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/8.3/sys/kern/subr_pcpu.c 221125 2011-04-27 18:00:46Z jhb $");
   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/lock.h>
   57 #include <sys/malloc.h>
   58 #include <sys/pcpu.h>
   59 #include <sys/proc.h>
   60 #include <sys/smp.h>
   61 #include <sys/sx.h>
   62 #include <ddb/ddb.h>
   63 
   64 MALLOC_DEFINE(M_PCPU, "Per-cpu", "Per-cpu resource accouting.");
   65 
   66 struct dpcpu_free {
   67         uintptr_t       df_start;
   68         int             df_len;
   69         TAILQ_ENTRY(dpcpu_free) df_link;
   70 };
   71 
   72 static DPCPU_DEFINE(char, modspace[DPCPU_MODMIN]);
   73 static TAILQ_HEAD(, dpcpu_free) dpcpu_head = TAILQ_HEAD_INITIALIZER(dpcpu_head);
   74 static struct sx dpcpu_lock;
   75 uintptr_t dpcpu_off[MAXCPU];
   76 struct pcpu *cpuid_to_pcpu[MAXCPU];
   77 struct cpuhead cpuhead = SLIST_HEAD_INITIALIZER(cpuhead);
   78 
   79 /*
   80  * Initialize the MI portions of a struct pcpu.
   81  */
   82 void
   83 pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
   84 {
   85 
   86         bzero(pcpu, size);
   87         KASSERT(cpuid >= 0 && cpuid < MAXCPU,
   88             ("pcpu_init: invalid cpuid %d", cpuid));
   89         pcpu->pc_cpuid = cpuid;
   90         pcpu->pc_cpumask = 1 << cpuid;
   91         cpuid_to_pcpu[cpuid] = pcpu;
   92         SLIST_INSERT_HEAD(&cpuhead, pcpu, pc_allcpu);
   93         cpu_pcpu_init(pcpu, cpuid, size);
   94         pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
   95         pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
   96 #ifdef KTR
   97         snprintf(pcpu->pc_name, sizeof(pcpu->pc_name), "CPU %d", cpuid);
   98 #endif
   99 }
  100 
  101 void
  102 dpcpu_init(void *dpcpu, int cpuid)
  103 {
  104         struct pcpu *pcpu;
  105 
  106         pcpu = pcpu_find(cpuid);
  107         pcpu->pc_dynamic = (uintptr_t)dpcpu - DPCPU_START;
  108 
  109         /*
  110          * Initialize defaults from our linker section.
  111          */
  112         memcpy(dpcpu, (void *)DPCPU_START, DPCPU_BYTES);
  113 
  114         /*
  115          * Place it in the global pcpu offset array.
  116          */
  117         dpcpu_off[cpuid] = pcpu->pc_dynamic;
  118 }
  119 
  120 static void
  121 dpcpu_startup(void *dummy __unused)
  122 {
  123         struct dpcpu_free *df;
  124 
  125         df = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  126         df->df_start = (uintptr_t)&DPCPU_NAME(modspace);
  127         df->df_len = DPCPU_MODMIN;
  128         TAILQ_INSERT_HEAD(&dpcpu_head, df, df_link);
  129         sx_init(&dpcpu_lock, "dpcpu alloc lock");
  130 }
  131 SYSINIT(dpcpu, SI_SUB_KLD, SI_ORDER_FIRST, dpcpu_startup, 0);
  132 
  133 /*
  134  * First-fit extent based allocator for allocating space in the per-cpu
  135  * region reserved for modules.  This is only intended for use by the
  136  * kernel linkers to place module linker sets.
  137  */
  138 void *
  139 dpcpu_alloc(int size)
  140 {
  141         struct dpcpu_free *df;
  142         void *s;
  143 
  144         s = NULL;
  145         size = roundup2(size, sizeof(void *));
  146         sx_xlock(&dpcpu_lock);
  147         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  148                 if (df->df_len < size)
  149                         continue;
  150                 if (df->df_len == size) {
  151                         s = (void *)df->df_start;
  152                         TAILQ_REMOVE(&dpcpu_head, df, df_link);
  153                         free(df, M_PCPU);
  154                         break;
  155                 }
  156                 s = (void *)df->df_start;
  157                 df->df_len -= size;
  158                 df->df_start = df->df_start + size;
  159                 break;
  160         }
  161         sx_xunlock(&dpcpu_lock);
  162 
  163         return (s);
  164 }
  165 
  166 /*
  167  * Free dynamic per-cpu space at module unload time. 
  168  */
  169 void
  170 dpcpu_free(void *s, int size)
  171 {
  172         struct dpcpu_free *df;
  173         struct dpcpu_free *dn;
  174         uintptr_t start;
  175         uintptr_t end;
  176 
  177         size = roundup2(size, sizeof(void *));
  178         start = (uintptr_t)s;
  179         end = start + size;
  180         /*
  181          * Free a region of space and merge it with as many neighbors as
  182          * possible.  Keeping the list sorted simplifies this operation.
  183          */
  184         sx_xlock(&dpcpu_lock);
  185         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  186                 if (df->df_start > end)
  187                         break;
  188                 /*
  189                  * If we expand at the end of an entry we may have to
  190                  * merge it with the one following it as well.
  191                  */
  192                 if (df->df_start + df->df_len == start) {
  193                         df->df_len += size;
  194                         dn = TAILQ_NEXT(df, df_link);
  195                         if (df->df_start + df->df_len == dn->df_start) {
  196                                 df->df_len += dn->df_len;
  197                                 TAILQ_REMOVE(&dpcpu_head, dn, df_link);
  198                                 free(dn, M_PCPU);
  199                         }
  200                         sx_xunlock(&dpcpu_lock);
  201                         return;
  202                 }
  203                 if (df->df_start == end) {
  204                         df->df_start = start;
  205                         df->df_len += size;
  206                         sx_xunlock(&dpcpu_lock);
  207                         return;
  208                 }
  209         }
  210         dn = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  211         dn->df_start = start;
  212         dn->df_len = size;
  213         if (df)
  214                 TAILQ_INSERT_BEFORE(df, dn, df_link);
  215         else
  216                 TAILQ_INSERT_TAIL(&dpcpu_head, dn, df_link);
  217         sx_xunlock(&dpcpu_lock);
  218 }
  219 
  220 /*
  221  * Initialize the per-cpu storage from an updated linker-set region.
  222  */
  223 void
  224 dpcpu_copy(void *s, int size)
  225 {
  226 #ifdef SMP
  227         uintptr_t dpcpu;
  228         int i;
  229 
  230         for (i = 0; i < mp_ncpus; ++i) {
  231                 dpcpu = dpcpu_off[i];
  232                 if (dpcpu == 0)
  233                         continue;
  234                 memcpy((void *)(dpcpu + (uintptr_t)s), s, size);
  235         }
  236 #else
  237         memcpy((void *)(dpcpu_off[0] + (uintptr_t)s), s, size);
  238 #endif
  239 }
  240 
  241 /*
  242  * Destroy a struct pcpu.
  243  */
  244 void
  245 pcpu_destroy(struct pcpu *pcpu)
  246 {
  247 
  248         SLIST_REMOVE(&cpuhead, pcpu, pcpu, pc_allcpu);
  249         cpuid_to_pcpu[pcpu->pc_cpuid] = NULL;
  250         dpcpu_off[pcpu->pc_cpuid] = 0;
  251 }
  252 
  253 /*
  254  * Locate a struct pcpu by cpu id.
  255  */
  256 struct pcpu *
  257 pcpu_find(u_int cpuid)
  258 {
  259 
  260         return (cpuid_to_pcpu[cpuid]);
  261 }
  262 
  263 int
  264 sysctl_dpcpu_quad(SYSCTL_HANDLER_ARGS)
  265 {
  266         uintptr_t dpcpu;
  267         int64_t count;
  268         int i;
  269 
  270         count = 0;
  271         for (i = 0; i < mp_ncpus; ++i) {
  272                 dpcpu = dpcpu_off[i];
  273                 if (dpcpu == 0)
  274                         continue;
  275                 count += *(int64_t *)(dpcpu + (uintptr_t)arg1);
  276         }
  277         return (SYSCTL_OUT(req, &count, sizeof(count)));
  278 }
  279 
  280 int
  281 sysctl_dpcpu_long(SYSCTL_HANDLER_ARGS)
  282 {
  283         uintptr_t dpcpu;
  284         long count;
  285         int i;
  286 
  287         count = 0;
  288         for (i = 0; i < mp_ncpus; ++i) {
  289                 dpcpu = dpcpu_off[i];
  290                 if (dpcpu == 0)
  291                         continue;
  292                 count += *(long *)(dpcpu + (uintptr_t)arg1);
  293         }
  294         return (SYSCTL_OUT(req, &count, sizeof(count)));
  295 }
  296 
  297 int
  298 sysctl_dpcpu_int(SYSCTL_HANDLER_ARGS)
  299 {
  300         uintptr_t dpcpu;
  301         int count;
  302         int i;
  303 
  304         count = 0;
  305         for (i = 0; i < mp_ncpus; ++i) {
  306                 dpcpu = dpcpu_off[i];
  307                 if (dpcpu == 0)
  308                         continue;
  309                 count += *(int *)(dpcpu + (uintptr_t)arg1);
  310         }
  311         return (SYSCTL_OUT(req, &count, sizeof(count)));
  312 }
  313 
  314 #ifdef DDB
  315 DB_SHOW_COMMAND(dpcpu_off, db_show_dpcpu_off)
  316 {
  317         int id;
  318 
  319         CPU_FOREACH(id) {
  320                 db_printf("dpcpu_off[%2d] = 0x%jx (+ DPCPU_START = %p)\n",
  321                     id, (uintmax_t)dpcpu_off[id],
  322                     (void *)(uintptr_t)(dpcpu_off[id] + DPCPU_START));
  323         }
  324 }
  325 
  326 static void
  327 show_pcpu(struct pcpu *pc)
  328 {
  329         struct thread *td;
  330 
  331         db_printf("cpuid        = %d\n", pc->pc_cpuid);
  332         db_printf("dynamic pcpu = %p\n", (void *)pc->pc_dynamic);
  333         db_printf("curthread    = ");
  334         td = pc->pc_curthread;
  335         if (td != NULL)
  336                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  337                     td->td_name);
  338         else
  339                 db_printf("none\n");
  340         db_printf("curpcb       = %p\n", pc->pc_curpcb);
  341         db_printf("fpcurthread  = ");
  342         td = pc->pc_fpcurthread;
  343         if (td != NULL)
  344                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  345                     td->td_name);
  346         else
  347                 db_printf("none\n");
  348         db_printf("idlethread   = ");
  349         td = pc->pc_idlethread;
  350         if (td != NULL)
  351                 db_printf("%p: tid %d \"%s\"\n", td, td->td_tid, td->td_name);
  352         else
  353                 db_printf("none\n");
  354         db_show_mdpcpu(pc);
  355 
  356 #ifdef VIMAGE
  357         db_printf("curvnet      = %p\n", pc->pc_curthread->td_vnet);
  358 #endif
  359 
  360 #ifdef WITNESS
  361         db_printf("spin locks held:\n");
  362         witness_list_locks(&pc->pc_spinlocks, db_printf);
  363 #endif
  364 }
  365 
  366 DB_SHOW_COMMAND(pcpu, db_show_pcpu)
  367 {
  368         struct pcpu *pc;
  369         int id;
  370 
  371         if (have_addr)
  372                 id = ((addr >> 4) % 16) * 10 + (addr % 16);
  373         else
  374                 id = PCPU_GET(cpuid);
  375         pc = pcpu_find(id);
  376         if (pc == NULL) {
  377                 db_printf("CPU %d not found\n", id);
  378                 return;
  379         }
  380         show_pcpu(pc);
  381 }
  382 
  383 DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all)
  384 {
  385         struct pcpu *pc;
  386         int id;
  387 
  388         db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid));
  389         for (id = 0; id <= mp_maxid; id++) {
  390                 pc = pcpu_find(id);
  391                 if (pc != NULL) {
  392                         show_pcpu(pc);
  393                         db_printf("\n");
  394                 }
  395         }
  396 }
  397 DB_SHOW_ALIAS(allpcpu, db_show_cpu_all);
  398 #endif

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