1 /* $NetBSD: kern_ras.c,v 1.40 2019/12/14 16:58:25 riastradh 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 1.40 2019/12/14 16:58:25 riastradh 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 xc_barrier(0); 69 } 70 } 71 72 /* 73 * Check the specified address to see if it is within the 74 * sequence. If it is found, we return the restart address, 75 * otherwise we return -1. If we do perform a restart, we 76 * mark the sequence as hit. 77 * 78 * No locking required: we disable preemption and ras_sync() 79 * guarantees that individual entries are valid while we still 80 * have visibility of them. 81 */ 82 void * 83 ras_lookup(struct proc *p, void *addr) 84 { 85 struct ras *rp; 86 void *startaddr; 87 lwp_t *l; 88 89 startaddr = (void *)-1; 90 l = curlwp; 91 92 KPREEMPT_DISABLE(l); 93 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 94 if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) { 95 startaddr = rp->ras_startaddr; 96 DPRINTF(("RAS hit: p=%p %p\n", p, addr)); 97 break; 98 } 99 } 100 KPREEMPT_ENABLE(l); 101 102 return startaddr; 103 } 104 105 /* 106 * During a fork, we copy all of the sequences from parent p1 to 107 * the child p2. 108 * 109 * No locking required as the parent must be paused. 110 */ 111 int 112 ras_fork(struct proc *p1, struct proc *p2) 113 { 114 struct ras *rp, *nrp; 115 116 for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) { 117 nrp = kmem_alloc(sizeof(*nrp), KM_SLEEP); 118 nrp->ras_startaddr = rp->ras_startaddr; 119 nrp->ras_endaddr = rp->ras_endaddr; 120 nrp->ras_next = p2->p_raslist; 121 p2->p_raslist = nrp; 122 } 123 124 DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2)); 125 126 return 0; 127 } 128 129 /* 130 * Nuke all sequences for this process. 131 */ 132 int 133 ras_purgeall(void) 134 { 135 struct ras *rp, *nrp; 136 proc_t *p; 137 138 p = curproc; 139 140 if (p->p_raslist == NULL) 141 return 0; 142 143 mutex_enter(&p->p_auxlock); 144 if ((rp = p->p_raslist) != NULL) { 145 p->p_raslist = NULL; 146 ras_sync(); 147 for(; rp != NULL; rp = nrp) { 148 nrp = rp->ras_next; 149 kmem_free(rp, sizeof(*rp)); 150 } 151 } 152 mutex_exit(&p->p_auxlock); 153 154 return 0; 155 } 156 157 #if defined(__HAVE_RAS) 158 159 #if __GNUC_PREREQ__(4, 8) 160 #define __WARNING_PUSH_LESS_NULL_PTR _Pragma("GCC diagnostic push") _Pragma("GCC diagnostic ignored \"-Wextra\"") 161 #define __WARNING_POP_LESS_NULL_PTR _Pragma("GCC diagnostic pop") 162 #else 163 #define __WARNING_PUSH_LESS_NULL_PTR 164 #define __WARNING_POP_LESS_NULL_PTR 165 #endif 166 167 /* 168 * Install the new sequence. If it already exists, return 169 * an error. 170 */ 171 static int 172 ras_install(void *addr, size_t len) 173 { 174 struct ras *rp; 175 struct ras *newrp; 176 void *endaddr; 177 int nras, error; 178 proc_t *p; 179 180 if (len == 0) 181 return EINVAL; 182 183 endaddr = (char *)addr + len; 184 185 /* Do not warn about < NULL pointer comparison */ 186 __WARNING_PUSH_LESS_NULL_PTR 187 if (addr < (void *)VM_MIN_ADDRESS || addr > (void *)VM_MAXUSER_ADDRESS) 188 return EINVAL; 189 if (endaddr > (void *)VM_MAXUSER_ADDRESS) 190 return EINVAL; 191 if (endaddr < addr) 192 return EINVAL; 193 __WARNING_POP_LESS_NULL_PTR 194 195 newrp = kmem_alloc(sizeof(*newrp), KM_SLEEP); 196 newrp->ras_startaddr = addr; 197 newrp->ras_endaddr = endaddr; 198 error = 0; 199 nras = 0; 200 p = curproc; 201 202 mutex_enter(&p->p_auxlock); 203 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 204 if (++nras >= ras_per_proc) { 205 error = EINVAL; 206 break; 207 } 208 if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) { 209 error = EEXIST; 210 break; 211 } 212 } 213 if (rp == NULL) { 214 newrp->ras_next = p->p_raslist; 215 p->p_raslist = newrp; 216 ras_sync(); 217 mutex_exit(&p->p_auxlock); 218 } else { 219 mutex_exit(&p->p_auxlock); 220 kmem_free(newrp, sizeof(*newrp)); 221 } 222 223 return error; 224 } 225 226 /* 227 * Nuke the specified sequence. Both address and len must 228 * match, otherwise we return an error. 229 */ 230 static int 231 ras_purge(void *addr, size_t len) 232 { 233 struct ras *rp, **link; 234 void *endaddr; 235 proc_t *p; 236 237 endaddr = (char *)addr + len; 238 p = curproc; 239 240 mutex_enter(&p->p_auxlock); 241 link = &p->p_raslist; 242 for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) { 243 if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr) 244 break; 245 } 246 if (rp != NULL) { 247 *link = rp->ras_next; 248 ras_sync(); 249 mutex_exit(&p->p_auxlock); 250 kmem_free(rp, sizeof(*rp)); 251 return 0; 252 } else { 253 mutex_exit(&p->p_auxlock); 254 return ESRCH; 255 } 256 } 257 258 #endif /* defined(__HAVE_RAS) */ 259 260 /*ARGSUSED*/ 261 int 262 sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval) 263 { 264 #if defined(__HAVE_RAS) 265 /* { 266 syscallarg(void *) addr; 267 syscallarg(size_t) len; 268 syscallarg(int) op; 269 } */ 270 void *addr; 271 size_t len; 272 int op; 273 int error; 274 275 /* 276 * first, extract syscall args from the uap. 277 */ 278 279 addr = (void *)SCARG(uap, addr); 280 len = (size_t)SCARG(uap, len); 281 op = SCARG(uap, op); 282 283 DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n", 284 curproc, addr, (long)len, op)); 285 286 switch (op) { 287 case RAS_INSTALL: 288 error = ras_install(addr, len); 289 break; 290 case RAS_PURGE: 291 error = ras_purge(addr, len); 292 break; 293 case RAS_PURGE_ALL: 294 error = ras_purgeall(); 295 break; 296 default: 297 error = EINVAL; 298 break; 299 } 300 301 return (error); 302 #else 303 return (EOPNOTSUPP); 304 #endif 305 } 306