1 /* $NetBSD: callcontext.c,v 1.30 2018/07/09 00:47:47 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2006, 2007, 2008 Antti Kantee. All Rights Reserved. 5 * 6 * Development of this software was supported by the 7 * Research Foundation of Helsinki University of Technology 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 19 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 21 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 #if !defined(lint) 33 __RCSID("$NetBSD: callcontext.c,v 1.30 2018/07/09 00:47:47 christos Exp $"); 34 #endif /* !lint */ 35 36 #include <sys/types.h> 37 #include <sys/mman.h> 38 39 #include <assert.h> 40 #include <errno.h> 41 #include <puffs.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <ucontext.h> 46 #include <unistd.h> 47 48 #include "puffs_priv.h" 49 50 #if 0 51 #define DPRINTF(x) printf x 52 #else 53 #define DPRINTF(x) 54 #endif 55 56 /* 57 * Set the following to 1 to not handle each request on a separate 58 * stack. This is highly volatile kludge, therefore no external 59 * interface. 60 */ 61 int puffs_fakecc; 62 63 /* 64 * user stuff 65 */ 66 67 /* 68 * So, we need to get back to where we came from. This can happen in two 69 * different ways: 70 * 1) PCC_MLCONT is set, in which case we need to go to the mainloop 71 * 2) It is not set, and we simply jump to pcc_uc_ret. 72 */ 73 void 74 puffs_cc_yield(struct puffs_cc *pcc) 75 { 76 struct puffs_cc *jumpcc; 77 int rv; 78 79 assert(puffs_fakecc == 0); 80 81 if ((~pcc->pcc_flags & (PCC_BORROWED|PCC_DONE)) == 0) { 82 pcc->pcc_flags &= ~(PCC_BORROWED|PCC_DONE); 83 /* 84 * see the XXX comment in puffs__cc_cont 85 */ 86 puffs__cc_destroy(pcc, 1); 87 setcontext(&pcc->pcc_uc_ret); 88 } 89 pcc->pcc_flags &= ~PCC_BORROWED; 90 91 /* romanes eunt domus */ 92 DPRINTF(("puffs_cc_yield: ")); 93 if ((pcc->pcc_flags & PCC_MLCONT) == 0) { 94 DPRINTF(("no mlcont, pcc %p\n", pcc)); 95 swapcontext(&pcc->pcc_uc, &pcc->pcc_uc_ret); 96 } else { 97 DPRINTF(("mlcont, pcc %p\n", pcc)); 98 pcc->pcc_flags &= ~PCC_MLCONT; 99 rv = puffs__cc_create(pcc->pcc_pu, puffs__theloop, &jumpcc); 100 if (rv) 101 abort(); /* p-p-p-pa-pa-panic (XXX: fixme) */ 102 swapcontext(&pcc->pcc_uc, &jumpcc->pcc_uc); 103 DPRINTF(("puffs_cc_yield: post swap pcc %p\n", pcc)); 104 } 105 } 106 107 /* 108 * Internal continue routine. This has slightly different semantics. 109 * We simply make our cc available in the freelist and jump to the 110 * indicated pcc. 111 */ 112 void 113 puffs__cc_cont(struct puffs_cc *pcc) 114 { 115 struct puffs_cc *mycc; 116 117 mycc = puffs_cc_getcc(pcc->pcc_pu); 118 DPRINTF(("puffs__cc_cont: pcc %p, mycc %p\n", pcc, mycc)); 119 120 /* 121 * XXX: race between setcontext() and recycle if 122 * we go multithreaded 123 */ 124 puffs__cc_destroy(mycc, 1); 125 pcc->pcc_flags |= PCC_MLCONT; 126 setcontext(&pcc->pcc_uc); 127 } 128 129 void 130 puffs_cc_continue(struct puffs_cc *pcc) 131 { 132 133 /* ramble on */ 134 DPRINTF(("puffs_cc_continue: pcc %p\n", pcc)); 135 if (puffs_fakecc) { 136 pcc->pcc_func(pcc->pcc_farg); 137 } else { 138 swapcontext(&pcc->pcc_uc_ret, &pcc->pcc_uc); 139 } 140 } 141 142 /* 143 * "Borrows" pcc, *NOT* called from pcc owner. Acts like continue. 144 * So the idea is to use this, give something the context back to 145 * run to completion and then jump back to where ever this was called 146 * from after the op dispatching is complete (or if the pcc decides to 147 * yield again). 148 */ 149 void 150 puffs__goto(struct puffs_cc *loanpcc) 151 { 152 153 loanpcc->pcc_flags |= PCC_BORROWED; 154 155 swapcontext(&loanpcc->pcc_uc_ret, &loanpcc->pcc_uc); 156 } 157 158 void 159 puffs_cc_schedule(struct puffs_cc *pcc) 160 { 161 struct puffs_usermount *pu = pcc->pcc_pu; 162 163 assert(pu->pu_state & PU_INLOOP); 164 TAILQ_INSERT_TAIL(&pu->pu_sched, pcc, pcc_schedent); 165 } 166 167 int 168 puffs_cc_getcaller(struct puffs_cc *pcc, pid_t *pid, lwpid_t *lid) 169 { 170 171 if ((pcc->pcc_flags & PCC_HASCALLER) == 0) { 172 errno = ESRCH; 173 return -1; 174 } 175 176 if (pid) 177 *pid = pcc->pcc_pid; 178 if (lid) 179 *lid = pcc->pcc_lid; 180 return 0; 181 } 182 183 static struct puffs_cc fakecc; 184 185 static struct puffs_cc * 186 slowccalloc(struct puffs_usermount *pu) 187 { 188 struct puffs_cc *volatile pcc; 189 void *sp; 190 size_t stacksize = 1<<pu->pu_cc_stackshift; 191 const long psize = sysconf(_SC_PAGESIZE); 192 193 if (puffs_fakecc) 194 return &fakecc; 195 196 sp = mmap(NULL, stacksize, PROT_READ|PROT_WRITE, 197 MAP_ANON|MAP_PRIVATE|MAP_ALIGNED(pu->pu_cc_stackshift), -1, 0); 198 if (sp == MAP_FAILED) 199 return NULL; 200 201 pcc = sp; 202 memset(pcc, 0, sizeof(struct puffs_cc)); 203 204 #ifndef __MACHINE_STACK_GROWS_UP 205 mprotect((uint8_t *)sp + psize, (size_t)psize, PROT_NONE); 206 #else 207 mprotect((uint8_t *)sp + stacksize - psize, (size_t)psize, PROT_NONE); 208 #endif 209 210 /* initialize both ucontext's */ 211 if (getcontext(&pcc->pcc_uc) == -1) { 212 munmap(pcc, stacksize); 213 return NULL; 214 } 215 if (getcontext(&pcc->pcc_uc_ret) == -1) { 216 munmap(pcc, stacksize); 217 return NULL; 218 } 219 220 return pcc; 221 } 222 223 int 224 puffs__cc_create(struct puffs_usermount *pu, puffs_ccfunc func, 225 struct puffs_cc **pccp) 226 { 227 struct puffs_cc *pcc; 228 size_t stacksize = 1<<pu->pu_cc_stackshift; 229 stack_t *st; 230 231 /* Do we have a cached copy? */ 232 if (pu->pu_cc_nstored == 0) { 233 pcc = slowccalloc(pu); 234 if (pcc == NULL) 235 return -1; 236 pcc->pcc_pu = pu; 237 DPRINTF(("puffs__cc_create: allocated pcc %p\n", pcc)); 238 } else { 239 pcc = LIST_FIRST(&pu->pu_ccmagazin); 240 assert(pcc != NULL); 241 242 LIST_REMOVE(pcc, pcc_rope); 243 pu->pu_cc_nstored--; 244 DPRINTF(("puffs__cc_create: magazin pcc %p\n", pcc)); 245 } 246 assert(pcc->pcc_pu == pu); 247 248 if (puffs_fakecc) { 249 pcc->pcc_func = func; 250 pcc->pcc_farg = pcc; 251 } else { 252 const long psize = sysconf(_SC_PAGESIZE); 253 254 /* link context */ 255 pcc->pcc_uc.uc_link = &pcc->pcc_uc_ret; 256 257 /* setup stack 258 * 259 * XXX: I guess this should theoretically be preserved by 260 * swapcontext(). However, it gets lost. So reinit it. 261 */ 262 st = &pcc->pcc_uc.uc_stack; 263 st->ss_sp = ((uint8_t *)(void *)pcc) + psize; 264 st->ss_size = stacksize - psize; 265 st->ss_flags = 0; 266 267 /* 268 * Give us an initial context to jump to. 269 * 270 * Our manual page says that portable code shouldn't 271 * rely on being able to pass pointers through makecontext(). 272 * kjk says that NetBSD code doesn't need to worry about this. 273 * uwe says it would be like putting a "keep away from 274 * children" sign on a box of toys. 275 */ 276 makecontext(&pcc->pcc_uc, (void *)func, 1, (uintptr_t)pcc); 277 } 278 279 *pccp = pcc; 280 return 0; 281 } 282 283 void 284 puffs__cc_setcaller(struct puffs_cc *pcc, pid_t pid, lwpid_t lid) 285 { 286 287 pcc->pcc_pid = pid; 288 pcc->pcc_lid = lid; 289 pcc->pcc_flags |= PCC_HASCALLER; 290 } 291 292 static void 293 cc_free(struct puffs_cc *pcc) 294 { 295 struct puffs_usermount *pu = pcc->pcc_pu; 296 size_t stacksize = 1<<pu->pu_cc_stackshift; 297 298 DPRINTF(("invalidating pcc %p\n", pcc)); 299 assert(!puffs_fakecc); 300 munmap(pcc, stacksize); 301 } 302 303 void 304 puffs__cc_destroy(struct puffs_cc *pcc, int nonuke) 305 { 306 struct puffs_usermount *pu = pcc->pcc_pu; 307 308 pcc->pcc_flags &= ~PCC_HASCALLER; 309 assert(pcc->pcc_flags == 0); 310 assert(!puffs_fakecc); 311 312 /* not over limit? stuff away in the store, otherwise nuke */ 313 if (nonuke || pu->pu_cc_nstored < PUFFS_CCMAXSTORE) { 314 pcc->pcc_pb = NULL; 315 DPRINTF(("puffs__cc_destroy: storing pcc %p\n", pcc)); 316 LIST_INSERT_HEAD(&pu->pu_ccmagazin, pcc, pcc_rope); 317 pu->pu_cc_nstored++; 318 } else { 319 cc_free(pcc); 320 } 321 } 322 323 void 324 puffs__cc_exit(struct puffs_usermount *pu) 325 { 326 struct puffs_cc *pcc; 327 328 while ((pcc = LIST_FIRST(&pu->pu_ccmagazin)) != NULL) { 329 LIST_REMOVE(pcc, pcc_rope); 330 cc_free(pcc); 331 } 332 } 333 334 struct puffs_cc * 335 puffs_cc_getcc(struct puffs_usermount *pu) 336 { 337 size_t stacksize = 1<<pu->pu_cc_stackshift; 338 uintptr_t bottom; 339 340 if (puffs_fakecc) 341 return &fakecc; 342 343 bottom = ((uintptr_t)&bottom) & ~(stacksize-1); 344 return (struct puffs_cc *)bottom; 345 } 346 347 int 348 puffs__cc_savemain(struct puffs_usermount *pu) 349 { 350 351 if (puffs_fakecc) 352 return 0; 353 354 PU_CLRSFLAG(pu, PU_MAINRESTORE); 355 return getcontext(&pu->pu_mainctx); 356 } 357 358 int 359 puffs__cc_restoremain(struct puffs_usermount *pu) 360 { 361 362 if (puffs_fakecc) 363 return 0; 364 365 puffs__cc_destroy(puffs_cc_getcc(pu), 1); 366 PU_SETSFLAG(pu, PU_MAINRESTORE); 367 return setcontext(&pu->pu_mainctx); 368 } 369