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;
59 #if defined(SMP) && defined(GUPROF)
65 cmpxchgl %edx,mcount_lock \n\
67 #define MPUNLOCK "movl $0,mcount_lock \n"
68 #else /* !(SMP && GUPROF) */
71 #endif /* SMP && GUPROF */
80 .type __mcount,@function \n\
83 # Check that we are profiling. Do it early for speed. \n\
85 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
88 # __mcount is the same as [.]mcount except the caller \n\
89 # hasn't changed the stack except to call here, so the \n\
90 # caller's raddr is above our raddr. \n\
99 movq 7*8+8(%rsp),%rdi \n\
105 cmpl $GMON_PROF_OFF,_gmonparam+GM_STATE \n\
108 # The caller's stack frame has already been built, so \n\
109 # %rbp is the caller's frame pointer. The caller's \n\
110 # raddr is in the caller's frame following the caller's \n\
111 # caller's frame pointer. \n\
120 movq 8(%rbp),%rdi \n\
123 # Our raddr is the caller's pc. \n\
125 movq 7*8(%rsp),%rsi \n\
143 #else /* !__GNUCLIKE_ASM */
144 #error "this file needs to be ported to your compiler"
145 #endif /* __GNUCLIKE_ASM */
149 * [.]mexitcount saves the return register(s), loads selfpc and calls
150 * mexitcount(selfpc) to do the work. Someday it should be in a machine
151 * dependent file together with cputime(), __mcount and [.]mcount. cputime()
152 * can't just be put in machdep.c because it has to be compiled without -pg.
154 #ifdef __GNUCLIKE_ASM
158 # Dummy label to be seen when gprof -u hides [.]mexitcount. \n\
161 .globl __mexitcount \n\
162 .type __mexitcount,@function \n\
166 GMON_PROF_HIRES = 4 \n\
169 .globl .mexitcount \n\
171 cmpl $GMON_PROF_HIRES,_gmonparam+GM_STATE \n\
172 jne .mexitcount_exit \n\
180 movq 7*8(%rsp),%rdi \n\
194 .mexitcount_exit: \n\
197 #endif /* __GNUCLIKE_ASM */
200 * Return the time elapsed since the last call. The units are machine-
209 static u_int prev_count;
211 if (cputime_clock == CPUTIME_CLOCK_TSC) {
213 * Scale the TSC a little to make cputime()'s frequency
214 * fit in an int, assuming that the TSC frequency fits
215 * in a u_int. Use a fixed scale since dynamic scaling
216 * would be slower and we can't really use the low bit
219 count = (u_int)rdtsc() & ~1u;
220 delta = (int)(count - prev_count) >> 1;
226 * Read the current value of the 8254 timer counter 0.
228 outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
229 low = inb(TIMER_CNTR0);
230 high = inb(TIMER_CNTR0);
231 count = ((high << 8) | low) << CPUTIME_CLOCK_I8254_SHIFT;
234 * The timer counts down from TIMER_CNTR0_MAX to 0 and then resets.
235 * While profiling is enabled, this routine is called at least twice
236 * per timer reset (for mcounting and mexitcounting hardclock()),
237 * so at most one reset has occurred since the last call, and one
238 * has occurred iff the current count is larger than the previous
239 * count. This allows counter underflow to be detected faster
240 * than in microtime().
242 delta = prev_count - count;
244 if ((int) delta <= 0)
245 return (delta + (i8254_max_count << CPUTIME_CLOCK_I8254_SHIFT));
250 sysctl_machdep_cputime_clock(SYSCTL_HANDLER_ARGS)
255 clock = cputime_clock;
256 error = sysctl_handle_opaque(oidp, &clock, sizeof clock, req);
257 if (error == 0 && req->newptr != NULL) {
258 if (clock < 0 || clock > CPUTIME_CLOCK_TSC)
260 cputime_clock = clock;
265 SYSCTL_PROC(_machdep, OID_AUTO, cputime_clock,
266 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, sizeof(u_int),
267 sysctl_machdep_cputime_clock, "I",
271 * The start and stop routines need not be here since we turn off profiling
272 * before calling them. They are here for convenience.
277 struct gmonparam *gp;
281 freq = atomic_load_acq_64(&tsc_freq);
282 if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
283 if (freq != 0 && mp_ncpus == 1)
284 cputime_clock = CPUTIME_CLOCK_TSC;
286 cputime_clock = CPUTIME_CLOCK_I8254;
288 if (cputime_clock == CPUTIME_CLOCK_TSC) {
289 gp->profrate = freq >> 1;
290 cputime_prof_active = 1;
292 gp->profrate = i8254_freq << CPUTIME_CLOCK_I8254_SHIFT;
299 struct gmonparam *gp;
301 if (cputime_clock == CPUTIME_CLOCK_TSC)
302 cputime_prof_active = 0;
305 /* If the cpu frequency changed while profiling, report a warning. */
307 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
311 * If there was an error during the transition or
312 * TSC is P-state invariant, don't do anything.
314 if (status != 0 || tsc_is_invariant)
316 if (cputime_prof_active && cputime_clock == CPUTIME_CLOCK_TSC)
317 printf("warning: cpu freq changed while profiling active\n");
320 EVENTHANDLER_DEFINE(cpufreq_post_change, tsc_freq_changed, NULL,
321 EVENTHANDLER_PRI_ANY);