diff options
Diffstat (limited to 'lib/libc/amd64/gen/makecontext.c')
| -rw-r--r-- | lib/libc/amd64/gen/makecontext.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/libc/amd64/gen/makecontext.c b/lib/libc/amd64/gen/makecontext.c new file mode 100644 index 0000000..87cf7bf --- /dev/null +++ b/lib/libc/amd64/gen/makecontext.c @@ -0,0 +1,103 @@ +/* + * Copyright (c) 2003 Marcel Moolenaar + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/types.h> +#include <sys/ucontext.h> +#include <stdarg.h> +#include <stdlib.h> + +typedef void (*func_t)(uint64_t, uint64_t, uint64_t, uint64_t, uint64_t, + uint64_t); + +/* Prototypes */ +static void ctx_wrapper(ucontext_t *ucp, func_t func, uint64_t *args); + +__weak_reference(__makecontext, makecontext); + +void +__makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...) +{ + uint64_t *args; + uint64_t *sp; + va_list ap; + int i; + + /* A valid context is required. */ + if ((ucp == NULL) || (ucp->uc_mcontext.mc_len != sizeof(mcontext_t))) + return; + else if ((argc < 0) || (argc > 6) || (ucp->uc_stack.ss_sp == NULL) || + (ucp->uc_stack.ss_size < MINSIGSTKSZ)) { + /* + * This should really return -1 with errno set to ENOMEM + * or something, but the spec says that makecontext is + * a void function. At least make sure that the context + * isn't valid so it can't be used without an error. + */ + ucp->uc_mcontext.mc_len = 0; + return; + } + + /* Align the stack to 16 bytes. */ + sp = (uint64_t *)(ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); + sp = (uint64_t *)((uint64_t)sp & -15UL); + + /* Allocate space for a maximum of 6 arguments on the stack. */ + args = sp - 6; + + /* Account for arguments on stack and align to 16 bytes. */ + sp -= 8; + + /* Add the arguments: */ + va_start(ap, argc); + for (i = 0; i < argc; i++) + args[i] = va_arg(ap, uint64_t); + va_end(ap); + for (i = argc; i < 6; i++) + args[i] = 0; + + ucp->uc_mcontext.mc_rdi = (register_t)ucp; + ucp->uc_mcontext.mc_rsi = (register_t)start; + ucp->uc_mcontext.mc_rdx = (register_t)args; + ucp->uc_mcontext.mc_rbp = (register_t)sp; + ucp->uc_mcontext.mc_rbx = (register_t)sp; + ucp->uc_mcontext.mc_rsp = (register_t)sp; + ucp->uc_mcontext.mc_rip = (register_t)ctx_wrapper; +} + +static void +ctx_wrapper(ucontext_t *ucp, func_t func, uint64_t *args) +{ + (*func)(args[0], args[1], args[2], args[3], args[4], args[5]); + if (ucp->uc_link == NULL) + exit(0); + setcontext((const ucontext_t *)ucp->uc_link); + /* should never get here */ + abort(); + /* NOTREACHED */ +} |
