127 struct binder_alloc *alloc, 128 uintptr_t user_ptr) 129 { 130 struct rb_node *n = alloc->allocated_buffers.rb_node; 131 struct binder_buffer *buffer; 132 void __user *uptr; 133 134 uptr = (void __user *)user_ptr; 135 136 while (n) { 137 buffer = rb_entry(n, struct binder_buffer, rb_node); 138 BUG_ON(buffer->free); 139 140 if (uptr < buffer->user_data) 141 n = n->rb_left; 142 else if (uptr > buffer->user_data) 143 n = n->rb_right; 144 else { 145 /* 146 * Guard against user threads attempting to 147 * free the buffer when in use by kernel or 148 * after it's already been freed. 149 */ 150 if (!buffer->allow_user_free) 151 return ERR_PTR(-EPERM); 152 buffer->allow_user_free = 0; 153 return buffer; 154 } 155 } 156 return NULL; 157 } 158 159 /** 160 * binder_alloc_prepare_to_free() - get buffer given user ptr 161 * @alloc: binder_alloc for this proc 162 * @user_ptr: User pointer to buffer data 163 * 164 * Validate userspace pointer to buffer data and return buffer corresponding to 165 * that user pointer. Search the rb tree for buffer that matches user data 166 * pointer. 167 * 168 * Return: Pointer to buffer or NULL 169 */ 170 struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc, 171 uintptr_t user_ptr) 172 { 173 struct binder_buffer *buffer; 174 175 mutex_lock(&alloc->mutex); 176 buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr); 177 mutex_unlock(&alloc->mutex); 178 return buffer; 179 } 180 181 static int binder_update_page_range(struct binder_alloc *alloc, int allocate, 182 void __user *start, void __user *end) 183 { 184 void __user *page_addr; 185 unsigned long user_page_addr; 186 struct binder_lru_page *page; 187 struct vm_area_struct *vma = NULL; 188 struct mm_struct *mm = NULL; 189 bool need_mm = false; 190 191 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 192 "%d: %s pages %pK-%pK\n", alloc->pid, 193 allocate ? "allocate" : "free", start, end); 194 195 if (end <= start) 196 return 0; 197 198 trace_binder_update_page_range(alloc, allocate, start, end); 199 200 if (allocate == 0) 201 goto free_range; 202 203 for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) { 204 page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE]; 205 if (!page->page_ptr) { 206 need_mm = true; 207 break; 208 } 209 } 210 211 if (need_mm && mmget_not_zero(alloc->vma_vm_mm)) 212 mm = alloc->vma_vm_mm; 213 214 if (mm) { 215 mmap_read_lock(mm); 216 vma = alloc->vma; 217 } 218 219 if (!vma && need_mm) { 220 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 221 "%d: binder_alloc_buf failed to map pages in userspace, no vma\n", 222 alloc->pid); 223 goto err_no_vma; 224 } 225 226 for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) { 227 int ret; 228 bool on_lru; 229 size_t index; 230 231 index = (page_addr - alloc->buffer) / PAGE_SIZE; 232 page = &alloc->pages[index]; 233 234 if (page->page_ptr) { 235 trace_binder_alloc_lru_start(alloc, index); 236 237 on_lru = list_lru_del(&binder_alloc_lru, &page->lru); 238 WARN_ON(!on_lru); 239 240 trace_binder_alloc_lru_end(alloc, index); 241 continue; 242 } 243 244 if (WARN_ON(!vma)) 245 goto err_page_ptr_cleared; 246 247 trace_binder_alloc_page_start(alloc, index); 248 page->page_ptr = alloc_page(GFP_KERNEL | 249 __GFP_HIGHMEM | 250 __GFP_ZERO); 251 if (!page->page_ptr) { 252 pr_err("%d: binder_alloc_buf failed for page at %pK\n", 253 alloc->pid, page_addr); 254 goto err_alloc_page_failed; 255 } 256 page->alloc = alloc; 257 INIT_LIST_HEAD(&page->lru); 258 259 user_page_addr = (uintptr_t)page_addr; 260 ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr); 261 if (ret) { 262 pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n", 263 alloc->pid, user_page_addr); 264 goto err_vm_insert_page_failed; 265 } 266 267 if (index + 1 > alloc->pages_high) 268 alloc->pages_high = index + 1; 269 270 trace_binder_alloc_page_end(alloc, index); 271 } 272 if (mm) { 273 mmap_read_unlock(mm); 274 mmput(mm); 275 } 276 return 0; 277 278 free_range: 279 for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) { 280 bool ret; 281 size_t index; 282 283 index = (page_addr - alloc->buffer) / PAGE_SIZE; 284 page = &alloc->pages[index]; 285 286 trace_binder_free_lru_start(alloc, index); 287 288 ret = list_lru_add(&binder_alloc_lru, &page->lru); 289 WARN_ON(!ret); 290 291 trace_binder_free_lru_end(alloc, index); 292 if (page_addr == start) 293 break; 294 continue; 295 296 err_vm_insert_page_failed: 297 __free_page(page->page_ptr); 298 page->page_ptr = NULL; 299 err_alloc_page_failed: 300 err_page_ptr_cleared: 301 if (page_addr == start) 302 break; 303 } 304 err_no_vma: 305 if (mm) { 306 mmap_read_unlock(mm); 307 mmput(mm); 308 } 309 return vma ? -ENOMEM : -ESRCH; 310 } 311 312 313 static inline void binder_alloc_set_vma(struct binder_alloc *alloc, 314 struct vm_area_struct *vma) 315 { 316 if (vma) 317 alloc->vma_vm_mm = vma->vm_mm; 318 /* 319 * If we see alloc->vma is not NULL, buffer data structures set up 320 * completely. Look at smp_rmb side binder_alloc_get_vma. 321 * We also want to guarantee new alloc->vma_vm_mm is always visible 322 * if alloc->vma is set. 323 */ 324 smp_wmb(); 325 alloc->vma = vma; 326 } 327 328 static inline struct vm_area_struct *binder_alloc_get_vma( 329 struct binder_alloc *alloc) 330 { 331 struct vm_area_struct *vma = NULL; 332 333 if (alloc->vma) { 334 /* Look at description in binder_alloc_set_vma */ 335 smp_rmb(); 336 vma = alloc->vma; 337 } 338 return vma; 339 } 340 341 static void debug_low_async_space_locked(struct binder_alloc *alloc, int pid) 342 { 343 /* 344 * Find the amount and size of buffers allocated by the current caller; 345 * The idea is that once we cross the threshold, whoever is responsible 346 * for the low async space is likely to try to send another async txn, 347 * and at some point we'll catch them in the act. This is more efficient 348 * than keeping a map per pid. 349 */ 350 struct rb_node *n; 351 struct binder_buffer *buffer; 352 size_t total_alloc_size = 0; 353 size_t num_buffers = 0; 354 355 for (n = rb_first(&alloc->allocated_buffers); n != NULL; 356 n = rb_next(n)) { 357 buffer = rb_entry(n, struct binder_buffer, rb_node); 358 if (buffer->pid != pid) 359 continue; 360 if (!buffer->async_transaction) 361 continue; 362 total_alloc_size += binder_alloc_buffer_size(alloc, buffer) 363 + sizeof(struct binder_buffer); 364 num_buffers++; 365 } 366 367 /* 368 * Warn if this pid has more than 50 transactions, or more than 50% of 369 * async space (which is 25% of total buffer size). 370 */ 371 if (num_buffers > 50 || total_alloc_size > alloc->buffer_size / 4) { 372 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 373 "%d: pid %d spamming oneway? %zd buffers allocated for a total size of %zd\n", 374 alloc->pid, pid, num_buffers, total_alloc_size); 375 } 376 } 377 378 static struct binder_buffer *binder_alloc_new_buf_locked( 379 struct binder_alloc *alloc, 380 size_t data_size, 381 size_t offsets_size, 382 size_t extra_buffers_size, 383 int is_async, 384 int pid) 385 { 386 struct rb_node *n = alloc->free_buffers.rb_node; 387 struct binder_buffer *buffer; 388 size_t buffer_size; 389 struct rb_node *best_fit = NULL; 390 void __user *has_page_addr; 391 void __user *end_page_addr; 392 size_t size, data_offsets_size; 393 int ret; 394 395 if (!binder_alloc_get_vma(alloc)) { 396 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 397 "%d: binder_alloc_buf, no vma\n", 398 alloc->pid); 399 return ERR_PTR(-ESRCH); 400 } 401 402 data_offsets_size = ALIGN(data_size, sizeof(void *)) + 403 ALIGN(offsets_size, sizeof(void *)); 404 405 if (data_offsets_size < data_size || data_offsets_size < offsets_size) { 406 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 407 "%d: got transaction with invalid size %zd-%zd\n", 408 alloc->pid, data_size, offsets_size); 409 return ERR_PTR(-EINVAL); 410 } 411 size = data_offsets_size + ALIGN(extra_buffers_size, sizeof(void *)); 412 if (size < data_offsets_size || size < extra_buffers_size) { 413 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 414 "%d: got transaction with invalid extra_buffers_size %zd\n", 415 alloc->pid, extra_buffers_size); 416 return ERR_PTR(-EINVAL); 417 } 418 if (is_async && 419 alloc->free_async_space < size + sizeof(struct binder_buffer)) { 420 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 421 "%d: binder_alloc_buf size %zd failed, no async space left\n", 422 alloc->pid, size); 423 return ERR_PTR(-ENOSPC); 424 } 425 426 /* Pad 0-size buffers so they get assigned unique addresses */ 427 size = max(size, sizeof(void *)); 428 429 while (n) { 430 buffer = rb_entry(n, struct binder_buffer, rb_node); 431 BUG_ON(!buffer->free); 432 buffer_size = binder_alloc_buffer_size(alloc, buffer); 433 434 if (size < buffer_size) { 435 best_fit = n; 436 n = n->rb_left; 437 } else if (size > buffer_size) 438 n = n->rb_right; 439 else { 440 best_fit = n; 441 break; 442 } 443 } 444 if (best_fit == NULL) { 445 size_t allocated_buffers = 0; 446 size_t largest_alloc_size = 0; 447 size_t total_alloc_size = 0; 448 size_t free_buffers = 0; 449 size_t largest_free_size = 0; 450 size_t total_free_size = 0; 451 452 for (n = rb_first(&alloc->allocated_buffers); n != NULL; 453 n = rb_next(n)) { 454 buffer = rb_entry(n, struct binder_buffer, rb_node); 455 buffer_size = binder_alloc_buffer_size(alloc, buffer); 456 allocated_buffers++; 457 total_alloc_size += buffer_size; 458 if (buffer_size > largest_alloc_size) 459 largest_alloc_size = buffer_size; 460 } 461 for (n = rb_first(&alloc->free_buffers); n != NULL; 462 n = rb_next(n)) { 463 buffer = rb_entry(n, struct binder_buffer, rb_node); 464 buffer_size = binder_alloc_buffer_size(alloc, buffer); 465 free_buffers++; 466 total_free_size += buffer_size; 467 if (buffer_size > largest_free_size) 468 largest_free_size = buffer_size; 469 } 470 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 471 "%d: binder_alloc_buf size %zd failed, no address space\n", 472 alloc->pid, size); 473 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 474 "allocated: %zd (num: %zd largest: %zd), free: %zd (num: %zd largest: %zd)\n", 475 total_alloc_size, allocated_buffers, 476 largest_alloc_size, total_free_size, 477 free_buffers, largest_free_size); 478 return ERR_PTR(-ENOSPC); 479 } 480 if (n == NULL) { 481 buffer = rb_entry(best_fit, struct binder_buffer, rb_node); 482 buffer_size = binder_alloc_buffer_size(alloc, buffer); 483 } 484 485 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 486 "%d: binder_alloc_buf size %zd got buffer %pK size %zd\n", 487 alloc->pid, size, buffer, buffer_size); 488 489 has_page_addr = (void __user *) 490 (((uintptr_t)buffer->user_data + buffer_size) & PAGE_MASK); 491 WARN_ON(n && buffer_size != size); 492 end_page_addr = 493 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size); 494 if (end_page_addr > has_page_addr) 495 end_page_addr = has_page_addr; 496 ret = binder_update_page_range(alloc, 1, (void __user *) 497 PAGE_ALIGN((uintptr_t)buffer->user_data), end_page_addr); 498 if (ret) 499 return ERR_PTR(ret); 500 501 if (buffer_size != size) { 502 struct binder_buffer *new_buffer; 503 504 new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); 505 if (!new_buffer) { 506 pr_err("%s: %d failed to alloc new buffer struct\n", 507 __func__, alloc->pid); 508 goto err_alloc_buf_struct_failed; 509 } 510 new_buffer->user_data = (u8 __user *)buffer->user_data + size; 511 list_add(&new_buffer->entry, &buffer->entry); 512 new_buffer->free = 1; 513 binder_insert_free_buffer(alloc, new_buffer); 514 } 515 516 rb_erase(best_fit, &alloc->free_buffers); 517 buffer->free = 0; 518 buffer->allow_user_free = 0; 519 binder_insert_allocated_buffer_locked(alloc, buffer); 520 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 521 "%d: binder_alloc_buf size %zd got %pK\n", 522 alloc->pid, size, buffer); 523 buffer->data_size = data_size; 524 buffer->offsets_size = offsets_size; 525 buffer->async_transaction = is_async; 526 buffer->extra_buffers_size = extra_buffers_size; 527 buffer->pid = pid; 528 if (is_async) { 529 alloc->free_async_space -= size + sizeof(struct binder_buffer); 530 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC, 531 "%d: binder_alloc_buf size %zd async free %zd\n", 532 alloc->pid, size, alloc->free_async_space); 533 if (alloc->free_async_space < alloc->buffer_size / 10) { 534 /* 535 * Start detecting spammers once we have less than 20% 536 * of async space left (which is less than 10% of total 537 * buffer size). 538 */ 539 debug_low_async_space_locked(alloc, pid); 540 } 541 } 542 return buffer; 543 544 err_alloc_buf_struct_failed: 545 binder_update_page_range(alloc, 0, (void __user *) 546 PAGE_ALIGN((uintptr_t)buffer->user_data), 547 end_page_addr); 548 return ERR_PTR(-ENOMEM); 549 } 550 551 /** 552 * binder_alloc_new_buf() - Allocate a new binder buffer 553 * @alloc: binder_alloc for this proc 554 * @data_size: size of user data buffer 555 * @offsets_size: user specified buffer offset 556 * @extra_buffers_size: size of extra space for meta-data (eg, security context) 557 * @is_async: buffer for async transaction 558 * @pid: pid to attribute allocation to (used for debugging) 559 * 560 * Allocate a new buffer given the requested sizes. Returns 561 * the kernel version of the buffer pointer. The size allocated 562 * is the sum of the three given sizes (each rounded up to 563 * pointer-sized boundary) 564 * 565 * Return: The allocated buffer or %NULL if error 566 */ 567 struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc, 568 size_t data_size, 569 size_t offsets_size, 570 size_t extra_buffers_size, 571 int is_async, 572 int pid) 573 { 574 struct binder_buffer *buffer; 575 576 mutex_lock(&alloc->mutex); 577 buffer = binder_alloc_new_buf_locked(alloc, data_size, offsets_size, 578 extra_buffers_size, is_async, pid); 579 mutex_unlock(&alloc->mutex); 580 return buffer; 581 } 582 583 static void __user *buffer_start_page(struct binder_buffer *buffer) 584 { 585 return (void __user *)((uintptr_t)buffer->user_data & PAGE_MASK); 586 } 587 588 static void __user *prev_buffer_end_page(struct binder_buffer *buffer) 589 { 590 return (void __user *) 591 (((uintptr_t)(buffer->user_data) - 1) & PAGE_MASK); 592 } 593 594 static void binder_delete_free_buffer(struct binder_alloc *alloc, 595 struct binder_buffer *buffer) 596 { 597 struct binder_buffer *prev, *next = NULL; 598 bool to_free = true; 599 600 BUG_ON(alloc->buffers.next == &buffer->entry); 601 prev = binder_buffer_prev(buffer); 602 BUG_ON(!prev->free); 603 if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) { 604 to_free = false; 605 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 606 "%d: merge free, buffer %pK share page with %pK\n", 607 alloc->pid, buffer->user_data, 608 prev->user_data); 609 } 610 611 if (!list_is_last(&buffer->entry, &alloc->buffers)) { 612 next = binder_buffer_next(buffer); 613 if (buffer_start_page(next) == buffer_start_page(buffer)) { 614 to_free = false; 615 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 616 "%d: merge free, buffer %pK share page with %pK\n", 617 alloc->pid, 618 buffer->user_data, 619 next->user_data); 620 } 621 } 622 623 if (PAGE_ALIGNED(buffer->user_data)) { 624 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 625 "%d: merge free, buffer start %pK is page aligned\n", 626 alloc->pid, buffer->user_data); 627 to_free = false; 628 } 629 630 if (to_free) { 631 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 632 "%d: merge free, buffer %pK do not share page with %pK or %pK\n", 633 alloc->pid, buffer->user_data, 634 prev->user_data, 635 next ? next->user_data : NULL); 636 binder_update_page_range(alloc, 0, buffer_start_page(buffer), 637 buffer_start_page(buffer) + PAGE_SIZE); 638 } 639 list_del(&buffer->entry); 640 kfree(buffer); 641 } 642 643 static void binder_free_buf_locked(struct binder_alloc *alloc, 644 struct binder_buffer *buffer) 645 { 646 size_t size, buffer_size; 647 648 buffer_size = binder_alloc_buffer_size(alloc, buffer); 649 650 size = ALIGN(buffer->data_size, sizeof(void *)) + 651 ALIGN(buffer->offsets_size, sizeof(void *)) + 652 ALIGN(buffer->extra_buffers_size, sizeof(void *)); 653 654 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 655 "%d: binder_free_buf %pK size %zd buffer_size %zd\n", 656 alloc->pid, buffer, size, buffer_size); 657 658 BUG_ON(buffer->free); 659 BUG_ON(size > buffer_size); 660 BUG_ON(buffer->transaction != NULL); 661 BUG_ON(buffer->user_data < alloc->buffer); 662 BUG_ON(buffer->user_data > alloc->buffer + alloc->buffer_size); 663 664 if (buffer->async_transaction) { 665 alloc->free_async_space += size + sizeof(struct binder_buffer); 666 667 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC_ASYNC, 668 "%d: binder_free_buf size %zd async free %zd\n", 669 alloc->pid, size, alloc->free_async_space); 670 } 671 672 binder_update_page_range(alloc, 0, 673 (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data), 674 (void __user *)(((uintptr_t) 675 buffer->user_data + buffer_size) & PAGE_MASK)); 676 677 rb_erase(&buffer->rb_node, &alloc->allocated_buffers); 678 buffer->free = 1; 679 if (!list_is_last(&buffer->entry, &alloc->buffers)) { 680 struct binder_buffer *next = binder_buffer_next(buffer); 681 682 if (next->free) { 683 rb_erase(&next->rb_node, &alloc->free_buffers); 684 binder_delete_free_buffer(alloc, next); 685 } 686 } 687 if (alloc->buffers.next != &buffer->entry) { 688 struct binder_buffer *prev = binder_buffer_prev(buffer); 689 690 if (prev->free) { 691 binder_delete_free_buffer(alloc, buffer); 692 rb_erase(&prev->rb_node, &alloc->free_buffers); 693 buffer = prev; 694 } 695 } 696 binder_insert_free_buffer(alloc, buffer); 697 } 698 699 /** 700 * binder_alloc_free_buf() - free a binder buffer 701 * @alloc: binder_alloc for this proc 702 * @buffer: kernel pointer to buffer 703 * 704 * Free the buffer allocated via binder_alloc_new_buf() 705 */ 706 void binder_alloc_free_buf(struct binder_alloc *alloc, 707 struct binder_buffer *buffer) 708 { 709 mutex_lock(&alloc->mutex); 710 binder_free_buf_locked(alloc, buffer); 711 mutex_unlock(&alloc->mutex); 712 } 713 714 /** 715 * binder_alloc_mmap_handler() - map virtual address space for proc 716 * @alloc: alloc structure for this proc 717 * @vma: vma passed to mmap() 718 * 719 * Called by binder_mmap() to initialize the space specified in 720 * vma for allocating binder buffers 721 * 722 * Return: 723 * 0 = success 724 * -EBUSY = address space already mapped 725 * -ENOMEM = failed to map memory to given address space 726 */ 727 int binder_alloc_mmap_handler(struct binder_alloc *alloc, 728 struct vm_area_struct *vma) 729 { 730 int ret; 731 const char *failure_string; 732 struct binder_buffer *buffer; 733 734 mutex_lock(&binder_alloc_mmap_lock); 735 if (alloc->buffer_size) { 736 ret = -EBUSY; 737 failure_string = "already mapped"; 738 goto err_already_mapped; 739 } 740 alloc->buffer_size = min_t(unsigned long, vma->vm_end - vma->vm_start, 741 SZ_4M); 742 mutex_unlock(&binder_alloc_mmap_lock); 743 744 alloc->buffer = (void __user *)vma->vm_start; 745 746 alloc->pages = kcalloc(alloc->buffer_size / PAGE_SIZE, 747 sizeof(alloc->pages[0]), 748 GFP_KERNEL); 749 if (alloc->pages == NULL) { 750 ret = -ENOMEM; 751 failure_string = "alloc page array"; 752 goto err_alloc_pages_failed; 753 } 754 755 buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); 756 if (!buffer) { 757 ret = -ENOMEM; 758 failure_string = "alloc buffer struct"; 759 goto err_alloc_buf_struct_failed; 760 } 761 762 buffer->user_data = alloc->buffer; 763 list_add(&buffer->entry, &alloc->buffers); 764 buffer->free = 1; 765 binder_insert_free_buffer(alloc, buffer); 766 alloc->free_async_space = alloc->buffer_size / 2; 767 binder_alloc_set_vma(alloc, vma); 768 mmgrab(alloc->vma_vm_mm); 769 770 return 0; 771 772 err_alloc_buf_struct_failed: 773 kfree(alloc->pages); 774 alloc->pages = NULL; 775 err_alloc_pages_failed: 776 alloc->buffer = NULL; 777 mutex_lock(&binder_alloc_mmap_lock); 778 alloc->buffer_size = 0; 779 err_already_mapped: 780 mutex_unlock(&binder_alloc_mmap_lock); 781 binder_alloc_debug(BINDER_DEBUG_USER_ERROR, 782 "%s: %d %lx-%lx %s failed %d\n", __func__, 783 alloc->pid, vma->vm_start, vma->vm_end, 784 failure_string, ret); 785 return ret; 786 } 787 788 789 void binder_alloc_deferred_release(struct binder_alloc *alloc) 790 { 791 struct rb_node *n; 792 int buffers, page_count; 793 struct binder_buffer *buffer; 794 795 buffers = 0; 796 mutex_lock(&alloc->mutex); 797 BUG_ON(alloc->vma); 798 799 while ((n = rb_first(&alloc->allocated_buffers))) { 800 buffer = rb_entry(n, struct binder_buffer, rb_node); 801 802 /* Transaction should already have been freed */ 803 BUG_ON(buffer->transaction); 804 805 binder_free_buf_locked(alloc, buffer); 806 buffers++; 807 } 808 809 while (!list_empty(&alloc->buffers)) { 810 buffer = list_first_entry(&alloc->buffers, 811 struct binder_buffer, entry); 812 WARN_ON(!buffer->free); 813 814 list_del(&buffer->entry); 815 WARN_ON_ONCE(!list_empty(&alloc->buffers)); 816 kfree(buffer); 817 } 818 819 page_count = 0; 820 if (alloc->pages) { 821 int i; 822 823 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) { 824 void __user *page_addr; 825 bool on_lru; 826 827 if (!alloc->pages[i].page_ptr) 828 continue; 829 830 on_lru = list_lru_del(&binder_alloc_lru, 831 &alloc->pages[i].lru); 832 page_addr = alloc->buffer + i * PAGE_SIZE; 833 binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC, 834 "%s: %d: page %d at %pK %s\n", 835 __func__, alloc->pid, i, page_addr, 836 on_lru ? "on lru" : "active"); 837 __free_page(alloc->pages[i].page_ptr); 838 page_count++; 839 } 840 kfree(alloc->pages); 841 } 842 mutex_unlock(&alloc->mutex); 843 if (alloc->vma_vm_mm) 844 mmdrop(alloc->vma_vm_mm); 845 846 binder_alloc_debug(BINDER_DEBUG_OPEN_CLOSE, 847 "%s: %d buffers %d, pages %d\n", 848 __func__, alloc->pid, buffers, page_count); 849 } 850 851 static void print_binder_buffer(struct seq_file *m, const char *prefix, 852 struct binder_buffer *buffer) 853 { 854 seq_printf(m, "%s %d: %pK size %zd:%zd:%zd %s\n", 855 prefix, buffer->debug_id, buffer->user_data, 856 buffer->data_size, buffer->offsets_size, 857 buffer->extra_buffers_size, 858 buffer->transaction ? "active" : "delivered"); 859 } 860 861 /** 862 * binder_alloc_print_allocated() - print buffer info 863 * @m: seq_file for output via seq_printf() 864 * @alloc: binder_alloc for this proc 865 * 866 * Prints information about every buffer associated with 867 * the binder_alloc state to the given seq_file 868 */ 869 void binder_alloc_print_allocated(struct seq_file *m, 870 struct binder_alloc *alloc) 871 { 872 struct rb_node *n; 873 874 mutex_lock(&alloc->mutex); 875 for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n)) 876 print_binder_buffer(m, " buffer", 877 rb_entry(n, struct binder_buffer, rb_node)); 878 mutex_unlock(&alloc->mutex); 879 } 880 881 /** 882 * binder_alloc_print_pages() - print page usage 883 * @m: seq_file for output via seq_printf() 884 * @alloc: binder_alloc for this proc 885 */ 886 void binder_alloc_print_pages(struct seq_file *m, 887 struct binder_alloc *alloc) 888 { 889 struct binder_lru_page *page; 890 int i; 891 int active = 0; 892 int lru = 0; 893 int free = 0; 894 895 mutex_lock(&alloc->mutex); 896 /* 897 * Make sure the binder_alloc is fully initialized, otherwise we might 898 * read inconsistent state. 899 */ 900 if (binder_alloc_get_vma(alloc) != NULL) { 901 for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) { 902 page = &alloc->pages[i]; 903 if (!page->page_ptr) 904 free++; 905 else if (list_empty(&page->lru)) 906 active++; 907 else 908 lru++; 909 } 910 } 911 mutex_unlock(&alloc->mutex); 912 seq_printf(m, " pages: %d:%d:%d\n", active, lru, free); 913 seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high); 914 } 915 916 /** 917 * binder_alloc_get_allocated_count() - return count of buffers 918 * @alloc: binder_alloc for this proc 919 * 920 * Return: count of allocated buffers 921 */ 922 int binder_alloc_get_allocated_count(struct binder_alloc *alloc) 923 { 924 struct rb_node *n; 925 int count = 0; 926 927 mutex_lock(&alloc->mutex); 928 for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n)) 929 count++; 930 mutex_unlock(&alloc->mutex); 931 return count; 932 } 933 934 935 /** 936 * binder_alloc_vma_close() - invalidate address space 937 * @alloc: binder_alloc for this proc 938 * 939 * Called from binder_vma_close() when releasing address space. 940 * Clears alloc->vma to prevent new incoming transactions from 941 * allocating more buffers. 942 */ 943 void binder_alloc_vma_close(struct binder_alloc *alloc) 944 { 945 binder_alloc_set_vma(alloc, NULL); 946 } 947 948 /** 949 * binder_alloc_free_page() - shrinker callback to free pages 950 * @item: item to free 951 * @lock: lock protecting the item 952 * @cb_arg: callback argument 953 * 954 * Called from list_lru_walk() in binder_shrink_scan() to free 955 * up pages when the system is under memory pressure. 956 */ 957 enum lru_status binder_alloc_free_page(struct list_head *item, 958 struct list_lru_one *lru, 959 spinlock_t *lock, 960 void *cb_arg) 961 __must_hold(lock) 962 { 963 struct mm_struct *mm = NULL; 964 struct binder_lru_page *page = container_of(item, 965 struct binder_lru_page, 966 lru); 967 struct binder_alloc *alloc; 968 uintptr_t page_addr; 969 size_t index; 970 struct vm_area_struct *vma; 971 972 alloc = page->alloc; 973 if (!mutex_trylock(&alloc->mutex)) 974 goto err_get_alloc_mutex_failed; 975 976 if (!page->page_ptr) 977 goto err_page_already_freed; 978 979 index = page - alloc->pages; 980 page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; 981 982 mm = alloc->vma_vm_mm; 983 if (!mmget_not_zero(mm)) 984 goto err_mmget; 985 if (!mmap_read_trylock(mm)) 986 goto err_mmap_read_lock_failed; 987 vma = binder_alloc_get_vma(alloc); 988 989 list_lru_isolate(lru, item); 990 spin_unlock(lock); 991 992 if (vma) { 993 trace_binder_unmap_user_start(alloc, index); 994 995 zap_page_range(vma, page_addr, PAGE_SIZE); 996 997 trace_binder_unmap_user_end(alloc, index); 998 } 999 mmap_read_unlock(mm); 1000 mmput_async(mm); 1001 1002 trace_binder_unmap_kernel_start(alloc, index); 1003 1004 __free_page(page->page_ptr); 1005 page->page_ptr = NULL; 1006 1007 trace_binder_unmap_kernel_end(alloc, index); 1008 1009 spin_lock(lock); 1010 mutex_unlock(&alloc->mutex); 1011 return LRU_REMOVED_RETRY; 1012 1013 err_mmap_read_lock_failed: 1014 mmput_async(mm); 1015 err_mmget: 1016 err_page_already_freed: 1017 mutex_unlock(&alloc->mutex); 1018 err_get_alloc_mutex_failed: 1019 return LRU_SKIP; 1020 } 1021 1022 static unsigned long 1023 binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc) 1024 { 1025 unsigned long ret = list_lru_count(&binder_alloc_lru); 1026 return ret; 1027 } 1028 1029 static unsigned long 1030 binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) 1031 { 1032 unsigned long ret; 1033 1034 ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page, 1035 NULL, sc->nr_to_scan); 1036 return ret; 1037 } 1038 1039 static struct shrinker binder_shrinker = { 1040 .count_objects = binder_shrink_count, 1041 .scan_objects = binder_shrink_scan, 1042 .seeks = DEFAULT_SEEKS, 1043 }; 1044 1045 /** 1046 * binder_alloc_init() - called by binder_open() for per-proc initialization 1047 * @alloc: binder_alloc for this proc 1048 * 1049 * Called from binder_open() to initialize binder_alloc fields for 1050 * new binder proc 1051 */ 1052 void binder_alloc_init(struct binder_alloc *alloc) 1053 { 1054 alloc->pid = current->group_leader->pid; 1055 mutex_init(&alloc->mutex); 1056 INIT_LIST_HEAD(&alloc->buffers); 1057 } 1058 1059 int binder_alloc_shrinker_init(void) 1060 { 1061 int ret = list_lru_init(&binder_alloc_lru); 1062 1063 if (ret == 0) { 1064 ret = register_shrinker(&binder_shrinker); 1065 if (ret) 1066 list_lru_destroy(&binder_alloc_lru); 1067 } 1068 return ret; 1069 } 1070 1071 /** 1072 * check_buffer() - verify that buffer/offset is safe to access 1073 * @alloc: binder_alloc for this proc 1074 * @buffer: binder buffer to be accessed 1075 * @offset: offset into @buffer data 1076 * @bytes: bytes to access from offset 1077 * 1078 * Check that the @offset/@bytes are within the size of the given 1079 * @buffer and that the buffer is currently active and not freeable. 1080 * Offsets must also be multiples of sizeof(u32). The kernel is 1081 * allowed to touch the buffer in two cases: 1082 * 1083 * 1) when the buffer is being created: 1084 * (buffer->free == 0 && buffer->allow_user_free == 0) 1085 * 2) when the buffer is being torn down: 1086 * (buffer->free == 0 && buffer->transaction == NULL). 1087 * 1088 * Return: true if the buffer is safe to access 1089 */ 1090 static inline bool check_buffer(struct binder_alloc *alloc, 1091 struct binder_buffer *buffer, 1092 binder_size_t offset, size_t bytes) 1093 { 1094 size_t buffer_size = binder_alloc_buffer_size(alloc, buffer); 1095 1096 return buffer_size >= bytes && 1097 offset <= buffer_size - bytes && 1098 IS_ALIGNED(offset, sizeof(u32)) && 1099 !buffer->free && 1100 (!buffer->allow_user_free || !buffer->transaction); 1101 } 1102 1103 /** 1104 * binder_alloc_get_page() - get kernel pointer for given buffer offset 1105 * @alloc: binder_alloc for this proc 1106 * @buffer: binder buffer to be accessed 1107 * @buffer_offset: offset into @buffer data 1108 * @pgoffp: address to copy final page offset to 1109 * 1110 * Lookup the struct page corresponding to the address 1111 * at @buffer_offset into @buffer->user_data. If @pgoffp is not 1112 * NULL, the byte-offset into the page is written there. 1113 * 1114 * The caller is responsible to ensure that the offset points 1115 * to a valid address within the @buffer and that @buffer is 1116 * not freeable by the user. Since it can't be freed, we are 1117 * guaranteed that the corresponding elements of @alloc->pages[] 1118 * cannot change. 1119 * 1120 * Return: struct page 1121 */ 1122 static struct page *binder_alloc_get_page(struct binder_alloc *alloc, 1123 struct binder_buffer *buffer, 1124 binder_size_t buffer_offset, 1125 pgoff_t *pgoffp) 1126 { 1127 binder_size_t buffer_space_offset = buffer_offset + 1128 (buffer->user_data - alloc->buffer); 1129 pgoff_t pgoff = buffer_space_offset & ~PAGE_MASK; 1130 size_t index = buffer_space_offset >> PAGE_SHIFT; 1131 struct binder_lru_page *lru_page; 1132 1133 lru_page = &alloc->pages[index]; 1134 *pgoffp = pgoff; 1135 return lru_page->page_ptr; 1136 } 1137 1138 /** 1139 * binder_alloc_copy_user_to_buffer() - copy src user to tgt user 1140 * @alloc: binder_alloc for this proc 1141 * @buffer: binder buffer to be accessed 1142 * @buffer_offset: offset into @buffer data 1143 * @from: userspace pointer to source buffer 1144 * @bytes: bytes to copy 1145 * 1146 * Copy bytes from source userspace to target buffer. 1147 * 1148 * Return: bytes remaining to be copied 1149 */ 1150 unsigned long 1151 binder_alloc_copy_user_to_buffer(struct binder_alloc *alloc, 1152 struct binder_buffer *buffer, 1153 binder_size_t buffer_offset, 1154 const void __user *from, 1155 size_t bytes) 1156 { 1157 if (!check_buffer(alloc, buffer, buffer_offset, bytes)) 1158 return bytes; 1159 1160 while (bytes) { 1161 unsigned long size; 1162 unsigned long ret; 1163 struct page *page; 1164 pgoff_t pgoff; 1165 void *kptr; 1166 1167 page = binder_alloc_get_page(alloc, buffer, 1168 buffer_offset, &pgoff); 1169 size = min_t(size_t, bytes, PAGE_SIZE - pgoff); 1170 kptr = kmap(page) + pgoff; 1171 ret = copy_from_user(kptr, from, size); 1172 kunmap(page); 1173 if (ret) 1174 return bytes - size + ret; 1175 bytes -= size; 1176 from += size; 1177 buffer_offset += size; 1178 } 1179 return 0; 1180 } 1181 1182 static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc, 1183 bool to_buffer, 1184 struct binder_buffer *buffer, 1185 binder_size_t buffer_offset, 1186 void *ptr, 1187 size_t bytes) 1188 { 1189 /* All copies must be 32-bit aligned and 32-bit size */ 1190 if (!check_buffer(alloc, buffer, buffer_offset, bytes)) 1191 return -EINVAL; 1192 1193 while (bytes) { 1194 unsigned long size; 1195 struct page *page; 1196 pgoff_t pgoff; 1197 void *tmpptr; 1198 void *base_ptr; 1199 1200 page = binder_alloc_get_page(alloc, buffer, 1201 buffer_offset, &pgoff); 1202 size = min_t(size_t, bytes, PAGE_SIZE - pgoff); 1203 base_ptr = kmap_atomic(page); 1204 tmpptr = base_ptr + pgoff; 1205 if (to_buffer) 1206 memcpy(tmpptr, ptr, size); 1207 else 1208 memcpy(ptr, tmpptr, size); 1209 /* 1210 * kunmap_atomic() takes care of flushing the cache 1211 * if this device has VIVT cache arch 1212 */ 1213 kunmap_atomic(base_ptr); 1214 bytes -= size; 1215 pgoff = 0; 1216 ptr = ptr + size; 1217 buffer_offset += size; 1218 } 1219 return 0; 1220 } 1221 1222 int binder_alloc_copy_to_buffer(struct binder_alloc *alloc, 1223 struct binder_buffer *buffer, 1224 binder_size_t buffer_offset, 1225 void *src, 1226 size_t bytes) 1227 { 1228 return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset, 1229 src, bytes); 1230 } 1231 1232 int binder_alloc_copy_from_buffer(struct binder_alloc *alloc, 1233 void *dest, 1234 struct binder_buffer *buffer, 1235 binder_size_t buffer_offset, 1236 size_t bytes) 1237 { 1238 return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset, 1239 dest, bytes); 1240 } 1241 1242