drivers/usb/mon/mon_text.c

   1 /*
   2  * The USB Monitor, inspired by Dave Harding's USBMon.
   3  *
   4  * This is a text format reader.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/list.h>
   9 #include <linux/usb.h>
  10 #include <linux/time.h>
  11 #include <asm/uaccess.h>
  12
  13 #include "usb_mon.h"
  14
  15 /*
  16  * No, we do not want arbitrarily long data strings.
  17  * Use the binary interface if you want to capture bulk data!
  18  */
  19 #define DATA_MAX  32
  20
  21 /*
  22  * Defined by USB 2.0 clause 9.3, table 9.2.
  23  */
  24 #define SETUP_MAX  8
  25
  26 /*
  27  * This limit exists to prevent OOMs when the user process stops reading.
  28  */
  29 #define EVENT_MAX  25
  30
  31 #define PRINTF_DFL  130
  32
  33 struct mon_event_text {
  34         struct list_head e_link;
  35         int type;               /* submit, complete, etc. */
  36         unsigned int pipe;      /* Pipe */
  37         unsigned long id;       /* From pointer, most of the time */
  38         unsigned int tstamp;
  39         int length;             /* Depends on type: xfer length or act length */
  40         int status;
  41         char setup_flag;
  42         char data_flag;
  43         unsigned char setup[SETUP_MAX];
  44         unsigned char data[DATA_MAX];
  45 };
  46
  47 #define SLAB_NAME_SZ  30
  48 struct mon_reader_text {
  49         kmem_cache_t *e_slab;
  50         int nevents;
  51         struct list_head e_list;
  52         struct mon_reader r;    /* In C, parent class can be placed anywhere */
  53
  54         wait_queue_head_t wait;
  55         int printf_size;
  56         char *printf_buf;
  57         struct semaphore printf_lock;
  58
  59         char slab_name[SLAB_NAME_SZ];
  60 };
  61
  62 static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
  63 static void mon_text_dtor(void *, kmem_cache_t *, unsigned long);
  64
  65 /*
  66  * mon_text_submit
  67  * mon_text_complete
  68  *
  69  * May be called from an interrupt.
  70  *
  71  * This is called with the whole mon_bus locked, so no additional lock.
  72  */
  73
  74 static inline char mon_text_get_setup(struct mon_event_text *ep,
  75     struct urb *urb, char ev_type)
  76 {
  77
  78         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
  79                 return '-';
  80
  81         if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
  82                 return 'D';
  83         if (urb->setup_packet == NULL)
  84                 return 'Z';     /* '0' would be not as pretty. */
  85
  86         memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
  87         return 0;
  88 }
  89
  90 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
  91     int len, char ev_type)
  92 {
  93         int pipe = urb->pipe;
  94         unsigned char *data;
  95
  96         /*
  97          * The check to see if it's safe to poke at data has an enormous
  98          * number of corner cases, but it seems that the following is
  99          * more or less safe.
 100          *
 101          * We do not even try to look transfer_buffer, because it can
 102          * contain non-NULL garbage in case the upper level promised to
 103          * set DMA for the HCD.
 104          */
 105         if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
 106                 return 'D';
 107
 108         if (len <= 0)
 109                 return 'L';
 110
 111         if ((data = urb->transfer_buffer) == NULL)
 112                 return 'Z';     /* '0' would be not as pretty. */
 113
 114         /*
 115          * Bulk is easy to shortcut reliably.
 116          * XXX Other pipe types need consideration. Currently, we overdo it
 117          * and collect garbage for them: better more than less.
 118          */
 119         if (usb_pipebulk(pipe) || usb_pipecontrol(pipe)) {
 120                 if (usb_pipein(pipe)) {
 121                         if (ev_type == 'S')
 122                                 return '<';
 123                 } else {
 124                         if (ev_type == 'C')
 125                                 return '>';
 126                 }
 127         }
 128
 129         if (len >= DATA_MAX)
 130                 len = DATA_MAX;
 131         memcpy(ep->data, urb->transfer_buffer, len);
 132         return 0;
 133 }
 134
 135 static inline unsigned int mon_get_timestamp(void)
 136 {
 137         struct timeval tval;
 138         unsigned int stamp;
 139
 140         do_gettimeofday(&tval);
 141         stamp = tval.tv_sec & 0xFFFF;   /* 2^32 = 4294967296. Limit to 4096s. */
 142         stamp = stamp * 1000000 + tval.tv_usec;
 143         return stamp;
 144 }
 145
 146 static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 147     char ev_type)
 148 {
 149         struct mon_event_text *ep;
 150         unsigned int stamp;
 151
 152         stamp = mon_get_timestamp();
 153
 154         if (rp->nevents >= EVENT_MAX ||
 155             (ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
 156                 rp->r.m_bus->cnt_text_lost++;
 157                 return;
 158         }
 159
 160         ep->type = ev_type;
 161         ep->pipe = urb->pipe;
 162         ep->id = (unsigned long) urb;
 163         ep->tstamp = stamp;
 164         ep->length = (ev_type == 'S') ?
 165             urb->transfer_buffer_length : urb->actual_length;
 166         /* Collecting status makes debugging sense for submits, too */
 167         ep->status = urb->status;
 168
 169         ep->setup_flag = mon_text_get_setup(ep, urb, ev_type);
 170         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
 171
 172         rp->nevents++;
 173         list_add_tail(&ep->e_link, &rp->e_list);
 174         wake_up(&rp->wait);
 175 }
 176
 177 static void mon_text_submit(void *data, struct urb *urb)
 178 {
 179         struct mon_reader_text *rp = data;
 180         mon_text_event(rp, urb, 'S');
 181 }
 182
 183 static void mon_text_complete(void *data, struct urb *urb)
 184 {
 185         struct mon_reader_text *rp = data;
 186         mon_text_event(rp, urb, 'C');
 187 }
 188
 189 /*
 190  * Fetch next event from the circular buffer.
 191  */
 192 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 193     struct mon_bus *mbus)
 194 {
 195         struct list_head *p;
 196         unsigned long flags;
 197
 198         spin_lock_irqsave(&mbus->lock, flags);
 199         if (list_empty(&rp->e_list)) {
 200                 spin_unlock_irqrestore(&mbus->lock, flags);
 201                 return NULL;
 202         }
 203         p = rp->e_list.next;
 204         list_del(p);
 205         --rp->nevents;
 206         spin_unlock_irqrestore(&mbus->lock, flags);
 207         return list_entry(p, struct mon_event_text, e_link);
 208 }
 209
 210 /*
 211  */
 212 static int mon_text_open(struct inode *inode, struct file *file)
 213 {
 214         struct mon_bus *mbus;
 215         struct usb_bus *ubus;
 216         struct mon_reader_text *rp;
 217         int rc;
 218
 219         down(&mon_lock);
 220         mbus = inode->u.generic_ip;
 221         ubus = mbus->u_bus;
 222
 223         rp = kmalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 224         if (rp == NULL) {
 225                 rc = -ENOMEM;
 226                 goto err_alloc;
 227         }
 228         memset(rp, 0, sizeof(struct mon_reader_text));
 229         INIT_LIST_HEAD(&rp->e_list);
 230         init_waitqueue_head(&rp->wait);
 231         init_MUTEX(&rp->printf_lock);
 232
 233         rp->printf_size = PRINTF_DFL;
 234         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 235         if (rp->printf_buf == NULL) {
 236                 rc = -ENOMEM;
 237                 goto err_alloc_pr;
 238         }
 239
 240         rp->r.m_bus = mbus;
 241         rp->r.r_data = rp;
 242         rp->r.rnf_submit = mon_text_submit;
 243         rp->r.rnf_complete = mon_text_complete;
 244
 245         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
 246             (long)rp);
 247         rp->e_slab = kmem_cache_create(rp->slab_name,
 248             sizeof(struct mon_event_text), sizeof(long), 0,
 249             mon_text_ctor, mon_text_dtor);
 250         if (rp->e_slab == NULL) {
 251                 rc = -ENOMEM;
 252                 goto err_slab;
 253         }
 254
 255         mon_reader_add(mbus, &rp->r);
 256
 257         file->private_data = rp;
 258         up(&mon_lock);
 259         return 0;
 260
 261 // err_busy:
 262 //      kmem_cache_destroy(rp->e_slab);
 263 err_slab:
 264         kfree(rp->printf_buf);
 265 err_alloc_pr:
 266         kfree(rp);
 267 err_alloc:
 268         up(&mon_lock);
 269         return rc;
 270 }
 271
 272 /*
 273  * For simplicity, we read one record in one system call and throw out
 274  * what does not fit. This means that the following does not work:
 275  *   dd if=/dbg/usbmon/0t bs=10
 276  * Also, we do not allow seeks and do not bother advancing the offset.
 277  */
 278 static ssize_t mon_text_read(struct file *file, char __user *buf,
 279                                 size_t nbytes, loff_t *ppos)
 280 {
 281         struct mon_reader_text *rp = file->private_data;
 282         struct mon_bus *mbus = rp->r.m_bus;
 283         DECLARE_WAITQUEUE(waita, current);
 284         struct mon_event_text *ep;
 285         int cnt, limit;
 286         char *pbuf;
 287         char udir, utype;
 288         int data_len, i;
 289
 290         add_wait_queue(&rp->wait, &waita);
 291         set_current_state(TASK_INTERRUPTIBLE);
 292         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 293                 if (file->f_flags & O_NONBLOCK) {
 294                         set_current_state(TASK_RUNNING);
 295                         remove_wait_queue(&rp->wait, &waita);
 296                         return -EWOULDBLOCK;    /* Same as EAGAIN in Linux */
 297                 }
 298                 /*
 299                  * We do not count nwaiters, because ->release is supposed
 300                  * to be called when all openers are gone only.
 301                  */
 302                 schedule();
 303                 if (signal_pending(current)) {
 304                         remove_wait_queue(&rp->wait, &waita);
 305                         return -EINTR;
 306                 }
 307                 set_current_state(TASK_INTERRUPTIBLE);
 308         }
 309         set_current_state(TASK_RUNNING);
 310         remove_wait_queue(&rp->wait, &waita);
 311
 312         down(&rp->printf_lock);
 313         cnt = 0;
 314         pbuf = rp->printf_buf;
 315         limit = rp->printf_size;
 316
 317         udir = usb_pipein(ep->pipe) ? 'i' : 'o';
 318         switch (usb_pipetype(ep->pipe)) {
 319         case PIPE_ISOCHRONOUS:  utype = 'Z'; break;
 320         case PIPE_INTERRUPT:    utype = 'I'; break;
 321         case PIPE_CONTROL:      utype = 'C'; break;
 322         default: /* PIPE_BULK */  utype = 'B';
 323         }
 324         cnt += snprintf(pbuf + cnt, limit - cnt,
 325             "%lx %u %c %c%c:%03u:%02u",
 326             ep->id, ep->tstamp, ep->type,
 327             utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe));
 328
 329         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 330                 cnt += snprintf(pbuf + cnt, limit - cnt,
 331                     " s %02x %02x %04x %04x %04x",
 332                     ep->setup[0],
 333                     ep->setup[1],
 334                     (ep->setup[3] << 8) | ep->setup[2],
 335                     (ep->setup[5] << 8) | ep->setup[4],
 336                     (ep->setup[7] << 8) | ep->setup[6]);
 337         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 338                 cnt += snprintf(pbuf + cnt, limit - cnt,
 339                     " %c __ __ ____ ____ ____", ep->setup_flag);
 340         } else {                     /* No setup for this kind of URB */
 341                 cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->status);
 342         }
 343         cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->length);
 344
 345         if ((data_len = ep->length) > 0) {
 346                 if (ep->data_flag == 0) {
 347                         cnt += snprintf(pbuf + cnt, limit - cnt, " =");
 348                         if (data_len >= DATA_MAX)
 349                                 data_len = DATA_MAX;
 350                         for (i = 0; i < data_len; i++) {
 351                                 if (i % 4 == 0) {
 352                                         cnt += snprintf(pbuf + cnt, limit - cnt,
 353                                             " ");
 354                                 }
 355                                 cnt += snprintf(pbuf + cnt, limit - cnt,
 356                                     "%02x", ep->data[i]);
 357                         }
 358                         cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 359                 } else {
 360                         cnt += snprintf(pbuf + cnt, limit - cnt,
 361                             " %c\n", ep->data_flag);
 362                 }
 363         } else {
 364                 cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 365         }
 366
 367         if (copy_to_user(buf, rp->printf_buf, cnt))
 368                 cnt = -EFAULT;
 369         up(&rp->printf_lock);
 370         kmem_cache_free(rp->e_slab, ep);
 371         return cnt;
 372 }
 373
 374 static int mon_text_release(struct inode *inode, struct file *file)
 375 {
 376         struct mon_reader_text *rp = file->private_data;
 377         struct mon_bus *mbus;
 378         /* unsigned long flags; */
 379         struct list_head *p;
 380         struct mon_event_text *ep;
 381
 382         down(&mon_lock);
 383         mbus = inode->u.generic_ip;
 384
 385         if (mbus->nreaders <= 0) {
 386                 printk(KERN_ERR TAG ": consistency error on close\n");
 387                 up(&mon_lock);
 388                 return 0;
 389         }
 390         mon_reader_del(mbus, &rp->r);
 391
 392         /*
 393          * In theory, e_list is protected by mbus->lock. However,
 394          * after mon_reader_del has finished, the following is the case:
 395          *  - we are not on reader list anymore, so new events won't be added;
 396          *  - whole mbus may be dropped if it was orphaned.
 397          * So, we better not touch mbus.
 398          */
 399         /* spin_lock_irqsave(&mbus->lock, flags); */
 400         while (!list_empty(&rp->e_list)) {
 401                 p = rp->e_list.next;
 402                 ep = list_entry(p, struct mon_event_text, e_link);
 403                 list_del(p);
 404                 --rp->nevents;
 405                 kmem_cache_free(rp->e_slab, ep);
 406         }
 407         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 408
 409         kmem_cache_destroy(rp->e_slab);
 410         kfree(rp->printf_buf);
 411         kfree(rp);
 412
 413         up(&mon_lock);
 414         return 0;
 415 }
 416
 417 struct file_operations mon_fops_text = {
 418         .owner =        THIS_MODULE,
 419         .open =         mon_text_open,
 420         .llseek =       no_llseek,
 421         .read =         mon_text_read,
 422         /* .write =     mon_text_write, */
 423         /* .poll =              mon_text_poll, */
 424         /* .ioctl =     mon_text_ioctl, */
 425         .release =      mon_text_release,
 426 };
 427
 428 /*
 429  * Slab interface: constructor.
 430  */
 431 static void mon_text_ctor(void *mem, kmem_cache_t *slab, unsigned long sflags)
 432 {
 433         /*
 434          * Nothing to initialize. No, really!
 435          * So, we fill it with garbage to emulate a reused object.
 436          */
 437         memset(mem, 0xe5, sizeof(struct mon_event_text));
 438 }
 439
 440 static void mon_text_dtor(void *mem, kmem_cache_t *slab, unsigned long sflags)
 441 {
 442         ;
 443 }