| /* |
| * CDDL HEADER START |
| * |
| * The contents of this file are subject to the terms of the |
| * Common Development and Distribution License, Version 1.0 only |
| * (the "License"). You may not use this file except in compliance |
| * with the License. |
| * |
| * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE |
| * or http://www.opensolaris.org/os/licensing. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| * |
| * When distributing Covered Code, include this CDDL HEADER in each |
| * file and include the License file at usr/src/OPENSOLARIS.LICENSE. |
| * If applicable, add the following below this CDDL HEADER, with the |
| * fields enclosed by brackets "[]" replaced with your own identifying |
| * information: Portions Copyright [yyyy] [name of copyright owner] |
| * |
| * CDDL HEADER END |
| */ |
| /* |
| * Copyright 2004 Sun Microsystems, Inc. All rights reserved. |
| * Use is subject to license terms. |
| */ |
| |
| #pragma ident "%Z%%M% %I% %E% SMI" |
| |
| /* |
| * Debugger co-routine context support: In order to implement the context- |
| * switching necessary for MDB pipes, we need the ability to establish a |
| * co-routine context that has a separate stack. We use this stack to execute |
| * the MDB parser, and then switch back and forth between this code and the |
| * dcmd which is producing output to be consumed. We implement a context by |
| * mapping a few pages of anonymous memory, and then using setcontext(2) to |
| * switch to this stack and begin execution of a new function. |
| */ |
| |
| #include <mdb/mdb_context_impl.h> |
| #include <mdb/mdb_modapi.h> |
| #include <mdb/mdb_debug.h> |
| #include <mdb/mdb_err.h> |
| |
| #include <sys/types.h> |
| #include <sys/mman.h> |
| |
| #include <ucontext.h> |
| #include <unistd.h> |
| #include <setjmp.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| |
| static void |
| context_init(mdb_context_t *volatile c) |
| { |
| c->ctx_status = c->ctx_func(); |
| ASSERT(c->ctx_resumes > 0); |
| longjmp(c->ctx_pcb, 1); |
| } |
| |
| mdb_context_t * |
| mdb_context_create(int (*func)(void)) |
| { |
| mdb_context_t *c = mdb_zalloc(sizeof (mdb_context_t), UM_NOSLEEP); |
| size_t pagesize = sysconf(_SC_PAGESIZE); |
| int prot = sysconf(_SC_STACK_PROT); |
| static int zfd = -1; |
| |
| if (c == NULL) |
| return (NULL); |
| |
| if (prot == -1) |
| prot = PROT_READ | PROT_WRITE | PROT_EXEC; |
| |
| c->ctx_func = func; |
| c->ctx_stacksize = pagesize * 4; |
| c->ctx_stack = mmap(NULL, c->ctx_stacksize, prot, |
| MAP_PRIVATE | MAP_ANON, -1, 0); |
| |
| /* |
| * If the mmap failed with EBADFD, this kernel doesn't have MAP_ANON |
| * support; fall back to opening /dev/zero, caching the fd, and using |
| * that to mmap chunks of anonymous memory. |
| */ |
| if (c->ctx_stack == MAP_FAILED && errno == EBADF) { |
| if (zfd == -1 && (zfd = open("/dev/zero", O_RDWR)) >= 0) |
| (void) fcntl(zfd, F_SETFD, FD_CLOEXEC); |
| |
| if (zfd >= 0) { |
| c->ctx_stack = mmap(NULL, c->ctx_stacksize, prot, |
| MAP_PRIVATE, zfd, 0); |
| } |
| } |
| |
| c->ctx_uc.uc_flags = UC_ALL; |
| if (c->ctx_stack == MAP_FAILED || getcontext(&c->ctx_uc) != 0) { |
| mdb_free(c, sizeof (mdb_context_t)); |
| return (NULL); |
| } |
| |
| c->ctx_uc.uc_stack.ss_sp = c->ctx_stack; |
| c->ctx_uc.uc_stack.ss_size = c->ctx_stacksize; |
| c->ctx_uc.uc_stack.ss_flags = 0; |
| c->ctx_uc.uc_link = NULL; |
| makecontext(&c->ctx_uc, context_init, 1, c); |
| |
| return (c); |
| } |
| |
| void |
| mdb_context_destroy(mdb_context_t *c) |
| { |
| if (munmap(c->ctx_stack, c->ctx_stacksize) == -1) |
| fail("failed to unmap stack %p", c->ctx_stack); |
| |
| mdb_free(c, sizeof (mdb_context_t)); |
| } |
| |
| void |
| mdb_context_switch(mdb_context_t *c) |
| { |
| if (setjmp(c->ctx_pcb) == 0 && setcontext(&c->ctx_uc) == -1) |
| fail("failed to change context to %p", (void *)c); |
| else |
| fail("unexpectedly returned from context %p", (void *)c); |
| } |
| |
| jmp_buf * |
| mdb_context_getpcb(mdb_context_t *c) |
| { |
| c->ctx_resumes++; |
| return (&c->ctx_pcb); |
| } |