drivers/gator/gator_cookies.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2013. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  */
   9
  10 #define COOKIEMAP_ENTRIES       1024    /* must be power of 2 */
  11 #define TRANSLATE_BUFFER_SIZE 512  // must be a power of 2 - 512/4 = 128 entries
  12 #define TRANSLATE_TEXT_SIZE             256
  13 #define MAX_COLLISIONS          2
  14
  15 static uint32_t *gator_crc32_table;
  16 static unsigned int translate_buffer_mask;
  17
  18 struct cookie_args {
  19         struct task_struct *task;
  20         const char *text;
  21 };
  22
  23 static DEFINE_PER_CPU(char *, translate_text);
  24 static DEFINE_PER_CPU(uint32_t, cookie_next_key);
  25 static DEFINE_PER_CPU(uint64_t *, cookie_keys);
  26 static DEFINE_PER_CPU(uint32_t *, cookie_values);
  27 static DEFINE_PER_CPU(int, translate_buffer_read);
  28 static DEFINE_PER_CPU(int, translate_buffer_write);
  29 static DEFINE_PER_CPU(struct cookie_args *, translate_buffer);
  30
  31 static uint32_t get_cookie(int cpu, struct task_struct *task, const char *text, bool from_wq);
  32 static void wq_cookie_handler(struct work_struct *unused);
  33 DECLARE_WORK(cookie_work, wq_cookie_handler);
  34 static struct timer_list app_process_wake_up_timer;
  35 static void app_process_wake_up_handler(unsigned long unused_data);
  36
  37 static uint32_t cookiemap_code(uint64_t value64)
  38 {
  39         uint32_t value = (uint32_t)((value64 >> 32) + value64);
  40         uint32_t cookiecode = (value >> 24) & 0xff;
  41         cookiecode = cookiecode * 31 + ((value >> 16) & 0xff);
  42         cookiecode = cookiecode * 31 + ((value >> 8) & 0xff);
  43         cookiecode = cookiecode * 31 + ((value >> 0) & 0xff);
  44         cookiecode &= (COOKIEMAP_ENTRIES - 1);
  45         return cookiecode * MAX_COLLISIONS;
  46 }
  47
  48 static uint32_t gator_chksum_crc32(const char *data)
  49 {
  50         register unsigned long crc;
  51         const unsigned char *block = data;
  52         int i, length = strlen(data);
  53
  54         crc = 0xFFFFFFFF;
  55         for (i = 0; i < length; i++) {
  56                 crc = ((crc >> 8) & 0x00FFFFFF) ^ gator_crc32_table[(crc ^ *block++) & 0xFF];
  57         }
  58
  59         return (crc ^ 0xFFFFFFFF);
  60 }
  61
  62 /*
  63  * Exists
  64  *  Pre:  [0][1][v][3]..[n-1]
  65  *  Post: [v][0][1][3]..[n-1]
  66  */
  67 static uint32_t cookiemap_exists(uint64_t key)
  68 {
  69         unsigned long x, flags, retval = 0;
  70         int cpu = get_physical_cpu();
  71         uint32_t cookiecode = cookiemap_code(key);
  72         uint64_t *keys = &(per_cpu(cookie_keys, cpu)[cookiecode]);
  73         uint32_t *values = &(per_cpu(cookie_values, cpu)[cookiecode]);
  74
  75         // Can be called from interrupt handler or from work queue
  76         local_irq_save(flags);
  77         for (x = 0; x < MAX_COLLISIONS; x++) {
  78                 if (keys[x] == key) {
  79                         uint32_t value = values[x];
  80                         for (; x > 0; x--) {
  81                                 keys[x] = keys[x - 1];
  82                                 values[x] = values[x - 1];
  83                         }
  84                         keys[0] = key;
  85                         values[0] = value;
  86                         retval = value;
  87                         break;
  88                 }
  89         }
  90         local_irq_restore(flags);
  91
  92         return retval;
  93 }
  94
  95 /*
  96  * Add
  97  *  Pre:  [0][1][2][3]..[n-1]
  98  *  Post: [v][0][1][2]..[n-2]
  99  */
 100 static void cookiemap_add(uint64_t key, uint32_t value)
 101 {
 102         int cpu = get_physical_cpu();
 103         int cookiecode = cookiemap_code(key);
 104         uint64_t *keys = &(per_cpu(cookie_keys, cpu)[cookiecode]);
 105         uint32_t *values = &(per_cpu(cookie_values, cpu)[cookiecode]);
 106         int x;
 107
 108         for (x = MAX_COLLISIONS - 1; x > 0; x--) {
 109                 keys[x] = keys[x - 1];
 110                 values[x] = values[x - 1];
 111         }
 112         keys[0] = key;
 113         values[0] = value;
 114 }
 115
 116 #ifndef CONFIG_PREEMPT_RT_FULL
 117 static void translate_buffer_write_args(int cpu, struct task_struct *task, const char *text)
 118 {
 119         unsigned long flags;
 120         int write;
 121         int next_write;
 122         struct cookie_args *args;
 123
 124         local_irq_save(flags);
 125
 126         write = per_cpu(translate_buffer_write, cpu);
 127         next_write = (write + 1) & translate_buffer_mask;
 128
 129         // At least one entry must always remain available as when read == write, the queue is empty not full
 130         if (next_write != per_cpu(translate_buffer_read, cpu)) {
 131                 args = &per_cpu(translate_buffer, cpu)[write];
 132                 args->task = task;
 133                 args->text = text;
 134                 get_task_struct(task);
 135                 per_cpu(translate_buffer_write, cpu) = next_write;
 136         }
 137
 138         local_irq_restore(flags);
 139 }
 140 #endif
 141
 142 static void translate_buffer_read_args(int cpu, struct cookie_args *args)
 143 {
 144         unsigned long flags;
 145         int read;
 146
 147         local_irq_save(flags);
 148
 149         read = per_cpu(translate_buffer_read, cpu);
 150         *args = per_cpu(translate_buffer, cpu)[read];
 151         per_cpu(translate_buffer_read, cpu) = (read + 1) & translate_buffer_mask;
 152
 153         local_irq_restore(flags);
 154 }
 155
 156 static void wq_cookie_handler(struct work_struct *unused)
 157 {
 158         struct cookie_args args;
 159         int cpu = get_physical_cpu(), cookie;
 160
 161         mutex_lock(&start_mutex);
 162
 163         if (gator_started != 0) {
 164                 while (per_cpu(translate_buffer_read, cpu) != per_cpu(translate_buffer_write, cpu)) {
 165                         translate_buffer_read_args(cpu, &args);
 166                         cookie = get_cookie(cpu, args.task, args.text, true);
 167                         marshal_link(cookie, args.task->tgid, args.task->pid);
 168                         put_task_struct(args.task);
 169                 }
 170         }
 171
 172         mutex_unlock(&start_mutex);
 173 }
 174
 175 static void app_process_wake_up_handler(unsigned long unused_data)
 176 {
 177         // had to delay scheduling work as attempting to schedule work during the context switch is illegal in kernel versions 3.5 and greater
 178         schedule_work(&cookie_work);
 179 }
 180
 181 // Retrieve full name from proc/pid/cmdline for java processes on Android
 182 static int translate_app_process(const char **text, int cpu, struct task_struct *task, bool from_wq)
 183 {
 184         void *maddr;
 185         unsigned int len;
 186         unsigned long addr;
 187         struct mm_struct *mm;
 188         struct page *page = NULL;
 189         struct vm_area_struct *page_vma;
 190         int bytes, offset, retval = 0;
 191         char *buf = per_cpu(translate_text, cpu);
 192
 193 #ifndef CONFIG_PREEMPT_RT_FULL
 194         // Push work into a work queue if in atomic context as the kernel functions below might sleep
 195         // Rely on the in_interrupt variable rather than in_irq() or in_interrupt() kernel functions, as the value of these functions seems
 196         //   inconsistent during a context switch between android/linux versions
 197         if (!from_wq) {
 198                 // Check if already in buffer
 199                 int pos = per_cpu(translate_buffer_read, cpu);
 200                 while (pos != per_cpu(translate_buffer_write, cpu)) {
 201                         if (per_cpu(translate_buffer, cpu)[pos].task == task)
 202                                 goto out;
 203                         pos = (pos + 1) & translate_buffer_mask;
 204                 }
 205
 206                 translate_buffer_write_args(cpu, task, *text);
 207
 208                 // Not safe to call in RT-Preempt full in schedule switch context
 209                 mod_timer(&app_process_wake_up_timer, jiffies + 1);
 210                 goto out;
 211         }
 212 #endif
 213
 214         mm = get_task_mm(task);
 215         if (!mm)
 216                 goto out;
 217         if (!mm->arg_end)
 218                 goto outmm;
 219         addr = mm->arg_start;
 220         len = mm->arg_end - mm->arg_start;
 221
 222         if (len > TRANSLATE_TEXT_SIZE)
 223                 len = TRANSLATE_TEXT_SIZE;
 224
 225         down_read(&mm->mmap_sem);
 226         while (len) {
 227                 if (get_user_pages(task, mm, addr, 1, 0, 1, &page, &page_vma) <= 0)
 228                         goto outsem;
 229
 230                 maddr = kmap(page);
 231                 offset = addr & (PAGE_SIZE - 1);
 232                 bytes = len;
 233                 if (bytes > PAGE_SIZE - offset)
 234                         bytes = PAGE_SIZE - offset;
 235
 236                 copy_from_user_page(page_vma, page, addr, buf, maddr + offset, bytes);
 237
 238                 kunmap(page);   // release page allocated by get_user_pages()
 239                 page_cache_release(page);
 240
 241                 len -= bytes;
 242                 buf += bytes;
 243                 addr += bytes;
 244
 245                 *text = per_cpu(translate_text, cpu);
 246                 retval = 1;
 247         }
 248
 249         // On app_process startup, /proc/pid/cmdline is initially "zygote" then "<pre-initialized>" but changes after an initial startup period
 250         if (strcmp(*text, "zygote") == 0 || strcmp(*text, "<pre-initialized>") == 0)
 251                 retval = 0;
 252
 253 outsem:
 254         up_read(&mm->mmap_sem);
 255 outmm:
 256         mmput(mm);
 257 out:
 258         return retval;
 259 }
 260
 261 static uint32_t get_cookie(int cpu, struct task_struct *task, const char *text, bool from_wq)
 262 {
 263         unsigned long flags, cookie;
 264         uint64_t key;
 265
 266         key = gator_chksum_crc32(text);
 267         key = (key << 32) | (uint32_t)task->tgid;
 268
 269         cookie = cookiemap_exists(key);
 270         if (cookie) {
 271                 return cookie;
 272         }
 273
 274         if (strcmp(text, "app_process") == 0) {
 275                 if (!translate_app_process(&text, cpu, task, from_wq))
 276                         return UNRESOLVED_COOKIE;
 277         }
 278
 279         // Can be called from interrupt handler or from work queue or from scheduler trace
 280         local_irq_save(flags);
 281
 282         cookie = UNRESOLVED_COOKIE;
 283         if (marshal_cookie_header(text)) {
 284                 cookie = per_cpu(cookie_next_key, cpu) += nr_cpu_ids;
 285                 cookiemap_add(key, cookie);
 286                 marshal_cookie(cookie, text);
 287         }
 288
 289         local_irq_restore(flags);
 290
 291         return cookie;
 292 }
 293
 294 static int get_exec_cookie(int cpu, struct task_struct *task)
 295 {
 296         struct mm_struct *mm = task->mm;
 297         const char *text;
 298
 299         // kernel threads have no address space
 300         if (!mm)
 301                 return NO_COOKIE;
 302
 303         if (task && task->mm && task->mm->exe_file) {
 304                 text = task->mm->exe_file->f_path.dentry->d_name.name;
 305                 return get_cookie(cpu, task, text, false);
 306         }
 307
 308         return UNRESOLVED_COOKIE;
 309 }
 310
 311 static unsigned long get_address_cookie(int cpu, struct task_struct *task, unsigned long addr, off_t *offset)
 312 {
 313         unsigned long cookie = NO_COOKIE;
 314         struct mm_struct *mm = task->mm;
 315         struct vm_area_struct *vma;
 316         const char *text;
 317
 318         if (!mm)
 319                 return cookie;
 320
 321         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
 322                 if (addr < vma->vm_start || addr >= vma->vm_end)
 323                         continue;
 324
 325                 if (vma->vm_file) {
 326                         text = vma->vm_file->f_path.dentry->d_name.name;
 327                         cookie = get_cookie(cpu, task, text, false);
 328                         *offset = (vma->vm_pgoff << PAGE_SHIFT) + addr - vma->vm_start;
 329                 } else {
 330                         /* must be an anonymous map */
 331                         *offset = addr;
 332                 }
 333
 334                 break;
 335         }
 336
 337         if (!vma)
 338                 cookie = UNRESOLVED_COOKIE;
 339
 340         return cookie;
 341 }
 342
 343 static int cookies_initialize(void)
 344 {
 345         uint32_t crc, poly;
 346         int i, j, cpu, size, err = 0;
 347
 348         translate_buffer_mask = TRANSLATE_BUFFER_SIZE / sizeof(per_cpu(translate_buffer, 0)[0]) - 1;
 349
 350         for_each_present_cpu(cpu) {
 351                 per_cpu(cookie_next_key, cpu) = nr_cpu_ids + cpu;
 352
 353                 size = COOKIEMAP_ENTRIES * MAX_COLLISIONS * sizeof(uint64_t);
 354                 per_cpu(cookie_keys, cpu) = (uint64_t *)kmalloc(size, GFP_KERNEL);
 355                 if (!per_cpu(cookie_keys, cpu)) {
 356                         err = -ENOMEM;
 357                         goto cookie_setup_error;
 358                 }
 359                 memset(per_cpu(cookie_keys, cpu), 0, size);
 360
 361                 size = COOKIEMAP_ENTRIES * MAX_COLLISIONS * sizeof(uint32_t);
 362                 per_cpu(cookie_values, cpu) = (uint32_t *)kmalloc(size, GFP_KERNEL);
 363                 if (!per_cpu(cookie_values, cpu)) {
 364                         err = -ENOMEM;
 365                         goto cookie_setup_error;
 366                 }
 367                 memset(per_cpu(cookie_values, cpu), 0, size);
 368
 369                 per_cpu(translate_buffer, cpu) = (struct cookie_args *)kmalloc(TRANSLATE_BUFFER_SIZE, GFP_KERNEL);
 370                 if (!per_cpu(translate_buffer, cpu)) {
 371                         err = -ENOMEM;
 372                         goto cookie_setup_error;
 373                 }
 374
 375                 per_cpu(translate_buffer_write, cpu) = 0;
 376                 per_cpu(translate_buffer_read, cpu) = 0;
 377
 378                 per_cpu(translate_text, cpu) = (char *)kmalloc(TRANSLATE_TEXT_SIZE, GFP_KERNEL);
 379                 if (!per_cpu(translate_text, cpu)) {
 380                         err = -ENOMEM;
 381                         goto cookie_setup_error;
 382                 }
 383         }
 384
 385         // build CRC32 table
 386         poly = 0x04c11db7;
 387         gator_crc32_table = (uint32_t *)kmalloc(256 * sizeof(uint32_t), GFP_KERNEL);
 388         if (!gator_crc32_table) {
 389                 err = -ENOMEM;
 390                 goto cookie_setup_error;
 391         }
 392         for (i = 0; i < 256; i++) {
 393                 crc = i;
 394                 for (j = 8; j > 0; j--) {
 395                         if (crc & 1) {
 396                                 crc = (crc >> 1) ^ poly;
 397                         } else {
 398                                 crc >>= 1;
 399                         }
 400                 }
 401                 gator_crc32_table[i] = crc;
 402         }
 403
 404         setup_timer(&app_process_wake_up_timer, app_process_wake_up_handler, 0);
 405
 406 cookie_setup_error:
 407         return err;
 408 }
 409
 410 static void cookies_release(void)
 411 {
 412         int cpu;
 413
 414         for_each_present_cpu(cpu) {
 415                 kfree(per_cpu(cookie_keys, cpu));
 416                 per_cpu(cookie_keys, cpu) = NULL;
 417
 418                 kfree(per_cpu(cookie_values, cpu));
 419                 per_cpu(cookie_values, cpu) = NULL;
 420
 421                 kfree(per_cpu(translate_buffer, cpu));
 422                 per_cpu(translate_buffer, cpu) = NULL;
 423                 per_cpu(translate_buffer_read, cpu) = 0;
 424                 per_cpu(translate_buffer_write, cpu) = 0;
 425
 426                 kfree(per_cpu(translate_text, cpu));
 427                 per_cpu(translate_text, cpu) = NULL;
 428         }
 429
 430         del_timer_sync(&app_process_wake_up_timer);
 431         kfree(gator_crc32_table);
 432         gator_crc32_table = NULL;
 433 }