369 lines
8.7 KiB
C
369 lines
8.7 KiB
C
/* $NetBSD: callcontext.c,v 1.30 2018/07/09 00:47:47 christos Exp $ */
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/*
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* Copyright (c) 2006, 2007, 2008 Antti Kantee. All Rights Reserved.
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*
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* Development of this software was supported by the
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* Research Foundation of Helsinki University of Technology
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if !defined(lint)
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__RCSID("$NetBSD: callcontext.c,v 1.30 2018/07/09 00:47:47 christos Exp $");
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#endif /* !lint */
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <assert.h>
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#include <errno.h>
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#include <puffs.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ucontext.h>
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#include <unistd.h>
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#include "puffs_priv.h"
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#if 0
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#define DPRINTF(x) printf x
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#else
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#define DPRINTF(x)
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#endif
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/*
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* Set the following to 1 to not handle each request on a separate
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* stack. This is highly volatile kludge, therefore no external
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* interface.
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*/
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int puffs_fakecc;
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/*
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* user stuff
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*/
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/*
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* So, we need to get back to where we came from. This can happen in two
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* different ways:
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* 1) PCC_MLCONT is set, in which case we need to go to the mainloop
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* 2) It is not set, and we simply jump to pcc_uc_ret.
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*/
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void
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puffs_cc_yield(struct puffs_cc *pcc)
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{
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struct puffs_cc *jumpcc;
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int rv;
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assert(puffs_fakecc == 0);
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if ((~pcc->pcc_flags & (PCC_BORROWED|PCC_DONE)) == 0) {
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pcc->pcc_flags &= ~(PCC_BORROWED|PCC_DONE);
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/*
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* see the XXX comment in puffs__cc_cont
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*/
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puffs__cc_destroy(pcc, 1);
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setcontext(&pcc->pcc_uc_ret);
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}
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pcc->pcc_flags &= ~PCC_BORROWED;
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/* romanes eunt domus */
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DPRINTF(("puffs_cc_yield: "));
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if ((pcc->pcc_flags & PCC_MLCONT) == 0) {
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DPRINTF(("no mlcont, pcc %p\n", pcc));
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swapcontext(&pcc->pcc_uc, &pcc->pcc_uc_ret);
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} else {
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DPRINTF(("mlcont, pcc %p\n", pcc));
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pcc->pcc_flags &= ~PCC_MLCONT;
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rv = puffs__cc_create(pcc->pcc_pu, puffs__theloop, &jumpcc);
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if (rv)
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abort(); /* p-p-p-pa-pa-panic (XXX: fixme) */
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swapcontext(&pcc->pcc_uc, &jumpcc->pcc_uc);
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DPRINTF(("puffs_cc_yield: post swap pcc %p\n", pcc));
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}
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}
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/*
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* Internal continue routine. This has slightly different semantics.
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* We simply make our cc available in the freelist and jump to the
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* indicated pcc.
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*/
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void
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puffs__cc_cont(struct puffs_cc *pcc)
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{
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struct puffs_cc *mycc;
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mycc = puffs_cc_getcc(pcc->pcc_pu);
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DPRINTF(("puffs__cc_cont: pcc %p, mycc %p\n", pcc, mycc));
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/*
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* XXX: race between setcontext() and recycle if
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* we go multithreaded
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*/
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puffs__cc_destroy(mycc, 1);
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pcc->pcc_flags |= PCC_MLCONT;
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setcontext(&pcc->pcc_uc);
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}
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void
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puffs_cc_continue(struct puffs_cc *pcc)
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{
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/* ramble on */
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DPRINTF(("puffs_cc_continue: pcc %p\n", pcc));
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if (puffs_fakecc) {
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pcc->pcc_func(pcc->pcc_farg);
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} else {
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swapcontext(&pcc->pcc_uc_ret, &pcc->pcc_uc);
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}
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}
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/*
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* "Borrows" pcc, *NOT* called from pcc owner. Acts like continue.
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* So the idea is to use this, give something the context back to
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* run to completion and then jump back to where ever this was called
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* from after the op dispatching is complete (or if the pcc decides to
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* yield again).
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*/
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void
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puffs__goto(struct puffs_cc *loanpcc)
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{
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loanpcc->pcc_flags |= PCC_BORROWED;
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swapcontext(&loanpcc->pcc_uc_ret, &loanpcc->pcc_uc);
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}
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void
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puffs_cc_schedule(struct puffs_cc *pcc)
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{
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struct puffs_usermount *pu = pcc->pcc_pu;
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assert(pu->pu_state & PU_INLOOP);
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TAILQ_INSERT_TAIL(&pu->pu_sched, pcc, pcc_schedent);
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}
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int
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puffs_cc_getcaller(struct puffs_cc *pcc, pid_t *pid, lwpid_t *lid)
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{
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if ((pcc->pcc_flags & PCC_HASCALLER) == 0) {
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errno = ESRCH;
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return -1;
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}
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if (pid)
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*pid = pcc->pcc_pid;
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if (lid)
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*lid = pcc->pcc_lid;
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return 0;
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}
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static struct puffs_cc fakecc;
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static struct puffs_cc *
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slowccalloc(struct puffs_usermount *pu)
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{
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struct puffs_cc *volatile pcc;
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void *sp;
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size_t stacksize = 1<<pu->pu_cc_stackshift;
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const long psize = sysconf(_SC_PAGESIZE);
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if (puffs_fakecc)
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return &fakecc;
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sp = mmap(NULL, stacksize, PROT_READ|PROT_WRITE,
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MAP_ANON|MAP_PRIVATE|MAP_ALIGNED(pu->pu_cc_stackshift), -1, 0);
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if (sp == MAP_FAILED)
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return NULL;
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pcc = sp;
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memset(pcc, 0, sizeof(struct puffs_cc));
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#ifndef __MACHINE_STACK_GROWS_UP
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mprotect((uint8_t *)sp + psize, (size_t)psize, PROT_NONE);
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#else
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mprotect((uint8_t *)sp + stacksize - psize, (size_t)psize, PROT_NONE);
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#endif
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/* initialize both ucontext's */
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if (getcontext(&pcc->pcc_uc) == -1) {
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munmap(pcc, stacksize);
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return NULL;
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}
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if (getcontext(&pcc->pcc_uc_ret) == -1) {
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munmap(pcc, stacksize);
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return NULL;
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}
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return pcc;
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}
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int
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puffs__cc_create(struct puffs_usermount *pu, puffs_ccfunc func,
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struct puffs_cc **pccp)
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{
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struct puffs_cc *pcc;
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size_t stacksize = 1<<pu->pu_cc_stackshift;
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stack_t *st;
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/* Do we have a cached copy? */
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if (pu->pu_cc_nstored == 0) {
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pcc = slowccalloc(pu);
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if (pcc == NULL)
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return -1;
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pcc->pcc_pu = pu;
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DPRINTF(("puffs__cc_create: allocated pcc %p\n", pcc));
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} else {
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pcc = LIST_FIRST(&pu->pu_ccmagazin);
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assert(pcc != NULL);
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LIST_REMOVE(pcc, pcc_rope);
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pu->pu_cc_nstored--;
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DPRINTF(("puffs__cc_create: magazin pcc %p\n", pcc));
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}
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assert(pcc->pcc_pu == pu);
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if (puffs_fakecc) {
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pcc->pcc_func = func;
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pcc->pcc_farg = pcc;
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} else {
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const long psize = sysconf(_SC_PAGESIZE);
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/* link context */
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pcc->pcc_uc.uc_link = &pcc->pcc_uc_ret;
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/* setup stack
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*
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* XXX: I guess this should theoretically be preserved by
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* swapcontext(). However, it gets lost. So reinit it.
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*/
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st = &pcc->pcc_uc.uc_stack;
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st->ss_sp = ((uint8_t *)(void *)pcc) + psize;
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st->ss_size = stacksize - psize;
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st->ss_flags = 0;
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/*
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* Give us an initial context to jump to.
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*
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* Our manual page says that portable code shouldn't
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* rely on being able to pass pointers through makecontext().
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* kjk says that NetBSD code doesn't need to worry about this.
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* uwe says it would be like putting a "keep away from
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* children" sign on a box of toys.
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*/
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makecontext(&pcc->pcc_uc, (void *)func, 1, (uintptr_t)pcc);
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}
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*pccp = pcc;
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return 0;
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}
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void
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puffs__cc_setcaller(struct puffs_cc *pcc, pid_t pid, lwpid_t lid)
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{
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pcc->pcc_pid = pid;
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pcc->pcc_lid = lid;
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pcc->pcc_flags |= PCC_HASCALLER;
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}
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static void
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cc_free(struct puffs_cc *pcc)
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{
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struct puffs_usermount *pu = pcc->pcc_pu;
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size_t stacksize = 1<<pu->pu_cc_stackshift;
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DPRINTF(("invalidating pcc %p\n", pcc));
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assert(!puffs_fakecc);
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munmap(pcc, stacksize);
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}
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void
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puffs__cc_destroy(struct puffs_cc *pcc, int nonuke)
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{
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struct puffs_usermount *pu = pcc->pcc_pu;
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pcc->pcc_flags &= ~PCC_HASCALLER;
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assert(pcc->pcc_flags == 0);
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assert(!puffs_fakecc);
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/* not over limit? stuff away in the store, otherwise nuke */
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if (nonuke || pu->pu_cc_nstored < PUFFS_CCMAXSTORE) {
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pcc->pcc_pb = NULL;
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DPRINTF(("puffs__cc_destroy: storing pcc %p\n", pcc));
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LIST_INSERT_HEAD(&pu->pu_ccmagazin, pcc, pcc_rope);
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pu->pu_cc_nstored++;
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} else {
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cc_free(pcc);
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}
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}
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void
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puffs__cc_exit(struct puffs_usermount *pu)
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{
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struct puffs_cc *pcc;
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while ((pcc = LIST_FIRST(&pu->pu_ccmagazin)) != NULL) {
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LIST_REMOVE(pcc, pcc_rope);
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cc_free(pcc);
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}
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}
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struct puffs_cc *
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puffs_cc_getcc(struct puffs_usermount *pu)
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{
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size_t stacksize = 1<<pu->pu_cc_stackshift;
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uintptr_t bottom;
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if (puffs_fakecc)
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return &fakecc;
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bottom = ((uintptr_t)&bottom) & ~(stacksize-1);
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return (struct puffs_cc *)bottom;
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}
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int
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puffs__cc_savemain(struct puffs_usermount *pu)
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{
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if (puffs_fakecc)
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return 0;
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PU_CLRSFLAG(pu, PU_MAINRESTORE);
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return getcontext(&pu->pu_mainctx);
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}
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int
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puffs__cc_restoremain(struct puffs_usermount *pu)
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{
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if (puffs_fakecc)
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return 0;
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puffs__cc_destroy(puffs_cc_getcc(pu), 1);
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PU_SETSFLAG(pu, PU_MAINRESTORE);
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return setcontext(&pu->pu_mainctx);
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}
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