summaryrefslogtreecommitdiffstats
path: root/arch/powerpc/platforms/pseries/dtl.c
blob: fafcaa0e81ef593c6ed346493ed76926f21120c5 (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
/*
 * 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/debugfs.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "plpar_wrappers.h"

/*
 * Layout of entries in the hypervisor's DTL buffer. Although we don't
 * actually access the internals of an entry (we only need to know the size),
 * we might as well define it here for reference.
 */
struct dtl_entry {
	u8	dispatch_reason;
	u8	preempt_reason;
	u16	processor_id;
	u32	enqueue_to_dispatch_time;
	u32	ready_to_enqueue_time;
	u32	waiting_to_ready_time;
	u64	timebase;
	u64	fault_addr;
	u64	srr0;
	u64	srr1;
};

struct dtl {
	struct dtl_entry	*buf;
	struct dentry		*file;
	int			cpu;
	int			buf_entries;
	u64			last_idx;
};
static DEFINE_PER_CPU(struct dtl, 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. Default is just under 16 pages worth.
 */
static int dtl_buf_entries = (16 * 85);


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

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

	/* we need to store the original allocation size for use during read */
	dtl->buf_entries = dtl_buf_entries;

	dtl->buf = kmalloc_node(dtl->buf_entries * sizeof(struct dtl_entry),
			GFP_KERNEL, cpu_to_node(dtl->cpu));
	if (!dtl->buf) {
		printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
				__func__, dtl->cpu);
		return -ENOMEM;
	}

	/* 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] = dtl->buf_entries * sizeof(struct dtl_entry);

	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);
		kfree(dtl->buf);
		return -EIO;
	}

	/* set our initial buffer indices */
	dtl->last_idx = lppaca[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[dtl->cpu].dtl_enable_mask = dtl_event_mask;

	return 0;
}

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

	lppaca[dtl->cpu].dtl_enable_mask = 0x0;

	unregister_dtl(hwcpu, __pa(dtl->buf));

	kfree(dtl->buf);
	dtl->buf = NULL;
	dtl->buf_entries = 0;
}

/* 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)
{
	int rc, cur_idx, last_idx, n_read, n_req, read_size;
	struct dtl *dtl;

	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;

	cur_idx = lppaca[dtl->cpu].dtl_idx;
	last_idx = dtl->last_idx;

	if (cur_idx - last_idx > dtl->buf_entries) {
		pr_debug("%s: hv buffer overflow for cpu %d, samples lost\n",
				__func__, dtl->cpu);
	}

	cur_idx  %= dtl->buf_entries;
	last_idx %= dtl->buf_entries;

	/* read the tail of the buffer if we've wrapped */
	if (last_idx > cur_idx) {
		read_size = min(n_req, dtl->buf_entries - last_idx);

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

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

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

	n_read += read_size;
	dtl->last_idx += n_read;

	return n_read * sizeof(struct dtl_entry);
}

static 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", 0600,
				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(dtl, i);
		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);