sys/kern/kern_sharedpage.c

   1 /*-
   2  * Copyright (c) 2010, 2012 Konstantin Belousov <kib@FreeBSD.org>
   3  * Copyright (c) 2015 The FreeBSD Foundation
   4  * All rights reserved.
   5  *
   6  * Portions of this software were developed by Konstantin Belousov
   7  * under sponsorship from the FreeBSD Foundation.
   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  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #include <sys/cdefs.h>
  32 __FBSDID("$FreeBSD$");
  33
  34 #include "opt_compat.h"
  35 #include "opt_vm.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/kernel.h>
  40 #include <sys/lock.h>
  41 #include <sys/malloc.h>
  42 #include <sys/rwlock.h>
  43 #include <sys/sysent.h>
  44 #include <sys/sysctl.h>
  45 #include <sys/vdso.h>
  46
  47 #include <vm/vm.h>
  48 #include <vm/vm_param.h>
  49 #include <vm/pmap.h>
  50 #include <vm/vm_extern.h>
  51 #include <vm/vm_kern.h>
  52 #include <vm/vm_map.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <vm/vm_pager.h>
  56
  57 static struct sx shared_page_alloc_sx;
  58 static vm_object_t shared_page_obj;
  59 static int shared_page_free;
  60 char *shared_page_mapping;
  61
  62 void
  63 shared_page_write(int base, int size, const void *data)
  64 {
  65
  66         bcopy(data, shared_page_mapping + base, size);
  67 }
  68
  69 static int
  70 shared_page_alloc_locked(int size, int align)
  71 {
  72         int res;
  73
  74         res = roundup(shared_page_free, align);
  75         if (res + size >= IDX_TO_OFF(shared_page_obj->size))
  76                 res = -1;
  77         else
  78                 shared_page_free = res + size;
  79         return (res);
  80 }
  81
  82 int
  83 shared_page_alloc(int size, int align)
  84 {
  85         int res;
  86
  87         sx_xlock(&shared_page_alloc_sx);
  88         res = shared_page_alloc_locked(size, align);
  89         sx_xunlock(&shared_page_alloc_sx);
  90         return (res);
  91 }
  92
  93 int
  94 shared_page_fill(int size, int align, const void *data)
  95 {
  96         int res;
  97
  98         sx_xlock(&shared_page_alloc_sx);
  99         res = shared_page_alloc_locked(size, align);
 100         if (res != -1)
 101                 shared_page_write(res, size, data);
 102         sx_xunlock(&shared_page_alloc_sx);
 103         return (res);
 104 }
 105
 106 static void
 107 shared_page_init(void *dummy __unused)
 108 {
 109         vm_page_t m;
 110         vm_offset_t addr;
 111
 112         sx_init(&shared_page_alloc_sx, "shpsx");
 113         shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
 114             VM_PROT_DEFAULT, 0, NULL);
 115         VM_OBJECT_WLOCK(shared_page_obj);
 116         m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
 117         m->valid = VM_PAGE_BITS_ALL;
 118         VM_OBJECT_WUNLOCK(shared_page_obj);
 119         addr = kva_alloc(PAGE_SIZE);
 120         pmap_qenter(addr, &m, 1);
 121         shared_page_mapping = (char *)addr;
 122 }
 123
 124 SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
 125     NULL);
 126
 127 /*
 128  * Push the timehands update to the shared page.
 129  *
 130  * The lockless update scheme is similar to the one used to update the
 131  * in-kernel timehands, see sys/kern/kern_tc.c:tc_windup() (which
 132  * calls us after the timehands are updated).
 133  */
 134 static void
 135 timehands_update(struct vdso_sv_tk *svtk)
 136 {
 137         struct vdso_timehands th;
 138         struct vdso_timekeep *tk;
 139         uint32_t enabled, idx;
 140
 141         enabled = tc_fill_vdso_timehands(&th);
 142         th.th_gen = 0;
 143         idx = svtk->sv_timekeep_curr;
 144         if (++idx >= VDSO_TH_NUM)
 145                 idx = 0;
 146         svtk->sv_timekeep_curr = idx;
 147         if (++svtk->sv_timekeep_gen == 0)
 148                 svtk->sv_timekeep_gen = 1;
 149
 150         tk = (struct vdso_timekeep *)(shared_page_mapping +
 151             svtk->sv_timekeep_off);
 152         tk->tk_th[idx].th_gen = 0;
 153         atomic_thread_fence_rel();
 154         if (enabled)
 155                 tk->tk_th[idx] = th;
 156         atomic_store_rel_32(&tk->tk_th[idx].th_gen, svtk->sv_timekeep_gen);
 157         atomic_store_rel_32(&tk->tk_current, idx);
 158
 159         /*
 160          * The ordering of the assignment to tk_enabled relative to
 161          * the update of the vdso_timehands is not important.
 162          */
 163         tk->tk_enabled = enabled;
 164 }
 165
 166 #ifdef COMPAT_FREEBSD32
 167 static void
 168 timehands_update32(struct vdso_sv_tk *svtk)
 169 {
 170         struct vdso_timehands32 th;
 171         struct vdso_timekeep32 *tk;
 172         uint32_t enabled, idx;
 173
 174         enabled = tc_fill_vdso_timehands32(&th);
 175         th.th_gen = 0;
 176         idx = svtk->sv_timekeep_curr;
 177         if (++idx >= VDSO_TH_NUM)
 178                 idx = 0;
 179         svtk->sv_timekeep_curr = idx;
 180         if (++svtk->sv_timekeep_gen == 0)
 181                 svtk->sv_timekeep_gen = 1;
 182
 183         tk = (struct vdso_timekeep32 *)(shared_page_mapping +
 184             svtk->sv_timekeep_off);
 185         tk->tk_th[idx].th_gen = 0;
 186         atomic_thread_fence_rel();
 187         if (enabled)
 188                 tk->tk_th[idx] = th;
 189         atomic_store_rel_32(&tk->tk_th[idx].th_gen, svtk->sv_timekeep_gen);
 190         atomic_store_rel_32(&tk->tk_current, idx);
 191         tk->tk_enabled = enabled;
 192 }
 193 #endif
 194
 195 /*
 196  * This is hackish, but easiest way to avoid creating list structures
 197  * that needs to be iterated over from the hardclock interrupt
 198  * context.
 199  */
 200 static struct vdso_sv_tk *host_svtk;
 201 #ifdef COMPAT_FREEBSD32
 202 static struct vdso_sv_tk *compat32_svtk;
 203 #endif
 204
 205 void
 206 timekeep_push_vdso(void)
 207 {
 208
 209         if (host_svtk != NULL)
 210                 timehands_update(host_svtk);
 211 #ifdef COMPAT_FREEBSD32
 212         if (compat32_svtk != NULL)
 213                 timehands_update32(compat32_svtk);
 214 #endif
 215 }
 216
 217 struct vdso_sv_tk *
 218 alloc_sv_tk(void)
 219 {
 220         struct vdso_sv_tk *svtk;
 221         int tk_base;
 222         uint32_t tk_ver;
 223
 224         tk_ver = VDSO_TK_VER_CURR;
 225         svtk = malloc(sizeof(struct vdso_sv_tk), M_TEMP, M_WAITOK | M_ZERO);
 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, tk_ver),
 230             sizeof(uint32_t), &tk_ver);
 231         svtk->sv_timekeep_off = tk_base;
 232         timekeep_push_vdso();
 233         return (svtk);
 234 }
 235
 236 #ifdef COMPAT_FREEBSD32
 237 struct vdso_sv_tk *
 238 alloc_sv_tk_compat32(void)
 239 {
 240         struct vdso_sv_tk *svtk;
 241         int tk_base;
 242         uint32_t tk_ver;
 243
 244         svtk = malloc(sizeof(struct vdso_sv_tk), M_TEMP, M_WAITOK | M_ZERO);
 245         tk_ver = VDSO_TK_VER_CURR;
 246         tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
 247             sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
 248         KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
 249         shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
 250             tk_ver), sizeof(uint32_t), &tk_ver);
 251         svtk->sv_timekeep_off = tk_base;
 252         timekeep_push_vdso();
 253         return (svtk);
 254 }
 255 #endif
 256
 257 void
 258 exec_sysvec_init(void *param)
 259 {
 260         struct sysentvec *sv;
 261
 262         sv = (struct sysentvec *)param;
 263         if ((sv->sv_flags & SV_SHP) == 0)
 264                 return;
 265         sv->sv_shared_page_obj = shared_page_obj;
 266         sv->sv_sigcode_base = sv->sv_shared_page_base +
 267             shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
 268         if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
 269                 return;
 270         if ((sv->sv_flags & SV_TIMEKEEP) != 0) {
 271 #ifdef COMPAT_FREEBSD32
 272                 if ((sv->sv_flags & SV_ILP32) != 0) {
 273                         KASSERT(compat32_svtk == NULL,
 274                             ("Compat32 already registered"));
 275                         compat32_svtk = alloc_sv_tk_compat32();
 276                         sv->sv_timekeep_base = sv->sv_shared_page_base +
 277                             compat32_svtk->sv_timekeep_off;
 278                 } else {
 279 #endif
 280                         KASSERT(host_svtk == NULL, ("Host already registered"));
 281                         host_svtk = alloc_sv_tk();
 282                         sv->sv_timekeep_base = sv->sv_shared_page_base +
 283                             host_svtk->sv_timekeep_off;
 284 #ifdef COMPAT_FREEBSD32
 285                 }
 286 #endif
 287         }
 288 }