libucontext/arch/or1k/makecontext.c

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2022-02-13 08:58:03 +00:00
/*
* Copyright (c) 2022 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.
*/
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <stdint.h>
#include <stdio.h>
#include "defs.h"
#include <libucontext/libucontext.h>
extern void libucontext_trampoline(void);
void
libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(void), int argc, ...)
{
libucontext_greg_t *sp;
va_list va;
int i;
/* set up and align the stack. */
sp = (libucontext_greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= argc < 6 ? 0 : (argc - 6);
sp = (libucontext_greg_t *) (((uintptr_t) sp & ~0x3));
/* set up the ucontext structure */
ucp->uc_mcontext.regs.gpr[REG_SP] = (libucontext_greg_t) sp;
ucp->uc_mcontext.regs.gpr[REG_RA] = (libucontext_greg_t) &libucontext_trampoline;
ucp->uc_mcontext.regs.gpr[REG_FP] = 0;
ucp->uc_mcontext.regs.gpr[REG_SA] = (libucontext_greg_t) func;
ucp->uc_mcontext.regs.gpr[REG_LR] = (libucontext_greg_t) ucp->uc_link;
va_start(va, argc);
/* args less than argv[6] have dedicated registers, else they overflow onto stack */
for (i = 0; i < argc; i++)
{
if (i < 6)
ucp->uc_mcontext.regs.gpr[i + 3] = va_arg (va, libucontext_greg_t);
else
sp[i - 6] = va_arg (va, libucontext_greg_t);
}
va_end(va);
}
#ifdef EXPORT_UNPREFIXED
extern __typeof(libucontext_makecontext) makecontext __attribute__((weak, __alias__("libucontext_makecontext")));
extern __typeof(libucontext_makecontext) __makecontext __attribute__((weak, __alias__("libucontext_makecontext")));
#endif