The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/prof_machdep.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 1996 Bruce D. Evans.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   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.
   15  *
   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
   26  * SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #ifdef GUPROF
   33 #include "opt_i586_guprof.h"
   34 #include "opt_perfmon.h"
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/bus.h>
   39 #include <sys/cpu.h>
   40 #include <sys/eventhandler.h>
   41 #include <sys/gmon.h>
   42 #include <sys/kernel.h>
   43 #include <sys/smp.h>
   44 #include <sys/sysctl.h>
   45 
   46 #include <machine/clock.h>
   47 #include <machine/perfmon.h>
   48 #include <machine/timerreg.h>
   49 
   50 #define CPUTIME_CLOCK_UNINITIALIZED     0
   51 #define CPUTIME_CLOCK_I8254             1
   52 #define CPUTIME_CLOCK_TSC               2
   53 #define CPUTIME_CLOCK_I586_PMC          3
   54 #define CPUTIME_CLOCK_I8254_SHIFT       7
   55 
   56 int     cputime_bias = 1;       /* initialize for locality of reference */
   57 
   58 static int      cputime_clock = CPUTIME_CLOCK_UNINITIALIZED;
   59 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
   60 static u_int    cputime_clock_pmc_conf = I586_PMC_GUPROF;
   61 static int      cputime_clock_pmc_init;
   62 static struct gmonparam saved_gmp;
   63 #endif
   64 #if defined(I586_CPU) || defined(I686_CPU)
   65 static int      cputime_prof_active;
   66 #endif
   67 #endif /* GUPROF */
   68 
   69 #ifdef __GNUCLIKE_ASM
   70 #if defined(SMP) && defined(GUPROF)
   71 #define MPLOCK "                                                \n\
   72         movl    $1,%edx                                         \n\
   73 9:                                                              \n\
   74         xorl    %eax,%eax                                       \n\
   75         lock                                                    \n\
   76         cmpxchgl %edx,mcount_lock                               \n\
   77         jne     9b                                              \n"
   78 #define MPUNLOCK "movl  $0,mcount_lock                          \n"
   79 #else /* !(SMP && GUPROF) */
   80 #define MPLOCK
   81 #define MPUNLOCK
   82 #endif /* SMP && GUPROF */
   83 
   84 __asm("                                                         \n\
   85 GM_STATE        =       0                                       \n\
   86 GMON_PROF_OFF   =       3                                       \n\
   87                                                                 \n\
   88         .text                                                   \n\
   89         .p2align 4,0x90                                         \n\
   90         .globl  __mcount                                        \n\
   91         .type   __mcount,@function                              \n\
   92 __mcount:                                                       \n\
   93         #                                                       \n\
   94         # Check that we are profiling.  Do it early for speed.  \n\
   95         #                                                       \n\
   96         cmpl    $GMON_PROF_OFF,_gmonparam+GM_STATE              \n\
   97         je      .mcount_exit                                    \n\
   98         #                                                       \n\
   99         # __mcount is the same as [.]mcount except the caller   \n\
  100         # hasn't changed the stack except to call here, so the  \n\
  101         # caller's raddr is above our raddr.                    \n\
  102         #                                                       \n\
  103         movl    4(%esp),%edx                                    \n\
  104         jmp     .got_frompc                                     \n\
  105                                                                 \n\
  106         .p2align 4,0x90                                         \n\
  107         .globl  .mcount                                         \n\
  108 .mcount:                                                        \n\
  109         cmpl    $GMON_PROF_OFF,_gmonparam+GM_STATE              \n\
  110         je      .mcount_exit                                    \n\
  111         #                                                       \n\
  112         # The caller's stack frame has already been built, so   \n\
  113         # %ebp is the caller's frame pointer.  The caller's     \n\
  114         # raddr is in the caller's frame following the caller's \n\
  115         # caller's frame pointer.                               \n\
  116         #                                                       \n\
  117         movl    4(%ebp),%edx                                    \n\
  118 .got_frompc:                                                    \n\
  119         #                                                       \n\
  120         # Our raddr is the caller's pc.                         \n\
  121         #                                                       \n\
  122         movl    (%esp),%eax                                     \n\
  123                                                                 \n\
  124         pushfl                                                  \n\
  125         pushl   %eax                                            \n\
  126         pushl   %edx                                            \n\
  127         cli                                                     \n"
  128         MPLOCK "                                                \n\
  129         call    mcount                                          \n"
  130         MPUNLOCK "                                              \n\
  131         addl    $8,%esp                                         \n\
  132         popfl                                                   \n\
  133 .mcount_exit:                                                   \n\
  134         ret     $0                                              \n\
  135 ");
  136 
  137 void    __mcount(void);
  138 void    (*__mcountp)(void) = __mcount;
  139 #else /* !__GNUCLIKE_ASM */
  140 #error "this file needs to be ported to your compiler"
  141 #endif /* __GNUCLIKE_ASM */
  142 
  143 #ifdef GUPROF
  144 /*
  145  * [.]mexitcount saves the return register(s), loads selfpc and calls
  146  * mexitcount(selfpc) to do the work.  Someday it should be in a machine
  147  * dependent file together with cputime(), __mcount and [.]mcount.  cputime()
  148  * can't just be put in machdep.c because it has to be compiled without -pg.
  149  */
  150 #ifdef __GNUCLIKE_ASM
  151 __asm("                                                         \n\
  152         .text                                                   \n\
  153 #                                                               \n\
  154 # Dummy label to be seen when gprof -u hides [.]mexitcount.     \n\
  155 #                                                               \n\
  156         .p2align 4,0x90                                         \n\
  157         .globl  __mexitcount                                    \n\
  158         .type   __mexitcount,@function                          \n\
  159 __mexitcount:                                                   \n\
  160         nop                                                     \n\
  161                                                                 \n\
  162 GMON_PROF_HIRES =       4                                       \n\
  163                                                                 \n\
  164         .p2align 4,0x90                                         \n\
  165         .globl  .mexitcount                                     \n\
  166 .mexitcount:                                                    \n\
  167         cmpl    $GMON_PROF_HIRES,_gmonparam+GM_STATE            \n\
  168         jne     .mexitcount_exit                                \n\
  169         pushl   %edx                                            \n\
  170         pushl   %eax                                            \n\
  171         movl    8(%esp),%eax                                    \n\
  172         pushfl                                                  \n\
  173         pushl   %eax                                            \n\
  174         cli                                                     \n"
  175         MPLOCK "                                                \n\
  176         call    mexitcount                                      \n"
  177         MPUNLOCK "                                              \n\
  178         addl    $4,%esp                                         \n\
  179         popfl                                                   \n\
  180         popl    %eax                                            \n\
  181         popl    %edx                                            \n\
  182 .mexitcount_exit:                                               \n\
  183         ret     $0                                              \n\
  184 ");
  185 #endif /* __GNUCLIKE_ASM */
  186 
  187 void    __mexitcount(void);
  188 void    (*__mexitcountp)(void) = __mexitcount;
  189 
  190 /*
  191  * Return the time elapsed since the last call.  The units are machine-
  192  * dependent.
  193  */
  194 int
  195 cputime()
  196 {
  197         u_int count;
  198         int delta;
  199 #if (defined(I586_CPU) || defined(I686_CPU)) && \
  200     defined(PERFMON) && defined(I586_PMC_GUPROF) && !defined(SMP)
  201         u_quad_t event_count;
  202 #endif
  203         u_char high, low;
  204         static u_int prev_count;
  205 
  206 #if defined(I586_CPU) || defined(I686_CPU)
  207         if (cputime_clock == CPUTIME_CLOCK_TSC) {
  208                 /*
  209                  * Scale the TSC a little to make cputime()'s frequency
  210                  * fit in an int, assuming that the TSC frequency fits
  211                  * in a u_int.  Use a fixed scale since dynamic scaling
  212                  * would be slower and we can't really use the low bit
  213                  * of precision.
  214                  */
  215                 count = (u_int)rdtsc() & ~1u;
  216                 delta = (int)(count - prev_count) >> 1;
  217                 prev_count = count;
  218                 return (delta);
  219         }
  220 #if defined(PERFMON) && defined(I586_PMC_GUPROF) && !defined(SMP)
  221         if (cputime_clock == CPUTIME_CLOCK_I586_PMC) {
  222                 /*
  223                  * XXX permon_read() should be inlined so that the
  224                  * perfmon module doesn't need to be compiled with
  225                  * profiling disabled and so that it is fast.
  226                  */
  227                 perfmon_read(0, &event_count);
  228 
  229                 count = (u_int)event_count;
  230                 delta = (int)(count - prev_count);
  231                 prev_count = count;
  232                 return (delta);
  233         }
  234 #endif /* PERFMON && I586_PMC_GUPROF && !SMP */
  235 #endif /* I586_CPU || I686_CPU */
  236 
  237         /*
  238          * Read the current value of the 8254 timer counter 0.
  239          */
  240         outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
  241         low = inb(TIMER_CNTR0);
  242         high = inb(TIMER_CNTR0);
  243         count = ((high << 8) | low) << CPUTIME_CLOCK_I8254_SHIFT;
  244 
  245         /*
  246          * The timer counts down from TIMER_CNTR0_MAX to 0 and then resets.
  247          * While profiling is enabled, this routine is called at least twice
  248          * per timer reset (for mcounting and mexitcounting hardclock()),
  249          * so at most one reset has occurred since the last call, and one
  250          * has occurred iff the current count is larger than the previous
  251          * count.  This allows counter underflow to be detected faster
  252          * than in microtime().
  253          */
  254         delta = prev_count - count;
  255         prev_count = count;
  256         if ((int) delta <= 0)
  257                 return (delta + (i8254_max_count << CPUTIME_CLOCK_I8254_SHIFT));
  258         return (delta);
  259 }
  260 
  261 static int
  262 sysctl_machdep_cputime_clock(SYSCTL_HANDLER_ARGS)
  263 {
  264         int clock;
  265         int error;
  266 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
  267         int event;
  268         struct pmc pmc;
  269 #endif
  270 
  271         clock = cputime_clock;
  272 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
  273         if (clock == CPUTIME_CLOCK_I586_PMC) {
  274                 pmc.pmc_val = cputime_clock_pmc_conf;
  275                 clock += pmc.pmc_event;
  276         }
  277 #endif
  278         error = sysctl_handle_opaque(oidp, &clock, sizeof clock, req);
  279         if (error == 0 && req->newptr != NULL) {
  280 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
  281                 if (clock >= CPUTIME_CLOCK_I586_PMC) {
  282                         event = clock - CPUTIME_CLOCK_I586_PMC;
  283                         if (event >= 256)
  284                                 return (EINVAL);
  285                         pmc.pmc_num = 0;
  286                         pmc.pmc_event = event;
  287                         pmc.pmc_unit = 0;
  288                         pmc.pmc_flags = PMCF_E | PMCF_OS | PMCF_USR;
  289                         pmc.pmc_mask = 0;
  290                         cputime_clock_pmc_conf = pmc.pmc_val;
  291                         cputime_clock = CPUTIME_CLOCK_I586_PMC;
  292                 } else
  293 #endif
  294                 {
  295                         if (clock < 0 || clock >= CPUTIME_CLOCK_I586_PMC)
  296                                 return (EINVAL);
  297                         cputime_clock = clock;
  298                 }
  299         }
  300         return (error);
  301 }
  302 
  303 SYSCTL_PROC(_machdep, OID_AUTO, cputime_clock,
  304     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, sizeof(u_int),
  305     sysctl_machdep_cputime_clock, "I",
  306     "");
  307 
  308 /*
  309  * The start and stop routines need not be here since we turn off profiling
  310  * before calling them.  They are here for convenience.
  311  */
  312 
  313 void
  314 startguprof(gp)
  315         struct gmonparam *gp;
  316 {
  317 #if defined(I586_CPU) || defined(I686_CPU)
  318         uint64_t freq;
  319 
  320         freq = atomic_load_acq_64(&tsc_freq);
  321         if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED) {
  322                 if (freq != 0 && mp_ncpus == 1)
  323                         cputime_clock = CPUTIME_CLOCK_TSC;
  324                 else
  325                         cputime_clock = CPUTIME_CLOCK_I8254;
  326         }
  327         if (cputime_clock == CPUTIME_CLOCK_TSC) {
  328                 gp->profrate = freq >> 1;
  329                 cputime_prof_active = 1;
  330         } else
  331                 gp->profrate = i8254_freq << CPUTIME_CLOCK_I8254_SHIFT;
  332 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
  333         if (cputime_clock == CPUTIME_CLOCK_I586_PMC) {
  334                 if (perfmon_avail() &&
  335                     perfmon_setup(0, cputime_clock_pmc_conf) == 0) {
  336                         if (perfmon_start(0) != 0)
  337                                 perfmon_fini(0);
  338                         else {
  339                                 /* XXX 1 event == 1 us. */
  340                                 gp->profrate = 1000000;
  341 
  342                                 saved_gmp = *gp;
  343 
  344                                 /* Zap overheads.  They are invalid. */
  345                                 gp->cputime_overhead = 0;
  346                                 gp->mcount_overhead = 0;
  347                                 gp->mcount_post_overhead = 0;
  348                                 gp->mcount_pre_overhead = 0;
  349                                 gp->mexitcount_overhead = 0;
  350                                 gp->mexitcount_post_overhead = 0;
  351                                 gp->mexitcount_pre_overhead = 0;
  352 
  353                                 cputime_clock_pmc_init = TRUE;
  354                         }
  355                 }
  356         }
  357 #endif /* PERFMON && I586_PMC_GUPROF */
  358 #else /* !(I586_CPU || I686_CPU) */
  359         if (cputime_clock == CPUTIME_CLOCK_UNINITIALIZED)
  360                 cputime_clock = CPUTIME_CLOCK_I8254;
  361         gp->profrate = i8254_freq << CPUTIME_CLOCK_I8254_SHIFT;
  362 #endif /* I586_CPU || I686_CPU */
  363         cputime_bias = 0;
  364         cputime();
  365 }
  366 
  367 void
  368 stopguprof(gp)
  369         struct gmonparam *gp;
  370 {
  371 #if defined(PERFMON) && defined(I586_PMC_GUPROF)
  372         if (cputime_clock_pmc_init) {
  373                 *gp = saved_gmp;
  374                 perfmon_fini(0);
  375                 cputime_clock_pmc_init = FALSE;
  376         }
  377 #endif
  378 #if defined(I586_CPU) || defined(I686_CPU)
  379         if (cputime_clock == CPUTIME_CLOCK_TSC)
  380                 cputime_prof_active = 0;
  381 #endif
  382 }
  383 
  384 #if defined(I586_CPU) || defined(I686_CPU)
  385 /* If the cpu frequency changed while profiling, report a warning. */
  386 static void
  387 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
  388 {
  389 
  390         /*
  391          * If there was an error during the transition or
  392          * TSC is P-state invariant, don't do anything.
  393          */
  394         if (status != 0 || tsc_is_invariant)
  395                 return;
  396         if (cputime_prof_active && cputime_clock == CPUTIME_CLOCK_TSC)
  397                 printf("warning: cpu freq changed while profiling active\n");
  398 }
  399 
  400 EVENTHANDLER_DEFINE(cpufreq_post_change, tsc_freq_changed, NULL,
  401     EVENTHANDLER_PRI_ANY);
  402 #endif /* I586_CPU || I686_CPU */
  403 
  404 #endif /* GUPROF */

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