/*
 * Copyright (c) 2002 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD$
 */

#include <sys/types.h>

#include <assert.h>
#include <dlfcn.h>
#include <stdlib.h>

#include <machine/elf.h>

#ifndef PT_IA_64_UNWIND
#define PT_IA_64_UNWIND         0x70000001
#endif

#define	SANITY	0

struct ia64_unwind_entry
{
	Elf64_Addr start;
	Elf64_Addr end;
	Elf64_Addr descr;
};

struct ia64_unwind_entry *
_Unwind_FindTableEntry(const void *pc, unsigned long *pseg, unsigned long *pgp)
{
	Dl_info info;
	Elf_Dyn *dyn;
	Elf_Ehdr *ehdr;
	Elf_Phdr *phdr;
	char *p, *p_top;
	struct ia64_unwind_entry *unw, *res;
	register unsigned long gp __asm__("gp");	/* XXX assumes gcc */
	unsigned long reloc, vaddr;
	size_t l, m, r;

	if (!dladdr(pc, &info))
		return NULL;

	ehdr = (Elf_Ehdr*)info.dli_fbase;

#if SANITY
	assert(IS_ELF(*ehdr));
	assert(ehdr->e_ident[EI_CLASS] == ELFCLASS64);
	assert(ehdr->e_ident[EI_DATA] == ELFDATA2LSB);
	assert(ehdr->e_machine == EM_IA_64);
#endif

	reloc = (ehdr->e_type == ET_DYN) ? (uintptr_t)info.dli_fbase : 0;
	*pgp = gp;
	*pseg = 0UL;
	res = NULL;

	p = (char*)info.dli_fbase + ehdr->e_phoff;
	p_top = p + ehdr->e_phnum * ehdr->e_phentsize;
	while (p < p_top) {
		phdr = (Elf_Phdr*)p;
		vaddr = phdr->p_vaddr + reloc;

		switch (phdr->p_type) {
		case PT_DYNAMIC:
			dyn = (Elf_Dyn*)vaddr;
			while (dyn->d_tag != DT_NULL) {
				if (dyn->d_tag == DT_PLTGOT) {
					*pgp = dyn->d_un.d_ptr + reloc;
					break;
				}
				dyn++;
			}
			break;
		case PT_LOAD:
			if (pc >= (void*)vaddr &&
			    pc < (void*)(vaddr + phdr->p_memsz))
				*pseg = vaddr;
			break;
		case PT_IA_64_UNWIND:
#if SANITY
			assert(*pseg != 0UL);
			assert(res == NULL);
#endif
			unw = (struct ia64_unwind_entry*)vaddr;
			l = 0;
			r = phdr->p_memsz / sizeof(struct ia64_unwind_entry);
			while (l < r) {
				m = (l + r) >> 1;
				res = unw + m;
				if (pc < (void*)(res->start + *pseg))
					r = m;
				else if (pc >= (void*)(res->end + *pseg))
					l = m + 1;
				else
					break;	/* found */
			}
			if (l >= r)
				res = NULL;
			break;
		}

		p += ehdr->e_phentsize;
	}

	return res;
}