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find_exidx.c revision 1.3 
      1 /*-
      2  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to The NetBSD Foundation
      6  * by Matt Thomas of 3am Software Foundry.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27  * POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include <sys/cdefs.h>
     31 #ifndef lint
     32 __RCSID("$NetBSD: find_exidx.c,v 1.3 2013/05/03 10:27:06 skrll Exp $");
     33 #endif /* not lint */
     34 
     35 #include "debug.h"
     36 #include "rtld.h"
     37 
     38 _Unwind_Ptr
     39 __gnu_Unwind_Find_exidx(_Unwind_Ptr pc, int * pcount)
     40 {
     41 	const Obj_Entry *obj;
     42 	_Unwind_Ptr start = NULL;
     43 	int count = 0;
     44 
     45 	dbg(("__gnu_Unwind_Find_exidx"));
     46 
     47 	_rtld_shared_enter();
     48 
     49 	vaddr_t va = (vaddr_t)pc;
     50 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
     51 		/*
     52 		 * If the address we are looking for is inside this object,
     53 		 * we've found the object to inspect.
     54 		 */
     55 		if ((vaddr_t)obj->mapbase <= va
     56 		    && va < (vaddr_t)obj->mapbase + obj->mapsize)
     57 			break;
     58 	}
     59 
     60 	/*
     61 	 * If we found an object and it has some exception data, we
     62 	 * need to see if the address matches a PT_LOAD section.
     63 	 */
     64 	if (obj != NULL && obj->exidx_start != NULL) {
     65 		va -= (vaddr_t)obj->relocbase;
     66 		const Elf_Phdr *ph = obj->phdr;
     67 		const Elf_Phdr * const phlimit = ph + obj->phsize / sizeof(*ph);
     68 		for (; ph < phlimit; ph++) {
     69 			if (ph->p_type == PT_LOAD
     70 			    && ph->p_vaddr <= va
     71 			    && va < ph->p_vaddr + ph->p_memsz) {
     72 				count = obj->exidx_sz / 8;
     73 				start = obj->exidx_start;
     74 				break;
     75 			}
     76 		}
     77 	}
     78 
     79 	_rtld_shared_exit();
     80 
     81 	/*
     82 	 * deal with the return values.
     83 	 */
     84 	*pcount = count;
     85 	return start;
     86 }
     87