libucontext/arch/arm/makecontext.c

66 lines
1.7 KiB
C

/*
* Copyright (c) 2018 Ariadne Conill <ariadne@dereferenced.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#define _GNU_SOURCE
#include <stddef.h>
#include <stdarg.h>
#include <signal.h>
#include <string.h>
#include <stdint.h>
#include <stdio.h>
extern void __start_context(void);
void
__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
{
unsigned long *sp;
unsigned long *regp;
va_list va;
int i;
sp = (unsigned long *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp = (unsigned long *) (((uintptr_t) sp & -16L) - 8);
if (argc > 4)
sp -= (argc - 4);
ucp->uc_mcontext.arm_sp = (uintptr_t) sp;
ucp->uc_mcontext.arm_pc = (uintptr_t) func;
ucp->uc_mcontext.arm_r4 = (uintptr_t) ucp->uc_link;
ucp->uc_mcontext.arm_lr = (uintptr_t) &__start_context;
va_start(va, argc);
regp = &(ucp->uc_mcontext.arm_r0);
for (i = 0; (i < argc && i < 4); i++)
*regp++ = va_arg (va, unsigned long);
for (; i < argc; i++)
*sp++ = va_arg (va, unsigned long);
va_end(va);
/*
printf("R4 offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_r4));
printf("SP offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_sp));
printf("LR offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_lr));
printf("PC offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_pc));
*/
}
extern __typeof(__makecontext) makecontext __attribute__((weak, __alias__("__makecontext")));