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/*
* 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;
}
}
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