root/drivers/gpu/drm/msm/msm_rd.c

DEFINITIONS

1. rd_write
2. rd_write_section
3. rd_read
4. rd_open
5. rd_release
6. rd_cleanup
7. rd_init
8. msm_rd_debugfs_init
9. msm_rd_debugfs_cleanup
10. snapshot_buf
11. should_dump
12. msm_rd_dump_submit

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2013 Red Hat
   4  * Author: Rob Clark <robdclark@gmail.com>
   5  */
   6 
   7 /* For debugging crashes, userspace can:
   8  *
   9  *   tail -f /sys/kernel/debug/dri/<minor>/rd > logfile.rd
  10  *
  11  * to log the cmdstream in a format that is understood by freedreno/cffdump
  12  * utility.  By comparing the last successfully completed fence #, to the
  13  * cmdstream for the next fence, you can narrow down which process and submit
  14  * caused the gpu crash/lockup.
  15  *
  16  * Additionally:
  17  *
  18  *   tail -f /sys/kernel/debug/dri/<minor>/hangrd > logfile.rd
  19  *
  20  * will capture just the cmdstream from submits which triggered a GPU hang.
  21  *
  22  * This bypasses drm_debugfs_create_files() mainly because we need to use
  23  * our own fops for a bit more control.  In particular, we don't want to
  24  * do anything if userspace doesn't have the debugfs file open.
  25  *
  26  * The module-param "rd_full", which defaults to false, enables snapshotting
  27  * all (non-written) buffers in the submit, rather than just cmdstream bo's.
  28  * This is useful to capture the contents of (for example) vbo's or textures,
  29  * or shader programs (if not emitted inline in cmdstream).
  30  */
  31 
  32 #ifdef CONFIG_DEBUG_FS
  33 
  34 #include <linux/circ_buf.h>
  35 #include <linux/debugfs.h>
  36 #include <linux/kfifo.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/wait.h>
  39 
  40 #include <drm/drm_file.h>
  41 
  42 #include "msm_drv.h"
  43 #include "msm_gpu.h"
  44 #include "msm_gem.h"
  45 
  46 static bool rd_full = false;
  47 MODULE_PARM_DESC(rd_full, "If true, $debugfs/.../rd will snapshot all buffer contents");
  48 module_param_named(rd_full, rd_full, bool, 0600);
  49 
  50 enum rd_sect_type {
  51         RD_NONE,
  52         RD_TEST,       /* ascii text */
  53         RD_CMD,        /* ascii text */
  54         RD_GPUADDR,    /* u32 gpuaddr, u32 size */
  55         RD_CONTEXT,    /* raw dump */
  56         RD_CMDSTREAM,  /* raw dump */
  57         RD_CMDSTREAM_ADDR, /* gpu addr of cmdstream */
  58         RD_PARAM,      /* u32 param_type, u32 param_val, u32 bitlen */
  59         RD_FLUSH,      /* empty, clear previous params */
  60         RD_PROGRAM,    /* shader program, raw dump */
  61         RD_VERT_SHADER,
  62         RD_FRAG_SHADER,
  63         RD_BUFFER_CONTENTS,
  64         RD_GPU_ID,
  65 };
  66 
  67 #define BUF_SZ 512  /* should be power of 2 */
  68 
  69 /* space used: */
  70 #define circ_count(circ) \
  71         (CIRC_CNT((circ)->head, (circ)->tail, BUF_SZ))
  72 #define circ_count_to_end(circ) \
  73         (CIRC_CNT_TO_END((circ)->head, (circ)->tail, BUF_SZ))
  74 /* space available: */
  75 #define circ_space(circ) \
  76         (CIRC_SPACE((circ)->head, (circ)->tail, BUF_SZ))
  77 #define circ_space_to_end(circ) \
  78         (CIRC_SPACE_TO_END((circ)->head, (circ)->tail, BUF_SZ))
  79 
  80 struct msm_rd_state {
  81         struct drm_device *dev;
  82 
  83         bool open;
  84 
  85         /* current submit to read out: */
  86         struct msm_gem_submit *submit;
  87 
  88         /* fifo access is synchronized on the producer side by
  89          * struct_mutex held by submit code (otherwise we could
  90          * end up w/ cmds logged in different order than they
  91          * were executed).  And read_lock synchronizes the reads
  92          */
  93         struct mutex read_lock;
  94 
  95         wait_queue_head_t fifo_event;
  96         struct circ_buf fifo;
  97 
  98         char buf[BUF_SZ];
  99 };
 100 
 101 static void rd_write(struct msm_rd_state *rd, const void *buf, int sz)
 102 {
 103         struct circ_buf *fifo = &rd->fifo;
 104         const char *ptr = buf;
 105 
 106         while (sz > 0) {
 107                 char *fptr = &fifo->buf[fifo->head];
 108                 int n;
 109 
 110                 wait_event(rd->fifo_event, circ_space(&rd->fifo) > 0 || !rd->open);
 111                 if (!rd->open)
 112                         return;
 113 
 114                 /* Note that smp_load_acquire() is not strictly required
 115                  * as CIRC_SPACE_TO_END() does not access the tail more
 116                  * than once.
 117                  */
 118                 n = min(sz, circ_space_to_end(&rd->fifo));
 119                 memcpy(fptr, ptr, n);
 120 
 121                 smp_store_release(&fifo->head, (fifo->head + n) & (BUF_SZ - 1));
 122                 sz  -= n;
 123                 ptr += n;
 124 
 125                 wake_up_all(&rd->fifo_event);
 126         }
 127 }
 128 
 129 static void rd_write_section(struct msm_rd_state *rd,
 130                 enum rd_sect_type type, const void *buf, int sz)
 131 {
 132         rd_write(rd, &type, 4);
 133         rd_write(rd, &sz, 4);
 134         rd_write(rd, buf, sz);
 135 }
 136 
 137 static ssize_t rd_read(struct file *file, char __user *buf,
 138                 size_t sz, loff_t *ppos)
 139 {
 140         struct msm_rd_state *rd = file->private_data;
 141         struct circ_buf *fifo = &rd->fifo;
 142         const char *fptr = &fifo->buf[fifo->tail];
 143         int n = 0, ret = 0;
 144 
 145         mutex_lock(&rd->read_lock);
 146 
 147         ret = wait_event_interruptible(rd->fifo_event,
 148                         circ_count(&rd->fifo) > 0);
 149         if (ret)
 150                 goto out;
 151 
 152         /* Note that smp_load_acquire() is not strictly required
 153          * as CIRC_CNT_TO_END() does not access the head more than
 154          * once.
 155          */
 156         n = min_t(int, sz, circ_count_to_end(&rd->fifo));
 157         if (copy_to_user(buf, fptr, n)) {
 158                 ret = -EFAULT;
 159                 goto out;
 160         }
 161 
 162         smp_store_release(&fifo->tail, (fifo->tail + n) & (BUF_SZ - 1));
 163         *ppos += n;
 164 
 165         wake_up_all(&rd->fifo_event);
 166 
 167 out:
 168         mutex_unlock(&rd->read_lock);
 169         if (ret)
 170                 return ret;
 171         return n;
 172 }
 173 
 174 static int rd_open(struct inode *inode, struct file *file)
 175 {
 176         struct msm_rd_state *rd = inode->i_private;
 177         struct drm_device *dev = rd->dev;
 178         struct msm_drm_private *priv = dev->dev_private;
 179         struct msm_gpu *gpu = priv->gpu;
 180         uint64_t val;
 181         uint32_t gpu_id;
 182         int ret = 0;
 183 
 184         mutex_lock(&dev->struct_mutex);
 185 
 186         if (rd->open || !gpu) {
 187                 ret = -EBUSY;
 188                 goto out;
 189         }
 190 
 191         file->private_data = rd;
 192         rd->open = true;
 193 
 194         /* the parsing tools need to know gpu-id to know which
 195          * register database to load.
 196          */
 197         gpu->funcs->get_param(gpu, MSM_PARAM_GPU_ID, &val);
 198         gpu_id = val;
 199 
 200         rd_write_section(rd, RD_GPU_ID, &gpu_id, sizeof(gpu_id));
 201 
 202 out:
 203         mutex_unlock(&dev->struct_mutex);
 204         return ret;
 205 }
 206 
 207 static int rd_release(struct inode *inode, struct file *file)
 208 {
 209         struct msm_rd_state *rd = inode->i_private;
 210 
 211         rd->open = false;
 212         wake_up_all(&rd->fifo_event);
 213 
 214         return 0;
 215 }
 216 
 217 
 218 static const struct file_operations rd_debugfs_fops = {
 219         .owner = THIS_MODULE,
 220         .open = rd_open,
 221         .read = rd_read,
 222         .llseek = no_llseek,
 223         .release = rd_release,
 224 };
 225 
 226 
 227 static void rd_cleanup(struct msm_rd_state *rd)
 228 {
 229         if (!rd)
 230                 return;
 231 
 232         mutex_destroy(&rd->read_lock);
 233         kfree(rd);
 234 }
 235 
 236 static struct msm_rd_state *rd_init(struct drm_minor *minor, const char *name)
 237 {
 238         struct msm_rd_state *rd;
 239 
 240         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
 241         if (!rd)
 242                 return ERR_PTR(-ENOMEM);
 243 
 244         rd->dev = minor->dev;
 245         rd->fifo.buf = rd->buf;
 246 
 247         mutex_init(&rd->read_lock);
 248 
 249         init_waitqueue_head(&rd->fifo_event);
 250 
 251         debugfs_create_file(name, S_IFREG | S_IRUGO, minor->debugfs_root, rd,
 252                             &rd_debugfs_fops);
 253 
 254         return rd;
 255 }
 256 
 257 int msm_rd_debugfs_init(struct drm_minor *minor)
 258 {
 259         struct msm_drm_private *priv = minor->dev->dev_private;
 260         struct msm_rd_state *rd;
 261         int ret;
 262 
 263         /* only create on first minor: */
 264         if (priv->rd)
 265                 return 0;
 266 
 267         rd = rd_init(minor, "rd");
 268         if (IS_ERR(rd)) {
 269                 ret = PTR_ERR(rd);
 270                 goto fail;
 271         }
 272 
 273         priv->rd = rd;
 274 
 275         rd = rd_init(minor, "hangrd");
 276         if (IS_ERR(rd)) {
 277                 ret = PTR_ERR(rd);
 278                 goto fail;
 279         }
 280 
 281         priv->hangrd = rd;
 282 
 283         return 0;
 284 
 285 fail:
 286         msm_rd_debugfs_cleanup(priv);
 287         return ret;
 288 }
 289 
 290 void msm_rd_debugfs_cleanup(struct msm_drm_private *priv)
 291 {
 292         rd_cleanup(priv->rd);
 293         priv->rd = NULL;
 294 
 295         rd_cleanup(priv->hangrd);
 296         priv->hangrd = NULL;
 297 }
 298 
 299 static void snapshot_buf(struct msm_rd_state *rd,
 300                 struct msm_gem_submit *submit, int idx,
 301                 uint64_t iova, uint32_t size)
 302 {
 303         struct msm_gem_object *obj = submit->bos[idx].obj;
 304         unsigned offset = 0;
 305         const char *buf;
 306 
 307         if (iova) {
 308                 offset = iova - submit->bos[idx].iova;
 309         } else {
 310                 iova = submit->bos[idx].iova;
 311                 size = obj->base.size;
 312         }
 313 
 314         /*
 315          * Always write the GPUADDR header so can get a complete list of all the
 316          * buffers in the cmd
 317          */
 318         rd_write_section(rd, RD_GPUADDR,
 319                         (uint32_t[3]){ iova, size, iova >> 32 }, 12);
 320 
 321         /* But only dump the contents of buffers marked READ */
 322         if (!(submit->bos[idx].flags & MSM_SUBMIT_BO_READ))
 323                 return;
 324 
 325         buf = msm_gem_get_vaddr_active(&obj->base);
 326         if (IS_ERR(buf))
 327                 return;
 328 
 329         buf += offset;
 330 
 331         rd_write_section(rd, RD_BUFFER_CONTENTS, buf, size);
 332 
 333         msm_gem_put_vaddr(&obj->base);
 334 }
 335 
 336 static bool
 337 should_dump(struct msm_gem_submit *submit, int idx)
 338 {
 339         return rd_full || (submit->bos[idx].flags & MSM_SUBMIT_BO_DUMP);
 340 }
 341 
 342 /* called under struct_mutex */
 343 void msm_rd_dump_submit(struct msm_rd_state *rd, struct msm_gem_submit *submit,
 344                 const char *fmt, ...)
 345 {
 346         struct drm_device *dev = submit->dev;
 347         struct task_struct *task;
 348         char msg[256];
 349         int i, n;
 350 
 351         if (!rd->open)
 352                 return;
 353 
 354         /* writing into fifo is serialized by caller, and
 355          * rd->read_lock is used to serialize the reads
 356          */
 357         WARN_ON(!mutex_is_locked(&dev->struct_mutex));
 358 
 359         if (fmt) {
 360                 va_list args;
 361 
 362                 va_start(args, fmt);
 363                 n = vscnprintf(msg, sizeof(msg), fmt, args);
 364                 va_end(args);
 365 
 366                 rd_write_section(rd, RD_CMD, msg, ALIGN(n, 4));
 367         }
 368 
 369         rcu_read_lock();
 370         task = pid_task(submit->pid, PIDTYPE_PID);
 371         if (task) {
 372                 n = scnprintf(msg, sizeof(msg), "%.*s/%d: fence=%u",
 373                                 TASK_COMM_LEN, task->comm,
 374                                 pid_nr(submit->pid), submit->seqno);
 375         } else {
 376                 n = scnprintf(msg, sizeof(msg), "???/%d: fence=%u",
 377                                 pid_nr(submit->pid), submit->seqno);
 378         }
 379         rcu_read_unlock();
 380 
 381         rd_write_section(rd, RD_CMD, msg, ALIGN(n, 4));
 382 
 383         for (i = 0; i < submit->nr_bos; i++)
 384                 if (should_dump(submit, i))
 385                         snapshot_buf(rd, submit, i, 0, 0);
 386 
 387         for (i = 0; i < submit->nr_cmds; i++) {
 388                 uint64_t iova = submit->cmd[i].iova;
 389                 uint32_t szd  = submit->cmd[i].size; /* in dwords */
 390 
 391                 /* snapshot cmdstream bo's (if we haven't already): */
 392                 if (!should_dump(submit, i)) {
 393                         snapshot_buf(rd, submit, submit->cmd[i].idx,
 394                                         submit->cmd[i].iova, szd * 4);
 395                 }
 396 
 397                 switch (submit->cmd[i].type) {
 398                 case MSM_SUBMIT_CMD_IB_TARGET_BUF:
 399                         /* ignore IB-targets, we've logged the buffer, the
 400                          * parser tool will follow the IB based on the logged
 401                          * buffer/gpuaddr, so nothing more to do.
 402                          */
 403                         break;
 404                 case MSM_SUBMIT_CMD_CTX_RESTORE_BUF:
 405                 case MSM_SUBMIT_CMD_BUF:
 406                         rd_write_section(rd, RD_CMDSTREAM_ADDR,
 407                                 (uint32_t[3]){ iova, szd, iova >> 32 }, 12);
 408                         break;
 409                 }
 410         }
 411 }
 412 #endif