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/11.1/sys/kern/kern_pmc.c 315285 2017-03-14 20:43:04Z mjg $");
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 __read_mostly (*pmc_hook)(struct thread *td, int function, void *arg) = NULL;
63
64 /* Interrupt handler */
65 int __read_mostly (*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 SYSCTL_INT(_kern_hwpmc, OID_AUTO, softevents, CTLFLAG_RDTUN,
100 &pmc_softevents, 0, "maximum number of soft events");
101
102 struct mtx pmc_softs_mtx;
103 int pmc_softs_count;
104 struct pmc_soft **pmc_softs;
105
106 MTX_SYSINIT(pmc_soft_mtx, &pmc_softs_mtx, "pmc-softs", MTX_SPIN);
107
108 static void
109 pmc_init_sx(void)
110 {
111 sx_init_flags(&pmc_sx, "pmc-sx", SX_NOWITNESS);
112 }
113
114 SYSINIT(pmcsx, SI_SUB_LOCK, SI_ORDER_MIDDLE, pmc_init_sx, NULL);
115
116 /*
117 * Helper functions.
118 */
119
120 /*
121 * A note on the CPU numbering scheme used by the hwpmc(4) driver.
122 *
123 * CPUs are denoted using numbers in the range 0..[pmc_cpu_max()-1].
124 * CPUs could be numbered "sparsely" in this range; the predicate
125 * `pmc_cpu_is_present()' is used to test whether a given CPU is
126 * physically present.
127 *
128 * Further, a CPU that is physically present may be administratively
129 * disabled or otherwise unavailable for use by hwpmc(4). The
130 * `pmc_cpu_is_active()' predicate tests for CPU usability. An
131 * "active" CPU participates in thread scheduling and can field
132 * interrupts raised by PMC hardware.
133 *
134 * On systems with hyperthreaded CPUs, multiple logical CPUs may share
135 * PMC hardware resources. For such processors one logical CPU is
136 * denoted as the primary owner of the in-CPU PMC resources. The
137 * pmc_cpu_is_primary() predicate is used to distinguish this primary
138 * CPU from the others.
139 */
140
141 int
142 pmc_cpu_is_active(int cpu)
143 {
144 #ifdef SMP
145 return (pmc_cpu_is_present(cpu) &&
146 !CPU_ISSET(cpu, &hlt_cpus_mask));
147 #else
148 return (1);
149 #endif
150 }
151
152 /* Deprecated. */
153 int
154 pmc_cpu_is_disabled(int cpu)
155 {
156 return (!pmc_cpu_is_active(cpu));
157 }
158
159 int
160 pmc_cpu_is_present(int cpu)
161 {
162 #ifdef SMP
163 return (!CPU_ABSENT(cpu));
164 #else
165 return (1);
166 #endif
167 }
168
169 int
170 pmc_cpu_is_primary(int cpu)
171 {
172 #ifdef SMP
173 return (!CPU_ISSET(cpu, &logical_cpus_mask));
174 #else
175 return (1);
176 #endif
177 }
178
179
180 /*
181 * Return the maximum CPU number supported by the system. The return
182 * value is used for scaling internal data structures and for runtime
183 * checks.
184 */
185 unsigned int
186 pmc_cpu_max(void)
187 {
188 #ifdef SMP
189 return (mp_maxid+1);
190 #else
191 return (1);
192 #endif
193 }
194
195 #ifdef INVARIANTS
196
197 /*
198 * Return the count of CPUs in the `active' state in the system.
199 */
200 int
201 pmc_cpu_max_active(void)
202 {
203 #ifdef SMP
204 /*
205 * When support for CPU hot-plugging is added to the kernel,
206 * this function would change to return the current number
207 * of "active" CPUs.
208 */
209 return (mp_ncpus);
210 #else
211 return (1);
212 #endif
213 }
214
215 #endif
216
217 /*
218 * Cleanup event name:
219 * - remove duplicate '_'
220 * - all uppercase
221 */
222 static void
223 pmc_soft_namecleanup(char *name)
224 {
225 char *p, *q;
226
227 p = q = name;
228
229 for ( ; *p == '_' ; p++)
230 ;
231 for ( ; *p ; p++) {
232 if (*p == '_' && (*(p + 1) == '_' || *(p + 1) == '\0'))
233 continue;
234 else
235 *q++ = toupper(*p);
236 }
237 *q = '\0';
238 }
239
240 void
241 pmc_soft_ev_register(struct pmc_soft *ps)
242 {
243 static int warned = 0;
244 int n;
245
246 ps->ps_running = 0;
247 ps->ps_ev.pm_ev_code = 0; /* invalid */
248 pmc_soft_namecleanup(ps->ps_ev.pm_ev_name);
249
250 mtx_lock_spin(&pmc_softs_mtx);
251
252 if (pmc_softs_count >= pmc_softevents) {
253 /*
254 * XXX Reusing events can enter a race condition where
255 * new allocated event will be used as an old one.
256 */
257 for (n = 0; n < pmc_softevents; n++)
258 if (pmc_softs[n] == NULL)
259 break;
260 if (n == pmc_softevents) {
261 mtx_unlock_spin(&pmc_softs_mtx);
262 if (!warned) {
263 printf("hwpmc: too many soft events, "
264 "increase kern.hwpmc.softevents tunable\n");
265 warned = 1;
266 }
267 return;
268 }
269
270 ps->ps_ev.pm_ev_code = PMC_EV_SOFT_FIRST + n;
271 pmc_softs[n] = ps;
272 } else {
273 ps->ps_ev.pm_ev_code = PMC_EV_SOFT_FIRST + pmc_softs_count;
274 pmc_softs[pmc_softs_count++] = ps;
275 }
276
277 mtx_unlock_spin(&pmc_softs_mtx);
278 }
279
280 void
281 pmc_soft_ev_deregister(struct pmc_soft *ps)
282 {
283
284 KASSERT(ps != NULL, ("pmc_soft_deregister: called with NULL"));
285
286 mtx_lock_spin(&pmc_softs_mtx);
287
288 if (ps->ps_ev.pm_ev_code != 0 &&
289 (ps->ps_ev.pm_ev_code - PMC_EV_SOFT_FIRST) < pmc_softevents) {
290 KASSERT(ps->ps_ev.pm_ev_code >= PMC_EV_SOFT_FIRST &&
291 ps->ps_ev.pm_ev_code <= PMC_EV_SOFT_LAST,
292 ("pmc_soft_deregister: invalid event value"));
293 pmc_softs[ps->ps_ev.pm_ev_code - PMC_EV_SOFT_FIRST] = NULL;
294 }
295
296 mtx_unlock_spin(&pmc_softs_mtx);
297 }
298
299 struct pmc_soft *
300 pmc_soft_ev_acquire(enum pmc_event ev)
301 {
302 struct pmc_soft *ps;
303
304 if (ev == 0 || (ev - PMC_EV_SOFT_FIRST) >= pmc_softevents)
305 return NULL;
306
307 KASSERT(ev >= PMC_EV_SOFT_FIRST &&
308 ev <= PMC_EV_SOFT_LAST,
309 ("event out of range"));
310
311 mtx_lock_spin(&pmc_softs_mtx);
312
313 ps = pmc_softs[ev - PMC_EV_SOFT_FIRST];
314 if (ps == NULL)
315 mtx_unlock_spin(&pmc_softs_mtx);
316
317 return ps;
318 }
319
320 void
321 pmc_soft_ev_release(struct pmc_soft *ps)
322 {
323
324 mtx_unlock_spin(&pmc_softs_mtx);
325 }
326
327 /*
328 * Initialise hwpmc.
329 */
330 static void
331 init_hwpmc(void *dummy __unused)
332 {
333 if (pmc_softevents <= 0 ||
334 pmc_softevents > PMC_EV_DYN_COUNT) {
335 (void) printf("hwpmc: tunable \"softevents\"=%d out of "
336 "range.\n", pmc_softevents);
337 pmc_softevents = PMC_EV_DYN_COUNT;
338 }
339 pmc_softs = malloc(pmc_softevents * sizeof(struct pmc_soft *), M_PMCHOOKS, M_NOWAIT|M_ZERO);
340 KASSERT(pmc_softs != NULL, ("cannot allocate soft events table"));
341 }
342
343 SYSINIT(hwpmc, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_hwpmc, NULL);
344
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