ddb: add support for ELF symbol tables

* ddb/db_elf.c: New file.
* ddb/db_elf.h: Likewise.
* Makefrag.am (libkernel_a_SOURCES): Add db_elf.{c,h}.
* ddb/db_sym.c (dummy_db_sym_init): New stub db_sym_init function.
(db_sym_switch): Add ELF functions.
* ddb/db_sym.h (SYMTAB_ELF): New macro.
(elf_db_sym_init): New declaration.
* i386/i386at/model_dep.c (c_boot_entry): Get ELF section header
information from the multiboot structure, and call elf_db_sym_init.

6 files changed, 335 insertions, 1 deletions

diff --git a/Makefrag.am b/Makefrag.am
index d6dd77f..5e98b21 100644
--- a/Makefrag.am
+++ b/Makefrag.am
@@ -25,6 +25,8 @@ libkernel_a_SOURCES += \
 	ddb/db_access.h \
 	ddb/db_aout.c \
 	ddb/db_aout.h \
+	ddb/db_elf.c \
+	ddb/db_elf.h \
 	ddb/db_break.c \
 	ddb/db_break.h \
 	ddb/db_command.c \
diff --git a/ddb/db_elf.c b/ddb/db_elf.c
new file mode 100644
index 0000000..10e7162
--- /dev/null
+++ b/ddb/db_elf.c
@@ -0,0 +1,232 @@
+/*
+ * Copyright (C) 2014 Free Software Foundation, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ *
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ *
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * Carnegie Mellon requests users of this software to return to
+ *
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ *
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+ *	Author: David B. Golub, Carnegie Mellon University
+ *	Date:	7/90
+ */
+
+#if MACH_KDB
+
+/*
+ * Symbol table routines for ELF format files.
+ */
+
+#include <string.h>
+#include <mach/std_types.h>
+#include <mach/exec/elf.h>
+#include <machine/db_machdep.h>		/* data types */
+#include <machine/vm_param.h>
+#include <ddb/db_output.h>
+#include <ddb/db_sym.h>
+#include <ddb/db_elf.h>
+
+#ifndef	DB_NO_ELF
+
+struct db_symtab_elf {
+  int		type;
+  Elf32_Sym	*start;
+  Elf32_Sym	*end;
+  char		*strings;
+  char		*map_pointer;	/* symbols are for this map only,
+				   if not null */
+  char		name[SYMTAB_NAME_LEN];
+  /* symtab name */
+};
+
+boolean_t
+elf_db_sym_init (unsigned shdr_num,
+		 vm_size_t shdr_size,
+		 vm_offset_t shdr_addr,
+		 unsigned shdr_shndx,
+		 char *name,
+		 char *task_addr)
+{
+  Elf32_Shdr *shdr, *symtab, *strtab;
+  const char *shstrtab;
+  int i;
+
+  if (shdr_num == 0)
+    return FALSE;
+
+  if (shdr_size != sizeof *shdr)
+    return FALSE;
+
+  shdr = (Elf32_Shdr *) shdr_addr;
+
+  if (shdr[shdr_shndx].sh_type != SHT_STRTAB)
+    return FALSE;
+
+  shstrtab = (const char *) phystokv (shdr[shdr_shndx].sh_addr);
+
+  symtab = strtab = NULL;
+  for (i = 0; i < shdr_num; i++)
+    switch (shdr[i].sh_type) {
+    case SHT_SYMTAB:
+      if (symtab)
+	db_printf ("Ignoring additional ELF symbol table at %d\n", i);
+      else
+	symtab = &shdr[i];
+      break;
+
+    case SHT_STRTAB:
+      if (strcmp (&shstrtab[shdr[i].sh_name], ".strtab") == 0) {
+	if (strtab)
+	  db_printf ("Ignoring additional ELF string table at %d\n", i);
+	else
+	  strtab = &shdr[i];
+      }
+      break;
+    }
+
+  if (symtab == NULL || strtab == NULL)
+    return FALSE;
+
+  if (db_add_symbol_table (SYMTAB_ELF,
+			   (char *) phystokv (symtab->sh_addr),
+			   (char *) phystokv (symtab->sh_addr)+symtab->sh_size,
+			   name,
+			   (char *) phystokv (strtab->sh_addr),
+			   task_addr)) {
+    db_printf ("Loaded ELF symbol table for %s (%d symbols)\n",
+	       name, symtab->sh_size / sizeof (Elf32_Sym));
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+/*
+ * lookup symbol by name
+ */
+db_sym_t
+elf_db_lookup (db_symtab_t *stab,
+	       char *symstr)
+{
+  struct db_symtab_elf *self = (struct db_symtab_elf *) stab;
+  Elf32_Sym *s;
+
+  for (s = self->start; s < self->end; s++)
+    if (strcmp (symstr, &self->strings[s->st_name]) == 0)
+      return (db_sym_t) s;
+
+  return NULL;
+}
+
+db_sym_t
+elf_db_search_symbol (db_symtab_t *stab,
+		      db_addr_t off,
+		      db_strategy_t strategy,
+		      db_expr_t *diffp)	/* in/out */
+{
+  struct db_symtab_elf *self = (struct db_symtab_elf *) stab;
+  unsigned long	diff = *diffp;
+  Elf32_Sym *s, *symp = NULL;
+
+  for (s = self->start; s < self->end; s++) {
+    if (s->st_name == 0)
+      continue;
+
+    if (strategy == DB_STGY_XTRN && (s->st_info & STB_GLOBAL) == 0)
+      continue;
+
+    if (off >= s->st_value) {
+      if (s->st_info == STT_FUNC)
+	continue;
+
+      if (off - s->st_value < diff) {
+	diff = off - s->st_value;
+	symp = s;
+	if (diff == 0 && (s->st_info & STB_GLOBAL))
+	  break;
+      } else if (off - s->st_value == diff) {
+	if (symp == NULL)
+	  symp = s;
+	else if ((symp->st_info & STB_GLOBAL) == 0
+		 && (s->st_info & STB_GLOBAL) != 0)
+	  symp = s;	/* pick the external symbol */
+      }
+    }
+  }
+
+  if (symp == NULL)
+    *diffp = off;
+  else
+    *diffp = diff;
+
+  return (db_sym_t) symp;
+}
+
+/*
+ * Return the name and value for a symbol.
+ */
+void
+elf_db_symbol_values (db_symtab_t *stab,
+		      db_sym_t sym,
+		      char **namep,
+		      db_expr_t *valuep)
+{
+  struct db_symtab_elf *self = (struct db_symtab_elf *) stab;
+  Elf32_Sym *s = (Elf32_Sym *) sym;
+
+  if (namep)
+    *namep = &self->strings[s->st_name];
+  if (valuep)
+    *valuep = s->st_value;
+}
+
+/*
+ * Find filename and lineno within, given the current pc.
+ */
+boolean_t
+elf_db_line_at_pc (db_symtab_t *stab,
+		   db_sym_t sym,
+		   char **file,
+		   int *line,
+		   db_addr_t pc)
+{
+  /* XXX Parse DWARF information.  */
+  return FALSE;
+}
+
+#endif	/* DB_NO_ELF */
+
+#endif /* MACH_KDB */
diff --git a/ddb/db_elf.h b/ddb/db_elf.h
new file mode 100644
index 0000000..12b8286
--- /dev/null
+++ b/ddb/db_elf.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2013 Free Software Foundation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _DDB_DB_ELF_H_
+#define _DDB_DB_ELF_H_
+
+#include <ddb/db_sym.h>
+#include <machine/db_machdep.h>
+
+extern boolean_t
+elf_db_line_at_pc(
+	db_symtab_t	*stab,
+	db_sym_t	sym,
+	char		**file,
+	int		*line,
+	db_addr_t	pc);
+
+extern db_sym_t
+elf_db_lookup(
+	db_symtab_t	*stab,
+	char *		symstr);
+
+extern db_sym_t
+elf_db_search_symbol(
+	db_symtab_t *	symtab,
+	db_addr_t	off,
+	db_strategy_t	strategy,
+	db_expr_t	*diffp);
+
+extern void
+elf_db_symbol_values(
+	db_symtab_t	*stab,
+	db_sym_t	sym,
+	char		**namep,
+	db_expr_t	*valuep);
+
+#endif /* _DDB_DB_ELF_H_ */
diff --git a/ddb/db_sym.c b/ddb/db_sym.c
index 7d97d15..0179137 100644
--- a/ddb/db_sym.c
+++ b/ddb/db_sym.c
@@ -38,6 +38,7 @@
 #include <ddb/db_sym.h>
 #include <ddb/db_task_thread.h>
 #include <ddb/db_aout.h>
+#include <ddb/db_elf.h>
 
 #include <vm/vm_map.h>	/* vm_map_t */
 
@@ -507,6 +508,10 @@ void db_free_symbol(db_sym_t s)
  */
 
 void dummy_db_free_symbol(db_sym_t symbol) { }
+boolean_t dummy_db_sym_init(char *a, char *b, char *c, char *d) {
+  return FALSE;
+}
+
 
 struct db_sym_switch x_db[] = {
 
@@ -521,7 +526,14 @@ struct db_sym_switch x_db[] = {
 	{ 0,},
 
 	/* Machdep, not inited here */
-	{ 0,}
+	{ 0,},
+
+#ifdef	DB_NO_ELF
+	{ 0,},
+#else	/* DB_NO_ELF */
+	{ dummy_db_sym_init, elf_db_lookup, elf_db_search_symbol,
+	  elf_db_line_at_pc, elf_db_symbol_values, dummy_db_free_symbol },
+#endif	/* DB_NO_ELF */
 
 };
 
diff --git a/ddb/db_sym.h b/ddb/db_sym.h
index 2c3e10a..d8f3387 100644
--- a/ddb/db_sym.h
+++ b/ddb/db_sym.h
@@ -46,6 +46,7 @@ typedef struct {
 #define	SYMTAB_AOUT	0
 #define	SYMTAB_COFF	1
 #define	SYMTAB_MACHDEP	2
+#define	SYMTAB_ELF	3
 	char		*start;		/* symtab location */
 	char		*end;
 	char		*private;	/* optional machdep pointer */
@@ -243,6 +244,14 @@ extern boolean_t aout_db_sym_init(
 	char *name,
 	char *task_addr);
 
+extern boolean_t elf_db_sym_init (
+	unsigned shdr_num,
+	vm_size_t shdr_size,
+	vm_offset_t shdr_addr,
+	unsigned shdr_shndx,
+	char *name,
+	char *task_addr);
+
 db_sym_t	db_lookup(char *);
 
 db_sym_t
diff --git a/i386/i386at/model_dep.c b/i386/i386at/model_dep.c
index 209cfb1..bc34c9b 100644
--- a/i386/i386at/model_dep.c
+++ b/i386/i386at/model_dep.c
@@ -82,7 +82,16 @@
 #if MACH_KDB
 #include <ddb/db_sym.h>
 #include <i386/db_interface.h>
+
+/* a.out symbol table */
 static vm_offset_t kern_sym_start, kern_sym_end;
+
+/* ELF section header */
+static unsigned elf_shdr_num;
+static vm_size_t elf_shdr_size;
+static vm_offset_t elf_shdr_addr;
+static unsigned elf_shdr_shndx;
+
 #else /* MACH_KDB */
 #define kern_sym_start	0
 #define kern_sym_end	0
@@ -570,6 +579,17 @@ void c_boot_entry(vm_offset_t bi)
 		       kern_sym_start, kern_sym_end,
 		       symtab_size, strtab_size);
 	}
+
+	if ((boot_info.flags & MULTIBOOT_ELF_SHDR)
+	    && boot_info.syms.e.num)
+	{
+		elf_shdr_num = boot_info.syms.e.num;
+		elf_shdr_size = boot_info.syms.e.size;
+		elf_shdr_addr = (vm_offset_t)phystokv(boot_info.syms.e.addr);
+		elf_shdr_shndx = boot_info.syms.e.shndx;
+
+		printf("ELF section header table at %08lx\n", elf_shdr_addr);
+	}
 #endif	/* MACH_KDB */
 #endif	/* MACH_XEN */
 
@@ -588,6 +608,13 @@ void c_boot_entry(vm_offset_t bi)
 	{
 		aout_db_sym_init((char *)kern_sym_start, (char *)kern_sym_end, "mach", (char *)0);
 	}
+
+	if (elf_shdr_num)
+	{
+		elf_db_sym_init(elf_shdr_num,elf_shdr_size,
+				elf_shdr_addr, elf_shdr_shndx,
+				"mach", NULL);
+	}
 #endif	/* MACH_KDB */
 
 	machine_slot[0].is_cpu = TRUE;