/* $NetBSD: db_elf.c,v 1.29 2017/11/06 04:08:02 christos Exp $ */
/*-
* Copyright (c) 1997, 2009 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, and by Andrew Doran.
*
* 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 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: db_elf.c,v 1.29 2017/11/06 04:08:02 christos Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <machine/db_machdep.h>
#include <machine/pmap.h>
#include <machine/vmparam.h>
#ifdef DB_ELF_SYMBOLS
#include <ddb/ddb.h>
#include <sys/exec_elf.h>
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))
static bool db_elf_sym_init(int, void *, void *, const char *);
static db_sym_t db_elf_lookup(db_symtab_t *, const char *);
static db_sym_t db_elf_search_symbol(db_symtab_t *, db_addr_t, db_strategy_t,
db_expr_t *);
static void db_elf_symbol_values(db_symtab_t *, db_sym_t, const char **,
db_expr_t *);
static bool db_elf_line_at_pc(db_symtab_t *, db_sym_t, char **, int *,
db_expr_t);
static bool db_elf_sym_numargs(db_symtab_t *, db_sym_t, int *, char **);
static void db_elf_forall(db_symtab_t *, db_forall_func_t db_forall_func,
void *);
const 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
};
static db_symtab_t db_symtabs;
/*
* Add symbol table, with given name, to symbol tables.
*/
static int
db_add_symbol_table(char *start, char *end, const char *name, char *ref)
{
db_symtabs.start = start;
db_symtabs.end = end;
db_symtabs.name = name;
db_symtabs.private = ref;
return(0);
}
/*
* Find the symbol table and strings; tell ddb about them.
*/
static bool
db_elf_sym_init(
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 *strtab_start, *strtab_end;
int i, j;
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 first (and, we hope, only) SHT_SYMTAB section in
* the file, and the SHT_STRTAB section that goes with it.
*/
if (elf->e_shoff == 0)
goto badheader;
shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff);
for (i = 0; i < elf->e_shnum; i++) {
if (shp[i].sh_type == SHT_SYMTAB) {
if (shp[i].sh_offset == 0)
continue;
/* Got the symbol table. */
symtab_start = (Elf_Sym *)((char *)symtab +
shp[i].sh_offset);
symtab_end = (Elf_Sym *)((char *)symtab +
shp[i].sh_offset + shp[i].sh_size);
/* Find the string table to go with it. */
j = shp[i].sh_link;
if (shp[j].sh_offset == 0)
continue;
strtab_start = (char *)symtab + shp[j].sh_offset;
strtab_end = (char *)symtab + shp[j].sh_offset +
shp[j].sh_size;
/* There should only be one symbol table. */
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.
*/
if (db_add_symbol_table((char *)symtab_start,
(char *)symtab_end, name, (char *)symtab) != -1) {
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(db_symtab_t *stab)
{
Elf_Ehdr *elf = STAB_TO_EHDR(stab);
Elf_Shdr *shp = STAB_TO_SHDR(stab, elf);
int i;
stab = &db_symtabs;
/*
* We don't load ELF header for ELF modules.
* Find out if this is a loadable module. If so,
* string table comes right after symbol table.
*/
if ((Elf_Sym *)elf == STAB_TO_SYMSTART(stab)) {
return ((char *)STAB_TO_SYMEND(stab));
}
for (i = 0; i < elf->e_shnum; i++) {
if (shp[i].sh_type == SHT_SYMTAB)
return ((char*)elf + shp[shp[i].sh_link].sh_offset);
}
return (NULL);
}
/*
* Lookup the symbol with the given name.
*/
static db_sym_t
db_elf_lookup(db_symtab_t *stab, const char *symstr)
{
Elf_Sym *symp, *symtab_start, *symtab_end;
char *strtab;
stab = &db_symtabs;
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).
*/
static db_sym_t
db_elf_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strategy,
db_expr_t *diffp)
{
Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end;
db_addr_t diff = *diffp;
symtab = &db_symtabs;
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_ST_TYPE(symp->st_info) != STT_OBJECT &&
ELF_ST_TYPE(symp->st_info) != STT_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.
*/
static void
db_elf_symbol_values(db_symtab_t *symtab, db_sym_t sym, const char **namep,
db_expr_t *valuep)
{
Elf_Sym *symp = (Elf_Sym *)sym;
char *strtab;
symtab = &db_symtabs;
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.
*/
static bool
db_elf_line_at_pc(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.
*/
static bool
db_elf_sym_numargs(db_symtab_t *symtab, db_sym_t cursym, int *nargp,
char **argnamep)
{
/*
* XXX We don't support this (yet).
*/
return (false);
}
static void
db_elf_forall(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;
stab = &db_symtabs;
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 */