1 /* $NetBSD: callcontext.c,v 1.27 2011/12/06 21:15:39 skrll 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 1.27 2011/12/06 21:15:39 skrll 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; 191 192 if (puffs_fakecc) 193 return &fakecc; 194 195 sp = mmap(NULL, stacksize, PROT_READ|PROT_WRITE, 196 MAP_ANON|MAP_PRIVATE, -1, 0); 197 if (sp == MAP_FAILED) 198 return NULL; 199 200 pcc = sp; 201 memset(pcc, 0, sizeof(struct puffs_cc)); 202 203 /* initialize both ucontext's */ 204 if (getcontext(&pcc->pcc_uc) == -1) { 205 munmap(pcc, stacksize); 206 return NULL; 207 } 208 if (getcontext(&pcc->pcc_uc_ret) == -1) { 209 munmap(pcc, stacksize); 210 return NULL; 211 } 212 213 return pcc; 214 } 215 216 int 217 puffs__cc_create(struct puffs_usermount *pu, puffs_ccfunc func, 218 struct puffs_cc **pccp) 219 { 220 struct puffs_cc *pcc; 221 size_t stacksize = 1<<pu->pu_cc_stackshift; 222 stack_t *st; 223 224 /* Do we have a cached copy? */ 225 if (pu->pu_cc_nstored == 0) { 226 pcc = slowccalloc(pu); 227 if (pcc == NULL) 228 return -1; 229 pcc->pcc_pu = pu; 230 DPRINTF(("puffs__cc_create: allocated pcc %p\n", pcc)); 231 } else { 232 pcc = LIST_FIRST(&pu->pu_ccmagazin); 233 assert(pcc != NULL); 234 235 LIST_REMOVE(pcc, pcc_rope); 236 pu->pu_cc_nstored--; 237 DPRINTF(("puffs__cc_create: magazin pcc %p\n", pcc)); 238 } 239 assert(pcc->pcc_pu == pu); 240 241 if (puffs_fakecc) { 242 pcc->pcc_func = func; 243 pcc->pcc_farg = pcc; 244 } else { 245 /* link context */ 246 pcc->pcc_uc.uc_link = &pcc->pcc_uc_ret; 247 248 /* setup stack 249 * 250 * XXX: I guess this should theoretically be preserved by 251 * swapcontext(). However, it gets lost. So reinit it. 252 */ 253 st = &pcc->pcc_uc.uc_stack; 254 st->ss_sp = pcc; 255 st->ss_size = stacksize; 256 st->ss_flags = 0; 257 258 /* 259 * Give us an initial context to jump to. 260 * 261 * Our manual page says that portable code shouldn't 262 * rely on being able to pass pointers through makecontext(). 263 * kjk says that NetBSD code doesn't need to worry about this. 264 * uwe says it would be like putting a "keep away from 265 * children" sign on a box of toys. 266 */ 267 makecontext(&pcc->pcc_uc, (void *)func, 1, (uintptr_t)pcc); 268 } 269 270 *pccp = pcc; 271 return 0; 272 } 273 274 void 275 puffs__cc_setcaller(struct puffs_cc *pcc, pid_t pid, lwpid_t lid) 276 { 277 278 pcc->pcc_pid = pid; 279 pcc->pcc_lid = lid; 280 pcc->pcc_flags |= PCC_HASCALLER; 281 } 282 283 static void 284 cc_free(struct puffs_cc *pcc) 285 { 286 struct puffs_usermount *pu = pcc->pcc_pu; 287 size_t stacksize = 1<<pu->pu_cc_stackshift; 288 289 DPRINTF(("invalidating pcc %p\n", pcc)); 290 assert(!puffs_fakecc); 291 munmap(pcc, stacksize); 292 } 293 294 void 295 puffs__cc_destroy(struct puffs_cc *pcc, int nonuke) 296 { 297 struct puffs_usermount *pu = pcc->pcc_pu; 298 299 pcc->pcc_flags &= ~PCC_HASCALLER; 300 assert(pcc->pcc_flags == 0); 301 assert(!puffs_fakecc); 302 303 /* not over limit? stuff away in the store, otherwise nuke */ 304 if (nonuke || pu->pu_cc_nstored < PUFFS_CCMAXSTORE) { 305 pcc->pcc_pb = NULL; 306 DPRINTF(("puffs__cc_destroy: storing pcc %p\n", pcc)); 307 LIST_INSERT_HEAD(&pu->pu_ccmagazin, pcc, pcc_rope); 308 pu->pu_cc_nstored++; 309 } else { 310 cc_free(pcc); 311 } 312 } 313 314 void 315 puffs__cc_exit(struct puffs_usermount *pu) 316 { 317 struct puffs_cc *pcc; 318 319 while ((pcc = LIST_FIRST(&pu->pu_ccmagazin)) != NULL) { 320 LIST_REMOVE(pcc, pcc_rope); 321 cc_free(pcc); 322 } 323 } 324 325 struct puffs_cc * 326 puffs_cc_getcc(struct puffs_usermount *pu) 327 { 328 size_t stacksize = 1<<pu->pu_cc_stackshift; 329 uintptr_t bottom; 330 331 if (puffs_fakecc) 332 return &fakecc; 333 334 bottom = ((uintptr_t)&bottom) & ~(stacksize-1); 335 return (struct puffs_cc *)bottom; 336 } 337 338 int 339 puffs__cc_savemain(struct puffs_usermount *pu) 340 { 341 342 if (puffs_fakecc) 343 return 0; 344 345 PU_CLRSFLAG(pu, PU_MAINRESTORE); 346 return getcontext(&pu->pu_mainctx); 347 } 348 349 int 350 puffs__cc_restoremain(struct puffs_usermount *pu) 351 { 352 353 if (puffs_fakecc) 354 return 0; 355 356 puffs__cc_destroy(puffs_cc_getcc(pu), 1); 357 PU_SETSFLAG(pu, PU_MAINRESTORE); 358 return setcontext(&pu->pu_mainctx); 359 } 360