arch/powerpc/platforms/pseries/dtl.c

   1 /*
   2  * Virtual Processor Dispatch Trace Log
   3  *
   4  * (C) Copyright IBM Corporation 2009
   5  *
   6  * Author: Jeremy Kerr <jk@ozlabs.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2, or (at your option)
  11  * any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21  */
  22
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25 #include <asm/smp.h>
  26 #include <linux/uaccess.h>
  27 #include <asm/firmware.h>
  28 #include <asm/lppaca.h>
  29 #include <asm/debugfs.h>
  30 #include <asm/plpar_wrappers.h>
  31 #include <asm/machdep.h>
  32
  33 struct dtl {
  34         struct dtl_entry        *buf;
  35         struct dentry           *file;
  36         int                     cpu;
  37         int                     buf_entries;
  38         u64                     last_idx;
  39         spinlock_t              lock;
  40 };
  41 static DEFINE_PER_CPU(struct dtl, cpu_dtl);
  42
  43 static u8 dtl_event_mask = DTL_LOG_ALL;
  44
  45
  46 /*
  47  * Size of per-cpu log buffers. Firmware requires that the buffer does
  48  * not cross a 4k boundary.
  49  */
  50 static int dtl_buf_entries = N_DISPATCH_LOG;
  51
  52 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
  53 struct dtl_ring {
  54         u64     write_index;
  55         struct dtl_entry *write_ptr;
  56         struct dtl_entry *buf;
  57         struct dtl_entry *buf_end;
  58         u8      saved_dtl_mask;
  59 };
  60
  61 static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);
  62
  63 static atomic_t dtl_count;
  64
  65 /*
  66  * The cpu accounting code controls the DTL ring buffer, and we get
  67  * given entries as they are processed.
  68  */
  69 static void consume_dtle(struct dtl_entry *dtle, u64 index)
  70 {
  71         struct dtl_ring *dtlr = this_cpu_ptr(&dtl_rings);
  72         struct dtl_entry *wp = dtlr->write_ptr;
  73         struct lppaca *vpa = local_paca->lppaca_ptr;
  74
  75         if (!wp)
  76                 return;
  77
  78         *wp = *dtle;
  79         barrier();
  80
  81         /* check for hypervisor ring buffer overflow, ignore this entry if so */
  82         if (index + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx))
  83                 return;
  84
  85         ++wp;
  86         if (wp == dtlr->buf_end)
  87                 wp = dtlr->buf;
  88         dtlr->write_ptr = wp;
  89
  90         /* incrementing write_index makes the new entry visible */
  91         smp_wmb();
  92         ++dtlr->write_index;
  93 }
  94
  95 static int dtl_start(struct dtl *dtl)
  96 {
  97         struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);
  98
  99         dtlr->buf = dtl->buf;
 100         dtlr->buf_end = dtl->buf + dtl->buf_entries;
 101         dtlr->write_index = 0;
 102
 103         /* setting write_ptr enables logging into our buffer */
 104         smp_wmb();
 105         dtlr->write_ptr = dtl->buf;
 106
 107         /* enable event logging */
 108         dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
 109         lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask;
 110
 111         dtl_consumer = consume_dtle;
 112         atomic_inc(&dtl_count);
 113         return 0;
 114 }
 115
 116 static void dtl_stop(struct dtl *dtl)
 117 {
 118         struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);
 119
 120         dtlr->write_ptr = NULL;
 121         smp_wmb();
 122
 123         dtlr->buf = NULL;
 124
 125         /* restore dtl_enable_mask */
 126         lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;
 127
 128         if (atomic_dec_and_test(&dtl_count))
 129                 dtl_consumer = NULL;
 130 }
 131
 132 static u64 dtl_current_index(struct dtl *dtl)
 133 {
 134         return per_cpu(dtl_rings, dtl->cpu).write_index;
 135 }
 136
 137 #else /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 138
 139 static int dtl_start(struct dtl *dtl)
 140 {
 141         unsigned long addr;
 142         int ret, hwcpu;
 143
 144         /* Register our dtl buffer with the hypervisor. The HV expects the
 145          * buffer size to be passed in the second word of the buffer */
 146         ((u32 *)dtl->buf)[1] = cpu_to_be32(DISPATCH_LOG_BYTES);
 147
 148         hwcpu = get_hard_smp_processor_id(dtl->cpu);
 149         addr = __pa(dtl->buf);
 150         ret = register_dtl(hwcpu, addr);
 151         if (ret) {
 152                 printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) "
 153                        "failed with %d\n", __func__, dtl->cpu, hwcpu, ret);
 154                 return -EIO;
 155         }
 156
 157         /* set our initial buffer indices */
 158         lppaca_of(dtl->cpu).dtl_idx = 0;
 159
 160         /* ensure that our updates to the lppaca fields have occurred before
 161          * we actually enable the logging */
 162         smp_wmb();
 163
 164         /* enable event logging */
 165         lppaca_of(dtl->cpu).dtl_enable_mask = dtl_event_mask;
 166
 167         return 0;
 168 }
 169
 170 static void dtl_stop(struct dtl *dtl)
 171 {
 172         int hwcpu = get_hard_smp_processor_id(dtl->cpu);
 173
 174         lppaca_of(dtl->cpu).dtl_enable_mask = 0x0;
 175
 176         unregister_dtl(hwcpu);
 177 }
 178
 179 static u64 dtl_current_index(struct dtl *dtl)
 180 {
 181         return be64_to_cpu(lppaca_of(dtl->cpu).dtl_idx);
 182 }
 183 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 184
 185 static int dtl_enable(struct dtl *dtl)
 186 {
 187         long int n_entries;
 188         long int rc;
 189         struct dtl_entry *buf = NULL;
 190
 191         if (!dtl_cache)
 192                 return -ENOMEM;
 193
 194         /* only allow one reader */
 195         if (dtl->buf)
 196                 return -EBUSY;
 197
 198         n_entries = dtl_buf_entries;
 199         buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu));
 200         if (!buf) {
 201                 printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
 202                                 __func__, dtl->cpu);
 203                 return -ENOMEM;
 204         }
 205
 206         spin_lock(&dtl->lock);
 207         rc = -EBUSY;
 208         if (!dtl->buf) {
 209                 /* store the original allocation size for use during read */
 210                 dtl->buf_entries = n_entries;
 211                 dtl->buf = buf;
 212                 dtl->last_idx = 0;
 213                 rc = dtl_start(dtl);
 214                 if (rc)
 215                         dtl->buf = NULL;
 216         }
 217         spin_unlock(&dtl->lock);
 218
 219         if (rc)
 220                 kmem_cache_free(dtl_cache, buf);
 221         return rc;
 222 }
 223
 224 static void dtl_disable(struct dtl *dtl)
 225 {
 226         spin_lock(&dtl->lock);
 227         dtl_stop(dtl);
 228         kmem_cache_free(dtl_cache, dtl->buf);
 229         dtl->buf = NULL;
 230         dtl->buf_entries = 0;
 231         spin_unlock(&dtl->lock);
 232 }
 233
 234 /* file interface */
 235
 236 static int dtl_file_open(struct inode *inode, struct file *filp)
 237 {
 238         struct dtl *dtl = inode->i_private;
 239         int rc;
 240
 241         rc = dtl_enable(dtl);
 242         if (rc)
 243                 return rc;
 244
 245         filp->private_data = dtl;
 246         return 0;
 247 }
 248
 249 static int dtl_file_release(struct inode *inode, struct file *filp)
 250 {
 251         struct dtl *dtl = inode->i_private;
 252         dtl_disable(dtl);
 253         return 0;
 254 }
 255
 256 static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len,
 257                 loff_t *pos)
 258 {
 259         long int rc, n_read, n_req, read_size;
 260         struct dtl *dtl;
 261         u64 cur_idx, last_idx, i;
 262
 263         if ((len % sizeof(struct dtl_entry)) != 0)
 264                 return -EINVAL;
 265
 266         dtl = filp->private_data;
 267
 268         /* requested number of entries to read */
 269         n_req = len / sizeof(struct dtl_entry);
 270
 271         /* actual number of entries read */
 272         n_read = 0;
 273
 274         spin_lock(&dtl->lock);
 275
 276         cur_idx = dtl_current_index(dtl);
 277         last_idx = dtl->last_idx;
 278
 279         if (last_idx + dtl->buf_entries <= cur_idx)
 280                 last_idx = cur_idx - dtl->buf_entries + 1;
 281
 282         if (last_idx + n_req > cur_idx)
 283                 n_req = cur_idx - last_idx;
 284
 285         if (n_req > 0)
 286                 dtl->last_idx = last_idx + n_req;
 287
 288         spin_unlock(&dtl->lock);
 289
 290         if (n_req <= 0)
 291                 return 0;
 292
 293         i = last_idx % dtl->buf_entries;
 294
 295         /* read the tail of the buffer if we've wrapped */
 296         if (i + n_req > dtl->buf_entries) {
 297                 read_size = dtl->buf_entries - i;
 298
 299                 rc = copy_to_user(buf, &dtl->buf[i],
 300                                 read_size * sizeof(struct dtl_entry));
 301                 if (rc)
 302                         return -EFAULT;
 303
 304                 i = 0;
 305                 n_req -= read_size;
 306                 n_read += read_size;
 307                 buf += read_size * sizeof(struct dtl_entry);
 308         }
 309
 310         /* .. and now the head */
 311         rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry));
 312         if (rc)
 313                 return -EFAULT;
 314
 315         n_read += n_req;
 316
 317         return n_read * sizeof(struct dtl_entry);
 318 }
 319
 320 static const struct file_operations dtl_fops = {
 321         .open           = dtl_file_open,
 322         .release        = dtl_file_release,
 323         .read           = dtl_file_read,
 324         .llseek         = no_llseek,
 325 };
 326
 327 static struct dentry *dtl_dir;
 328
 329 static int dtl_setup_file(struct dtl *dtl)
 330 {
 331         char name[10];
 332
 333         sprintf(name, "cpu-%d", dtl->cpu);
 334
 335         dtl->file = debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops);
 336         if (!dtl->file)
 337                 return -ENOMEM;
 338
 339         return 0;
 340 }
 341
 342 static int dtl_init(void)
 343 {
 344         struct dentry *event_mask_file, *buf_entries_file;
 345         int rc, i;
 346
 347         if (!firmware_has_feature(FW_FEATURE_SPLPAR))
 348                 return -ENODEV;
 349
 350         /* set up common debugfs structure */
 351
 352         rc = -ENOMEM;
 353         dtl_dir = debugfs_create_dir("dtl", powerpc_debugfs_root);
 354         if (!dtl_dir) {
 355                 printk(KERN_WARNING "%s: can't create dtl root dir\n",
 356                                 __func__);
 357                 goto err;
 358         }
 359
 360         event_mask_file = debugfs_create_x8("dtl_event_mask", 0600,
 361                                 dtl_dir, &dtl_event_mask);
 362         buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0400,
 363                                 dtl_dir, &dtl_buf_entries);
 364
 365         if (!event_mask_file || !buf_entries_file) {
 366                 printk(KERN_WARNING "%s: can't create dtl files\n", __func__);
 367                 goto err_remove_dir;
 368         }
 369
 370         /* set up the per-cpu log structures */
 371         for_each_possible_cpu(i) {
 372                 struct dtl *dtl = &per_cpu(cpu_dtl, i);
 373                 spin_lock_init(&dtl->lock);
 374                 dtl->cpu = i;
 375
 376                 rc = dtl_setup_file(dtl);
 377                 if (rc)
 378                         goto err_remove_dir;
 379         }
 380
 381         return 0;
 382
 383 err_remove_dir:
 384         debugfs_remove_recursive(dtl_dir);
 385 err:
 386         return rc;
 387 }
 388 machine_arch_initcall(pseries, dtl_init);