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  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2001 Wind River Systems, Inc.
    5  * All rights reserved.
    6  * Written by: John Baldwin <jhb@FreeBSD.org>
    7  *
    8  * Copyright (c) 2009 Jeffrey Roberson <jeff@freebsd.org>
    9  * All rights reserved.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 3. Neither the name of the author nor the names of any co-contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  */
   35 
   36 /*
   37  * This module provides MI support for per-cpu data.
   38  *
   39  * Each architecture determines the mapping of logical CPU IDs to physical
   40  * CPUs.  The requirements of this mapping are as follows:
   41  *  - Logical CPU IDs must reside in the range 0 ... MAXCPU - 1.
   42  *  - The mapping is not required to be dense.  That is, there may be
   43  *    gaps in the mappings.
   44  *  - The platform sets the value of MAXCPU in <machine/param.h>.
   45  *  - It is suggested, but not required, that in the non-SMP case, the
   46  *    platform define MAXCPU to be 1 and define the logical ID of the
   47  *    sole CPU as 0.
   48  */
   49 
   50 #include <sys/cdefs.h>
   51 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_pcpu.c 336906 2018-07-30 14:25:17Z andrew $");
   52 
   53 #include "opt_ddb.h"
   54 
   55 #include <sys/param.h>
   56 #include <sys/systm.h>
   57 #include <sys/sysctl.h>
   58 #include <sys/lock.h>
   59 #include <sys/malloc.h>
   60 #include <sys/pcpu.h>
   61 #include <sys/proc.h>
   62 #include <sys/smp.h>
   63 #include <sys/sx.h>
   64 #include <vm/uma.h>
   65 #include <ddb/ddb.h>
   66 
   67 static MALLOC_DEFINE(M_PCPU, "Per-cpu", "Per-cpu resource accouting.");
   68 
   69 struct dpcpu_free {
   70         uintptr_t       df_start;
   71         int             df_len;
   72         TAILQ_ENTRY(dpcpu_free) df_link;
   73 };
   74 
   75 DPCPU_DEFINE_STATIC(char, modspace[DPCPU_MODMIN] __aligned(__alignof(void *)));
   76 static TAILQ_HEAD(, dpcpu_free) dpcpu_head = TAILQ_HEAD_INITIALIZER(dpcpu_head);
   77 static struct sx dpcpu_lock;
   78 uintptr_t dpcpu_off[MAXCPU];
   79 struct pcpu *cpuid_to_pcpu[MAXCPU];
   80 struct cpuhead cpuhead = STAILQ_HEAD_INITIALIZER(cpuhead);
   81 
   82 /*
   83  * Initialize the MI portions of a struct pcpu.
   84  */
   85 void
   86 pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
   87 {
   88 
   89         bzero(pcpu, size);
   90         KASSERT(cpuid >= 0 && cpuid < MAXCPU,
   91             ("pcpu_init: invalid cpuid %d", cpuid));
   92         pcpu->pc_cpuid = cpuid;
   93         cpuid_to_pcpu[cpuid] = pcpu;
   94         STAILQ_INSERT_TAIL(&cpuhead, pcpu, pc_allcpu);
   95         cpu_pcpu_init(pcpu, cpuid, size);
   96         pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
   97         pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
   98 }
   99 
  100 void
  101 dpcpu_init(void *dpcpu, int cpuid)
  102 {
  103         struct pcpu *pcpu;
  104 
  105         pcpu = pcpu_find(cpuid);
  106         pcpu->pc_dynamic = (uintptr_t)dpcpu - DPCPU_START;
  107 
  108         /*
  109          * Initialize defaults from our linker section.
  110          */
  111         memcpy(dpcpu, (void *)DPCPU_START, DPCPU_BYTES);
  112 
  113         /*
  114          * Place it in the global pcpu offset array.
  115          */
  116         dpcpu_off[cpuid] = pcpu->pc_dynamic;
  117 }
  118 
  119 static void
  120 dpcpu_startup(void *dummy __unused)
  121 {
  122         struct dpcpu_free *df;
  123 
  124         df = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  125         df->df_start = (uintptr_t)&DPCPU_NAME(modspace);
  126         df->df_len = DPCPU_MODMIN;
  127         TAILQ_INSERT_HEAD(&dpcpu_head, df, df_link);
  128         sx_init(&dpcpu_lock, "dpcpu alloc lock");
  129 }
  130 SYSINIT(dpcpu, SI_SUB_KLD, SI_ORDER_FIRST, dpcpu_startup, NULL);
  131 
  132 /*
  133  * UMA_PCPU_ZONE zones, that are available for all kernel
  134  * consumers. Right now 64 bit zone is used for counter(9)
  135  * and pointer zone is used by flowtable.
  136  */
  137 
  138 uma_zone_t pcpu_zone_64;
  139 uma_zone_t pcpu_zone_ptr;
  140 
  141 static void
  142 pcpu_zones_startup(void)
  143 {
  144 
  145         pcpu_zone_64 = uma_zcreate("64 pcpu", sizeof(uint64_t),
  146             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_PCPU);
  147 
  148         if (sizeof(uint64_t) == sizeof(void *))
  149                 pcpu_zone_ptr = pcpu_zone_64;
  150         else
  151                 pcpu_zone_ptr = uma_zcreate("ptr pcpu", sizeof(void *),
  152                     NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_PCPU);
  153 }
  154 SYSINIT(pcpu_zones, SI_SUB_VM, SI_ORDER_ANY, pcpu_zones_startup, NULL);
  155 
  156 /*
  157  * First-fit extent based allocator for allocating space in the per-cpu
  158  * region reserved for modules.  This is only intended for use by the
  159  * kernel linkers to place module linker sets.
  160  */
  161 void *
  162 dpcpu_alloc(int size)
  163 {
  164         struct dpcpu_free *df;
  165         void *s;
  166 
  167         s = NULL;
  168         size = roundup2(size, sizeof(void *));
  169         sx_xlock(&dpcpu_lock);
  170         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  171                 if (df->df_len < size)
  172                         continue;
  173                 if (df->df_len == size) {
  174                         s = (void *)df->df_start;
  175                         TAILQ_REMOVE(&dpcpu_head, df, df_link);
  176                         free(df, M_PCPU);
  177                         break;
  178                 }
  179                 s = (void *)df->df_start;
  180                 df->df_len -= size;
  181                 df->df_start = df->df_start + size;
  182                 break;
  183         }
  184         sx_xunlock(&dpcpu_lock);
  185 
  186         return (s);
  187 }
  188 
  189 /*
  190  * Free dynamic per-cpu space at module unload time. 
  191  */
  192 void
  193 dpcpu_free(void *s, int size)
  194 {
  195         struct dpcpu_free *df;
  196         struct dpcpu_free *dn;
  197         uintptr_t start;
  198         uintptr_t end;
  199 
  200         size = roundup2(size, sizeof(void *));
  201         start = (uintptr_t)s;
  202         end = start + size;
  203         /*
  204          * Free a region of space and merge it with as many neighbors as
  205          * possible.  Keeping the list sorted simplifies this operation.
  206          */
  207         sx_xlock(&dpcpu_lock);
  208         TAILQ_FOREACH(df, &dpcpu_head, df_link) {
  209                 if (df->df_start > end)
  210                         break;
  211                 /*
  212                  * If we expand at the end of an entry we may have to
  213                  * merge it with the one following it as well.
  214                  */
  215                 if (df->df_start + df->df_len == start) {
  216                         df->df_len += size;
  217                         dn = TAILQ_NEXT(df, df_link);
  218                         if (df->df_start + df->df_len == dn->df_start) {
  219                                 df->df_len += dn->df_len;
  220                                 TAILQ_REMOVE(&dpcpu_head, dn, df_link);
  221                                 free(dn, M_PCPU);
  222                         }
  223                         sx_xunlock(&dpcpu_lock);
  224                         return;
  225                 }
  226                 if (df->df_start == end) {
  227                         df->df_start = start;
  228                         df->df_len += size;
  229                         sx_xunlock(&dpcpu_lock);
  230                         return;
  231                 }
  232         }
  233         dn = malloc(sizeof(*df), M_PCPU, M_WAITOK | M_ZERO);
  234         dn->df_start = start;
  235         dn->df_len = size;
  236         if (df)
  237                 TAILQ_INSERT_BEFORE(df, dn, df_link);
  238         else
  239                 TAILQ_INSERT_TAIL(&dpcpu_head, dn, df_link);
  240         sx_xunlock(&dpcpu_lock);
  241 }
  242 
  243 /*
  244  * Initialize the per-cpu storage from an updated linker-set region.
  245  */
  246 void
  247 dpcpu_copy(void *s, int size)
  248 {
  249 #ifdef SMP
  250         uintptr_t dpcpu;
  251         int i;
  252 
  253         CPU_FOREACH(i) {
  254                 dpcpu = dpcpu_off[i];
  255                 if (dpcpu == 0)
  256                         continue;
  257                 memcpy((void *)(dpcpu + (uintptr_t)s), s, size);
  258         }
  259 #else
  260         memcpy((void *)(dpcpu_off[0] + (uintptr_t)s), s, size);
  261 #endif
  262 }
  263 
  264 /*
  265  * Destroy a struct pcpu.
  266  */
  267 void
  268 pcpu_destroy(struct pcpu *pcpu)
  269 {
  270 
  271         STAILQ_REMOVE(&cpuhead, pcpu, pcpu, pc_allcpu);
  272         cpuid_to_pcpu[pcpu->pc_cpuid] = NULL;
  273         dpcpu_off[pcpu->pc_cpuid] = 0;
  274 }
  275 
  276 /*
  277  * Locate a struct pcpu by cpu id.
  278  */
  279 struct pcpu *
  280 pcpu_find(u_int cpuid)
  281 {
  282 
  283         return (cpuid_to_pcpu[cpuid]);
  284 }
  285 
  286 int
  287 sysctl_dpcpu_quad(SYSCTL_HANDLER_ARGS)
  288 {
  289         uintptr_t dpcpu;
  290         int64_t count;
  291         int i;
  292 
  293         count = 0;
  294         CPU_FOREACH(i) {
  295                 dpcpu = dpcpu_off[i];
  296                 if (dpcpu == 0)
  297                         continue;
  298                 count += *(int64_t *)(dpcpu + (uintptr_t)arg1);
  299         }
  300         return (SYSCTL_OUT(req, &count, sizeof(count)));
  301 }
  302 
  303 int
  304 sysctl_dpcpu_long(SYSCTL_HANDLER_ARGS)
  305 {
  306         uintptr_t dpcpu;
  307         long count;
  308         int i;
  309 
  310         count = 0;
  311         CPU_FOREACH(i) {
  312                 dpcpu = dpcpu_off[i];
  313                 if (dpcpu == 0)
  314                         continue;
  315                 count += *(long *)(dpcpu + (uintptr_t)arg1);
  316         }
  317         return (SYSCTL_OUT(req, &count, sizeof(count)));
  318 }
  319 
  320 int
  321 sysctl_dpcpu_int(SYSCTL_HANDLER_ARGS)
  322 {
  323         uintptr_t dpcpu;
  324         int count;
  325         int i;
  326 
  327         count = 0;
  328         CPU_FOREACH(i) {
  329                 dpcpu = dpcpu_off[i];
  330                 if (dpcpu == 0)
  331                         continue;
  332                 count += *(int *)(dpcpu + (uintptr_t)arg1);
  333         }
  334         return (SYSCTL_OUT(req, &count, sizeof(count)));
  335 }
  336 
  337 #ifdef DDB
  338 DB_SHOW_COMMAND(dpcpu_off, db_show_dpcpu_off)
  339 {
  340         int id;
  341 
  342         CPU_FOREACH(id) {
  343                 db_printf("dpcpu_off[%2d] = 0x%jx (+ DPCPU_START = %p)\n",
  344                     id, (uintmax_t)dpcpu_off[id],
  345                     (void *)(uintptr_t)(dpcpu_off[id] + DPCPU_START));
  346         }
  347 }
  348 
  349 static void
  350 show_pcpu(struct pcpu *pc)
  351 {
  352         struct thread *td;
  353 
  354         db_printf("cpuid        = %d\n", pc->pc_cpuid);
  355         db_printf("dynamic pcpu = %p\n", (void *)pc->pc_dynamic);
  356         db_printf("curthread    = ");
  357         td = pc->pc_curthread;
  358         if (td != NULL)
  359                 db_printf("%p: pid %d tid %d \"%s\"\n", td, td->td_proc->p_pid,
  360                     td->td_tid, td->td_name);
  361         else
  362                 db_printf("none\n");
  363         db_printf("curpcb       = %p\n", pc->pc_curpcb);
  364         db_printf("fpcurthread  = ");
  365         td = pc->pc_fpcurthread;
  366         if (td != NULL)
  367                 db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
  368                     td->td_name);
  369         else
  370                 db_printf("none\n");
  371         db_printf("idlethread   = ");
  372         td = pc->pc_idlethread;
  373         if (td != NULL)
  374                 db_printf("%p: tid %d \"%s\"\n", td, td->td_tid, td->td_name);
  375         else
  376                 db_printf("none\n");
  377         db_show_mdpcpu(pc);
  378 
  379 #ifdef VIMAGE
  380         db_printf("curvnet      = %p\n", pc->pc_curthread->td_vnet);
  381 #endif
  382 
  383 #ifdef WITNESS
  384         db_printf("spin locks held:\n");
  385         witness_list_locks(&pc->pc_spinlocks, db_printf);
  386 #endif
  387 }
  388 
  389 DB_SHOW_COMMAND(pcpu, db_show_pcpu)
  390 {
  391         struct pcpu *pc;
  392         int id;
  393 
  394         if (have_addr)
  395                 id = ((addr >> 4) % 16) * 10 + (addr % 16);
  396         else
  397                 id = PCPU_GET(cpuid);
  398         pc = pcpu_find(id);
  399         if (pc == NULL) {
  400                 db_printf("CPU %d not found\n", id);
  401                 return;
  402         }
  403         show_pcpu(pc);
  404 }
  405 
  406 DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all)
  407 {
  408         struct pcpu *pc;
  409         int id;
  410 
  411         db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid));
  412         CPU_FOREACH(id) {
  413                 pc = pcpu_find(id);
  414                 if (pc != NULL) {
  415                         show_pcpu(pc);
  416                         db_printf("\n");
  417                 }
  418         }
  419 }
  420 DB_SHOW_ALIAS(allpcpu, db_show_cpu_all);
  421 #endif

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