sys/kern/kern_sharedpage.c

   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("$FreeBSD$");
  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 /*
 123  * Push the timehands update to the shared page.
 124  *
 125  * The lockless update scheme is similar to the one used to update the
 126  * in-kernel timehands, see sys/kern/kern_tc.c:tc_windup() (which
 127  * calls us after the timehands are updated).
 128  */
 129 static void
 130 timehands_update(struct sysentvec *sv)
 131 {
 132         struct vdso_timehands th;
 133         struct vdso_timekeep *tk;
 134         uint32_t enabled, idx;
 135
 136         enabled = tc_fill_vdso_timehands(&th);
 137         th.th_gen = 0;
 138         idx = sv->sv_timekeep_curr;
 139         if (++idx >= VDSO_TH_NUM)
 140                 idx = 0;
 141         sv->sv_timekeep_curr = idx;
 142         if (++sv->sv_timekeep_gen == 0)
 143                 sv->sv_timekeep_gen = 1;
 144
 145         tk = (struct vdso_timekeep *)(shared_page_mapping +
 146             sv->sv_timekeep_off);
 147         tk->tk_th[idx].th_gen = 0;
 148         atomic_thread_fence_rel();
 149         if (enabled)
 150                 tk->tk_th[idx] = th;
 151         atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
 152         atomic_store_rel_32(&tk->tk_current, idx);
 153
 154         /*
 155          * The ordering of the assignment to tk_enabled relative to
 156          * the update of the vdso_timehands is not important.
 157          */
 158         tk->tk_enabled = enabled;
 159 }
 160
 161 #ifdef COMPAT_FREEBSD32
 162 static void
 163 timehands_update32(struct sysentvec *sv)
 164 {
 165         struct vdso_timehands32 th;
 166         struct vdso_timekeep32 *tk;
 167         uint32_t enabled, idx;
 168
 169         enabled = tc_fill_vdso_timehands32(&th);
 170         th.th_gen = 0;
 171         idx = sv->sv_timekeep_curr;
 172         if (++idx >= VDSO_TH_NUM)
 173                 idx = 0;
 174         sv->sv_timekeep_curr = idx;
 175         if (++sv->sv_timekeep_gen == 0)
 176                 sv->sv_timekeep_gen = 1;
 177
 178         tk = (struct vdso_timekeep32 *)(shared_page_mapping +
 179             sv->sv_timekeep_off);
 180         tk->tk_th[idx].th_gen = 0;
 181         atomic_thread_fence_rel();
 182         if (enabled)
 183                 tk->tk_th[idx] = th;
 184         atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
 185         atomic_store_rel_32(&tk->tk_current, idx);
 186         tk->tk_enabled = enabled;
 187 }
 188 #endif
 189
 190 /*
 191  * This is hackish, but easiest way to avoid creating list structures
 192  * that needs to be iterated over from the hardclock interrupt
 193  * context.
 194  */
 195 static struct sysentvec *host_sysentvec;
 196 #ifdef COMPAT_FREEBSD32
 197 static struct sysentvec *compat32_sysentvec;
 198 #endif
 199
 200 void
 201 timekeep_push_vdso(void)
 202 {
 203
 204         if (host_sysentvec != NULL && host_sysentvec->sv_timekeep_base != 0)
 205                 timehands_update(host_sysentvec);
 206 #ifdef COMPAT_FREEBSD32
 207         if (compat32_sysentvec != NULL &&
 208             compat32_sysentvec->sv_timekeep_base != 0)
 209                 timehands_update32(compat32_sysentvec);
 210 #endif
 211 }
 212
 213 void
 214 exec_sysvec_init(void *param)
 215 {
 216         struct sysentvec *sv;
 217         int tk_base;
 218         uint32_t tk_ver;
 219
 220         sv = (struct sysentvec *)param;
 221
 222         if ((sv->sv_flags & SV_SHP) == 0)
 223                 return;
 224         sv->sv_shared_page_obj = shared_page_obj;
 225         sv->sv_sigcode_base = sv->sv_shared_page_base +
 226             shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
 227         if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
 228                 return;
 229         tk_ver = VDSO_TK_VER_CURR;
 230 #ifdef COMPAT_FREEBSD32
 231         if ((sv->sv_flags & SV_ILP32) != 0) {
 232                 tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
 233                     sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
 234                 KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
 235                 shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
 236                     tk_ver), sizeof(uint32_t), &tk_ver);
 237                 KASSERT(compat32_sysentvec == 0,
 238                     ("Native compat32 already registered"));
 239                 compat32_sysentvec = sv;
 240         } else {
 241 #endif
 242                 tk_base = shared_page_alloc(sizeof(struct vdso_timekeep) +
 243                     sizeof(struct vdso_timehands) * VDSO_TH_NUM, 16);
 244                 KASSERT(tk_base != -1, ("tk_base -1 for native"));
 245                 shared_page_write(tk_base + offsetof(struct vdso_timekeep,
 246                     tk_ver), sizeof(uint32_t), &tk_ver);
 247                 KASSERT(host_sysentvec == 0, ("Native already registered"));
 248                 host_sysentvec = sv;
 249 #ifdef COMPAT_FREEBSD32
 250         }
 251 #endif
 252         sv->sv_timekeep_base = sv->sv_shared_page_base + tk_base;
 253         sv->sv_timekeep_off = tk_base;
 254         timekeep_push_vdso();
 255 }