libucontext/arch/ppc64/makecontext.c

77 lines
1.8 KiB
C

/*
* Copyright (c) 2018 William Pitcock <nenolod@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 "defs.h"
extern void __start_context(void);
void
__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
{
greg_t *sp, *argp;
va_list va;
int i;
unsigned int uc_link, stack_args;
stack_args = argc > 8 ? argc - 8 : 0;
uc_link = stack_args + 1;
sp = (greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= (uc_link + 1);
sp = (greg_t *) (((uintptr_t) sp & -16L));
ucp->uc_mcontext.gp_regs[REG_NIP] = (uintptr_t) func;
ucp->uc_mcontext.gp_regs[REG_LNK] = (uintptr_t) &__start_context;
ucp->uc_mcontext.gp_regs[REG_SP] = (uintptr_t) sp;
ucp->uc_mcontext.gp_regs[REG_ENTRY] = (uintptr_t) func;
ucp->uc_mcontext.gp_regs[REG_R31] = (uintptr_t) ucp->uc_link;
sp[0] = (uintptr_t) &__start_context;
sp[uc_link] = (uintptr_t) ucp->uc_link;
argp = &sp[2];
va_start(va, argc);
for (i = 0; i < argc; i++)
switch (i)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
ucp->uc_mcontext.gp_regs[i + 3] = va_arg (va, greg_t);
break;
default:
*argp++ = va_arg (va, greg_t);
break;
}
va_end(va);
}
extern __typeof(__makecontext) makecontext __attribute__((weak, __alias__("__makecontext")));