66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
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/*
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* Copyright (c) 2018 William Pitcock <nenolod@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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#define _GNU_SOURCE
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#include <stddef.h>
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#include <stdarg.h>
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#include <signal.h>
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#include <string.h>
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#include <stdint.h>
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#include <stdio.h>
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extern void __start_context(void);
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void
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__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
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{
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unsigned long *sp;
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unsigned long *regp;
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va_list va;
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int i;
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sp = (unsigned long *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
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sp = (unsigned long *) (((uintptr_t) sp & -16L) - 8);
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if (argc > 4)
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sp -= (argc - 4);
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ucp->uc_mcontext.arm_sp = (uintptr_t) sp;
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ucp->uc_mcontext.arm_pc = (uintptr_t) func;
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ucp->uc_mcontext.arm_r4 = (uintptr_t) ucp->uc_link;
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ucp->uc_mcontext.arm_lr = (uintptr_t) &__start_context;
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va_start(va, argc);
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regp = &(ucp->uc_mcontext.arm_r0);
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for (i = 0; (i < argc && i < 4); i++)
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*regp++ = va_arg (va, unsigned long);
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for (; i < argc; i++)
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*sp++ = va_arg (va, unsigned long);
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va_end(va);
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/*
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printf("R4 offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_r4));
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printf("SP offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_sp));
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printf("LR offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_lr));
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printf("PC offset = %d\n", offsetof(ucontext_t, uc_mcontext.arm_pc));
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*/
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}
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extern __typeof(__makecontext) makecontext __attribute__((weak, __alias__("__makecontext")));
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