drivers/android/binder_alloc_selftest.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* binder_alloc_selftest.c
   3  *
   4  * Android IPC Subsystem
   5  *
   6  * Copyright (C) 2017 Google, Inc.
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/mm_types.h>
  12 #include <linux/err.h>
  13 #include "binder_alloc.h"
  14
  15 #define BUFFER_NUM 5
  16 #define BUFFER_MIN_SIZE (PAGE_SIZE / 8)
  17
  18 static bool binder_selftest_run = true;
  19 static int binder_selftest_failures;
  20 static DEFINE_MUTEX(binder_selftest_lock);
  21
  22 /**
  23  * enum buf_end_align_type - Page alignment of a buffer
  24  * end with regard to the end of the previous buffer.
  25  *
  26  * In the pictures below, buf2 refers to the buffer we
  27  * are aligning. buf1 refers to previous buffer by addr.
  28  * Symbol [ means the start of a buffer, ] means the end
  29  * of a buffer, and | means page boundaries.
  30  */
  31 enum buf_end_align_type {
  32         /**
  33          * @SAME_PAGE_UNALIGNED: The end of this buffer is on
  34          * the same page as the end of the previous buffer and
  35          * is not page aligned. Examples:
  36          * buf1 ][ buf2 ][ ...
  37          * buf1 ]|[ buf2 ][ ...
  38          */
  39         SAME_PAGE_UNALIGNED = 0,
  40         /**
  41          * @SAME_PAGE_ALIGNED: When the end of the previous buffer
  42          * is not page aligned, the end of this buffer is on the
  43          * same page as the end of the previous buffer and is page
  44          * aligned. When the previous buffer is page aligned, the
  45          * end of this buffer is aligned to the next page boundary.
  46          * Examples:
  47          * buf1 ][ buf2 ]| ...
  48          * buf1 ]|[ buf2 ]| ...
  49          */
  50         SAME_PAGE_ALIGNED,
  51         /**
  52          * @NEXT_PAGE_UNALIGNED: The end of this buffer is on
  53          * the page next to the end of the previous buffer and
  54          * is not page aligned. Examples:
  55          * buf1 ][ buf2 | buf2 ][ ...
  56          * buf1 ]|[ buf2 | buf2 ][ ...
  57          */
  58         NEXT_PAGE_UNALIGNED,
  59         /**
  60          * @NEXT_PAGE_ALIGNED: The end of this buffer is on
  61          * the page next to the end of the previous buffer and
  62          * is page aligned. Examples:
  63          * buf1 ][ buf2 | buf2 ]| ...
  64          * buf1 ]|[ buf2 | buf2 ]| ...
  65          */
  66         NEXT_PAGE_ALIGNED,
  67         /**
  68          * @NEXT_NEXT_UNALIGNED: The end of this buffer is on
  69          * the page that follows the page after the end of the
  70          * previous buffer and is not page aligned. Examples:
  71          * buf1 ][ buf2 | buf2 | buf2 ][ ...
  72          * buf1 ]|[ buf2 | buf2 | buf2 ][ ...
  73          */
  74         NEXT_NEXT_UNALIGNED,
  75         LOOP_END,
  76 };
  77
  78 static void pr_err_size_seq(size_t *sizes, int *seq)
  79 {
  80         int i;
  81
  82         pr_err("alloc sizes: ");
  83         for (i = 0; i < BUFFER_NUM; i++)
  84                 pr_cont("[%zu]", sizes[i]);
  85         pr_cont("\n");
  86         pr_err("free seq: ");
  87         for (i = 0; i < BUFFER_NUM; i++)
  88                 pr_cont("[%d]", seq[i]);
  89         pr_cont("\n");
  90 }
  91
  92 static bool check_buffer_pages_allocated(struct binder_alloc *alloc,
  93                                          struct binder_buffer *buffer,
  94                                          size_t size)
  95 {
  96         void __user *page_addr;
  97         void __user *end;
  98         int page_index;
  99
 100         end = (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
 101         page_addr = buffer->user_data;
 102         for (; page_addr < end; page_addr += PAGE_SIZE) {
 103                 page_index = (page_addr - alloc->buffer) / PAGE_SIZE;
 104                 if (!alloc->pages[page_index].page_ptr ||
 105                     !list_empty(&alloc->pages[page_index].lru)) {
 106                         pr_err("expect alloc but is %s at page index %d\n",
 107                                alloc->pages[page_index].page_ptr ?
 108                                "lru" : "free", page_index);
 109                         return false;
 110                 }
 111         }
 112         return true;
 113 }
 114
 115 static void binder_selftest_alloc_buf(struct binder_alloc *alloc,
 116                                       struct binder_buffer *buffers[],
 117                                       size_t *sizes, int *seq)
 118 {
 119         int i;
 120
 121         for (i = 0; i < BUFFER_NUM; i++) {
 122                 buffers[i] = binder_alloc_new_buf(alloc, sizes[i], 0, 0, 0, 0);
 123                 if (IS_ERR(buffers[i]) ||
 124                     !check_buffer_pages_allocated(alloc, buffers[i],
 125                                                   sizes[i])) {
 126                         pr_err_size_seq(sizes, seq);
 127                         binder_selftest_failures++;
 128                 }
 129         }
 130 }
 131
 132 static void binder_selftest_free_buf(struct binder_alloc *alloc,
 133                                      struct binder_buffer *buffers[],
 134                                      size_t *sizes, int *seq, size_t end)
 135 {
 136         int i;
 137
 138         for (i = 0; i < BUFFER_NUM; i++)
 139                 binder_alloc_free_buf(alloc, buffers[seq[i]]);
 140
 141         for (i = 0; i < end / PAGE_SIZE; i++) {
 142                 /**
 143                  * Error message on a free page can be false positive
 144                  * if binder shrinker ran during binder_alloc_free_buf
 145                  * calls above.
 146                  */
 147                 if (list_empty(&alloc->pages[i].lru)) {
 148                         pr_err_size_seq(sizes, seq);
 149                         pr_err("expect lru but is %s at page index %d\n",
 150                                alloc->pages[i].page_ptr ? "alloc" : "free", i);
 151                         binder_selftest_failures++;
 152                 }
 153         }
 154 }
 155
 156 static void binder_selftest_free_page(struct binder_alloc *alloc)
 157 {
 158         int i;
 159         unsigned long count;
 160
 161         while ((count = list_lru_count(&binder_alloc_lru))) {
 162                 list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
 163                               NULL, count);
 164         }
 165
 166         for (i = 0; i < (alloc->buffer_size / PAGE_SIZE); i++) {
 167                 if (alloc->pages[i].page_ptr) {
 168                         pr_err("expect free but is %s at page index %d\n",
 169                                list_empty(&alloc->pages[i].lru) ?
 170                                "alloc" : "lru", i);
 171                         binder_selftest_failures++;
 172                 }
 173         }
 174 }
 175
 176 static void binder_selftest_alloc_free(struct binder_alloc *alloc,
 177                                        size_t *sizes, int *seq, size_t end)
 178 {
 179         struct binder_buffer *buffers[BUFFER_NUM];
 180
 181         binder_selftest_alloc_buf(alloc, buffers, sizes, seq);
 182         binder_selftest_free_buf(alloc, buffers, sizes, seq, end);
 183
 184         /* Allocate from lru. */
 185         binder_selftest_alloc_buf(alloc, buffers, sizes, seq);
 186         if (list_lru_count(&binder_alloc_lru))
 187                 pr_err("lru list should be empty but is not\n");
 188
 189         binder_selftest_free_buf(alloc, buffers, sizes, seq, end);
 190         binder_selftest_free_page(alloc);
 191 }
 192
 193 static bool is_dup(int *seq, int index, int val)
 194 {
 195         int i;
 196
 197         for (i = 0; i < index; i++) {
 198                 if (seq[i] == val)
 199                         return true;
 200         }
 201         return false;
 202 }
 203
 204 /* Generate BUFFER_NUM factorial free orders. */
 205 static void binder_selftest_free_seq(struct binder_alloc *alloc,
 206                                      size_t *sizes, int *seq,
 207                                      int index, size_t end)
 208 {
 209         int i;
 210
 211         if (index == BUFFER_NUM) {
 212                 binder_selftest_alloc_free(alloc, sizes, seq, end);
 213                 return;
 214         }
 215         for (i = 0; i < BUFFER_NUM; i++) {
 216                 if (is_dup(seq, index, i))
 217                         continue;
 218                 seq[index] = i;
 219                 binder_selftest_free_seq(alloc, sizes, seq, index + 1, end);
 220         }
 221 }
 222
 223 static void binder_selftest_alloc_size(struct binder_alloc *alloc,
 224                                        size_t *end_offset)
 225 {
 226         int i;
 227         int seq[BUFFER_NUM] = {0};
 228         size_t front_sizes[BUFFER_NUM];
 229         size_t back_sizes[BUFFER_NUM];
 230         size_t last_offset, offset = 0;
 231
 232         for (i = 0; i < BUFFER_NUM; i++) {
 233                 last_offset = offset;
 234                 offset = end_offset[i];
 235                 front_sizes[i] = offset - last_offset;
 236                 back_sizes[BUFFER_NUM - i - 1] = front_sizes[i];
 237         }
 238         /*
 239          * Buffers share the first or last few pages.
 240          * Only BUFFER_NUM - 1 buffer sizes are adjustable since
 241          * we need one giant buffer before getting to the last page.
 242          */
 243         back_sizes[0] += alloc->buffer_size - end_offset[BUFFER_NUM - 1];
 244         binder_selftest_free_seq(alloc, front_sizes, seq, 0,
 245                                  end_offset[BUFFER_NUM - 1]);
 246         binder_selftest_free_seq(alloc, back_sizes, seq, 0, alloc->buffer_size);
 247 }
 248
 249 static void binder_selftest_alloc_offset(struct binder_alloc *alloc,
 250                                          size_t *end_offset, int index)
 251 {
 252         int align;
 253         size_t end, prev;
 254
 255         if (index == BUFFER_NUM) {
 256                 binder_selftest_alloc_size(alloc, end_offset);
 257                 return;
 258         }
 259         prev = index == 0 ? 0 : end_offset[index - 1];
 260         end = prev;
 261
 262         BUILD_BUG_ON(BUFFER_MIN_SIZE * BUFFER_NUM >= PAGE_SIZE);
 263
 264         for (align = SAME_PAGE_UNALIGNED; align < LOOP_END; align++) {
 265                 if (align % 2)
 266                         end = ALIGN(end, PAGE_SIZE);
 267                 else
 268                         end += BUFFER_MIN_SIZE;
 269                 end_offset[index] = end;
 270                 binder_selftest_alloc_offset(alloc, end_offset, index + 1);
 271         }
 272 }
 273
 274 /**
 275  * binder_selftest_alloc() - Test alloc and free of buffer pages.
 276  * @alloc: Pointer to alloc struct.
 277  *
 278  * Allocate BUFFER_NUM buffers to cover all page alignment cases,
 279  * then free them in all orders possible. Check that pages are
 280  * correctly allocated, put onto lru when buffers are freed, and
 281  * are freed when binder_alloc_free_page is called.
 282  */
 283 void binder_selftest_alloc(struct binder_alloc *alloc)
 284 {
 285         size_t end_offset[BUFFER_NUM];
 286
 287         if (!binder_selftest_run)
 288                 return;
 289         mutex_lock(&binder_selftest_lock);
 290         if (!binder_selftest_run || !alloc->vma)
 291                 goto done;
 292         pr_info("STARTED\n");
 293         binder_selftest_alloc_offset(alloc, end_offset, 0);
 294         binder_selftest_run = false;
 295         if (binder_selftest_failures > 0)
 296                 pr_info("%d tests FAILED\n", binder_selftest_failures);
 297         else
 298                 pr_info("PASSED\n");
 299
 300 done:
 301         mutex_unlock(&binder_selftest_lock);
 302 }