1 /* $NetBSD: kern_ras.c,v 1.31 2008/05/27 17:42:14 ad 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 1.31 2008/05/27 17:42:14 ad 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/xcall.h> 42 #include <sys/syscallargs.h> 43 44 #include <uvm/uvm_extern.h> 45 46 #define MAX_RAS_PER_PROC 16 47 48 u_int ras_per_proc = MAX_RAS_PER_PROC; 49 50 #ifdef DEBUG 51 int ras_debug = 0; 52 #define DPRINTF(x) if (ras_debug) printf x 53 #else 54 #define DPRINTF(x) /* nothing */ 55 #endif 56 57 /* 58 * Force all CPUs through cpu_switchto(), waiting until complete. 59 * Context switching will drain the write buffer on the calling 60 * CPU. 61 */ 62 static void 63 ras_sync(void) 64 { 65 66 /* No need to sync if exiting or single threaded. */ 67 if (curproc->p_nlwps > 1 && ncpu > 1) { 68 #ifdef NO_SOFTWARE_PATENTS 69 uint64_t where; 70 where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); 71 xc_wait(where); 72 #else 73 /* 74 * Assumptions: 75 * 76 * o preemption is disabled by the thread in 77 * ras_lookup(). 78 * o proc::p_raslist is only inspected with 79 * preemption disabled. 80 * o ras_lookup() plus loads reordered in advance 81 * will take no longer than 1/8s to complete. 82 */ 83 const int delta = hz >> 3; 84 int target = hardclock_ticks + delta; 85 do { 86 kpause("ras", false, delta, NULL); 87 } while (hardclock_ticks < target); 88 #endif 89 } 90 } 91 92 /* 93 * Check the specified address to see if it is within the 94 * sequence. If it is found, we return the restart address, 95 * otherwise we return -1. If we do perform a restart, we 96 * mark the sequence as hit. 97 * 98 * No locking required: we disable preemption and ras_sync() 99 * guarantees that individual entries are valid while we still 100 * have visibility of them. 101 */ 102 void * 103 ras_lookup(struct proc *p, void *addr) 104 { 105 struct ras *rp; 106 void *startaddr; 107 lwp_t *l; 108 109 startaddr = (void *)-1; 110 l = curlwp; 111 112 KPREEMPT_DISABLE(l); 113 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 114 if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) { 115 startaddr = rp->ras_startaddr; 116 DPRINTF(("RAS hit: p=%p %p\n", p, addr)); 117 break; 118 } 119 } 120 KPREEMPT_ENABLE(l); 121 122 return startaddr; 123 } 124 125 /* 126 * During a fork, we copy all of the sequences from parent p1 to 127 * the child p2. 128 * 129 * No locking required as the parent must be paused. 130 */ 131 int 132 ras_fork(struct proc *p1, struct proc *p2) 133 { 134 struct ras *rp, *nrp; 135 136 for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) { 137 nrp = kmem_alloc(sizeof(*nrp), KM_SLEEP); 138 nrp->ras_startaddr = rp->ras_startaddr; 139 nrp->ras_endaddr = rp->ras_endaddr; 140 nrp->ras_next = p2->p_raslist; 141 p2->p_raslist = nrp; 142 } 143 144 DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2)); 145 146 return 0; 147 } 148 149 /* 150 * Nuke all sequences for this process. 151 */ 152 int 153 ras_purgeall(void) 154 { 155 struct ras *rp, *nrp; 156 proc_t *p; 157 158 p = curproc; 159 160 mutex_enter(&p->p_auxlock); 161 if ((rp = p->p_raslist) != NULL) { 162 p->p_raslist = NULL; 163 ras_sync(); 164 for(; rp != NULL; rp = nrp) { 165 nrp = rp->ras_next; 166 kmem_free(rp, sizeof(*rp)); 167 } 168 } 169 mutex_exit(&p->p_auxlock); 170 171 return 0; 172 } 173 174 #if defined(__HAVE_RAS) 175 176 /* 177 * Install the new sequence. If it already exists, return 178 * an error. 179 */ 180 static int 181 ras_install(void *addr, size_t len) 182 { 183 struct ras *rp; 184 struct ras *newrp; 185 void *endaddr; 186 int nras, error; 187 proc_t *p; 188 189 endaddr = (char *)addr + len; 190 191 if (addr < (void *)VM_MIN_ADDRESS || 192 endaddr > (void *)VM_MAXUSER_ADDRESS) 193 return (EINVAL); 194 195 if (len <= 0) 196 return (EINVAL); 197 198 newrp = kmem_alloc(sizeof(*newrp), KM_SLEEP); 199 newrp->ras_startaddr = addr; 200 newrp->ras_endaddr = endaddr; 201 error = 0; 202 nras = 0; 203 p = curproc; 204 205 mutex_enter(&p->p_auxlock); 206 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 207 if (++nras >= ras_per_proc) { 208 error = EINVAL; 209 break; 210 } 211 if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) { 212 error = EEXIST; 213 break; 214 } 215 } 216 if (rp == NULL) { 217 newrp->ras_next = p->p_raslist; 218 p->p_raslist = newrp; 219 ras_sync(); 220 mutex_exit(&p->p_auxlock); 221 } else { 222 mutex_exit(&p->p_auxlock); 223 kmem_free(newrp, sizeof(*newrp)); 224 } 225 226 return error; 227 } 228 229 /* 230 * Nuke the specified sequence. Both address and len must 231 * match, otherwise we return an error. 232 */ 233 static int 234 ras_purge(void *addr, size_t len) 235 { 236 struct ras *rp, **link; 237 void *endaddr; 238 proc_t *p; 239 240 endaddr = (char *)addr + len; 241 p = curproc; 242 243 mutex_enter(&p->p_auxlock); 244 link = &p->p_raslist; 245 for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) { 246 if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr) 247 break; 248 } 249 if (rp != NULL) { 250 *link = rp->ras_next; 251 ras_sync(); 252 mutex_exit(&p->p_auxlock); 253 kmem_free(rp, sizeof(*rp)); 254 return 0; 255 } else { 256 mutex_exit(&p->p_auxlock); 257 return ESRCH; 258 } 259 } 260 261 #endif /* defined(__HAVE_RAS) */ 262 263 /*ARGSUSED*/ 264 int 265 sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval) 266 { 267 268 #if defined(__HAVE_RAS) 269 /* { 270 syscallarg(void *) addr; 271 syscallarg(size_t) len; 272 syscallarg(int) op; 273 } */ 274 void *addr; 275 size_t len; 276 int op; 277 int error; 278 279 /* 280 * first, extract syscall args from the uap. 281 */ 282 283 addr = (void *)SCARG(uap, addr); 284 len = (size_t)SCARG(uap, len); 285 op = SCARG(uap, op); 286 287 DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n", 288 curproc, addr, (long)len, op)); 289 290 switch (op) { 291 case RAS_INSTALL: 292 error = ras_install(addr, len); 293 break; 294 case RAS_PURGE: 295 error = ras_purge(addr, len); 296 break; 297 case RAS_PURGE_ALL: 298 error = ras_purgeall(); 299 break; 300 default: 301 error = EINVAL; 302 break; 303 } 304 305 return (error); 306 307 #else 308 309 return (EOPNOTSUPP); 310 311 #endif 312 313 } 314