/* Copyright (C) 2012 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 <http://www.gnu.org/licenses/>. */ #include <stdarg.h> #include <ucontext.h> /* Number of arguments that go in registers. */ #define NREG_ARGS 4 /* Take a context previously prepared via getcontext() and set to call func() with the given int only args. */ void __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) { extern void __startcontext (void); unsigned long *funcstack; va_list vl; unsigned long *regptr; unsigned int reg; int misaligned; /* Start at the top of stack. */ funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); /* Ensure the stack stays eight byte aligned. */ misaligned = ((unsigned long) funcstack & 4) != 0; if ((argc > NREG_ARGS) && (argc & 1) != 0) misaligned = !misaligned; if (misaligned) funcstack -= 1; va_start (vl, argc); /* Reserve space for the on-stack arguments. */ if (argc > NREG_ARGS) funcstack -= (argc - NREG_ARGS); ucp->uc_mcontext.arm_sp = (unsigned long) funcstack; ucp->uc_mcontext.arm_pc = (unsigned long) func; /* Exit to startcontext() with the next context in R4 */ ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link; ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext; /* The first four arguments go into registers. */ regptr = &(ucp->uc_mcontext.arm_r0); for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++) *regptr++ = va_arg (vl, unsigned long); /* And the remainder on the stack. */ for (; reg < argc; reg++) *funcstack++ = va_arg (vl, unsigned long); va_end (vl); } weak_alias (__makecontext, makecontext)