forked from ariadne/libucontext
69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
/*
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* Copyright (c) 2018, 2020 Ariadne Conill <ariadne@dereferenced.org>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* This software is provided 'as is' and without any warranty, express or
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* implied. In no event shall the authors be liable for any damages arising
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* from the use of this software.
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*/
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#include <stddef.h>
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#include <stdarg.h>
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#include <string.h>
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#include <stdint.h>
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#include "defs.h"
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#include <libucontext/libucontext.h>
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extern void libucontext_trampoline(void);
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extern int libucontext_setcontext(const libucontext_ucontext_t *ucp);
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void
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libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(void), int argc, ...)
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{
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libucontext_greg_t *sp;
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va_list va;
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int i;
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sp = (libucontext_greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
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sp = (libucontext_greg_t *) (((uintptr_t) sp & -8L));
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ucp->uc_mcontext.gregs[7] = (uintptr_t) func;
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ucp->uc_mcontext.gregs[8] = (uintptr_t) ucp->uc_link;
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ucp->uc_mcontext.gregs[9] = (uintptr_t) &libucontext_setcontext;
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ucp->uc_mcontext.gregs[14] = (uintptr_t) &libucontext_trampoline;
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va_start(va, argc);
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for (i = 0; i < argc && i < 5; i++)
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ucp->uc_mcontext.gregs[i + 2] = va_arg (va, libucontext_greg_t);
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if (argc > 5)
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{
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sp -= argc - 5;
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for (i = 5; i < argc; i++)
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sp[i - 5] = va_arg (va, libucontext_greg_t);
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}
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va_end(va);
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/* make room for backchain / register save area */
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sp -= 20;
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*sp = 0;
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/* set up %r15 as sp */
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ucp->uc_mcontext.gregs[15] = (uintptr_t) sp;
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}
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#ifdef EXPORT_UNPREFIXED
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extern __typeof(libucontext_makecontext) makecontext __attribute__((weak, __alias__("libucontext_makecontext")));
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extern __typeof(libucontext_makecontext) __makecontext __attribute__((weak, __alias__("libucontext_makecontext")));
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#endif
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