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/kern_sharedpage.c

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    1 /*-
    2  * Copyright (c) 2010, 2012 Konstantin Belousov <kib@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: stable/10/sys/kern/kern_sharedpage.c 254649 2013-08-22 07:39:53Z kib $");
   29 
   30 #include "opt_compat.h"
   31 #include "opt_vm.h"
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/kernel.h>
   36 #include <sys/lock.h>
   37 #include <sys/rwlock.h>
   38 #include <sys/sysent.h>
   39 #include <sys/sysctl.h>
   40 #include <sys/vdso.h>
   41 
   42 #include <vm/vm.h>
   43 #include <vm/vm_param.h>
   44 #include <vm/pmap.h>
   45 #include <vm/vm_extern.h>
   46 #include <vm/vm_kern.h>
   47 #include <vm/vm_map.h>
   48 #include <vm/vm_object.h>
   49 #include <vm/vm_page.h>
   50 #include <vm/vm_pager.h>
   51 
   52 static struct sx shared_page_alloc_sx;
   53 static vm_object_t shared_page_obj;
   54 static int shared_page_free;
   55 char *shared_page_mapping;
   56 
   57 void
   58 shared_page_write(int base, int size, const void *data)
   59 {
   60 
   61         bcopy(data, shared_page_mapping + base, size);
   62 }
   63 
   64 static int
   65 shared_page_alloc_locked(int size, int align)
   66 {
   67         int res;
   68 
   69         res = roundup(shared_page_free, align);
   70         if (res + size >= IDX_TO_OFF(shared_page_obj->size))
   71                 res = -1;
   72         else
   73                 shared_page_free = res + size;
   74         return (res);
   75 }
   76 
   77 int
   78 shared_page_alloc(int size, int align)
   79 {
   80         int res;
   81 
   82         sx_xlock(&shared_page_alloc_sx);
   83         res = shared_page_alloc_locked(size, align);
   84         sx_xunlock(&shared_page_alloc_sx);
   85         return (res);
   86 }
   87 
   88 int
   89 shared_page_fill(int size, int align, const void *data)
   90 {
   91         int res;
   92 
   93         sx_xlock(&shared_page_alloc_sx);
   94         res = shared_page_alloc_locked(size, align);
   95         if (res != -1)
   96                 shared_page_write(res, size, data);
   97         sx_xunlock(&shared_page_alloc_sx);
   98         return (res);
   99 }
  100 
  101 static void
  102 shared_page_init(void *dummy __unused)
  103 {
  104         vm_page_t m;
  105         vm_offset_t addr;
  106 
  107         sx_init(&shared_page_alloc_sx, "shpsx");
  108         shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
  109             VM_PROT_DEFAULT, 0, NULL);
  110         VM_OBJECT_WLOCK(shared_page_obj);
  111         m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
  112         m->valid = VM_PAGE_BITS_ALL;
  113         VM_OBJECT_WUNLOCK(shared_page_obj);
  114         addr = kva_alloc(PAGE_SIZE);
  115         pmap_qenter(addr, &m, 1);
  116         shared_page_mapping = (char *)addr;
  117 }
  118 
  119 SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
  120     NULL);
  121 
  122 static void
  123 timehands_update(struct sysentvec *sv)
  124 {
  125         struct vdso_timehands th;
  126         struct vdso_timekeep *tk;
  127         uint32_t enabled, idx;
  128 
  129         enabled = tc_fill_vdso_timehands(&th);
  130         tk = (struct vdso_timekeep *)(shared_page_mapping +
  131             sv->sv_timekeep_off);
  132         idx = sv->sv_timekeep_curr;
  133         atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
  134         if (++idx >= VDSO_TH_NUM)
  135                 idx = 0;
  136         sv->sv_timekeep_curr = idx;
  137         if (++sv->sv_timekeep_gen == 0)
  138                 sv->sv_timekeep_gen = 1;
  139         th.th_gen = 0;
  140         if (enabled)
  141                 tk->tk_th[idx] = th;
  142         tk->tk_enabled = enabled;
  143         atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
  144         tk->tk_current = idx;
  145 }
  146 
  147 #ifdef COMPAT_FREEBSD32
  148 static void
  149 timehands_update32(struct sysentvec *sv)
  150 {
  151         struct vdso_timekeep32 *tk;
  152         struct vdso_timehands32 th;
  153         uint32_t enabled, idx;
  154 
  155         enabled = tc_fill_vdso_timehands32(&th);
  156         tk = (struct vdso_timekeep32 *)(shared_page_mapping +
  157             sv->sv_timekeep_off);
  158         idx = sv->sv_timekeep_curr;
  159         atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
  160         if (++idx >= VDSO_TH_NUM)
  161                 idx = 0;
  162         sv->sv_timekeep_curr = idx;
  163         if (++sv->sv_timekeep_gen == 0)
  164                 sv->sv_timekeep_gen = 1;
  165         th.th_gen = 0;
  166         if (enabled)
  167                 tk->tk_th[idx] = th;
  168         tk->tk_enabled = enabled;
  169         atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
  170         tk->tk_current = idx;
  171 }
  172 #endif
  173 
  174 /*
  175  * This is hackish, but easiest way to avoid creating list structures
  176  * that needs to be iterated over from the hardclock interrupt
  177  * context.
  178  */
  179 static struct sysentvec *host_sysentvec;
  180 #ifdef COMPAT_FREEBSD32
  181 static struct sysentvec *compat32_sysentvec;
  182 #endif
  183 
  184 void
  185 timekeep_push_vdso(void)
  186 {
  187 
  188         if (host_sysentvec != NULL && host_sysentvec->sv_timekeep_base != 0)
  189                 timehands_update(host_sysentvec);
  190 #ifdef COMPAT_FREEBSD32
  191         if (compat32_sysentvec != NULL &&
  192             compat32_sysentvec->sv_timekeep_base != 0)
  193                 timehands_update32(compat32_sysentvec);
  194 #endif
  195 }
  196 
  197 void
  198 exec_sysvec_init(void *param)
  199 {
  200         struct sysentvec *sv;
  201         int tk_base;
  202         uint32_t tk_ver;
  203 
  204         sv = (struct sysentvec *)param;
  205 
  206         if ((sv->sv_flags & SV_SHP) == 0)
  207                 return;
  208         sv->sv_shared_page_obj = shared_page_obj;
  209         sv->sv_sigcode_base = sv->sv_shared_page_base +
  210             shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
  211         if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
  212                 return;
  213         tk_ver = VDSO_TK_VER_CURR;
  214 #ifdef COMPAT_FREEBSD32
  215         if ((sv->sv_flags & SV_ILP32) != 0) {
  216                 tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
  217                     sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
  218                 KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
  219                 shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
  220                     tk_ver), sizeof(uint32_t), &tk_ver);
  221                 KASSERT(compat32_sysentvec == 0,
  222                     ("Native compat32 already registered"));
  223                 compat32_sysentvec = sv;
  224         } else {
  225 #endif
  226                 tk_base = shared_page_alloc(sizeof(struct vdso_timekeep) +
  227                     sizeof(struct vdso_timehands) * VDSO_TH_NUM, 16);
  228                 KASSERT(tk_base != -1, ("tk_base -1 for native"));
  229                 shared_page_write(tk_base + offsetof(struct vdso_timekeep,
  230                     tk_ver), sizeof(uint32_t), &tk_ver);
  231                 KASSERT(host_sysentvec == 0, ("Native already registered"));
  232                 host_sysentvec = sv;
  233 #ifdef COMPAT_FREEBSD32
  234         }
  235 #endif
  236         sv->sv_timekeep_base = sv->sv_shared_page_base + tk_base;
  237         sv->sv_timekeep_off = tk_base;
  238         timekeep_push_vdso();
  239 }

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