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[bitrig.git] / sys / ddb / db_elf.c

/*      $OpenBSD: db_elf.c,v 1.9 2008/06/26 05:42:14 ray Exp $  */
/*      $NetBSD: db_elf.c,v 1.13 2000/07/07 21:55:18 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.
 *
 * 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 <sys/exec.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(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(int, void *, void *, const char *);
db_sym_t        db_elf_lookup(db_symtab_t *, char *);
db_sym_t        db_elf_search_symbol(db_symtab_t *, db_addr_t,
                    db_strategy_t, db_expr_t *);
void            db_elf_symbol_values(db_symtab_t *, db_sym_t,
                    char **, db_expr_t *);
boolean_t       db_elf_line_at_pc(db_symtab_t *, db_sym_t,
                    char **, int *, db_expr_t);
boolean_t       db_elf_sym_numargs(db_symtab_t *, db_sym_t, int *,
                    char **);
void            db_elf_forall(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.
 *
 * symsize:     size of symbol table
 * symtab:      pointer to start of symbol table
 * esymtab:     pointer to end of string table, for checking - rounded up to
 *                  integer boundry
 */
boolean_t
db_elf_sym_init(int symsize, void *symtab, void *esymtab, const char *name)
{
        Elf_Ehdr *elf;
        Elf_Shdr *shp;
        Elf_Sym *symp, *symtab_start, *symtab_end;
        char *shstrtab, *strtab_start, *strtab_end;
        int i;
        char *errstr = "";

        if (ALIGNED_POINTER(symtab, long) == 0) {
                db_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) {
                errstr = "bad magic";
                goto badheader;
        }

        if (elf->e_machine != ELF_TARG_MACH) {
                errstr = "bad e_machine";
                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 bsd.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 (shp[i].sh_type == SHT_SYMTAB) {
                        int j;

                        if (shp[i].sh_offset == 0)
                                continue;
                        symtab_start = (Elf_Sym *)((char *)symtab +
                            shp[i].sh_offset);
                        symtab_end = (Elf_Sym *)((char *)symtab +
                            shp[i].sh_offset + shp[i].sh_size);
                        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;
                        break;
                }

                /*
                 * This is the old way of doing things.
                 * XXX - verify that it's not needed.
                 */
                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) {
                errstr = "symtab unaligned";
                goto badheader;
        }
        for (symp = symtab_start; symp < symtab_end; symp++)
                if (symp->st_name + strtab_start > strtab_end) {
                        errstr = "symtab corrupted";
                        goto badheader;
                }

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

        return (FALSE);

 badheader:
        db_printf("[ %s ELF symbol table not valid: %s ]\n", name, errstr);
        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);
        char *shstrtab;
        int i;

        shstrtab = (char *)elf + shp[elf->e_shstrndx].sh_offset;
        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);
                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(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(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_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(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(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(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(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 */