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