summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/platforms/pseries/dtl.c
blob: 0e8656370063fe6bf005e59032a67c414efe729f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/*
 * Virtual Processor Dispatch Trace Log
 *
 * (C) Copyright IBM Corporation 2009
 *
 * Author: Jeremy Kerr <jk@ozlabs.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/spinlock.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/firmware.h>
#include <asm/lppaca.h>

#include "plpar_wrappers.h"

struct dtl {
	struct dtl_entry	*buf;
	struct dentry		*file;
	int			cpu;
	int			buf_entries;
	u64			last_idx;
	spinlock_t		lock;
};
static DEFINE_PER_CPU(struct dtl, cpu_dtl);

/*
 * Dispatch trace log event mask:
 * 0x7: 0x1: voluntary virtual processor waits
 *      0x2: time-slice preempts
 *      0x4: virtual partition memory page faults
 */
static u8 dtl_event_mask = 0x7;


/*
 * Size of per-cpu log buffers. Firmware requires that the buffer does
 * not cross a 4k boundary.
 */
static int dtl_buf_entries = N_DISPATCH_LOG;

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
struct dtl_ring {
	u64	write_index;
	struct dtl_entry *write_ptr;
	struct dtl_entry *buf;
	struct dtl_entry *buf_end;
	u8	saved_dtl_mask;
};

static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);

static atomic_t dtl_count;

/*
 * The cpu accounting code controls the DTL ring buffer, and we get
 * given entries as they are processed.
 */
static void consume_dtle(struct dtl_entry *dtle, u64 index)
{
	struct dtl_ring *dtlr = &__get_cpu_var(dtl_rings);
	struct dtl_entry *wp = dtlr->write_ptr;
	struct lppaca *vpa = local_paca->lppaca_ptr;

	if (!wp)
		return;

	*wp = *dtle;
	barrier();

	/* check for hypervisor ring buffer overflow, ignore this entry if so */
	if (index + N_DISPATCH_LOG < vpa->dtl_idx)
		return;

	++wp;
	if (wp == dtlr->buf_end)
		wp = dtlr->buf;
	dtlr->write_ptr = wp;

	/* incrementing write_index makes the new entry visible */
	smp_wmb();
	++dtlr->write_index;
}

static int dtl_start(struct dtl *dtl)
{
	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

	dtlr->buf = dtl->buf;
	dtlr->buf_end = dtl->buf + dtl->buf_entries;
	dtlr->write_index = 0;

	/* setting write_ptr enables logging into our buffer */
	smp_wmb();
	dtlr->write_ptr = dtl->buf;

	/* enable event logging */
	dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
	lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask;

	dtl_consumer = consume_dtle;
	atomic_inc(&dtl_count);
	return 0;
}

static void dtl_stop(struct dtl *dtl)
{
	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

	dtlr->write_ptr = NULL;
	smp_wmb();

	dtlr->buf = NULL;

	/* restore dtl_enable_mask */
	lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;

	if (atomic_dec_and_test(&dtl_count))
		dtl_consumer = NULL;
}

static u64 dtl_current_index(struct dtl *dtl)
{
	return per_cpu(dtl_rings, dtl->cpu).write_index;
}

#else /* CONFIG_VIRT_CPU_ACCOUNTING */

static int dtl_start(struct dtl *dtl)
{
	unsigned long addr;
	int ret, hwcpu;

	/* Register our dtl buffer with the hypervisor. The HV expects the
	 * buffer size to be passed in the second word of the buffer */
	((u32 *)dtl->buf)[1] = DISPATCH_LOG_BYTES;

	hwcpu = get_hard_smp_processor_id(dtl->cpu);
	addr = __pa(dtl->buf);
	ret = register_dtl(hwcpu, addr);
	if (ret) {
		printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) "
		       "failed with %d\n", __func__, dtl->cpu, hwcpu, ret);
		return -EIO;
	}

	/* set our initial buffer indices */
	lppaca_of(dtl->cpu).dtl_idx = 0;

	/* ensure that our updates to the lppaca fields have occurred before
	 * we actually enable the logging */
	smp_wmb();

	/* enable event logging */
	lppaca_of(dtl->cpu).dtl_enable_mask = dtl_event_mask;

	return 0;
}

static void dtl_stop(struct dtl *dtl)
{
	int hwcpu = get_hard_smp_processor_id(dtl->cpu);

	lppaca_of(dtl->cpu).dtl_enable_mask = 0x0;

	unregister_dtl(hwcpu);
}

static u64 dtl_current_index(struct dtl *dtl)
{
	return lppaca_of(dtl->cpu).dtl_idx;
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING */

static int dtl_enable(struct dtl *dtl)
{
	long int n_entries;
	long int rc;
	struct dtl_entry *buf = NULL;

	if (!dtl_cache)
		return -ENOMEM;

	/* only allow one reader */
	if (dtl->buf)
		return -EBUSY;

	n_entries = dtl_buf_entries;
	buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu));
	if (!buf) {
		printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
				__func__, dtl->cpu);
		return -ENOMEM;
	}

	spin_lock(&dtl->lock);
	rc = -EBUSY;
	if (!dtl->buf) {
		/* store the original allocation size for use during read */
		dtl->buf_entries = n_entries;
		dtl->buf = buf;
		dtl->last_idx = 0;
		rc = dtl_start(dtl);
		if (rc)
			dtl->buf = NULL;
	}
	spin_unlock(&dtl->lock);

	if (rc)
		kmem_cache_free(dtl_cache, buf);
	return rc;
}

static void dtl_disable(struct dtl *dtl)
{
	spin_lock(&dtl->lock);
	dtl_stop(dtl);
	kmem_cache_free(dtl_cache, dtl->buf);
	dtl->buf = NULL;
	dtl->buf_entries = 0;
	spin_unlock(&dtl->lock);
}

/* file interface */

static int dtl_file_open(struct inode *inode, struct file *filp)
{
	struct dtl *dtl = inode->i_private;
	int rc;

	rc = dtl_enable(dtl);
	if (rc)
		return rc;

	filp->private_data = dtl;
	return 0;
}

static int dtl_file_release(struct inode *inode, struct file *filp)
{
	struct dtl *dtl = inode->i_private;
	dtl_disable(dtl);
	return 0;
}

static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len,
		loff_t *pos)
{
	long int rc, n_read, n_req, read_size;
	struct dtl *dtl;
	u64 cur_idx, last_idx, i;

	if ((len % sizeof(struct dtl_entry)) != 0)
		return -EINVAL;

	dtl = filp->private_data;

	/* requested number of entries to read */
	n_req = len / sizeof(struct dtl_entry);

	/* actual number of entries read */
	n_read = 0;

	spin_lock(&dtl->lock);

	cur_idx = dtl_current_index(dtl);
	last_idx = dtl->last_idx;

	if (last_idx + dtl->buf_entries <= cur_idx)
		last_idx = cur_idx - dtl->buf_entries + 1;

	if (last_idx + n_req > cur_idx)
		n_req = cur_idx - last_idx;

	if (n_req > 0)
		dtl->last_idx = last_idx + n_req;

	spin_unlock(&dtl->lock);

	if (n_req <= 0)
		return 0;

	i = last_idx % dtl->buf_entries;

	/* read the tail of the buffer if we've wrapped */
	if (i + n_req > dtl->buf_entries) {
		read_size = dtl->buf_entries - i;

		rc = copy_to_user(buf, &dtl->buf[i],
				read_size * sizeof(struct dtl_entry));
		if (rc)
			return -EFAULT;

		i = 0;
		n_req -= read_size;
		n_read += read_size;
		buf += read_size * sizeof(struct dtl_entry);
	}

	/* .. and now the head */
	rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry));
	if (rc)
		return -EFAULT;

	n_read += n_req;

	return n_read * sizeof(struct dtl_entry);
}

static const struct file_operations dtl_fops = {
	.open		= dtl_file_open,
	.release	= dtl_file_release,
	.read		= dtl_file_read,
	.llseek		= no_llseek,
};

static struct dentry *dtl_dir;

static int dtl_setup_file(struct dtl *dtl)
{
	char name[10];

	sprintf(name, "cpu-%d", dtl->cpu);

	dtl->file = debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops);
	if (!dtl->file)
		return -ENOMEM;

	return 0;
}

static int dtl_init(void)
{
	struct dentry *event_mask_file, *buf_entries_file;
	int rc, i;

	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
		return -ENODEV;

	/* set up common debugfs structure */

	rc = -ENOMEM;
	dtl_dir = debugfs_create_dir("dtl", powerpc_debugfs_root);
	if (!dtl_dir) {
		printk(KERN_WARNING "%s: can't create dtl root dir\n",
				__func__);
		goto err;
	}

	event_mask_file = debugfs_create_x8("dtl_event_mask", 0600,
				dtl_dir, &dtl_event_mask);
	buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0400,
				dtl_dir, &dtl_buf_entries);

	if (!event_mask_file || !buf_entries_file) {
		printk(KERN_WARNING "%s: can't create dtl files\n", __func__);
		goto err_remove_dir;
	}

	/* set up the per-cpu log structures */
	for_each_possible_cpu(i) {
		struct dtl *dtl = &per_cpu(cpu_dtl, i);
		spin_lock_init(&dtl->lock);
		dtl->cpu = i;

		rc = dtl_setup_file(dtl);
		if (rc)
			goto err_remove_dir;
	}

	return 0;

err_remove_dir:
	debugfs_remove_recursive(dtl_dir);
err:
	return rc;
}
arch_initcall(dtl_init);
OpenPOWER on IntegriCloud