freebsd-dev/sys/ddb/db_elf.c

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/* $NetBSD: db_elf.c,v 1.4 1998/05/03 18:49:54 thorpej 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.
*/
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#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#ifdef DDB_NOKLDSYM
#include <sys/param.h>
#include <sys/systm.h>
#ifdef __i386__
#include <machine/bootinfo.h>
#endif
#include <ddb/ddb.h>
#include <ddb/db_sym.h>
#include <machine/elf.h>
#ifndef _ALIGNED_POINTER
#define _ALIGNED_POINTER(ptr, type) 1
#endif
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static char *db_elf_find_strtab(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))
void X_db_sym_init(void *symtab, void *esymtab, char *name);
/*
* Find the symbol table and strings; tell ddb about them.
*/
void
X_db_sym_init(symtab, esymtab, name)
void *symtab; /* pointer to start of symbol table */
void *esymtab; /* pointer to end of string table,
for checking - rounded up to integer
boundary */
char *name;
{
Elf_Ehdr *elf;
Elf_Shdr *shp;
Elf_Sym *symp, *symtab_start, *symtab_end;
char *strtab_start, *strtab_end;
int i;
if (_ALIGNED_POINTER(symtab, long) == 0) {
printf("DDB: bad symbol table start address %p\n", symtab);
return;
}
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 (elf->e_ident[EI_MAG0] != ELFMAG0
|| elf->e_ident[EI_MAG1] != ELFMAG1
|| elf->e_ident[EI_MAG2] != ELFMAG2
|| elf->e_ident[EI_MAG3] != ELFMAG3)
goto badheader;
if (!ELF_MACHINE_OK(elf->e_machine))
goto badheader;
/*
* We need to avoid the section header string table (small string
* table which names the sections). We do this by assuming that
* the following two conditions will be true:
*
* (1) .shstrtab will be smaller than one page.
* (2) .strtab will be larger than one page.
*
* When we encounter what we think is the .shstrtab, we change
* its section type Elf_sht_null so that it will be ignored
* later.
*/
shp = (Elf_Shdr *)((char*)symtab + elf->e_shoff);
for (i = 0; i < elf->e_shnum; i++) {
if (shp[i].sh_addr || i == elf->e_shstrndx)
continue;
switch (shp[i].sh_type) {
case SHT_STRTAB:
if (shp[i].sh_size < PAGE_SIZE) {
shp[i].sh_type = SHT_NULL;
continue;
}
if (strtab_start != NULL)
goto multiple_strtab;
strtab_start = (char *)symtab + shp[i].sh_offset;
strtab_end = (char *)symtab + shp[i].sh_offset +
shp[i].sh_size;
break;
case SHT_SYMTAB:
if (symtab_start != NULL)
goto multiple_symtab;
symtab_start = (Elf_Sym *)((char*)symtab + shp[i].sh_offset);
symtab_end = (Elf_Sym *)((char*)symtab + shp[i].sh_offset +
shp[i].sh_size);
break;
default:
/* Ignore all other sections. */
break;
}
}
/*
* 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.
*/
db_add_symbol_table((char *)symtab_start,
(char *)symtab_end, name, (char *)symtab);
printf("[ preserving %lu bytes of %s symbol table ]\n",
(u_long)roundup(((char*)esymtab - (char*)symtab), sizeof(u_long)), name);
return;
badheader:
printf("[ %s symbol table not valid ]\n", name);
return;
multiple_strtab:
printf("[ %s has multiple string tables ]\n", name);
return;
multiple_symtab:
printf("[ %s has multiple symbol tables ]\n", name);
return;
}
/*
* 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);
int i;
for (i = 0; i < elf->e_shnum; i++) {
if (shp[i].sh_type == SHT_STRTAB
&& !shp[i].sh_addr && i != elf->e_shstrndx)
return (stab->private + shp[i].sh_offset);
}
return (NULL);
}
/*
* Lookup the symbol with the given name.
*/
c_db_sym_t
X_db_lookup(stab, symstr)
db_symtab_t *stab;
const 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).
*/
c_db_sym_t
X_db_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 (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 &&
ELF_ST_TYPE(symp->st_info) ==
STT_FUNC &&
ELF_ST_BIND(symp->st_info) !=
STB_LOCAL)
break;
if (strategy == DB_STGY_ANY &&
ELF_ST_BIND(symp->st_info) !=
STB_LOCAL)
break;
}
} else if ((off - symp->st_value) == diff) {
if (rsymp == NULL)
rsymp = symp;
else if (ELF_ST_BIND(rsymp->st_info) ==
STB_LOCAL &&
ELF_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
X_db_symbol_values(symtab, sym, namep, valuep)
db_symtab_t *symtab;
c_db_sym_t sym;
const char **namep;
db_expr_t *valuep;
{
const Elf_Sym *symp = (const 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
X_db_line_at_pc(symtab, cursym, filename, linenum, off)
db_symtab_t *symtab;
c_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
X_db_sym_numargs(symtab, cursym, nargp, argnamep)
db_symtab_t *symtab;
c_db_sym_t cursym;
int *nargp;
char **argnamep;
{
/*
* XXX We don't support this (yet).
*/
return (FALSE);
}
/*
* Initialization routine for Elf files.
*/
#ifdef __i386__
void *ksym_start, *ksym_end;
#else
extern void *ksym_start, *ksym_end;
#endif
void
kdb_init(void)
{
static Elf_Ehdr elf;
static Elf_Shdr sh[2];
#ifdef __i386__
ksym_start = (void *)bootinfo.bi_symtab;
ksym_end = (void *)bootinfo.bi_esymtab;
#endif
if (ksym_end <= ksym_start)
return;
/*
* The FreeBSD boot program doesn't actually load any headers, so
* fake just enough for the routines in this file to work.
*/
elf.e_ident[EI_MAG0] = ELFMAG0;
elf.e_ident[EI_MAG1] = ELFMAG1;
elf.e_ident[EI_MAG2] = ELFMAG2;
elf.e_ident[EI_MAG3] = ELFMAG3;
elf.e_machine = EM_486;
elf.e_shoff = (uintptr_t)(void *)&sh[0] - (uintptr_t)(void *)&elf;
sh[0].sh_type = SHT_SYMTAB;
sh[0].sh_offset = (uintptr_t)ksym_start + sizeof(long) -
(uintptr_t)(void *)&elf;
sh[0].sh_size = *(int *)ksym_start;
sh[1].sh_type = SHT_STRTAB;
sh[1].sh_offset = sh[0].sh_offset + sh[0].sh_size + sizeof(long);
sh[1].sh_size = (uintptr_t)ksym_end - (uintptr_t)ksym_start -
sizeof(long) - sh[0].sh_size - sizeof(long);
elf.e_shstrndx = -1;
elf.e_shnum = 2;
X_db_sym_init(&elf, ksym_end, "kernel");
}
#endif /* DDB_NOKLDSYM */