diff options
Diffstat (limited to 'lib/libc/alpha/gen/makecontext.c')
| -rw-r--r-- | lib/libc/alpha/gen/makecontext.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/lib/libc/alpha/gen/makecontext.c b/lib/libc/alpha/gen/makecontext.c new file mode 100644 index 0000000..bc8ea03 --- /dev/null +++ b/lib/libc/alpha/gen/makecontext.c @@ -0,0 +1,172 @@ +/* + * Copyright (c) 2001 Daniel M. Eischen <deischen@freebsd.org> + * 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. Neither the name of the author nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/param.h> +#include <sys/signal.h> + +#include <errno.h> +#include <stdarg.h> +#include <stdlib.h> +#include <ucontext.h> +#include <unistd.h> + + +/* Prototypes */ +extern void _ctx_start(int argc, ...); + + +__weak_reference(__makecontext, makecontext); + +void +_ctx_done (ucontext_t *ucp) +{ + if (ucp->uc_link == NULL) + exit(0); + else { + /* + * Since this context has finished, don't allow it + * to be restarted without being reinitialized (via + * setcontext or swapcontext). + */ + ucp->uc_mcontext.mc_format = 0; + + /* Set context to next one in link */ + /* XXX - what to do for error, abort? */ + setcontext((const ucontext_t *)ucp->uc_link); + abort(); /* should never get here */ + } +} + +void +__makecontext(ucontext_t *ucp, void (*start)(void), int argc, ...) +{ + va_list ap; + char *stack_top; + intptr_t *argp; + int i; + + if (ucp == NULL) + return; + else if ((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_format = 0; + } + /* XXX - Do we want to sanity check argc? */ + else if ((argc < 0) || (argc > NCARGS)) { + ucp->uc_mcontext.mc_format = 0; + } + /* + * Make sure the context is valid. For now, we only allow + * trapframe format contexts to be used for makecontext. + */ + else if (ucp->uc_mcontext.mc_format == _MC_REV0_TRAPFRAME) { + /* + * Alpha passes the first 6 parameters in registers and + * remaining parameters on the stack. Set up the context + * accordingly, with the user start routine in register + * S0, and the context start wrapper (_ctx_start) in the + * program counter and return address. The context must + * be in trapframe format. + * + * Note: The context start wrapper needs to retrieve the + * ucontext pointer. Place this in register S1 + * which must be saved by the callee. + */ + stack_top = (char *)(ucp->uc_stack.ss_sp + + ucp->uc_stack.ss_size - sizeof(double)); + stack_top = (char *)ALIGN(stack_top); + + /* + * Adjust top of stack to allow for any additional integer + * arguments beyond 6. + */ + if (argc > 6) + stack_top = stack_top - (sizeof(intptr_t) * (argc - 6)); + + argp = (intptr_t *)stack_top; + + va_start(ap, argc); + for (i = 0; i < argc; i++) { + switch (i) { + case 0: ucp->uc_mcontext.mc_regs[FRAME_A0] = + (unsigned long)va_arg(ap, intptr_t); + break; + + case 1: ucp->uc_mcontext.mc_regs[FRAME_A1] = + (unsigned long)va_arg(ap, intptr_t); + break; + + case 2: ucp->uc_mcontext.mc_regs[FRAME_A2] = + (unsigned long)va_arg(ap, intptr_t); + break; + + case 3: ucp->uc_mcontext.mc_regs[FRAME_A3] = + (unsigned long)va_arg(ap, intptr_t); + break; + + case 4: ucp->uc_mcontext.mc_regs[FRAME_A4] = + (unsigned long)va_arg(ap, intptr_t); + break; + + case 5: ucp->uc_mcontext.mc_regs[FRAME_A5] = + (unsigned long)va_arg(ap, intptr_t); + break; + + default: + *argp = va_arg(ap, intptr_t); + argp++; + break; + } + } + va_end(ap); + + /* + * The start routine and ucontext are placed in registers + * S0 and S1 respectively. + */ + ucp->uc_mcontext.mc_regs[FRAME_S0] = (unsigned long)start; + ucp->uc_mcontext.mc_regs[FRAME_S1] = (unsigned long)ucp; + + /* + * Set the machine context to point to the top of the stack, + * and the program counter and return address to the context + * start wrapper. + */ + ucp->uc_mcontext.mc_regs[FRAME_SP] = (unsigned long)stack_top; + ucp->uc_mcontext.mc_regs[FRAME_PC] = (unsigned long)_ctx_start; + ucp->uc_mcontext.mc_regs[FRAME_RA] = (unsigned long)_ctx_start; + ucp->uc_mcontext.mc_regs[FRAME_T12] = (unsigned long)_ctx_start; + } +} |
