mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-27 07:20:11 +00:00
121 lines
3.9 KiB
C
121 lines
3.9 KiB
C
/* Create new context.
|
|
Copyright (C) 2002, 2004, 2005, 2008 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Andreas Jaeger <aj@suse.de>, 2002.
|
|
|
|
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
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <sysdep.h>
|
|
#include <stdarg.h>
|
|
#include <stdint.h>
|
|
#include <ucontext.h>
|
|
|
|
#include "ucontext_i.h"
|
|
|
|
/* This implementation can handle any ARGC value but only
|
|
normal integer parameters.
|
|
makecontext sets up a stack and the registers for the
|
|
user context. The stack looks like this:
|
|
+-----------------------+
|
|
| next context |
|
|
+-----------------------+
|
|
| parameter 7-n |
|
|
+-----------------------+
|
|
| trampoline address |
|
|
%rsp -> +-----------------------+
|
|
|
|
The registers are set up like this:
|
|
%rdi,%rsi,%rdx,%rcx,%r8,%r9: parameter 1 to 6
|
|
%rbx : address of next context
|
|
%rsp : stack pointer.
|
|
*/
|
|
|
|
/* XXX: This implementation currently only handles integer arguments.
|
|
To handle long int and pointer arguments the va_arg arguments needs
|
|
to be changed to long and also the stdlib/tst-setcontext.c file needs
|
|
to be changed to pass long arguments to makecontext. */
|
|
|
|
|
|
void
|
|
__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
|
|
{
|
|
extern void __start_context (void);
|
|
unsigned long int *sp, idx_uc_link;
|
|
va_list ap;
|
|
int i;
|
|
|
|
/* Generate room on stack for parameter if needed and uc_link. */
|
|
sp = (unsigned long int *) ((uintptr_t) ucp->uc_stack.ss_sp
|
|
+ ucp->uc_stack.ss_size);
|
|
sp -= (argc > 6 ? argc - 6 : 0) + 1;
|
|
/* Align stack and make space for trampoline address. */
|
|
sp = (unsigned long int *) ((((uintptr_t) sp) & -16L) - 8);
|
|
|
|
idx_uc_link = (argc > 6 ? argc - 6 : 0) + 1;
|
|
|
|
/* Setup context ucp. */
|
|
/* Address to jump to. */
|
|
ucp->uc_mcontext.gregs[REG_RIP] = (long int) func;
|
|
/* Setup rbx.*/
|
|
ucp->uc_mcontext.gregs[REG_RBX] = (long int) &sp[idx_uc_link];
|
|
ucp->uc_mcontext.gregs[REG_RSP] = (long int) sp;
|
|
|
|
/* Setup stack. */
|
|
sp[0] = (unsigned long int) &__start_context;
|
|
sp[idx_uc_link] = (unsigned long int) ucp->uc_link;
|
|
|
|
va_start (ap, argc);
|
|
/* Handle arguments.
|
|
|
|
The standard says the parameters must all be int values. This is
|
|
an historic accident and would be done differently today. For
|
|
x86-64 all integer values are passed as 64-bit values and
|
|
therefore extending the API to copy 64-bit values instead of
|
|
32-bit ints makes sense. It does not break existing
|
|
functionality and it does not violate the standard which says
|
|
that passing non-int values means undefined behavior. */
|
|
for (i = 0; i < argc; ++i)
|
|
switch (i)
|
|
{
|
|
case 0:
|
|
ucp->uc_mcontext.gregs[REG_RDI] = va_arg (ap, long int);
|
|
break;
|
|
case 1:
|
|
ucp->uc_mcontext.gregs[REG_RSI] = va_arg (ap, long int);
|
|
break;
|
|
case 2:
|
|
ucp->uc_mcontext.gregs[REG_RDX] = va_arg (ap, long int);
|
|
break;
|
|
case 3:
|
|
ucp->uc_mcontext.gregs[REG_RCX] = va_arg (ap, long int);
|
|
break;
|
|
case 4:
|
|
ucp->uc_mcontext.gregs[REG_R8] = va_arg (ap, long int);
|
|
break;
|
|
case 5:
|
|
ucp->uc_mcontext.gregs[REG_R9] = va_arg (ap, long int);
|
|
break;
|
|
default:
|
|
/* Put value on stack. */
|
|
sp[i - 5] = va_arg (ap, unsigned long int);
|
|
break;
|
|
}
|
|
va_end (ap);
|
|
|
|
}
|
|
|
|
|
|
weak_alias (__makecontext, makecontext)
|