Added a new "--kaslr <offset>" command line option for X86 or

X86_64 kernels that are configured with CONFIG_RANDOMIZE_BASE.
The offset value must be equal to the difference between the
symbol values compiled into the vmlinux file and their relocated
value.
(ahonig@google.com, anderson@redhat.com)

crash.8

@@ -399,7 +399,8 @@ or
 .TP
 .B --less
 Use 
-.I /usr/bin/less as the command output scroller, overriding 
+.I /usr/bin/less 
+as the command output scroller, overriding 
 any settings in either 
 .I ./.crashrc 
 or 
@@ -447,6 +448,12 @@ command, search for their object files in
 .I directory
 instead of in the standard location.
 .TP
+.BI --kaslr \ offset
+If an x86 or x86_64 kernel was configured with 
+.B CONFIG_RANDOMIZE_BASE,
+the offset value is equal to the difference between the symbol values 
+compiled into the vmlinux file and their relocated value.
+.TP
 .BI --reloc \ size
 When analyzing live x86 kernels that were configured with a
 .B CONFIG_PHYSICAL_START

defs.h

@@ -2417,6 +2417,8 @@ struct symbol_table_data {
 	ulong __per_cpu_end;
 	off_t dwarf_debug_frame_file_offset;
 	ulong dwarf_debug_frame_size;
+	ulong first_section_start;
+	ulong last_section_end;
 };
 
 /* flags for st */

help.c

@@ -297,6 +297,11 @@ char *program_usage_info[] = {
     "    be necessary to enter a relocation size equal to the difference between",
     "    the two values.",
     "",
+    "  --kaslr offset",
+    "    If an x86 or x86_64 kernel was configured with CONFIG_RANDOMIZE_BASE,",
+    "    the offset value is equal to the difference between the symbol values ",
+    "    compiled into the vmlinux file and their relocated value.", 
+    "",
     "  --minimal",
     "    Bring up a session that is restricted to the log, dis, rd, sym,",
     "    eval, set and exit commands.  This option may provide a way to",

main.c

@@ -1,8 +1,8 @@
 /* main.c - core analysis suite
  *
  * Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
- * Copyright (C) 2002-2013 David Anderson
- * Copyright (C) 2002-2013 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2002-2014 David Anderson
+ * Copyright (C) 2002-2014 Red Hat, Inc. All rights reserved.
  *
  * 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
@@ -57,6 +57,7 @@ static struct option long_options[] = {
         {"CRASHPAGER", 0, 0, 0},
         {"no_scroll", 0, 0, 0},
         {"reloc", required_argument, 0, 0},
+	{"kaslr", required_argument, 0, 0},
 	{"active", 0, 0, 0},
 	{"minimal", 0, 0, 0},
 	{"mod", required_argument, 0, 0},
@@ -216,12 +217,21 @@ main(int argc, char **argv)
 		        else if (STREQ(long_options[option_index].name, "mod"))
 				kt->module_tree = optarg;
 
-		        else if (STREQ(long_options[option_index].name, "reloc")) {
+			else if (STREQ(long_options[option_index].name, "kaslr")) {
+				if (!calculate(optarg, &kt->relocate, NULL, 0)) {
+					error(INFO, "invalid --kaslr argument: %s\n",
+						optarg);
+					program_usage(SHORT_FORM);
+				}
+				kt->relocate *= -1;
+				kt->flags |= RELOC_SET;
+
+			} else if (STREQ(long_options[option_index].name, "reloc")) {
 				if (!calculate(optarg, &kt->relocate, NULL, 0)) {
 					error(INFO, "invalid --reloc argument: %s\n",
 						optarg);
 					program_usage(SHORT_FORM);
-				} 
+				}
 				kt->flags |= RELOC_SET;
 			}
 

symbols.c

@@ -198,22 +198,6 @@ symtab_init(void)
 			no_debugging_data(FATAL);
 	}
 
-	symcount = bfd_read_minisymbols(st->bfd, FALSE, &minisyms, &size);
-
-	if (symcount <= 0)
-		no_debugging_data(FATAL);
-
-	sort_x = bfd_make_empty_symbol(st->bfd);
-	sort_y = bfd_make_empty_symbol(st->bfd);
-	if (sort_x == NULL || sort_y == NULL)
-		error(FATAL, "bfd_make_empty_symbol() failed\n");
-
-	gnu_qsort(st->bfd, minisyms, symcount, size, sort_x, sort_y);
-
-	store_symbols(st->bfd, FALSE, minisyms, symcount, size);
-
-	free(minisyms);
-
 	/*
 	 *  Gather references to the kernel sections.
 	 */
@@ -222,6 +206,7 @@ symtab_init(void)
                 error(FATAL, "symbol table section array malloc: %s\n",
                         strerror(errno));
 	BZERO(st->sections, st->bfd->section_count * sizeof(struct sec *));
+	st->first_section_start = st->last_section_end = 0;
 
 	bfd_map_over_sections(st->bfd, section_header_info, KERNEL_SECTIONS);
 	if ((st->flags & (NO_SEC_LOAD|NO_SEC_CONTENTS)) ==
@@ -233,6 +218,22 @@ symtab_init(void)
 		}
 	}
 
+	symcount = bfd_read_minisymbols(st->bfd, FALSE, &minisyms, &size);
+
+	if (symcount <= 0)
+		no_debugging_data(FATAL);
+
+	sort_x = bfd_make_empty_symbol(st->bfd);
+	sort_y = bfd_make_empty_symbol(st->bfd);
+	if (sort_x == NULL || sort_y == NULL)
+		error(FATAL, "bfd_make_empty_symbol() failed\n");
+
+	gnu_qsort(st->bfd, minisyms, symcount, size, sort_x, sort_y);
+
+	store_symbols(st->bfd, FALSE, minisyms, symcount, size);
+
+	free(minisyms);
+
 	symname_hash_init();
 	symval_hash_init();
 }                           
@@ -590,7 +591,7 @@ store_symbols(bfd *abfd, int dynamic, void *minisyms, long symcount,
 	st->symcnt = 0;
 	sp = st->symtable;
 
-	if (machine_type("X86")) {
+	if (machine_type("X86") || machine_type("X86_64")) {
 		if (!(kt->flags & RELOC_SET))
 			kt->flags |= RELOC_FORCE;
 	} else
@@ -663,7 +664,7 @@ store_sysmap_symbols(void)
                 error(FATAL, "symbol table namespace malloc: %s\n",
                         strerror(errno));
 
-	if (!machine_type("X86"))
+	if (!machine_type("X86") && !machine_type("X86_64"))
 		kt->flags &= ~RELOC_SET;
 
 	first = 0;
@@ -735,7 +736,20 @@ relocate(ulong symval, char *symname, int first_symbol)
 		break;
 	}
 
-	return (symval - kt->relocate);
+	if (machine_type("X86_64")) {
+		/*
+		 * There are some symbols which are outside of any section
+		 * either because they are offsets or because they are absolute
+		 * addresses.  These should not be relocated.
+		 */
+		if (symval >= st->first_section_start &&
+			symval <= st->last_section_end) {
+			return symval - kt->relocate;
+		} else {
+			return symval;
+		}
+	} else
+		return symval - kt->relocate;
 }
 
 /*
@@ -2722,6 +2736,9 @@ dump_symbol_table(void)
 		fprintf(fp, "       __per_cpu_end: (unused)\n");
 	}
 
+	fprintf(fp, " first_section_start: %lx\n", st->first_section_start);
+	fprintf(fp, "    last_section_end: %lx\n", st->last_section_end);
+
         fprintf(fp, "    symval_hash[%d]: %lx\n", SYMVAL_HASH,
                 (ulong)&st->symval_hash[0]);
 
@@ -9679,6 +9696,7 @@ section_header_info(bfd *bfd, asection *section, void *reqptr)
 	struct load_module *lm;
 	ulong request;
         asection **sec;
+	ulong section_end_address;
 
 	request = ((ulong)reqptr);
 
@@ -9697,6 +9715,11 @@ section_header_info(bfd *bfd, asection *section, void *reqptr)
                 	kt->etext_init = kt->stext_init +
                         	(ulong)bfd_section_size(bfd, section);
 		}
+
+		if (STREQ(bfd_get_section_name(bfd, section), ".text")) {
+			st->first_section_start = (ulong)
+				bfd_get_section_vma(bfd, section);
+		}
                 if (STREQ(bfd_get_section_name(bfd, section), ".text") ||
                     STREQ(bfd_get_section_name(bfd, section), ".data")) {
                         if (!(bfd_get_section_flags(bfd, section) & SEC_LOAD))
@@ -9713,6 +9736,14 @@ section_header_info(bfd *bfd, asection *section, void *reqptr)
 			st->dwarf_debug_frame_file_offset = (off_t)section->filepos;
 			st->dwarf_debug_frame_size = (ulong)bfd_section_size(bfd, section);
 		}
+
+		if (st->first_section_start != 0) {
+			section_end_address =
+				(ulong) bfd_get_section_vma(bfd, section) +
+				(ulong) bfd_section_size(bfd, section);
+			if (section_end_address > st->last_section_end)
+				st->last_section_end = section_end_address;
+		}
 		break;
 
 	case (ulong)MODULE_SECTIONS: