FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_sharedpage.c

     /*-
      * Copyright (c) 2010, 2012 Konstantin Belousov <kib@FreeBSD.org>
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_compat.h"
    #include "opt_vm.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/sysent.h>
    #include <sys/sysctl.h>
    #include <sys/vdso.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/pmap.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    
    static struct sx shared_page_alloc_sx;
    static vm_object_t shared_page_obj;
    static int shared_page_free;
    char *shared_page_mapping;
    
    void
    shared_page_write(int base, int size, const void *data)
    {
    
            bcopy(data, shared_page_mapping + base, size);
    }
    
    static int
    shared_page_alloc_locked(int size, int align)
    {
            int res;
    
            res = roundup(shared_page_free, align);
            if (res + size >= IDX_TO_OFF(shared_page_obj->size))
                    res = -1;
            else
                    shared_page_free = res + size;
            return (res);
    }
    
    int
    shared_page_alloc(int size, int align)
    {
            int res;
    
            sx_xlock(&shared_page_alloc_sx);
            res = shared_page_alloc_locked(size, align);
            sx_xunlock(&shared_page_alloc_sx);
            return (res);
    }
    
    int
    shared_page_fill(int size, int align, const void *data)
    {
            int res;
    
            sx_xlock(&shared_page_alloc_sx);
            res = shared_page_alloc_locked(size, align);
            if (res != -1)
                    shared_page_write(res, size, data);
            sx_xunlock(&shared_page_alloc_sx);
            return (res);
    }
   
   static void
   shared_page_init(void *dummy __unused)
   {
           vm_page_t m;
           vm_offset_t addr;
   
           sx_init(&shared_page_alloc_sx, "shpsx");
           shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
               VM_PROT_DEFAULT, 0, NULL);
           VM_OBJECT_LOCK(shared_page_obj);
           m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_RETRY | VM_ALLOC_NOBUSY |
               VM_ALLOC_ZERO);
           m->valid = VM_PAGE_BITS_ALL;
           VM_OBJECT_UNLOCK(shared_page_obj);
           addr = kmem_alloc_nofault(kernel_map, PAGE_SIZE);
           pmap_qenter(addr, &m, 1);
           shared_page_mapping = (char *)addr;
   }
   
   SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
       NULL);
   
   static void
   timehands_update(struct sysentvec *sv)
   {
           struct vdso_timehands th;
           struct vdso_timekeep *tk;
           uint32_t enabled, idx;
   
           enabled = tc_fill_vdso_timehands(&th);
           tk = (struct vdso_timekeep *)(shared_page_mapping +
               sv->sv_timekeep_off);
           idx = sv->sv_timekeep_curr;
           atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
           if (++idx >= VDSO_TH_NUM)
                   idx = 0;
           sv->sv_timekeep_curr = idx;
           if (++sv->sv_timekeep_gen == 0)
                   sv->sv_timekeep_gen = 1;
           th.th_gen = 0;
           if (enabled)
                   tk->tk_th[idx] = th;
           tk->tk_enabled = enabled;
           atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
           tk->tk_current = idx;
   }
   
   #ifdef COMPAT_FREEBSD32
   static void
   timehands_update32(struct sysentvec *sv)
   {
           struct vdso_timekeep32 *tk;
           struct vdso_timehands32 th;
           uint32_t enabled, idx;
   
           enabled = tc_fill_vdso_timehands32(&th);
           tk = (struct vdso_timekeep32 *)(shared_page_mapping +
               sv->sv_timekeep_off);
           idx = sv->sv_timekeep_curr;
           atomic_store_rel_32(&tk->tk_th[idx].th_gen, 0);
           if (++idx >= VDSO_TH_NUM)
                   idx = 0;
           sv->sv_timekeep_curr = idx;
           if (++sv->sv_timekeep_gen == 0)
                   sv->sv_timekeep_gen = 1;
           th.th_gen = 0;
           if (enabled)
                   tk->tk_th[idx] = th;
           tk->tk_enabled = enabled;
           atomic_store_rel_32(&tk->tk_th[idx].th_gen, sv->sv_timekeep_gen);
           tk->tk_current = idx;
   }
   #endif
   
   /*
    * This is hackish, but easiest way to avoid creating list structures
    * that needs to be iterated over from the hardclock interrupt
    * context.
    */
   static struct sysentvec *host_sysentvec;
   #ifdef COMPAT_FREEBSD32
   static struct sysentvec *compat32_sysentvec;
   #endif
   
   void
   timekeep_push_vdso(void)
   {
   
           if (host_sysentvec != NULL && host_sysentvec->sv_timekeep_base != 0)
                   timehands_update(host_sysentvec);
   #ifdef COMPAT_FREEBSD32
           if (compat32_sysentvec != NULL &&
               compat32_sysentvec->sv_timekeep_base != 0)
                   timehands_update32(compat32_sysentvec);
   #endif
   }
   
   void
   exec_sysvec_init(void *param)
   {
           struct sysentvec *sv;
           int tk_base;
           uint32_t tk_ver;
   
           sv = (struct sysentvec *)param;
   
           if ((sv->sv_flags & SV_SHP) == 0)
                   return;
           sv->sv_shared_page_obj = shared_page_obj;
           sv->sv_sigcode_base = sv->sv_shared_page_base +
               shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
           if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
                   return;
           tk_ver = VDSO_TK_VER_CURR;
   #ifdef COMPAT_FREEBSD32
           if ((sv->sv_flags & SV_ILP32) != 0) {
                   tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
                       sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
                   KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
                   shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
                       tk_ver), sizeof(uint32_t), &tk_ver);
                   KASSERT(compat32_sysentvec == 0,
                       ("Native compat32 already registered"));
                   compat32_sysentvec = sv;
           } else {
   #endif
                   tk_base = shared_page_alloc(sizeof(struct vdso_timekeep) +
                       sizeof(struct vdso_timehands) * VDSO_TH_NUM, 16);
                   KASSERT(tk_base != -1, ("tk_base -1 for native"));
                   shared_page_write(tk_base + offsetof(struct vdso_timekeep,
                       tk_ver), sizeof(uint32_t), &tk_ver);
                   KASSERT(host_sysentvec == 0, ("Native already registered"));
                   host_sysentvec = sv;
   #ifdef COMPAT_FREEBSD32
           }
   #endif
           sv->sv_timekeep_base = sv->sv_shared_page_base + tk_base;
           sv->sv_timekeep_off = tk_base;
           timekeep_push_vdso();
   }

Cache object: 7a736899e6791ce9e36042bee49fc2f4