114 lines
3.4 KiB
C
114 lines
3.4 KiB
C
/* Create new context.
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Copyright (C) 2002 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Andreas Jaeger <aj@suse.de>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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#include <stdarg.h>
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#include <ucontext.h>
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#include "ucontext_i.h"
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/* This implementation can handle any ARGC value but only
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normal integer parameters.
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makecontext sets up a stack and the registers for the
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user context. The stack looks like this:
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+-----------------------+
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| next context |
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+-----------------------+
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| parameter 7-n |
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+-----------------------+
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| trampoline address |
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%rsp -> +-----------------------+
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The registers are set up like this:
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%rdi,%rsi,%rdx,%rcx,%r8,%r9: parameter 1 to 6
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%rbx : address of next context
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%rsp : stack pointer.
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*/
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/* XXX: This implementation currently only handles integer arguments.
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To handle long int and pointer arguments the va_arg arguments needs
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to be changed to long and also the stdlib/tst-setcontext.c file needs
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to be changed to pass long arguments to makecontext. */
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void
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__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
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{
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extern void __start_context (void);
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unsigned long *sp, idx_uc_link;
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va_list ap;
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int i;
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/* Generate room on stack for parameter if needed and uc_link. */
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sp = (long *) ((long) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
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sp -= (argc > 6 ? argc : 0) + 1;
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/* Align stack. */
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sp = (long *) (((long) sp) & -16L);
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/* Make space for trampoline address. */
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sp -= 8;
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idx_uc_link = (argc > 6 ? argc : 0) + 1;
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/* Setup context ucp. */
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/* Address to jump to. */
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ucp->uc_mcontext.gregs[REG_RIP] = (long) func;
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/* Setup rbx.*/
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ucp->uc_mcontext.gregs[REG_RBX] = (long) &sp[idx_uc_link];
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ucp->uc_mcontext.gregs[REG_RSP] = (long) sp;
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/* Setup stack. */
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sp[0] = (long) &__start_context;
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sp[idx_uc_link] = (long) ucp->uc_link;
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va_start (ap, argc);
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/* Handle arguments. */
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for (i = 0; i < argc; ++i)
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switch (i)
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{
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case 0:
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ucp->uc_mcontext.gregs [REG_RDI] = va_arg (ap, int);
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break;
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case 1:
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ucp->uc_mcontext.gregs [REG_RSI] = va_arg (ap, int);
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break;
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case 2:
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ucp->uc_mcontext.gregs [REG_RDX] = va_arg (ap, int);
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break;
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case 3:
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ucp->uc_mcontext.gregs [REG_RCX] = va_arg (ap, int);
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break;
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case 4:
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ucp->uc_mcontext.gregs [REG_R8] = va_arg (ap, int);
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break;
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case 5:
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ucp->uc_mcontext.gregs [REG_R9] = va_arg (ap, int);
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break;
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default:
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/* Put value on stack. */
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sp[8 + (i - 5)] = va_arg (ap, int);
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break;
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}
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va_end (ap);
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}
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weak_alias(__makecontext, makecontext)
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