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_ras.c

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    1 /*      $NetBSD: kern_ras.c,v 1.34 2008/10/15 06:51:20 wrstuden Exp $   */
    2 
    3 /*-
    4  * Copyright (c) 2002, 2006, 2007, 2008 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Gregory McGarry, and by Andrew Doran.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   29  * POSSIBILITY OF SUCH DAMAGE.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.34 2008/10/15 06:51:20 wrstuden Exp $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/kernel.h>
   38 #include <sys/kmem.h>
   39 #include <sys/proc.h>
   40 #include <sys/ras.h>
   41 #include <sys/sa.h>
   42 #include <sys/savar.h>
   43 #include <sys/xcall.h>
   44 #include <sys/syscallargs.h>
   45 
   46 #include <uvm/uvm_extern.h>
   47 
   48 #define MAX_RAS_PER_PROC        16
   49 
   50 u_int ras_per_proc = MAX_RAS_PER_PROC;
   51 
   52 #ifdef DEBUG
   53 int ras_debug = 0;
   54 #define DPRINTF(x)      if (ras_debug) printf x
   55 #else
   56 #define DPRINTF(x)      /* nothing */
   57 #endif
   58 
   59 /*
   60  * Force all CPUs through cpu_switchto(), waiting until complete.
   61  * Context switching will drain the write buffer on the calling
   62  * CPU.
   63  */
   64 static void
   65 ras_sync(void)
   66 {
   67 
   68         /* No need to sync if exiting or single threaded. */
   69         if (curproc->p_nlwps > 1 && ncpu > 1) {
   70 #ifdef NO_SOFTWARE_PATENTS
   71                 uint64_t where;
   72                 where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
   73                 xc_wait(where);
   74 #else
   75                 /*
   76                  * Assumptions:
   77                  *
   78                  * o preemption is disabled by the thread in
   79                  *   ras_lookup().
   80                  * o proc::p_raslist is only inspected with
   81                  *   preemption disabled.
   82                  * o ras_lookup() plus loads reordered in advance
   83                  *   will take no longer than 1/8s to complete.
   84                  */
   85                 const int delta = hz >> 3;
   86                 int target = hardclock_ticks + delta;
   87                 do {
   88                         kpause("ras", false, delta, NULL);
   89                 } while (hardclock_ticks < target);
   90 #endif
   91         }
   92 }
   93 
   94 /*
   95  * Check the specified address to see if it is within the
   96  * sequence.  If it is found, we return the restart address,
   97  * otherwise we return -1.  If we do perform a restart, we
   98  * mark the sequence as hit.
   99  *
  100  * No locking required: we disable preemption and ras_sync()
  101  * guarantees that individual entries are valid while we still
  102  * have visibility of them.
  103  */
  104 void *
  105 ras_lookup(struct proc *p, void *addr)
  106 {
  107         struct ras *rp;
  108         void *startaddr;
  109         lwp_t *l;
  110 
  111         startaddr = (void *)-1;
  112         l = curlwp;
  113 
  114         KPREEMPT_DISABLE(l);
  115         for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) {
  116                 if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) {
  117                         startaddr = rp->ras_startaddr;
  118                         DPRINTF(("RAS hit: p=%p %p\n", p, addr));
  119                         break;
  120                 }
  121         }
  122         KPREEMPT_ENABLE(l);
  123 
  124         return startaddr;
  125 }
  126 
  127 /*
  128  * During a fork, we copy all of the sequences from parent p1 to
  129  * the child p2.
  130  *
  131  * No locking required as the parent must be paused.
  132  */
  133 int
  134 ras_fork(struct proc *p1, struct proc *p2)
  135 {
  136         struct ras *rp, *nrp;
  137 
  138         for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) {
  139                 nrp = kmem_alloc(sizeof(*nrp), KM_SLEEP);
  140                 nrp->ras_startaddr = rp->ras_startaddr;
  141                 nrp->ras_endaddr = rp->ras_endaddr;
  142                 nrp->ras_next = p2->p_raslist;
  143                 p2->p_raslist = nrp;
  144         }
  145 
  146         DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2));
  147 
  148         return 0;
  149 }
  150 
  151 /*
  152  * Nuke all sequences for this process.
  153  */
  154 int
  155 ras_purgeall(void)
  156 {
  157         struct ras *rp, *nrp;
  158         proc_t *p;
  159 
  160         p = curproc;
  161 
  162         if (p->p_raslist == NULL)
  163                 return 0;
  164 
  165         mutex_enter(&p->p_auxlock);
  166         if ((rp = p->p_raslist) != NULL) {
  167                 p->p_raslist = NULL;
  168                 ras_sync();
  169                 for(; rp != NULL; rp = nrp) {
  170                         nrp = rp->ras_next;
  171                         kmem_free(rp, sizeof(*rp));
  172                 }
  173         }
  174         mutex_exit(&p->p_auxlock);
  175 
  176         return 0;
  177 }
  178 
  179 #if defined(__HAVE_RAS)
  180 
  181 /*
  182  * Install the new sequence.  If it already exists, return
  183  * an error.
  184  */
  185 static int
  186 ras_install(void *addr, size_t len)
  187 {
  188         struct ras *rp;
  189         struct ras *newrp;
  190         void *endaddr;
  191         int nras, error;
  192         proc_t *p;
  193 
  194         endaddr = (char *)addr + len;
  195 
  196         if (addr < (void *)VM_MIN_ADDRESS ||
  197             endaddr > (void *)VM_MAXUSER_ADDRESS)
  198                 return (EINVAL);
  199 
  200         if (len <= 0)
  201                 return (EINVAL);
  202 
  203         newrp = kmem_alloc(sizeof(*newrp), KM_SLEEP);
  204         newrp->ras_startaddr = addr;
  205         newrp->ras_endaddr = endaddr;
  206         error = 0;
  207         nras = 0;
  208         p = curproc;
  209 
  210         mutex_enter(&p->p_auxlock);
  211         for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) {
  212                 if (++nras >= ras_per_proc) {
  213                         error = EINVAL;
  214                         break;
  215                 }
  216                 if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) {
  217                         error = EEXIST;
  218                         break;
  219                 }
  220         }
  221         if (rp == NULL) {
  222                 newrp->ras_next = p->p_raslist;
  223                 p->p_raslist = newrp;
  224                 ras_sync();
  225                 mutex_exit(&p->p_auxlock);
  226         } else {
  227                 mutex_exit(&p->p_auxlock);
  228                 kmem_free(newrp, sizeof(*newrp));
  229         }
  230 
  231         return error;
  232 }
  233 
  234 /*
  235  * Nuke the specified sequence.  Both address and len must
  236  * match, otherwise we return an error.
  237  */
  238 static int
  239 ras_purge(void *addr, size_t len)
  240 {
  241         struct ras *rp, **link;
  242         void *endaddr;
  243         proc_t *p;
  244 
  245         endaddr = (char *)addr + len;
  246         p = curproc;
  247 
  248         mutex_enter(&p->p_auxlock);
  249         link = &p->p_raslist;
  250         for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) {
  251                 if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr)
  252                         break;
  253         }
  254         if (rp != NULL) {
  255                 *link = rp->ras_next;
  256                 ras_sync();
  257                 mutex_exit(&p->p_auxlock);
  258                 kmem_free(rp, sizeof(*rp));
  259                 return 0;
  260         } else {
  261                 mutex_exit(&p->p_auxlock);
  262                 return ESRCH;
  263         }
  264 }
  265 
  266 #endif /* defined(__HAVE_RAS) */
  267 
  268 /*ARGSUSED*/
  269 int
  270 sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval)
  271 {
  272 
  273 #if defined(__HAVE_RAS)
  274         /* {
  275                 syscallarg(void *) addr;
  276                 syscallarg(size_t) len;
  277                 syscallarg(int) op;
  278         } */
  279         void *addr;
  280         size_t len;
  281         int op;
  282         int error;
  283 
  284         /*
  285          * first, extract syscall args from the uap.
  286          */
  287 
  288         addr = (void *)SCARG(uap, addr);
  289         len = (size_t)SCARG(uap, len);
  290         op = SCARG(uap, op);
  291 
  292         DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n",
  293             curproc, addr, (long)len, op));
  294 
  295         switch (op) {
  296         case RAS_INSTALL:
  297                 error = ras_install(addr, len);
  298                 break;
  299         case RAS_PURGE:
  300                 error = ras_purge(addr, len);
  301                 break;
  302         case RAS_PURGE_ALL:
  303                 error = ras_purgeall();
  304                 break;
  305         default:
  306                 error = EINVAL;
  307                 break;
  308         }
  309 
  310         return (error);
  311 
  312 #else
  313 
  314         return (EOPNOTSUPP);
  315 
  316 #endif
  317 
  318 }

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