The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_pcpu.c

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    1 /*-
    2  * Copyright (c) 2001 Wind River Systems, Inc.
    3  * All rights reserved.
    4  * Written by: John Baldwin <jhb@FreeBSD.org>
    5  *
    6  * Copyright (c) 2009 Jeffrey Roberson <jeff@freebsd.org>
    7  * All rights reserved.
    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  * 4. Neither the name of the author nor the names of any co-contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  */
   33 
   34 /*
   35  * This module provides MI support for per-cpu data.
   36  *
   37  * Each architecture determines the mapping of logical CPU IDs to physical
   38  * CPUs.  The requirements of this mapping are as follows:
   39  *  - Logical CPU IDs must reside in the range 0 ... MAXCPU - 1.
   40  *  - The mapping is not required to be dense.  That is, there may be
   41  *    gaps in the mappings.
   42  *  - The platform sets the value of MAXCPU in <machine/param.h>.
   43  *  - It is suggested, but not required, that in the non-SMP case, the
   44  *    platform define MAXCPU to be 1 and define the logical ID of the
   45  *    sole CPU as 0.
   46  */
   47 
   48 #include <sys/cdefs.h>
   49 __FBSDID("$FreeBSD: releng/8.0/sys/kern/subr_pcpu.c 196134 2009-08-12 12:10:28Z bz $");
   50 
   51 #include "opt_ddb.h"
   52 
   53 #include <sys/param.h>
   54 #include <sys/systm.h>
   55 #include <sys/sysctl.h>
   56 #include <sys/linker_set.h>
   57 #include <sys/lock.h>
   58 #include <sys/malloc.h>
   59 #include <sys/pcpu.h>
   60 #include <sys/proc.h>
   61 #include <sys/smp.h>
   62 #include <sys/sx.h>
   63 #include <ddb/ddb.h>
   64 
   65 MALLOC_DEFINE(M_PCPU, "Per-cpu", "Per-cpu resource accouting.");
   66 
   67 struct dpcpu_free {
   68         uintptr_t       df_start;
   69         int             df_len;
   70         TAILQ_ENTRY(dpcpu_free) df_link;
   71 };
   72 
   73 static DPCPU_DEFINE(char, modspace[DPCPU_MODMIN]);
   74 static TAILQ_HEAD(, dpcpu_free) dpcpu_head = TAILQ_HEAD_INITIALIZER(dpcpu_head);
   75 static struct sx dpcpu_lock;
   76 uintptr_t dpcpu_off[MAXCPU];
   77 struct pcpu *cpuid_to_pcpu[MAXCPU];
   78 struct cpuhead cpuhead = SLIST_HEAD_INITIALIZER(cpuhead);
   79 
   80 /*
   81  * Initialize the MI portions of a struct pcpu.
   82  */
   83 void
   84 pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
   85 {
   86 
   87         bzero(pcpu, size);
   88         KASSERT(cpuid >= 0 && cpuid < MAXCPU,
   89             ("pcpu_init: invalid cpuid %d", cpuid));
   90         pcpu->pc_cpuid = cpuid;
   91         pcpu->pc_cpumask = 1 << cpuid;
   92         cpuid_to_pcpu[cpuid] = pcpu;
   93         SLIST_INSERT_HEAD(&cpuhead, pcpu, pc_allcpu);
   94         cpu_pcpu_init(pcpu, cpuid, size);
   95         pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
   96         pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
   97 #ifdef KTR
   98         snprintf(pcpu->pc_name, sizeof(pcpu->pc_name), "CPU %d", cpuid);
   99 #endif
  100 }
  101 
  102 void
  103 dpcpu_init(void *dpcpu, int cpuid)
  104 {
  105         struct pcpu *pcpu;
  106 
  107         pcpu = pcpu_find(cpuid);
  108         pcpu->pc_dynamic = (uintptr_t)dpcpu - DPCPU_START;
  109 
  110         /*
  111          * Initialize defaults from our linker section.
  112          */
  113         memcpy(dpcpu, (void *)DPCPU_START, DPCPU_BYTES);
  114 
  115         /*
  116          * Place it in the global pcpu offset array.
  117          */
  118         dpcpu_off[cpuid] = pcpu->pc_dynamic;
  119 }
  120 
  121 static void
  122 dpcpu_startup(void *dummy __unused)
  123 {
  124         struct dpcpu_free *df;
  125 
  126         df = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  127         df->df_start = (uintptr_t)&DPCPU_NAME(modspace);
  128         df->df_len = DPCPU_MODSIZE;
  129         TAILQ_INSERT_HEAD(&dpcpu_head, df, df_link);
  130         sx_init(&dpcpu_lock, "dpcpu alloc lock");
  131 }
  132 SYSINIT(dpcpu, SI_SUB_KLD, SI_ORDER_FIRST, dpcpu_startup, 0);
  133 
  134 /*
  135  * First-fit extent based allocator for allocating space in the per-cpu
  136  * region reserved for modules.  This is only intended for use by the
  137  * kernel linkers to place module linker sets.
  138  */
  139 void *
  140 dpcpu_alloc(int size)
  141 {
  142         struct dpcpu_free *df;
  143         void *s;
  144 
  145         s = NULL;
  146         size = roundup2(size, sizeof(void *));
  147         sx_xlock(&dpcpu_lock);
  148         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  149                 if (df->df_len < size)
  150                         continue;
  151                 if (df->df_len == size) {
  152                         s = (void *)df->df_start;
  153                         TAILQ_REMOVE(&dpcpu_head, df, df_link);
  154                         free(df, M_PCPU);
  155                         break;
  156                 }
  157                 s = (void *)df->df_start;
  158                 df->df_len -= size;
  159                 df->df_start = df->df_start + size;
  160                 break;
  161         }
  162         sx_xunlock(&dpcpu_lock);
  163 
  164         return (s);
  165 }
  166 
  167 /*
  168  * Free dynamic per-cpu space at module unload time. 
  169  */
  170 void
  171 dpcpu_free(void *s, int size)
  172 {
  173         struct dpcpu_free *df;
  174         struct dpcpu_free *dn;
  175         uintptr_t start;
  176         uintptr_t end;
  177 
  178         size = roundup2(size, sizeof(void *));
  179         start = (uintptr_t)s;
  180         end = start + size;
  181         /*
  182          * Free a region of space and merge it with as many neighbors as
  183          * possible.  Keeping the list sorted simplifies this operation.
  184          */
  185         sx_xlock(&dpcpu_lock);
  186         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  187                 if (df->df_start > end)
  188                         break;
  189                 /*
  190                  * If we expand at the end of an entry we may have to
  191                  * merge it with the one following it as well.
  192                  */
  193                 if (df->df_start + df->df_len == start) {
  194                         df->df_len += size;
  195                         dn = TAILQ_NEXT(df, df_link);
  196                         if (df->df_start + df->df_len == dn->df_start) {
  197                                 df->df_len += dn->df_len;
  198                                 TAILQ_REMOVE(&dpcpu_head, dn, df_link);
  199                                 free(dn, M_PCPU);
  200                         }
  201                         sx_xunlock(&dpcpu_lock);
  202                         return;
  203                 }
  204                 if (df->df_start == end) {
  205                         df->df_start = start;
  206                         df->df_len += size;
  207                         sx_xunlock(&dpcpu_lock);
  208                         return;
  209                 }
  210         }
  211         dn = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  212         dn->df_start = start;
  213         dn->df_len = size;
  214         if (df)
  215                 TAILQ_INSERT_BEFORE(df, dn, df_link);
  216         else
  217                 TAILQ_INSERT_TAIL(&dpcpu_head, dn, df_link);
  218         sx_xunlock(&dpcpu_lock);
  219 }
  220 
  221 /*
  222  * Initialize the per-cpu storage from an updated linker-set region.
  223  */
  224 void
  225 dpcpu_copy(void *s, int size)
  226 {
  227 #ifdef SMP
  228         uintptr_t dpcpu;
  229         int i;
  230 
  231         for (i = 0; i < mp_ncpus; ++i) {
  232                 dpcpu = dpcpu_off[i];
  233                 if (dpcpu == 0)
  234                         continue;
  235                 memcpy((void *)(dpcpu + (uintptr_t)s), s, size);
  236         }
  237 #else
  238         memcpy((void *)(dpcpu_off[0] + (uintptr_t)s), s, size);
  239 #endif
  240 }
  241 
  242 /*
  243  * Destroy a struct pcpu.
  244  */
  245 void
  246 pcpu_destroy(struct pcpu *pcpu)
  247 {
  248 
  249         SLIST_REMOVE(&cpuhead, pcpu, pcpu, pc_allcpu);
  250         cpuid_to_pcpu[pcpu->pc_cpuid] = NULL;
  251         dpcpu_off[pcpu->pc_cpuid] = 0;
  252 }
  253 
  254 /*
  255  * Locate a struct pcpu by cpu id.
  256  */
  257 struct pcpu *
  258 pcpu_find(u_int cpuid)
  259 {
  260 
  261         return (cpuid_to_pcpu[cpuid]);
  262 }
  263 
  264 int
  265 sysctl_dpcpu_quad(SYSCTL_HANDLER_ARGS)
  266 {
  267         uintptr_t dpcpu;
  268         int64_t count;
  269         int i;
  270 
  271         count = 0;
  272         for (i = 0; i < mp_ncpus; ++i) {
  273                 dpcpu = dpcpu_off[i];
  274                 if (dpcpu == 0)
  275                         continue;
  276                 count += *(int64_t *)(dpcpu + (uintptr_t)arg1);
  277         }
  278         return (SYSCTL_OUT(req, &count, sizeof(count)));
  279 }
  280 
  281 int
  282 sysctl_dpcpu_long(SYSCTL_HANDLER_ARGS)
  283 {
  284         uintptr_t dpcpu;
  285         long count;
  286         int i;
  287 
  288         count = 0;
  289         for (i = 0; i < mp_ncpus; ++i) {
  290                 dpcpu = dpcpu_off[i];
  291                 if (dpcpu == 0)
  292                         continue;
  293                 count += *(long *)(dpcpu + (uintptr_t)arg1);
  294         }
  295         return (SYSCTL_OUT(req, &count, sizeof(count)));
  296 }
  297 
  298 int
  299 sysctl_dpcpu_int(SYSCTL_HANDLER_ARGS)
  300 {
  301         uintptr_t dpcpu;
  302         int count;
  303         int i;
  304 
  305         count = 0;
  306         for (i = 0; i < mp_ncpus; ++i) {
  307                 dpcpu = dpcpu_off[i];
  308                 if (dpcpu == 0)
  309                         continue;
  310                 count += *(int *)(dpcpu + (uintptr_t)arg1);
  311         }
  312         return (SYSCTL_OUT(req, &count, sizeof(count)));
  313 }
  314 
  315 #ifdef DDB
  316 DB_SHOW_COMMAND(dpcpu_off, db_show_dpcpu_off)
  317 {
  318         int id;
  319 
  320         for (id = 0; id <= mp_maxid; id++) {
  321                 if (CPU_ABSENT(id))
  322                         continue;
  323                 db_printf("dpcpu_off[%2d] = 0x%jx (+ DPCPU_START = %p)\n",
  324                     id, (uintmax_t)dpcpu_off[id],
  325                     (void *)(uintptr_t)(dpcpu_off[id] + DPCPU_START));
  326         }
  327 }
  328 
  329 static void
  330 show_pcpu(struct pcpu *pc)
  331 {
  332         struct thread *td;
  333 
  334         db_printf("cpuid        = %d\n", pc->pc_cpuid);
  335         db_printf("dynamic pcpu = %p\n", (void *)pc->pc_dynamic);
  336         db_printf("curthread    = ");
  337         td = pc->pc_curthread;
  338         if (td != NULL)
  339                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  340                     td->td_name);
  341         else
  342                 db_printf("none\n");
  343         db_printf("curpcb       = %p\n", pc->pc_curpcb);
  344         db_printf("fpcurthread  = ");
  345         td = pc->pc_fpcurthread;
  346         if (td != NULL)
  347                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  348                     td->td_name);
  349         else
  350                 db_printf("none\n");
  351         db_printf("idlethread   = ");
  352         td = pc->pc_idlethread;
  353         if (td != NULL)
  354                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  355                     td->td_name);
  356         else
  357                 db_printf("none\n");
  358         db_show_mdpcpu(pc);
  359                 
  360 #ifdef VIMAGE
  361         db_printf("curvnet      = %p\n", pc->pc_curthread->td_vnet);
  362 #endif
  363 
  364 #ifdef WITNESS
  365         db_printf("spin locks held:\n");
  366         witness_list_locks(&pc->pc_spinlocks);
  367 #endif
  368 }
  369 
  370 DB_SHOW_COMMAND(pcpu, db_show_pcpu)
  371 {
  372         struct pcpu *pc;
  373         int id;
  374 
  375         if (have_addr)
  376                 id = ((addr >> 4) % 16) * 10 + (addr % 16);
  377         else
  378                 id = PCPU_GET(cpuid);
  379         pc = pcpu_find(id);
  380         if (pc == NULL) {
  381                 db_printf("CPU %d not found\n", id);
  382                 return;
  383         }
  384         show_pcpu(pc);
  385 }
  386 
  387 DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all)
  388 {
  389         struct pcpu *pc;
  390         int id;
  391 
  392         db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid));
  393         for (id = 0; id <= mp_maxid; id++) {
  394                 pc = pcpu_find(id);
  395                 if (pc != NULL) {
  396                         show_pcpu(pc);
  397                         db_printf("\n");
  398                 }
  399         }
  400 }
  401 DB_SHOW_ALIAS(allpcpu, db_show_cpu_all);
  402 #endif

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