2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 1996 Bruce D. Evans.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
34 #include <sys/param.h>
35 #include <sys/systm.h>
38 #include <sys/eventhandler.h>
40 #include <sys/kernel.h>
42 #include <sys/sysctl.h>
44 #include <machine/clock.h>
45 #include <machine/timerreg.h>
47 #define CPUTIME_CLOCK_UNINITIALIZED 0
48 #define CPUTIME_CLOCK_I8254 1
49 #define CPUTIME_CLOCK_TSC 2
50 #define CPUTIME_CLOCK_I8254_SHIFT 7
52 int cputime_bias = 1; /* initialize for locality of reference */
54 static int cputime_clock = CPUTIME_CLOCK_UNINITIALIZED;
55 static int cputime_prof_active;
66 .type __mcount,@function \n\
69 # Check that we are profiling. Do it early for speed. \n\
71 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
74 # __mcount is the same as [.]mcount except the caller \n\
75 # hasn't changed the stack except to call here, so the \n\
76 # caller's raddr is above our raddr. \n\
85 movq 7*8+8(%rsp),%rdi \n\
91 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
94 # The caller's stack frame has already been built, so \n\
95 # %rbp is the caller's frame pointer. The caller's \n\
96 # raddr is in the caller's frame following the caller's \n\
97 # caller's frame pointer. \n\
106 movq 8(%rbp),%rdi \n\
109 # Our raddr is the caller's pc. \n\
111 movq 7*8(%rsp),%rsi \n\
127 #else /* !__GNUCLIKE_ASM */
128 #error "this file needs to be ported to your compiler"
129 #endif /* __GNUCLIKE_ASM */
133 * [.]mexitcount saves the return register(s), loads selfpc and calls
134 * mexitcount(selfpc) to do the work. Someday it should be in a machine
135 * dependent file together with cputime(), __mcount and [.]mcount. cputime()
136 * can't just be put in machdep.c because it has to be compiled without -pg.
138 #ifdef __GNUCLIKE_ASM
142 # Dummy label to be seen when gprof -u hides [.]mexitcount. \n\
145 .globl __mexitcount \n\
146 .type __mexitcount,@function \n\
150 GMON_PROF_HIRES = 4 \n\
153 .globl .mexitcount \n\
155 cmpl $GMON_PROF_HIRES,_gmonparam+GM_STATE \n\
156 jne .mexitcount_exit \n\
164 movq 7*8(%rsp),%rdi \n\
176 .mexitcount_exit: \n\
179 #endif /* __GNUCLIKE_ASM */
182 * Return the time elapsed since the last call. The units are machine-
191 static u_int prev_count;
193 if (cputime_clock == CPUTIME_CLOCK_TSC) {
195 * Scale the TSC a little to make cputime()'s frequency
196 * fit in an int, assuming that the TSC frequency fits
197 * in a u_int. Use a fixed scale since dynamic scaling
198 * would be slower and we can't really use the low bit
201 count = (u_int)rdtsc() & ~1u;
202 delta = (int)(count - prev_count) >> 1;
208 * Read the current value of the 8254 timer counter 0.
210 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
211 low = inb(TIMER_CNTR0);
212 high = inb(TIMER_CNTR0);
213 count = ((high << 8) | low) << CPUTIME_CLOCK_I8254_SHIFT;
216 * The timer counts down from TIMER_CNTR0_MAX to 0 and then resets.
217 * While profiling is enabled, this routine is called at least twice
218 * per timer reset (for mcounting and mexitcounting hardclock()),
219 * so at most one reset has occurred since the last call, and one
220 * has occurred iff the current count is larger than the previous
221 * count. This allows counter underflow to be detected faster
222 * than in microtime().
224 delta = prev_count - count;
226 if ((int) delta <= 0)
227 return (delta + (i8254_max_count << CPUTIME_CLOCK_I8254_SHIFT));
232 sysctl_machdep_cputime_clock(SYSCTL_HANDLER_ARGS)
237 clock = cputime_clock;
238 error = sysctl_handle_opaque(oidp, &clock, sizeof clock, req);
239 if (error == 0 && req->newptr != NULL) {
240 if (clock < 0 || clock > CPUTIME_CLOCK_TSC)
242 cputime_clock = clock;
247 SYSCTL_PROC(_machdep, OID_AUTO, cputime_clock, CTLTYPE_INT | CTLFLAG_RW,
248 0, sizeof(u_int), sysctl_machdep_cputime_clock, "I", "");
251 * The start and stop routines need not be here since we turn off profiling
252 * before calling them. They are here for convenience.
257 struct gmonparam *gp;
261 freq = atomic_load_acq_64(&tsc_freq);
262 if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
263 if (freq != 0 && mp_ncpus == 1)
264 cputime_clock = CPUTIME_CLOCK_TSC;
266 cputime_clock = CPUTIME_CLOCK_I8254;
268 if (cputime_clock == CPUTIME_CLOCK_TSC) {
269 gp->profrate = freq >> 1;
270 cputime_prof_active = 1;
272 gp->profrate = i8254_freq << CPUTIME_CLOCK_I8254_SHIFT;
279 struct gmonparam *gp;
281 if (cputime_clock == CPUTIME_CLOCK_TSC)
282 cputime_prof_active = 0;
285 /* If the cpu frequency changed while profiling, report a warning. */
287 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
291 * If there was an error during the transition or
292 * TSC is P-state invariant, don't do anything.
294 if (status != 0 || tsc_is_invariant)
296 if (cputime_prof_active && cputime_clock == CPUTIME_CLOCK_TSC)
297 printf("warning: cpu freq changed while profiling active\n");
300 EVENTHANDLER_DEFINE(cpufreq_post_change, tsc_freq_changed, NULL,
301 EVENTHANDLER_PRI_ANY);