1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 #include <sys/dtrace.h> 30 #include <sys/fasttrap.h> 31 #include <sys/x_call.h> 32 #include <sys/cmn_err.h> 33 #include <sys/trap.h> 34 #include <sys/psw.h> 35 #include <sys/privregs.h> 36 #include <sys/machsystm.h> 37 #include <vm/seg_kmem.h> 38 39 typedef struct dtrace_invop_hdlr { 40 int (*dtih_func)(uintptr_t, uintptr_t *, uintptr_t); 41 struct dtrace_invop_hdlr *dtih_next; 42 } dtrace_invop_hdlr_t; 43 44 dtrace_invop_hdlr_t *dtrace_invop_hdlr; 45 46 int 47 dtrace_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax) 48 { 49 dtrace_invop_hdlr_t *hdlr; 50 int rval; 51 52 for (hdlr = dtrace_invop_hdlr; hdlr != NULL; hdlr = hdlr->dtih_next) { 53 if ((rval = hdlr->dtih_func(addr, stack, eax)) != 0) 54 return (rval); 55 } 56 57 return (0); 58 } 59 60 void 61 dtrace_invop_add(int (*func)(uintptr_t, uintptr_t *, uintptr_t)) 62 { 63 dtrace_invop_hdlr_t *hdlr; 64 65 hdlr = kmem_alloc(sizeof (dtrace_invop_hdlr_t), KM_SLEEP); 66 hdlr->dtih_func = func; 67 hdlr->dtih_next = dtrace_invop_hdlr; 68 dtrace_invop_hdlr = hdlr; 69 } 70 71 void 72 dtrace_invop_remove(int (*func)(uintptr_t, uintptr_t *, uintptr_t)) 73 { 74 dtrace_invop_hdlr_t *hdlr = dtrace_invop_hdlr, *prev = NULL; 75 76 for (;;) { 77 if (hdlr == NULL) 78 panic("attempt to remove non-existent invop handler"); 79 80 if (hdlr->dtih_func == func) 81 break; 82 83 prev = hdlr; 84 hdlr = hdlr->dtih_next; 85 } 86 87 if (prev == NULL) { 88 ASSERT(dtrace_invop_hdlr == hdlr); 89 dtrace_invop_hdlr = hdlr->dtih_next; 90 } else { 91 ASSERT(dtrace_invop_hdlr != hdlr); 92 prev->dtih_next = hdlr->dtih_next; 93 } 94 95 kmem_free(hdlr, sizeof (dtrace_invop_hdlr_t)); 96 } 97 98 int 99 dtrace_getipl(void) 100 { 101 return (CPU->cpu_pri); 102 } 103 104 /*ARGSUSED*/ 105 void 106 dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit)) 107 { 108 #ifdef __amd64 109 extern uintptr_t toxic_addr; 110 extern size_t toxic_size; 111 112 (*func)(0, _userlimit); 113 114 if (hole_end > hole_start) 115 (*func)(hole_start, hole_end); 116 (*func)(toxic_addr, toxic_addr + toxic_size); 117 #else 118 extern void *device_arena_contains(void *, size_t, size_t *); 119 caddr_t vaddr; 120 size_t len; 121 122 for (vaddr = (caddr_t)kernelbase; vaddr < (caddr_t)KERNEL_TEXT; 123 vaddr += len) { 124 len = (caddr_t)KERNEL_TEXT - vaddr; 125 vaddr = device_arena_contains(vaddr, len, &len); 126 if (vaddr == NULL) 127 break; 128 (*func)((uintptr_t)vaddr, (uintptr_t)vaddr + len); 129 } 130 #endif 131 (*func)(0, _userlimit); 132 } 133 134 static int 135 dtrace_xcall_func(dtrace_xcall_t func, void *arg) 136 { 137 (*func)(arg); 138 139 return (0); 140 } 141 142 /*ARGSUSED*/ 143 void 144 dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg) 145 { 146 cpuset_t set; 147 148 CPUSET_ZERO(set); 149 150 if (cpu == DTRACE_CPUALL) { 151 CPUSET_ALL(set); 152 } else { 153 CPUSET_ADD(set, cpu); 154 } 155 156 kpreempt_disable(); 157 xc_sync((xc_arg_t)func, (xc_arg_t)arg, 0, X_CALL_HIPRI, set, 158 (xc_func_t)dtrace_xcall_func); 159 kpreempt_enable(); 160 } 161 162 void 163 dtrace_sync_func(void) 164 {} 165 166 void 167 dtrace_sync(void) 168 { 169 dtrace_xcall(DTRACE_CPUALL, (dtrace_xcall_t)dtrace_sync_func, NULL); 170 } 171 172 int (*dtrace_pid_probe_ptr)(struct regs *); 173 int (*dtrace_return_probe_ptr)(struct regs *); 174 175 void 176 dtrace_user_probe(struct regs *rp, caddr_t addr, processorid_t cpuid) 177 { 178 krwlock_t *rwp; 179 proc_t *p = curproc; 180 extern void trap(struct regs *, caddr_t, processorid_t); 181 182 if (USERMODE(rp->r_cs) || (rp->r_ps & PS_VM)) { 183 if (curthread->t_cred != p->p_cred) { 184 cred_t *oldcred = curthread->t_cred; 185 /* 186 * DTrace accesses t_cred in probe context. t_cred 187 * must always be either NULL, or point to a valid, 188 * allocated cred structure. 189 */ 190 curthread->t_cred = crgetcred(); 191 crfree(oldcred); 192 } 193 } 194 195 if (rp->r_trapno == T_DTRACE_RET) { 196 uint8_t step = curthread->t_dtrace_step; 197 uint8_t ret = curthread->t_dtrace_ret; 198 uintptr_t npc = curthread->t_dtrace_npc; 199 200 if (curthread->t_dtrace_ast) { 201 aston(curthread); 202 curthread->t_sig_check = 1; 203 } 204 205 /* 206 * Clear all user tracing flags. 207 */ 208 curthread->t_dtrace_ft = 0; 209 210 /* 211 * If we weren't expecting to take a return probe trap, kill 212 * the process as though it had just executed an unassigned 213 * trap instruction. 214 */ 215 if (step == 0) { 216 tsignal(curthread, SIGILL); 217 return; 218 } 219 220 /* 221 * If we hit this trap unrelated to a return probe, we're 222 * just here to reset the AST flag since we deferred a signal 223 * until after we logically single-stepped the instruction we 224 * copied out. 225 */ 226 if (ret == 0) { 227 rp->r_pc = npc; 228 return; 229 } 230 231 /* 232 * We need to wait until after we've called the 233 * dtrace_return_probe_ptr function pointer to set %pc. 234 */ 235 rwp = &CPU->cpu_ft_lock; 236 rw_enter(rwp, RW_READER); 237 if (dtrace_return_probe_ptr != NULL) 238 (void) (*dtrace_return_probe_ptr)(rp); 239 rw_exit(rwp); 240 rp->r_pc = npc; 241 242 } else if (rp->r_trapno == T_BPTFLT) { 243 uint8_t instr, instr2; 244 caddr_t linearpc; 245 rwp = &CPU->cpu_ft_lock; 246 247 /* 248 * The DTrace fasttrap provider uses the breakpoint trap 249 * (int 3). We let DTrace take the first crack at handling 250 * this trap; if it's not a probe that DTrace knowns about, 251 * we call into the trap() routine to handle it like a 252 * breakpoint placed by a conventional debugger. 253 */ 254 rw_enter(rwp, RW_READER); 255 if (dtrace_pid_probe_ptr != NULL && 256 (*dtrace_pid_probe_ptr)(rp) == 0) { 257 rw_exit(rwp); 258 return; 259 } 260 rw_exit(rwp); 261 262 if (dtrace_linear_pc(rp, p, &linearpc) != 0) { 263 trap(rp, addr, cpuid); 264 return; 265 } 266 267 /* 268 * If the instruction that caused the breakpoint trap doesn't 269 * look like an int 3 anymore, it may be that this tracepoint 270 * was removed just after the user thread executed it. In 271 * that case, return to user land to retry the instuction. 272 * Note that we assume the length of the instruction to retry 273 * is 1 byte because that's the length of FASTTRAP_INSTR. 274 * We check for r_pc > 0 and > 2 so that we don't have to 275 * deal with segment wraparound. 276 */ 277 if (rp->r_pc > 0 && fuword8(linearpc - 1, &instr) == 0 && 278 instr != FASTTRAP_INSTR && 279 (instr != 3 || (rp->r_pc >= 2 && 280 (fuword8(linearpc - 2, &instr2) != 0 || instr2 != 0xCD)))) { 281 rp->r_pc--; 282 return; 283 } 284 285 trap(rp, addr, cpuid); 286 287 } else { 288 trap(rp, addr, cpuid); 289 } 290 } 291 292 void 293 dtrace_safe_synchronous_signal(void) 294 { 295 kthread_t *t = curthread; 296 struct regs *rp = lwptoregs(ttolwp(t)); 297 size_t isz = t->t_dtrace_npc - t->t_dtrace_pc; 298 299 ASSERT(t->t_dtrace_on); 300 301 /* 302 * If we're not in the range of scratch addresses, we're not actually 303 * tracing user instructions so turn off the flags. If the instruction 304 * we copied out caused a synchonous trap, reset the pc back to its 305 * original value and turn off the flags. 306 */ 307 if (rp->r_pc < t->t_dtrace_scrpc || 308 rp->r_pc > t->t_dtrace_astpc + isz) { 309 t->t_dtrace_ft = 0; 310 } else if (rp->r_pc == t->t_dtrace_scrpc || 311 rp->r_pc == t->t_dtrace_astpc) { 312 rp->r_pc = t->t_dtrace_pc; 313 t->t_dtrace_ft = 0; 314 } 315 } 316 317 int 318 dtrace_safe_defer_signal(void) 319 { 320 kthread_t *t = curthread; 321 struct regs *rp = lwptoregs(ttolwp(t)); 322 size_t isz = t->t_dtrace_npc - t->t_dtrace_pc; 323 324 ASSERT(t->t_dtrace_on); 325 326 /* 327 * If we're not in the range of scratch addresses, we're not actually 328 * tracing user instructions so turn off the flags. 329 */ 330 if (rp->r_pc < t->t_dtrace_scrpc || 331 rp->r_pc > t->t_dtrace_astpc + isz) { 332 t->t_dtrace_ft = 0; 333 return (0); 334 } 335 336 /* 337 * If we've executed the original instruction, but haven't performed 338 * the jmp back to t->t_dtrace_npc or the clean up of any registers 339 * used to emulate %rip-relative instructions in 64-bit mode, do that 340 * here and take the signal right away. We detect this condition by 341 * seeing if the program counter is the range [scrpc + isz, astpc). 342 */ 343 if (t->t_dtrace_astpc - rp->r_pc < 344 t->t_dtrace_astpc - t->t_dtrace_scrpc - isz) { 345 #ifdef __amd64 346 /* 347 * If there is a scratch register and we're on the 348 * instruction immediately after the modified instruction, 349 * restore the value of that scratch register. 350 */ 351 if (t->t_dtrace_reg != 0 && 352 rp->r_pc == t->t_dtrace_scrpc + isz) { 353 switch (t->t_dtrace_reg) { 354 case REG_RAX: 355 rp->r_rax = t->t_dtrace_regv; 356 break; 357 case REG_RCX: 358 rp->r_rcx = t->t_dtrace_regv; 359 break; 360 case REG_R8: 361 rp->r_r8 = t->t_dtrace_regv; 362 break; 363 case REG_R9: 364 rp->r_r9 = t->t_dtrace_regv; 365 break; 366 } 367 } 368 #endif 369 rp->r_pc = t->t_dtrace_npc; 370 t->t_dtrace_ft = 0; 371 return (0); 372 } 373 374 /* 375 * Otherwise, make sure we'll return to the kernel after executing 376 * the copied out instruction and defer the signal. 377 */ 378 if (!t->t_dtrace_step) { 379 ASSERT(rp->r_pc < t->t_dtrace_astpc); 380 rp->r_pc += t->t_dtrace_astpc - t->t_dtrace_scrpc; 381 t->t_dtrace_step = 1; 382 } 383 384 t->t_dtrace_ast = 1; 385 386 return (1); 387 } 388 389 /* 390 * Additional artificial frames for the machine type. For i86pc, we're already 391 * accounted for, so return 0. On the hypervisor, we have an additional frame 392 * (xen_callback_handler). 393 */ 394 int 395 dtrace_mach_aframes(void) 396 { 397 #ifdef __xpv 398 return (1); 399 #else 400 return (0); 401 #endif 402 } 403