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/9.0/sys/kern/subr_pcpu.c 224218 2011-07-19 14:57:59Z attilio $");
   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 = STAILQ_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         cpuid_to_pcpu[cpuid] = pcpu;
   91         STAILQ_INSERT_TAIL(&cpuhead, pcpu, pc_allcpu);
   92         cpu_pcpu_init(pcpu, cpuid, size);
   93         pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
   94         pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
   95 }
   96 
   97 void
   98 dpcpu_init(void *dpcpu, int cpuid)
   99 {
  100         struct pcpu *pcpu;
  101 
  102         pcpu = pcpu_find(cpuid);
  103         pcpu->pc_dynamic = (uintptr_t)dpcpu - DPCPU_START;
  104 
  105         /*
  106          * Initialize defaults from our linker section.
  107          */
  108         memcpy(dpcpu, (void *)DPCPU_START, DPCPU_BYTES);
  109 
  110         /*
  111          * Place it in the global pcpu offset array.
  112          */
  113         dpcpu_off[cpuid] = pcpu->pc_dynamic;
  114 }
  115 
  116 static void
  117 dpcpu_startup(void *dummy __unused)
  118 {
  119         struct dpcpu_free *df;
  120 
  121         df = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  122         df->df_start = (uintptr_t)&DPCPU_NAME(modspace);
  123         df->df_len = DPCPU_MODMIN;
  124         TAILQ_INSERT_HEAD(&dpcpu_head, df, df_link);
  125         sx_init(&dpcpu_lock, "dpcpu alloc lock");
  126 }
  127 SYSINIT(dpcpu, SI_SUB_KLD, SI_ORDER_FIRST, dpcpu_startup, 0);
  128 
  129 /*
  130  * First-fit extent based allocator for allocating space in the per-cpu
  131  * region reserved for modules.  This is only intended for use by the
  132  * kernel linkers to place module linker sets.
  133  */
  134 void *
  135 dpcpu_alloc(int size)
  136 {
  137         struct dpcpu_free *df;
  138         void *s;
  139 
  140         s = NULL;
  141         size = roundup2(size, sizeof(void *));
  142         sx_xlock(&dpcpu_lock);
  143         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  144                 if (df->df_len < size)
  145                         continue;
  146                 if (df->df_len == size) {
  147                         s = (void *)df->df_start;
  148                         TAILQ_REMOVE(&dpcpu_head, df, df_link);
  149                         free(df, M_PCPU);
  150                         break;
  151                 }
  152                 s = (void *)df->df_start;
  153                 df->df_len -= size;
  154                 df->df_start = df->df_start + size;
  155                 break;
  156         }
  157         sx_xunlock(&dpcpu_lock);
  158 
  159         return (s);
  160 }
  161 
  162 /*
  163  * Free dynamic per-cpu space at module unload time. 
  164  */
  165 void
  166 dpcpu_free(void *s, int size)
  167 {
  168         struct dpcpu_free *df;
  169         struct dpcpu_free *dn;
  170         uintptr_t start;
  171         uintptr_t end;
  172 
  173         size = roundup2(size, sizeof(void *));
  174         start = (uintptr_t)s;
  175         end = start + size;
  176         /*
  177          * Free a region of space and merge it with as many neighbors as
  178          * possible.  Keeping the list sorted simplifies this operation.
  179          */
  180         sx_xlock(&dpcpu_lock);
  181         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  182                 if (df->df_start > end)
  183                         break;
  184                 /*
  185                  * If we expand at the end of an entry we may have to
  186                  * merge it with the one following it as well.
  187                  */
  188                 if (df->df_start + df->df_len == start) {
  189                         df->df_len += size;
  190                         dn = TAILQ_NEXT(df, df_link);
  191                         if (df->df_start + df->df_len == dn->df_start) {
  192                                 df->df_len += dn->df_len;
  193                                 TAILQ_REMOVE(&dpcpu_head, dn, df_link);
  194                                 free(dn, M_PCPU);
  195                         }
  196                         sx_xunlock(&dpcpu_lock);
  197                         return;
  198                 }
  199                 if (df->df_start == end) {
  200                         df->df_start = start;
  201                         df->df_len += size;
  202                         sx_xunlock(&dpcpu_lock);
  203                         return;
  204                 }
  205         }
  206         dn = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  207         dn->df_start = start;
  208         dn->df_len = size;
  209         if (df)
  210                 TAILQ_INSERT_BEFORE(df, dn, df_link);
  211         else
  212                 TAILQ_INSERT_TAIL(&dpcpu_head, dn, df_link);
  213         sx_xunlock(&dpcpu_lock);
  214 }
  215 
  216 /*
  217  * Initialize the per-cpu storage from an updated linker-set region.
  218  */
  219 void
  220 dpcpu_copy(void *s, int size)
  221 {
  222 #ifdef SMP
  223         uintptr_t dpcpu;
  224         int i;
  225 
  226         for (i = 0; i < mp_ncpus; ++i) {
  227                 dpcpu = dpcpu_off[i];
  228                 if (dpcpu == 0)
  229                         continue;
  230                 memcpy((void *)(dpcpu + (uintptr_t)s), s, size);
  231         }
  232 #else
  233         memcpy((void *)(dpcpu_off[0] + (uintptr_t)s), s, size);
  234 #endif
  235 }
  236 
  237 /*
  238  * Destroy a struct pcpu.
  239  */
  240 void
  241 pcpu_destroy(struct pcpu *pcpu)
  242 {
  243 
  244         STAILQ_REMOVE(&cpuhead, pcpu, pcpu, pc_allcpu);
  245         cpuid_to_pcpu[pcpu->pc_cpuid] = NULL;
  246         dpcpu_off[pcpu->pc_cpuid] = 0;
  247 }
  248 
  249 /*
  250  * Locate a struct pcpu by cpu id.
  251  */
  252 struct pcpu *
  253 pcpu_find(u_int cpuid)
  254 {
  255 
  256         return (cpuid_to_pcpu[cpuid]);
  257 }
  258 
  259 int
  260 sysctl_dpcpu_quad(SYSCTL_HANDLER_ARGS)
  261 {
  262         uintptr_t dpcpu;
  263         int64_t count;
  264         int i;
  265 
  266         count = 0;
  267         for (i = 0; i < mp_ncpus; ++i) {
  268                 dpcpu = dpcpu_off[i];
  269                 if (dpcpu == 0)
  270                         continue;
  271                 count += *(int64_t *)(dpcpu + (uintptr_t)arg1);
  272         }
  273         return (SYSCTL_OUT(req, &count, sizeof(count)));
  274 }
  275 
  276 int
  277 sysctl_dpcpu_long(SYSCTL_HANDLER_ARGS)
  278 {
  279         uintptr_t dpcpu;
  280         long count;
  281         int i;
  282 
  283         count = 0;
  284         for (i = 0; i < mp_ncpus; ++i) {
  285                 dpcpu = dpcpu_off[i];
  286                 if (dpcpu == 0)
  287                         continue;
  288                 count += *(long *)(dpcpu + (uintptr_t)arg1);
  289         }
  290         return (SYSCTL_OUT(req, &count, sizeof(count)));
  291 }
  292 
  293 int
  294 sysctl_dpcpu_int(SYSCTL_HANDLER_ARGS)
  295 {
  296         uintptr_t dpcpu;
  297         int count;
  298         int i;
  299 
  300         count = 0;
  301         for (i = 0; i < mp_ncpus; ++i) {
  302                 dpcpu = dpcpu_off[i];
  303                 if (dpcpu == 0)
  304                         continue;
  305                 count += *(int *)(dpcpu + (uintptr_t)arg1);
  306         }
  307         return (SYSCTL_OUT(req, &count, sizeof(count)));
  308 }
  309 
  310 #ifdef DDB
  311 DB_SHOW_COMMAND(dpcpu_off, db_show_dpcpu_off)
  312 {
  313         int id;
  314 
  315         CPU_FOREACH(id) {
  316                 db_printf("dpcpu_off[%2d] = 0x%jx (+ DPCPU_START = %p)\n",
  317                     id, (uintmax_t)dpcpu_off[id],
  318                     (void *)(uintptr_t)(dpcpu_off[id] + DPCPU_START));
  319         }
  320 }
  321 
  322 static void
  323 show_pcpu(struct pcpu *pc)
  324 {
  325         struct thread *td;
  326 
  327         db_printf("cpuid        = %d\n", pc->pc_cpuid);
  328         db_printf("dynamic pcpu = %p\n", (void *)pc->pc_dynamic);
  329         db_printf("curthread    = ");
  330         td = pc->pc_curthread;
  331         if (td != NULL)
  332                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  333                     td->td_name);
  334         else
  335                 db_printf("none\n");
  336         db_printf("curpcb       = %p\n", pc->pc_curpcb);
  337         db_printf("fpcurthread  = ");
  338         td = pc->pc_fpcurthread;
  339         if (td != NULL)
  340                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  341                     td->td_name);
  342         else
  343                 db_printf("none\n");
  344         db_printf("idlethread   = ");
  345         td = pc->pc_idlethread;
  346         if (td != NULL)
  347                 db_printf("%p: tid %d \"%s\"\n", td, td->td_tid, td->td_name);
  348         else
  349                 db_printf("none\n");
  350         db_show_mdpcpu(pc);
  351 
  352 #ifdef VIMAGE
  353         db_printf("curvnet      = %p\n", pc->pc_curthread->td_vnet);
  354 #endif
  355 
  356 #ifdef WITNESS
  357         db_printf("spin locks held:\n");
  358         witness_list_locks(&pc->pc_spinlocks, db_printf);
  359 #endif
  360 }
  361 
  362 DB_SHOW_COMMAND(pcpu, db_show_pcpu)
  363 {
  364         struct pcpu *pc;
  365         int id;
  366 
  367         if (have_addr)
  368                 id = ((addr >> 4) % 16) * 10 + (addr % 16);
  369         else
  370                 id = PCPU_GET(cpuid);
  371         pc = pcpu_find(id);
  372         if (pc == NULL) {
  373                 db_printf("CPU %d not found\n", id);
  374                 return;
  375         }
  376         show_pcpu(pc);
  377 }
  378 
  379 DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all)
  380 {
  381         struct pcpu *pc;
  382         int id;
  383 
  384         db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid));
  385         for (id = 0; id <= mp_maxid; id++) {
  386                 pc = pcpu_find(id);
  387                 if (pc != NULL) {
  388                         show_pcpu(pc);
  389                         db_printf("\n");
  390                 }
  391         }
  392 }
  393 DB_SHOW_ALIAS(allpcpu, db_show_cpu_all);
  394 #endif

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