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File: [cvs.NetBSD.org] / src / sys / ddb / db_elf.c (download)

Revision 1.11.4.1, Wed Jul 12 21:49:06 2000 UTC (20 years, 3 months ago) by jhawk
Branch: netbsd-1-5
CVS Tags: netbsd-1-5-RELEASE, netbsd-1-5-PATCH003, netbsd-1-5-PATCH002, netbsd-1-5-PATCH001, netbsd-1-5-BETA2, netbsd-1-5-BETA, netbsd-1-5-ALPHA2
Changes since 1.11: +14 -40 lines

Pullup rev 1.12, approved by thorpej:
  Detect ELF sections (string and symbol tables) by looking them
  up by name (in .shstrtab) instead of guessing based on section
  type (and throwing away the small one). In addition to being cleaner,
  multiple symbol tables are no longer and error condition, so
  booting netbsd.gdb no longer results in ddb being unable to use
  *any* symbols.

/*	$NetBSD: db_elf.c,v 1.11.4.1 2000/07/12 21:49:06 jhawk Exp $	*/

/*-
 * Copyright (c) 1997 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>  
#include <sys/proc.h>

#include <machine/db_machdep.h>

#include <ddb/db_sym.h>
#include <ddb/db_output.h>
#include <ddb/db_extern.h>

#ifdef DB_ELF_SYMBOLS

#ifndef DB_ELFSIZE
#error Must define DB_ELFSIZE!
#endif

#define	ELFSIZE		DB_ELFSIZE

#include <sys/exec_elf.h>

static char *db_elf_find_strtab __P((db_symtab_t *));

#define	STAB_TO_SYMSTART(stab)	((Elf_Sym *)((stab)->start))
#define	STAB_TO_SYMEND(stab)	((Elf_Sym *)((stab)->end))
#define	STAB_TO_EHDR(stab)	((Elf_Ehdr *)((stab)->private))
#define	STAB_TO_SHDR(stab, e)	((Elf_Shdr *)((stab)->private + (e)->e_shoff))

boolean_t	db_elf_sym_init __P((int, void *, void *, const char *));
db_sym_t	db_elf_lookup __P((db_symtab_t *, char *));
db_sym_t	db_elf_search_symbol __P((db_symtab_t *, db_addr_t,
		    db_strategy_t, db_expr_t *));
void		db_elf_symbol_values __P((db_symtab_t *, db_sym_t,
		    char **, db_expr_t *));
boolean_t	db_elf_line_at_pc __P((db_symtab_t *, db_sym_t,
		    char **, int *, db_expr_t));
boolean_t	db_elf_sym_numargs __P((db_symtab_t *, db_sym_t, int *,
		    char **));
void		db_elf_forall __P((db_symtab_t *,
		    db_forall_func_t db_forall_func, void *));

db_symformat_t db_symformat_elf = {
	"ELF",
	db_elf_sym_init,
	db_elf_lookup,
	db_elf_search_symbol,
	db_elf_symbol_values,
	db_elf_line_at_pc,
	db_elf_sym_numargs,
	db_elf_forall
};

/*
 * Find the symbol table and strings; tell ddb about them.
 */
boolean_t
db_elf_sym_init(symsize, symtab, esymtab, name)
	int symsize;		/* size of symbol table */
	void *symtab;		/* pointer to start of symbol table */
	void *esymtab;		/* pointer to end of string table,
				   for checking - rounded up to integer
				   boundary */
	const char *name;
{
	Elf_Ehdr *elf;
	Elf_Shdr *shp;
	Elf_Sym *symp, *symtab_start, *symtab_end;
	char *shstrtab, *strtab_start, *strtab_end;
	int i;

	if (ALIGNED_POINTER(symtab, long) == 0) {
		printf("[ %s symbol table has bad start address %p ]\n",
		    name, symtab);
		return (FALSE);
	}

	symtab_start = symtab_end = NULL;
	strtab_start = strtab_end = NULL;

	/*
	 * The format of the symbols loaded by the boot program is:
	 *
	 *	Elf exec header
	 *	first section header
	 *	. . .
	 *	. . .
	 *	last section header
	 *	first symbol or string table section
	 *	. . .
	 *	. . .
	 *	last symbol or string table section
	 */

	/*
	 * Validate the Elf header.
	 */
	elf = (Elf_Ehdr *)symtab;
	if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 ||
	    elf->e_ident[EI_CLASS] != ELFCLASS)
		goto badheader;

	switch (elf->e_machine) {

	ELFDEFNNAME(MACHDEP_ID_CASES)

	default:
		goto badheader;
	}

	/*
	 * Find the section header string table (.shstrtab), and look up
	 * the symbol table (.symtab) and string table (.strtab) via their
	 * names in shstrtab, rather than by table type.
	 * This works in the presence of multiple string tables, such as
	 * stabs data found when booting netbsd.gdb.
	 */
	shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff);
	shstrtab = (char*)symtab + shp[elf->e_shstrndx].sh_offset;
	for (i = 0; i < elf->e_shnum; i++) {
		if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) {
			strtab_start = (char *)symtab + shp[i].sh_offset;
			strtab_end = (char *)symtab + shp[i].sh_offset +
			    shp[i].sh_size;
		} else if (strcmp(".symtab", shstrtab+shp[i].sh_name) == 0) {
			symtab_start = (Elf_Sym *)((char *)symtab + 
			    shp[i].sh_offset);
			symtab_end = (Elf_Sym *)((char *)symtab + 
			    shp[i].sh_offset + shp[i].sh_size);
		}
	}

	/*
	 * Now, sanity check the symbols against the string table.
	 */
	if (symtab_start == NULL || strtab_start == NULL ||
	    ALIGNED_POINTER(symtab_start, long) == 0 ||
	    ALIGNED_POINTER(strtab_start, long) == 0)
		goto badheader;
	for (symp = symtab_start; symp < symtab_end; symp++)
		if (symp->st_name + strtab_start > strtab_end)
			goto badheader;

	/*
	 * Link the symbol table into the debugger.
	 */
	if (db_add_symbol_table((char *)symtab_start,
	    (char *)symtab_end, name, (char *)symtab) != -1) {
		printf("[ preserving %lu bytes of %s ELF symbol table ]\n",
		    (u_long)roundup(((char *)esymtab - (char *)symtab), 
				    sizeof(u_long)), name);
		return (TRUE);
	}

	return (FALSE);

 badheader:
	printf("[ %s ELF symbol table not valid ]\n", name);
	return (FALSE);
}

/*
 * Internal helper function - return a pointer to the string table
 * for the current symbol table.
 */
static char *
db_elf_find_strtab(stab)
	db_symtab_t *stab;
{
	Elf_Ehdr *elf = STAB_TO_EHDR(stab);
	Elf_Shdr *shp = STAB_TO_SHDR(stab, elf);
	char *shstrtab;
	int i;

	shstrtab = (char*)elf + shp[elf->e_shstrndx].sh_offset;
	for (i = 0; i < elf->e_shnum; i++) {
		if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0)
			return ((char*)elf + shp[i].sh_offset);
	}

	return (NULL);
}

/*
 * Lookup the symbol with the given name.
 */
db_sym_t
db_elf_lookup(stab, symstr)
	db_symtab_t *stab;
	char *symstr;
{
	Elf_Sym *symp, *symtab_start, *symtab_end;
	char *strtab;

	symtab_start = STAB_TO_SYMSTART(stab);
	symtab_end = STAB_TO_SYMEND(stab);

	strtab = db_elf_find_strtab(stab);
	if (strtab == NULL)
		return ((db_sym_t)0);

	for (symp = symtab_start; symp < symtab_end; symp++) {
		if (symp->st_name != 0 &&
		    db_eqname(strtab + symp->st_name, symstr, 0))
			return ((db_sym_t)symp);
	}

	return ((db_sym_t)0);
}

/*
 * Search for the symbol with the given address (matching within the
 * provided threshold).
 */
db_sym_t
db_elf_search_symbol(symtab, off, strategy, diffp)
	db_symtab_t *symtab;
	db_addr_t off;
	db_strategy_t strategy;
	db_expr_t *diffp;		/* in/out */
{
	Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end;
	db_expr_t diff = *diffp;

	symtab_start = STAB_TO_SYMSTART(symtab);
	symtab_end = STAB_TO_SYMEND(symtab);

	rsymp = NULL;

	for (symp = symtab_start; symp < symtab_end; symp++) {
		if (symp->st_name == 0)
			continue;
#if 0
		/* This prevents me from seeing anythin in locore.s -- eeh */
		if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object &&
		    ELF_SYM_TYPE(symp->st_info) != Elf_estt_func)
			continue;
#endif

		if (off >= symp->st_value) {
			if ((off - symp->st_value) < diff) {
				diff = off - symp->st_value;
				rsymp = symp;
				if (diff == 0) {
					if (strategy == DB_STGY_PROC &&
					    ELFDEFNNAME(ST_TYPE)(symp->st_info)
					      == STT_FUNC &&
					    ELFDEFNNAME(ST_BIND)(symp->st_info)
					      != STB_LOCAL)
						break;
					if (strategy == DB_STGY_ANY &&
					    ELFDEFNNAME(ST_BIND)(symp->st_info)
					      != STB_LOCAL)
						break;
				}
			} else if ((off - symp->st_value) == diff) {
				if (rsymp == NULL)
					rsymp = symp;
				else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info)
				      == STB_LOCAL &&
				    ELFDEFNNAME(ST_BIND)(symp->st_info)
				      != STB_LOCAL) {
					/* pick the external symbol */
					rsymp = symp;
				}
			}
		}
	}

	if (rsymp == NULL)
		*diffp = off;
	else
		*diffp = diff;

	return ((db_sym_t)rsymp);
}

/*
 * Return the name and value for a symbol.
 */
void
db_elf_symbol_values(symtab, sym, namep, valuep)
	db_symtab_t *symtab;
	db_sym_t sym;
	char **namep;
	db_expr_t *valuep;
{
	Elf_Sym *symp = (Elf_Sym *)sym;
	char *strtab;

	if (namep) {
		strtab = db_elf_find_strtab(symtab);
		if (strtab == NULL)
			*namep = NULL;
		else
			*namep = strtab + symp->st_name;
	}

	if (valuep)
		*valuep = symp->st_value;
}

/*
 * Return the file and line number of the current program counter
 * if we can find the appropriate debugging symbol.
 */
boolean_t
db_elf_line_at_pc(symtab, cursym, filename, linenum, off)
	db_symtab_t *symtab;
	db_sym_t cursym;
	char **filename;
	int *linenum;
	db_expr_t off;
{

	/*
	 * XXX We don't support this (yet).
	 */
	return (FALSE);
}

/*
 * Returns the number of arguments to a function and their
 * names if we can find the appropriate debugging symbol.
 */
boolean_t
db_elf_sym_numargs(symtab, cursym, nargp, argnamep)
	db_symtab_t *symtab;
	db_sym_t cursym;
	int *nargp;
	char **argnamep;
{

	/*
	 * XXX We don't support this (yet).
	 */
	return (FALSE);
}

void
db_elf_forall(stab, db_forall_func, arg)
	db_symtab_t *stab;
	db_forall_func_t db_forall_func;
	void *arg;
{
	char *strtab;
	static char suffix[2];
	Elf_Sym *symp, *symtab_start, *symtab_end;

	symtab_start = STAB_TO_SYMSTART(stab);
	symtab_end = STAB_TO_SYMEND(stab);

	strtab = db_elf_find_strtab(stab);
	if (strtab == NULL)
		return;

	for (symp = symtab_start; symp < symtab_end; symp++)
		if (symp->st_name != 0) {
			suffix[1] = '\0';
			switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) {
			case STT_OBJECT:
				suffix[0] = '+';
				break;
			case STT_FUNC:
				suffix[0] = '*';
				break;
			case STT_SECTION:
				suffix[0] = '&';
				break;
			case STT_FILE:
				suffix[0] = '/';
				break;
			default:
				suffix[0] = '\0';
			}
			(*db_forall_func)(stab, (db_sym_t)symp,
			    strtab + symp->st_name, suffix, 0, arg);
		}
	return;
}
#endif /* DB_ELF_SYMBOLS */