sys/kern/subr_prof.c

   1 /*      $NetBSD: subr_prof.c,v 1.44 2009/12/12 17:48:54 dsl Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1982, 1986, 1993
   5  *      The Regents of the University of California.  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  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)subr_prof.c 8.4 (Berkeley) 2/14/95
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __KERNEL_RCSID(0, "$NetBSD: subr_prof.c,v 1.44 2009/12/12 17:48:54 dsl Exp $");
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/kernel.h>
  40 #include <sys/proc.h>
  41 #include <sys/mount.h>
  42 #include <sys/syscallargs.h>
  43 #include <sys/sysctl.h>
  44
  45 #include <sys/cpu.h>
  46
  47 #ifdef GPROF
  48 #include <sys/malloc.h>
  49 #include <sys/gmon.h>
  50
  51 MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
  52
  53 /*
  54  * Froms is actually a bunch of unsigned shorts indexing tos
  55  */
  56 struct gmonparam _gmonparam = { .state = GMON_PROF_OFF };
  57
  58 /* Actual start of the kernel text segment. */
  59 extern char kernel_text[];
  60
  61 extern char etext[];
  62
  63
  64 void
  65 kmstartup(void)
  66 {
  67         char *cp;
  68         struct gmonparam *p = &_gmonparam;
  69         /*
  70          * Round lowpc and highpc to multiples of the density we're using
  71          * so the rest of the scaling (here and in gprof) stays in ints.
  72          */
  73         p->lowpc = rounddown(((u_long)kernel_text),
  74                 HISTFRACTION * sizeof(HISTCOUNTER));
  75         p->highpc = roundup((u_long)etext,
  76                 HISTFRACTION * sizeof(HISTCOUNTER));
  77         p->textsize = p->highpc - p->lowpc;
  78         printf("Profiling kernel, textsize=%ld [%lx..%lx]\n",
  79                p->textsize, p->lowpc, p->highpc);
  80         p->kcountsize = p->textsize / HISTFRACTION;
  81         p->hashfraction = HASHFRACTION;
  82         p->fromssize = p->textsize / HASHFRACTION;
  83         p->tolimit = p->textsize * ARCDENSITY / 100;
  84         if (p->tolimit < MINARCS)
  85                 p->tolimit = MINARCS;
  86         else if (p->tolimit > MAXARCS)
  87                 p->tolimit = MAXARCS;
  88         p->tossize = p->tolimit * sizeof(struct tostruct);
  89         cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
  90             M_GPROF, M_NOWAIT | M_ZERO);
  91         if (cp == 0) {
  92                 printf("No memory for profiling.\n");
  93                 return;
  94         }
  95         p->tos = (struct tostruct *)cp;
  96         cp += p->tossize;
  97         p->kcount = (u_short *)cp;
  98         cp += p->kcountsize;
  99         p->froms = (u_short *)cp;
 100 }
 101
 102 /*
 103  * Return kernel profiling information.
 104  */
 105 /*
 106  * sysctl helper routine for kern.profiling subtree.  enables/disables
 107  * kernel profiling and gives out copies of the profiling data.
 108  */
 109 static int
 110 sysctl_kern_profiling(SYSCTLFN_ARGS)
 111 {
 112         struct gmonparam *gp = &_gmonparam;
 113         int error;
 114         struct sysctlnode node;
 115
 116         node = *rnode;
 117
 118         switch (node.sysctl_num) {
 119         case GPROF_STATE:
 120                 node.sysctl_data = &gp->state;
 121                 break;
 122         case GPROF_COUNT:
 123                 node.sysctl_data = gp->kcount;
 124                 node.sysctl_size = gp->kcountsize;
 125                 break;
 126         case GPROF_FROMS:
 127                 node.sysctl_data = gp->froms;
 128                 node.sysctl_size = gp->fromssize;
 129                 break;
 130         case GPROF_TOS:
 131                 node.sysctl_data = gp->tos;
 132                 node.sysctl_size = gp->tossize;
 133                 break;
 134         case GPROF_GMONPARAM:
 135                 node.sysctl_data = gp;
 136                 node.sysctl_size = sizeof(*gp);
 137                 break;
 138         default:
 139                 return (EOPNOTSUPP);
 140         }
 141
 142         error = sysctl_lookup(SYSCTLFN_CALL(&node));
 143         if (error || newp == NULL)
 144                 return (error);
 145
 146         if (node.sysctl_num == GPROF_STATE) {
 147                 mutex_spin_enter(&proc0.p_stmutex);
 148                 if (gp->state == GMON_PROF_OFF)
 149                         stopprofclock(&proc0);
 150                 else
 151                         startprofclock(&proc0);
 152                 mutex_spin_exit(&proc0.p_stmutex);
 153         }
 154
 155         return (0);
 156 }
 157
 158 SYSCTL_SETUP(sysctl_kern_gprof_setup, "sysctl kern.profiling subtree setup")
 159 {
 160
 161         sysctl_createv(clog, 0, NULL, NULL,
 162                        CTLFLAG_PERMANENT,
 163                        CTLTYPE_NODE, "kern", NULL,
 164                        NULL, 0, NULL, 0,
 165                        CTL_KERN, CTL_EOL);
 166         sysctl_createv(clog, 0, NULL, NULL,
 167                        CTLFLAG_PERMANENT,
 168                        CTLTYPE_NODE, "profiling",
 169                        SYSCTL_DESCR("Profiling information (available)"),
 170                        NULL, 0, NULL, 0,
 171                        CTL_KERN, KERN_PROF, CTL_EOL);
 172
 173         sysctl_createv(clog, 0, NULL, NULL,
 174                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 175                        CTLTYPE_INT, "state",
 176                        SYSCTL_DESCR("Profiling state"),
 177                        sysctl_kern_profiling, 0, NULL, 0,
 178                        CTL_KERN, KERN_PROF, GPROF_STATE, CTL_EOL);
 179         sysctl_createv(clog, 0, NULL, NULL,
 180                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 181                        CTLTYPE_STRUCT, "count",
 182                        SYSCTL_DESCR("Array of statistical program counters"),
 183                        sysctl_kern_profiling, 0, NULL, 0,
 184                        CTL_KERN, KERN_PROF, GPROF_COUNT, CTL_EOL);
 185         sysctl_createv(clog, 0, NULL, NULL,
 186                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 187                        CTLTYPE_STRUCT, "froms",
 188                        SYSCTL_DESCR("Array indexed by program counter of "
 189                                     "call-from points"),
 190                        sysctl_kern_profiling, 0, NULL, 0,
 191                        CTL_KERN, KERN_PROF, GPROF_FROMS, CTL_EOL);
 192         sysctl_createv(clog, 0, NULL, NULL,
 193                        CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
 194                        CTLTYPE_STRUCT, "tos",
 195                        SYSCTL_DESCR("Array of structures describing "
 196                                     "destination of calls and their counts"),
 197                        sysctl_kern_profiling, 0, NULL, 0,
 198                        CTL_KERN, KERN_PROF, GPROF_TOS, CTL_EOL);
 199         sysctl_createv(clog, 0, NULL, NULL,
 200                        CTLFLAG_PERMANENT,
 201                        CTLTYPE_STRUCT, "gmonparam",
 202                        SYSCTL_DESCR("Structure giving the sizes of the above "
 203                                     "arrays"),
 204                        sysctl_kern_profiling, 0, NULL, 0,
 205                        CTL_KERN, KERN_PROF, GPROF_GMONPARAM, CTL_EOL);
 206 }
 207 #endif /* GPROF */
 208
 209 /*
 210  * Profiling system call.
 211  *
 212  * The scale factor is a fixed point number with 16 bits of fraction, so that
 213  * 1.0 is represented as 0x10000.  A scale factor of 0 turns off profiling.
 214  */
 215 /* ARGSUSED */
 216 int
 217 sys_profil(struct lwp *l, const struct sys_profil_args *uap, register_t *retval)
 218 {
 219         /* {
 220                 syscallarg(char *) samples;
 221                 syscallarg(size_t) size;
 222                 syscallarg(u_long) offset;
 223                 syscallarg(u_int) scale;
 224         } */
 225         struct proc *p = l->l_proc;
 226         struct uprof *upp;
 227
 228         if (SCARG(uap, scale) > (1 << 16))
 229                 return (EINVAL);
 230         if (SCARG(uap, scale) == 0) {
 231                 mutex_spin_enter(&p->p_stmutex);
 232                 stopprofclock(p);
 233                 mutex_spin_exit(&p->p_stmutex);
 234                 return (0);
 235         }
 236         upp = &p->p_stats->p_prof;
 237
 238         /* Block profile interrupts while changing state. */
 239         mutex_spin_enter(&p->p_stmutex);
 240         upp->pr_off = SCARG(uap, offset);
 241         upp->pr_scale = SCARG(uap, scale);
 242         upp->pr_base = SCARG(uap, samples);
 243         upp->pr_size = SCARG(uap, size);
 244         startprofclock(p);
 245         mutex_spin_exit(&p->p_stmutex);
 246
 247         return (0);
 248 }
 249
 250 /*
 251  * Scale is a fixed-point number with the binary point 16 bits
 252  * into the value, and is <= 1.0.  pc is at most 32 bits, so the
 253  * intermediate result is at most 48 bits.
 254  */
 255 #define PC_TO_INDEX(pc, prof) \
 256         ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
 257             (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
 258
 259 /*
 260  * Collect user-level profiling statistics; called on a profiling tick,
 261  * when a process is running in user-mode.  This routine may be called
 262  * from an interrupt context.  We try to update the user profiling buffers
 263  * cheaply with fuswintr() and suswintr().  If that fails, we revert to
 264  * an AST that will vector us to trap() with a context in which copyin
 265  * and copyout will work.  Trap will then call addupc_task().
 266  *
 267  * Note that we may (rarely) not get around to the AST soon enough, and
 268  * lose profile ticks when the next tick overwrites this one, but in this
 269  * case the system is overloaded and the profile is probably already
 270  * inaccurate.
 271  */
 272 void
 273 addupc_intr(struct lwp *l, u_long pc)
 274 {
 275         struct uprof *prof;
 276         struct proc *p;
 277         void *addr;
 278         u_int i;
 279         int v;
 280
 281         p = l->l_proc;
 282
 283         KASSERT(mutex_owned(&p->p_stmutex));
 284
 285         prof = &p->p_stats->p_prof;
 286         if (pc < prof->pr_off ||
 287             (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
 288                 return;                 /* out of range; ignore */
 289
 290         addr = prof->pr_base + i;
 291         mutex_spin_exit(&p->p_stmutex);
 292         if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + 1) == -1) {
 293                 /* XXXSMP */
 294                 prof->pr_addr = pc;
 295                 prof->pr_ticks++;
 296                 cpu_need_proftick(l);
 297         }
 298         mutex_spin_enter(&p->p_stmutex);
 299 }
 300
 301 /*
 302  * Much like before, but we can afford to take faults here.  If the
 303  * update fails, we simply turn off profiling.
 304  */
 305 void
 306 addupc_task(struct lwp *l, u_long pc, u_int ticks)
 307 {
 308         struct uprof *prof;
 309         struct proc *p;
 310         void *addr;
 311         int error;
 312         u_int i;
 313         u_short v;
 314
 315         p = l->l_proc;
 316
 317         if (ticks == 0)
 318                 return;
 319
 320         mutex_spin_enter(&p->p_stmutex);
 321         prof = &p->p_stats->p_prof;
 322
 323         /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
 324         if ((p->p_stflag & PST_PROFIL) == 0 || pc < prof->pr_off ||
 325             (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
 326                 mutex_spin_exit(&p->p_stmutex);
 327                 return;
 328         }
 329
 330         addr = prof->pr_base + i;
 331         mutex_spin_exit(&p->p_stmutex);
 332         if ((error = copyin(addr, (void *)&v, sizeof(v))) == 0) {
 333                 v += ticks;
 334                 error = copyout((void *)&v, addr, sizeof(v));
 335         }
 336         if (error != 0) {
 337                 mutex_spin_enter(&p->p_stmutex);
 338                 stopprofclock(p);
 339                 mutex_spin_exit(&p->p_stmutex);
 340         }
 341 }