1 /* $NetBSD: kern_ras.c,v 1.27 2008/01/07 20:56:32 dsl Exp $ */ 2 3 /*- 4 * Copyright (c) 2002, 2006, 2007 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.27 2008/01/07 20:56:32 dsl Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/kernel.h> 45 #include <sys/pool.h> 46 #include <sys/proc.h> 47 #include <sys/ras.h> 48 #include <sys/xcall.h> 49 #include <sys/syscallargs.h> 50 51 #include <uvm/uvm_extern.h> 52 53 POOL_INIT(ras_pool, sizeof(struct ras), 0, 0, 0, "raspl", 54 &pool_allocator_nointr, IPL_NONE); 55 56 #define MAX_RAS_PER_PROC 16 57 58 u_int ras_per_proc = MAX_RAS_PER_PROC; 59 60 #ifdef DEBUG 61 int ras_debug = 0; 62 #define DPRINTF(x) if (ras_debug) printf x 63 #else 64 #define DPRINTF(x) /* nothing */ 65 #endif 66 67 /* 68 * Force all CPUs through cpu_switchto(), waiting until complete. 69 * Context switching will drain the write buffer on the calling 70 * CPU. 71 */ 72 static void 73 ras_sync(void) 74 { 75 76 /* No need to sync if exiting or single threaded. */ 77 if (curproc->p_nlwps > 1 && ncpu > 1) { 78 #ifdef NO_SOFTWARE_PATENTS 79 uint64_t where; 80 where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); 81 xc_wait(where); 82 #else 83 /* 84 * Assumptions: 85 * 86 * o preemption is disabled by the thread in 87 * ras_lookup(). 88 * o proc::p_raslist is only inspected with 89 * preemption disabled. 90 * o ras_lookup() plus loads reordered in advance 91 * will take no longer than 1/8s to complete. 92 */ 93 const int delta = hz >> 3; 94 int target = hardclock_ticks + delta; 95 do { 96 kpause("ras", false, delta, NULL); 97 } while (hardclock_ticks < target); 98 #endif 99 } 100 } 101 102 /* 103 * Check the specified address to see if it is within the 104 * sequence. If it is found, we return the restart address, 105 * otherwise we return -1. If we do perform a restart, we 106 * mark the sequence as hit. 107 * 108 * No locking required: we disable preemption and ras_sync() 109 * guarantees that individual entries are valid while we still 110 * have visibility of them. 111 */ 112 void * 113 ras_lookup(struct proc *p, void *addr) 114 { 115 struct ras *rp; 116 void *startaddr; 117 118 startaddr = (void *)-1; 119 120 crit_enter(); 121 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 122 if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) { 123 startaddr = rp->ras_startaddr; 124 DPRINTF(("RAS hit: p=%p %p\n", p, addr)); 125 break; 126 } 127 } 128 crit_exit(); 129 130 return startaddr; 131 } 132 133 /* 134 * During a fork, we copy all of the sequences from parent p1 to 135 * the child p2. 136 * 137 * No locking required as the parent must be paused. 138 */ 139 int 140 ras_fork(struct proc *p1, struct proc *p2) 141 { 142 struct ras *rp, *nrp; 143 144 for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) { 145 nrp = pool_get(&ras_pool, PR_WAITOK); 146 nrp->ras_startaddr = rp->ras_startaddr; 147 nrp->ras_endaddr = rp->ras_endaddr; 148 nrp->ras_next = p2->p_raslist; 149 p2->p_raslist = nrp; 150 } 151 152 DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2)); 153 154 return 0; 155 } 156 157 /* 158 * Nuke all sequences for this process. 159 */ 160 int 161 ras_purgeall(void) 162 { 163 struct ras *rp, *nrp; 164 proc_t *p; 165 166 p = curproc; 167 168 mutex_enter(&p->p_auxlock); 169 if ((rp = p->p_raslist) != NULL) { 170 p->p_raslist = NULL; 171 ras_sync(); 172 for(; rp != NULL; rp = nrp) { 173 nrp = rp->ras_next; 174 pool_put(&ras_pool, rp); 175 } 176 } 177 mutex_exit(&p->p_auxlock); 178 179 return 0; 180 } 181 182 #if defined(__HAVE_RAS) 183 184 /* 185 * Install the new sequence. If it already exists, return 186 * an error. 187 */ 188 static int 189 ras_install(void *addr, size_t len) 190 { 191 struct ras *rp; 192 struct ras *newrp; 193 void *endaddr; 194 int nras, error; 195 proc_t *p; 196 197 endaddr = (char *)addr + len; 198 199 if (addr < (void *)VM_MIN_ADDRESS || 200 endaddr > (void *)VM_MAXUSER_ADDRESS) 201 return (EINVAL); 202 203 if (len <= 0) 204 return (EINVAL); 205 206 newrp = pool_get(&ras_pool, PR_WAITOK); 207 newrp->ras_startaddr = addr; 208 newrp->ras_endaddr = endaddr; 209 error = 0; 210 nras = 0; 211 p = curproc; 212 213 mutex_enter(&p->p_auxlock); 214 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 215 if (++nras >= ras_per_proc) { 216 error = EINVAL; 217 break; 218 } 219 if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) { 220 error = EEXIST; 221 break; 222 } 223 } 224 if (rp == NULL) { 225 newrp->ras_next = p->p_raslist; 226 p->p_raslist = newrp; 227 ras_sync(); 228 mutex_exit(&p->p_auxlock); 229 } else { 230 mutex_exit(&p->p_auxlock); 231 pool_put(&ras_pool, newrp); 232 } 233 234 return error; 235 } 236 237 /* 238 * Nuke the specified sequence. Both address and len must 239 * match, otherwise we return an error. 240 */ 241 static int 242 ras_purge(void *addr, size_t len) 243 { 244 struct ras *rp, **link; 245 void *endaddr; 246 proc_t *p; 247 248 endaddr = (char *)addr + len; 249 p = curproc; 250 251 mutex_enter(&p->p_auxlock); 252 link = &p->p_raslist; 253 for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) { 254 if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr) 255 break; 256 } 257 if (rp != NULL) { 258 *link = rp->ras_next; 259 ras_sync(); 260 mutex_exit(&p->p_auxlock); 261 pool_put(&ras_pool, rp); 262 return 0; 263 } else { 264 mutex_exit(&p->p_auxlock); 265 return ESRCH; 266 } 267 } 268 269 #endif /* defined(__HAVE_RAS) */ 270 271 /*ARGSUSED*/ 272 int 273 sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval) 274 { 275 276 #if defined(__HAVE_RAS) 277 /* { 278 syscallarg(void *) addr; 279 syscallarg(size_t) len; 280 syscallarg(int) op; 281 } */ 282 void *addr; 283 size_t len; 284 int op; 285 int error; 286 287 /* 288 * first, extract syscall args from the uap. 289 */ 290 291 addr = (void *)SCARG(uap, addr); 292 len = (size_t)SCARG(uap, len); 293 op = SCARG(uap, op); 294 295 DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n", 296 curproc, addr, (long)len, op)); 297 298 switch (op) { 299 case RAS_INSTALL: 300 error = ras_install(addr, len); 301 break; 302 case RAS_PURGE: 303 error = ras_purge(addr, len); 304 break; 305 case RAS_PURGE_ALL: 306 error = ras_purgeall(); 307 break; 308 default: 309 error = EINVAL; 310 break; 311 } 312 313 return (error); 314 315 #else 316 317 return (EOPNOTSUPP); 318 319 #endif 320 321 } 322