FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_pmc.c
1 /*-
2 * Copyright (c) 2003-2008 Joseph Koshy
3 * Copyright (c) 2007 The FreeBSD Foundation
4 * All rights reserved.
5 *
6 * Portions of this software were developed by A. Joseph Koshy under
7 * sponsorship from the FreeBSD Foundation and Google, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD: releng/9.1/sys/kern/kern_pmc.c 236238 2012-05-29 14:50:21Z fabient $");
33
34 #include "opt_hwpmc_hooks.h"
35
36 #include <sys/types.h>
37 #include <sys/ctype.h>
38 #include <sys/param.h>
39 #include <sys/malloc.h>
40 #include <sys/kernel.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/pmc.h>
44 #include <sys/pmckern.h>
45 #include <sys/smp.h>
46 #include <sys/sysctl.h>
47 #include <sys/systm.h>
48
49 #ifdef HWPMC_HOOKS
50 FEATURE(hwpmc_hooks, "Kernel support for HW PMC");
51 #define PMC_KERNEL_VERSION PMC_VERSION
52 #else
53 #define PMC_KERNEL_VERSION 0
54 #endif
55
56 MALLOC_DECLARE(M_PMCHOOKS);
57 MALLOC_DEFINE(M_PMCHOOKS, "pmchooks", "Memory space for PMC hooks");
58
59 const int pmc_kernel_version = PMC_KERNEL_VERSION;
60
61 /* Hook variable. */
62 int (*pmc_hook)(struct thread *td, int function, void *arg) = NULL;
63
64 /* Interrupt handler */
65 int (*pmc_intr)(int cpu, struct trapframe *tf) = NULL;
66
67 /* Bitmask of CPUs requiring servicing at hardclock time */
68 volatile cpuset_t pmc_cpumask;
69
70 /*
71 * A global count of SS mode PMCs. When non-zero, this means that
72 * we have processes that are sampling the system as a whole.
73 */
74 volatile int pmc_ss_count;
75
76 /*
77 * Since PMC(4) may not be loaded in the current kernel, the
78 * convention followed is that a non-NULL value of 'pmc_hook' implies
79 * the presence of this kernel module.
80 *
81 * This requires us to protect 'pmc_hook' with a
82 * shared (sx) lock -- thus making the process of calling into PMC(4)
83 * somewhat more expensive than a simple 'if' check and indirect call.
84 */
85 struct sx pmc_sx;
86
87 /*
88 * PMC Soft per cpu trapframe.
89 */
90 struct trapframe pmc_tf[MAXCPU];
91
92 /*
93 * PMC Soft use a global table to store registered events.
94 */
95
96 SYSCTL_NODE(_kern, OID_AUTO, hwpmc, CTLFLAG_RW, 0, "HWPMC parameters");
97
98 static int pmc_softevents = 16;
99 TUNABLE_INT(PMC_SYSCTL_NAME_PREFIX "softevents", &pmc_softevents);
100 SYSCTL_INT(_kern_hwpmc, OID_AUTO, softevents, CTLFLAG_TUN|CTLFLAG_RD,
101 &pmc_softevents, 0, "maximum number of soft events");
102
103 struct mtx pmc_softs_mtx;
104 int pmc_softs_count;
105 struct pmc_soft **pmc_softs;
106
107 MTX_SYSINIT(pmc_soft_mtx, &pmc_softs_mtx, "pmc-softs", MTX_SPIN);
108
109 static void
110 pmc_init_sx(void)
111 {
112 sx_init_flags(&pmc_sx, "pmc-sx", SX_NOWITNESS);
113 }
114
115 SYSINIT(pmcsx, SI_SUB_LOCK, SI_ORDER_MIDDLE, pmc_init_sx, NULL);
116
117 /*
118 * Helper functions.
119 */
120
121 /*
122 * A note on the CPU numbering scheme used by the hwpmc(4) driver.
123 *
124 * CPUs are denoted using numbers in the range 0..[pmc_cpu_max()-1].
125 * CPUs could be numbered "sparsely" in this range; the predicate
126 * `pmc_cpu_is_present()' is used to test whether a given CPU is
127 * physically present.
128 *
129 * Further, a CPU that is physically present may be administratively
130 * disabled or otherwise unavailable for use by hwpmc(4). The
131 * `pmc_cpu_is_active()' predicate tests for CPU usability. An
132 * "active" CPU participates in thread scheduling and can field
133 * interrupts raised by PMC hardware.
134 *
135 * On systems with hyperthreaded CPUs, multiple logical CPUs may share
136 * PMC hardware resources. For such processors one logical CPU is
137 * denoted as the primary owner of the in-CPU PMC resources. The
138 * pmc_cpu_is_primary() predicate is used to distinguish this primary
139 * CPU from the others.
140 */
141
142 int
143 pmc_cpu_is_active(int cpu)
144 {
145 #ifdef SMP
146 return (pmc_cpu_is_present(cpu) &&
147 !CPU_ISSET(cpu, &hlt_cpus_mask));
148 #else
149 return (1);
150 #endif
151 }
152
153 /* Deprecated. */
154 int
155 pmc_cpu_is_disabled(int cpu)
156 {
157 return (!pmc_cpu_is_active(cpu));
158 }
159
160 int
161 pmc_cpu_is_present(int cpu)
162 {
163 #ifdef SMP
164 return (!CPU_ABSENT(cpu));
165 #else
166 return (1);
167 #endif
168 }
169
170 int
171 pmc_cpu_is_primary(int cpu)
172 {
173 #ifdef SMP
174 return (!CPU_ISSET(cpu, &logical_cpus_mask));
175 #else
176 return (1);
177 #endif
178 }
179
180
181 /*
182 * Return the maximum CPU number supported by the system. The return
183 * value is used for scaling internal data structures and for runtime
184 * checks.
185 */
186 unsigned int
187 pmc_cpu_max(void)
188 {
189 #ifdef SMP
190 return (mp_maxid+1);
191 #else
192 return (1);
193 #endif
194 }
195
196 #ifdef INVARIANTS
197
198 /*
199 * Return the count of CPUs in the `active' state in the system.
200 */
201 int
202 pmc_cpu_max_active(void)
203 {
204 #ifdef SMP
205 /*
206 * When support for CPU hot-plugging is added to the kernel,
207 * this function would change to return the current number
208 * of "active" CPUs.
209 */
210 return (mp_ncpus);
211 #else
212 return (1);
213 #endif
214 }
215
216 #endif
217
218 /*
219 * Cleanup event name:
220 * - remove duplicate '_'
221 * - all uppercase
222 */
223 static void
224 pmc_soft_namecleanup(char *name)
225 {
226 char *p, *q;
227
228 p = q = name;
229
230 for ( ; *p == '_' ; p++)
231 ;
232 for ( ; *p ; p++) {
233 if (*p == '_' && (*(p + 1) == '_' || *(p + 1) == '\0'))
234 continue;
235 else
236 *q++ = toupper(*p);
237 }
238 *q = '\0';
239 }
240
241 void
242 pmc_soft_ev_register(struct pmc_soft *ps)
243 {
244 static int warned = 0;
245 int n;
246
247 ps->ps_running = 0;
248 ps->ps_ev.pm_ev_code = 0; /* invalid */
249 pmc_soft_namecleanup(ps->ps_ev.pm_ev_name);
250
251 mtx_lock_spin(&pmc_softs_mtx);
252
253 if (pmc_softs_count >= pmc_softevents) {
254 /*
255 * XXX Reusing events can enter a race condition where
256 * new allocated event will be used as an old one.
257 */
258 for (n = 0; n < pmc_softevents; n++)
259 if (pmc_softs[n] == NULL)
260 break;
261 if (n == pmc_softevents) {
262 mtx_unlock_spin(&pmc_softs_mtx);
263 if (!warned) {
264 printf("hwpmc: too many soft events, "
265 "increase kern.hwpmc.softevents tunable\n");
266 warned = 1;
267 }
268 return;
269 }
270
271 ps->ps_ev.pm_ev_code = PMC_EV_SOFT_FIRST + n;
272 pmc_softs[n] = ps;
273 } else {
274 ps->ps_ev.pm_ev_code = PMC_EV_SOFT_FIRST + pmc_softs_count;
275 pmc_softs[pmc_softs_count++] = ps;
276 }
277
278 mtx_unlock_spin(&pmc_softs_mtx);
279 }
280
281 void
282 pmc_soft_ev_deregister(struct pmc_soft *ps)
283 {
284
285 KASSERT(ps != NULL, ("pmc_soft_deregister: called with NULL"));
286
287 mtx_lock_spin(&pmc_softs_mtx);
288
289 if (ps->ps_ev.pm_ev_code != 0 &&
290 (ps->ps_ev.pm_ev_code - PMC_EV_SOFT_FIRST) < pmc_softevents) {
291 KASSERT(ps->ps_ev.pm_ev_code >= PMC_EV_SOFT_FIRST &&
292 ps->ps_ev.pm_ev_code <= PMC_EV_SOFT_LAST,
293 ("pmc_soft_deregister: invalid event value"));
294 pmc_softs[ps->ps_ev.pm_ev_code - PMC_EV_SOFT_FIRST] = NULL;
295 }
296
297 mtx_unlock_spin(&pmc_softs_mtx);
298 }
299
300 struct pmc_soft *
301 pmc_soft_ev_acquire(enum pmc_event ev)
302 {
303 struct pmc_soft *ps;
304
305 if (ev == 0 || (ev - PMC_EV_SOFT_FIRST) >= pmc_softevents)
306 return NULL;
307
308 KASSERT(ev >= PMC_EV_SOFT_FIRST &&
309 ev <= PMC_EV_SOFT_LAST,
310 ("event out of range"));
311
312 mtx_lock_spin(&pmc_softs_mtx);
313
314 ps = pmc_softs[ev - PMC_EV_SOFT_FIRST];
315 if (ps == NULL)
316 mtx_unlock_spin(&pmc_softs_mtx);
317
318 return ps;
319 }
320
321 void
322 pmc_soft_ev_release(struct pmc_soft *ps)
323 {
324
325 mtx_unlock_spin(&pmc_softs_mtx);
326 }
327
328 /*
329 * Initialise hwpmc.
330 */
331 static void
332 init_hwpmc(void *dummy __unused)
333 {
334 if (pmc_softevents <= 0 ||
335 pmc_softevents > PMC_EV_DYN_COUNT) {
336 (void) printf("hwpmc: tunable \"softevents\"=%d out of "
337 "range.\n", pmc_softevents);
338 pmc_softevents = PMC_EV_DYN_COUNT;
339 }
340 pmc_softs = malloc(pmc_softevents * sizeof(struct pmc_soft *), M_PMCHOOKS, M_NOWAIT|M_ZERO);
341 KASSERT(pmc_softs != NULL, ("cannot allocate soft events table"));
342 }
343
344 SYSINIT(hwpmc, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_hwpmc, NULL);
345
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