1 /* $NetBSD: callcontext.c,v 1.26 2011/11/02 16:43:04 yamt 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 1.26 2011/11/02 16:43:04 yamt 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 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 mprotect((uint8_t *)sp + psize, (size_t)psize, PROT_NONE); 205 206 /* initialize both ucontext's */ 207 if (getcontext(&pcc->pcc_uc) == -1) { 208 munmap(pcc, stacksize); 209 return NULL; 210 } 211 if (getcontext(&pcc->pcc_uc_ret) == -1) { 212 munmap(pcc, stacksize); 213 return NULL; 214 } 215 216 return pcc; 217 } 218 219 int 220 puffs__cc_create(struct puffs_usermount *pu, puffs_ccfunc func, 221 struct puffs_cc **pccp) 222 { 223 struct puffs_cc *pcc; 224 size_t stacksize = 1<<pu->pu_cc_stackshift; 225 stack_t *st; 226 227 /* Do we have a cached copy? */ 228 if (pu->pu_cc_nstored == 0) { 229 pcc = slowccalloc(pu); 230 if (pcc == NULL) 231 return -1; 232 pcc->pcc_pu = pu; 233 DPRINTF(("puffs__cc_create: allocated pcc %p\n", pcc)); 234 } else { 235 pcc = LIST_FIRST(&pu->pu_ccmagazin); 236 assert(pcc != NULL); 237 238 LIST_REMOVE(pcc, pcc_rope); 239 pu->pu_cc_nstored--; 240 DPRINTF(("puffs__cc_create: magazin pcc %p\n", pcc)); 241 } 242 assert(pcc->pcc_pu == pu); 243 244 if (puffs_fakecc) { 245 pcc->pcc_func = func; 246 pcc->pcc_farg = pcc; 247 } else { 248 /* link context */ 249 pcc->pcc_uc.uc_link = &pcc->pcc_uc_ret; 250 251 /* setup stack 252 * 253 * XXX: I guess this should theoretically be preserved by 254 * swapcontext(). However, it gets lost. So reinit it. 255 */ 256 st = &pcc->pcc_uc.uc_stack; 257 st->ss_sp = pcc; 258 st->ss_size = stacksize; 259 st->ss_flags = 0; 260 261 /* 262 * Give us an initial context to jump to. 263 * 264 * Our manual page says that portable code shouldn't 265 * rely on being able to pass pointers through makecontext(). 266 * kjk says that NetBSD code doesn't need to worry about this. 267 * uwe says it would be like putting a "keep away from 268 * children" sign on a box of toys. 269 */ 270 makecontext(&pcc->pcc_uc, (void *)func, 1, (uintptr_t)pcc); 271 } 272 273 *pccp = pcc; 274 return 0; 275 } 276 277 void 278 puffs__cc_setcaller(struct puffs_cc *pcc, pid_t pid, lwpid_t lid) 279 { 280 281 pcc->pcc_pid = pid; 282 pcc->pcc_lid = lid; 283 pcc->pcc_flags |= PCC_HASCALLER; 284 } 285 286 static void 287 cc_free(struct puffs_cc *pcc) 288 { 289 struct puffs_usermount *pu = pcc->pcc_pu; 290 size_t stacksize = 1<<pu->pu_cc_stackshift; 291 292 DPRINTF(("invalidating pcc %p\n", pcc)); 293 assert(!puffs_fakecc); 294 munmap(pcc, stacksize); 295 } 296 297 void 298 puffs__cc_destroy(struct puffs_cc *pcc, int nonuke) 299 { 300 struct puffs_usermount *pu = pcc->pcc_pu; 301 302 pcc->pcc_flags &= ~PCC_HASCALLER; 303 assert(pcc->pcc_flags == 0); 304 assert(!puffs_fakecc); 305 306 /* not over limit? stuff away in the store, otherwise nuke */ 307 if (nonuke || pu->pu_cc_nstored < PUFFS_CCMAXSTORE) { 308 pcc->pcc_pb = NULL; 309 DPRINTF(("puffs__cc_destroy: storing pcc %p\n", pcc)); 310 LIST_INSERT_HEAD(&pu->pu_ccmagazin, pcc, pcc_rope); 311 pu->pu_cc_nstored++; 312 } else { 313 cc_free(pcc); 314 } 315 } 316 317 void 318 puffs__cc_exit(struct puffs_usermount *pu) 319 { 320 struct puffs_cc *pcc; 321 322 while ((pcc = LIST_FIRST(&pu->pu_ccmagazin)) != NULL) { 323 LIST_REMOVE(pcc, pcc_rope); 324 cc_free(pcc); 325 } 326 } 327 328 struct puffs_cc * 329 puffs_cc_getcc(struct puffs_usermount *pu) 330 { 331 size_t stacksize = 1<<pu->pu_cc_stackshift; 332 uintptr_t bottom; 333 334 if (puffs_fakecc) 335 return &fakecc; 336 337 bottom = ((uintptr_t)&bottom) & ~(stacksize-1); 338 return (struct puffs_cc *)bottom; 339 } 340 341 int 342 puffs__cc_savemain(struct puffs_usermount *pu) 343 { 344 345 if (puffs_fakecc) 346 return 0; 347 348 PU_CLRSFLAG(pu, PU_MAINRESTORE); 349 return getcontext(&pu->pu_mainctx); 350 } 351 352 int 353 puffs__cc_restoremain(struct puffs_usermount *pu) 354 { 355 356 if (puffs_fakecc) 357 return 0; 358 359 puffs__cc_destroy(puffs_cc_getcc(pu), 1); 360 PU_SETSFLAG(pu, PU_MAINRESTORE); 361 return setcontext(&pu->pu_mainctx); 362 } 363