libucontext/arch/ppc64/makecontext.c

61 lines
1.6 KiB
C

/*
* Copyright (c) 2018 Ariadne Conill <ariadne@dereferenced.org>
* Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
*
* 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 <stdarg.h>
#include <stdint.h>
#include "defs.h"
extern void libucontext_trampoline(void);
void
libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(), int argc, ...)
{
libucontext_greg_t *sp;
va_list va;
int i;
unsigned int stack_args;
stack_args = argc > 8 ? argc : 0;
sp = (libucontext_greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= stack_args + 4;
sp = (libucontext_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) &libucontext_trampoline;
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] = 0;
va_start(va, argc);
for (i = 0; i < argc; i++) {
if (i < 8)
ucp->uc_mcontext.gp_regs[i + 3] = va_arg (va, libucontext_greg_t);
else
sp[i + 4] = va_arg (va, libucontext_greg_t);
}
va_end(va);
}
extern __typeof(libucontext_makecontext) makecontext __attribute__((weak, __alias__("libucontext_makecontext")));