mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-29 16:21:07 +00:00
96 lines
3.0 KiB
C
96 lines
3.0 KiB
C
/* Copyright (C) 2001-2023 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <libintl.h>
|
|
#include <stdarg.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <ucontext.h>
|
|
|
|
/* This implementation can handle any ARGC value but only
|
|
normal integer type parameters. Parameters of type float,
|
|
double, complex and structure with sizes 0, 2, 4 or 8
|
|
won't work.
|
|
makecontext sets up a stack and the registers for the
|
|
user context. The stack looks like this:
|
|
size offset
|
|
%r15 -> +-----------------------+
|
|
8 | back chain (zero) | 0
|
|
8 | reserved | 8
|
|
144 | save area for (*func) | 16
|
|
+-----------------------+
|
|
n | overflow parameters | 160
|
|
+-----------------------+
|
|
The registers are set up like this:
|
|
%r2-%r6: parameters 1 to 5
|
|
%r7 : (*func) pointer
|
|
%r8 : uc_link from ucontext structure
|
|
%r9 : address of setcontext
|
|
%r14 : return address to uc_link trampoline
|
|
%r15 : stack pointer.
|
|
|
|
The trampoline looks like this:
|
|
basr %r14,%r7
|
|
lgr %r2,%r8
|
|
br %r9. */
|
|
|
|
void
|
|
__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
|
|
{
|
|
extern void __makecontext_ret (void);
|
|
unsigned long int *sp;
|
|
va_list ap;
|
|
|
|
sp = (unsigned long int *) (((unsigned long int) ucp->uc_stack.ss_sp
|
|
+ ucp->uc_stack.ss_size) & -8L);
|
|
|
|
/* Set the return address to trampoline. */
|
|
ucp->uc_mcontext.gregs[14] = (long int) __makecontext_ret;
|
|
|
|
/* Set register parameters. */
|
|
va_start (ap, argc);
|
|
for (int i = 0; i < argc && i < 5; ++i)
|
|
ucp->uc_mcontext.gregs[2 + i] = va_arg (ap, long int);
|
|
|
|
/* The remaining arguments go to the overflow area. */
|
|
if (argc > 5)
|
|
{
|
|
sp -= argc - 5;
|
|
for (int i = 5; i < argc; ++i)
|
|
sp[i - 5] = va_arg (ap, long int);
|
|
}
|
|
va_end (ap);
|
|
|
|
/* Make room for the save area and set the backchain. */
|
|
sp -= 20;
|
|
*sp = 0;
|
|
|
|
/* Pass (*func) to __makecontext_ret in %r7. */
|
|
ucp->uc_mcontext.gregs[7] = (long int) func;
|
|
|
|
/* Pass ucp->uc_link to __makecontext_ret in %r8. */
|
|
ucp->uc_mcontext.gregs[8] = (long int) ucp->uc_link;
|
|
|
|
/* Pass address of setcontext in %r9. */
|
|
ucp->uc_mcontext.gregs[9] = (long int) &setcontext;
|
|
|
|
/* Set stack pointer. */
|
|
ucp->uc_mcontext.gregs[15] = (long int) sp;
|
|
}
|
|
|
|
weak_alias (__makecontext, makecontext)
|