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symbols.c
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symbols.c
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/* symbols.c - core analysis suite
*
* Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc.
* Copyright (C) 2002-2020 David Anderson
* Copyright (C) 2002-2020 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
* 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.
*/
#include "defs.h"
#include <elf.h>
#if defined(GDB_7_6) || defined(GDB_10_2)
#define __CONFIG_H__ 1
#include "config.h"
#endif
#include "bfd.h"
static void store_symbols(bfd *, int, void *, long, unsigned int);
static void store_sysmap_symbols(void);
static ulong relocate(ulong, char *, int);
static int relocate_force(ulong, char *);
static void kaslr_init(void);
static void strip_module_symbol_end(char *s);
static int compare_syms(const void *, const void *);
static int compare_mods(const void *, const void *);
static int compare_prios(const void *v1, const void *v2);
static int compare_size_name(const void *, const void *);
struct type_request;
static void append_struct_symbol (struct gnu_request *, void *);
static void request_types(ulong, ulong, char *);
static asection *get_kernel_section(char *);
static char * get_section(ulong vaddr, char *buf);
static void symbol_dump(ulong, char *);
static void check_for_dups(struct load_module *);
static struct syment *kallsyms_module_symbol(struct load_module *, symbol_info *);
static int kallsyms_module_function_size(struct syment *, struct load_module *, ulong *);
static void store_load_module_symbols \
(bfd *, int, void *, long, uint, ulong, char *);
static int load_module_index(struct syment *);
static void section_header_info(bfd *, asection *, void *);
static void store_section_data(struct load_module *, bfd *, asection *);
static void calculate_load_order_v1(struct load_module *, bfd *);
static void calculate_load_order_v2(struct load_module *, bfd *, int, void *, long, unsigned int);
static void calculate_load_order_6_4(struct load_module *, bfd *, int, void *, long, unsigned int);
static void check_insmod_builtin(struct load_module *, int, ulong *);
static int is_insmod_builtin(struct load_module *, struct syment *);
struct load_module;
static int add_symbol_file(struct load_module *);
static int add_symbol_file_kallsyms(struct load_module *, struct gnu_request *);
static void find_mod_etext(struct load_module *);
static long rodata_search(ulong *, ulong);
static int ascii_long(ulong word);
static int is_bfd_format(char *);
static int is_binary_stripped(char *);
static int namespace_ctl(int, struct symbol_namespace *, void *, void *);
static void symval_hash_init(void);
static struct syment *symval_hash_search(ulong);
static void symname_hash_init(void);
static void symname_hash_install(struct syment *);
static struct syment *symname_hash_search(struct syment *[], char *);
static void gnu_qsort(bfd *, void *, long, unsigned int, asymbol *, asymbol *);
static int check_gnu_debuglink(bfd *);
static int separate_debug_file_exists(const char *, unsigned long, int *);
static int store_module_kallsyms_v1(struct load_module *, int, int, char *);
static int store_module_kallsyms_v2(struct load_module *, int, int, char *);
static void datatype_error(void **, char *, char *, char *, int);
static char *get_thisfile(void);
struct elf_common;
static void Elf32_Sym_to_common(Elf32_Sym *, struct elf_common *);
static void Elf64_Sym_to_common(Elf64_Sym *, struct elf_common *);
static void cmd_datatype_common(ulong);
static void do_datatype_addr(struct datatype_member *, ulong, int,
ulong, char **, int);
static void process_gdb_output(char *, unsigned, const char *, int);
static char *expr_type_name(const char *);
static int display_per_cpu_info(struct syment *, int, char *);
static struct load_module *get_module_percpu_sym_owner(struct syment *);
static int is_percpu_symbol(struct syment *);
static void dump_percpu_symbols(struct load_module *);
static void print_struct_with_dereference(ulong, struct datatype_member *, ulong);
static int dereference_pointer(ulong, struct datatype_member *, ulong);
#define KERNEL_SECTIONS (void *)(1)
#define MODULE_SECTIONS (void *)(2)
#define VERIFY_SECTIONS (void *)(3)
#define EV_DWARFEXTRACT 101010101
#define PARSE_FOR_DATA (1)
#define PARSE_FOR_DECLARATION (2)
static void parse_for_member(struct datatype_member *, ulong);
static int show_member_offset(FILE *, struct datatype_member *, char *);
struct struct_elem;
static void free_structure(struct struct_elem *);
static unsigned char is_right_brace(const char *);
static struct struct_elem *find_node(struct struct_elem *, char *);
static void dump_node(struct struct_elem *, char *, unsigned char, unsigned char);
static int module_mem_type(ulong, struct load_module *);
static ulong module_mem_end(ulong, struct load_module *);
static int in_module_range(ulong, struct load_module *, int, int);
static struct syment *value_search_module_6_4(ulong, ulong *);
static struct syment *next_symbol_by_symname(char *);
static struct syment *prev_symbol_by_symname(char *);
static struct syment *next_module_symbol_by_value(ulong);
static struct syment *prev_module_symbol_by_value(ulong);
static struct syment *next_module_symbol_by_syment(struct syment *);
static struct syment *prev_module_symbol_by_syment(struct syment *);
struct module_tag {
char *start;
char *end;
char *start_str;
char *end_str;
};
#define MODULE_TAG(type, suffix) ("_MODULE_" #type "_" #suffix "_")
#define MODULE_STR(type, suffix) ( "MODULE " #type " " #suffix)
#define MODULE_TAGS(type) { \
.start = MODULE_TAG(type, START), \
.end = MODULE_TAG(type, END), \
.start_str = MODULE_STR(type, START), \
.end_str = MODULE_STR(type, END) \
}
static const struct module_tag module_tag[] = {
MODULE_TAGS(TEXT),
MODULE_TAGS(DATA),
MODULE_TAGS(RODATA),
MODULE_TAGS(RO_AFTER_INIT),
MODULE_TAGS(INIT_TEXT),
MODULE_TAGS(INIT_DATA),
MODULE_TAGS(INIT_RODATA),
};
/*
* structure/union printing stuff
*/
#define UINT8 (0x1)
#define INT8 (0x2)
#define UINT16 (0x4)
#define INT16 (0x8)
#define UINT32 (0x10)
#define INT32 (0x20)
#define UINT64 (0x40)
#define INT64 (0x80)
#define POINTER (0x100)
#define FUNCTION (0x200)
#define UNION_REQUEST (0x400)
#define STRUCT_REQUEST (0x800)
#define ARRAY (0x1000)
#define ENUM (0x2000)
#define TYPEDEF (0x4000)
#define STRUCT_VERBOSE (0x8000)
#define SHOW_OFFSET (0x10000)
#define IN_UNION (0x20000)
#define IN_STRUCT (0x40000)
#define DATATYPE_QUERY (0x80000)
#define ANON_MEMBER_QUERY (0x100000)
#define SHOW_RAW_DATA (0x200000)
#define DEREF_POINTERS (0x400000)
#define INTEGER_TYPE (UINT8|INT8|UINT16|INT16|UINT32|INT32|UINT64|INT64)
#define INITIAL_INDENT (4)
#define INDENT_INCR (2)
static void whatis_datatype(char *, ulong, FILE *);
static void whatis_variable(struct syment *);
static void print_struct(char *, ulong);
static void print_union(char *, ulong);
static void dump_datatype_member(FILE *, struct datatype_member *);
static void dump_datatype_flags(ulong, FILE *);
static long anon_member_offset(char *, char *);
static long anon_member_size(char *, char *);
static int gdb_whatis(char *);
static void do_datatype_declaration(struct datatype_member *, ulong);
static int member_to_datatype(char *, struct datatype_member *, ulong);
#define DEBUGINFO_ERROR_MESSAGE1 \
"the use of a System.map file requires that the accompanying namelist\nargument is a kernel file built with the -g CFLAG. The namelist argument\nsupplied in this case is a debuginfo file, which must be accompanied by the\nkernel file from which it was derived.\n"
#define DEBUGINFO_ERROR_MESSAGE2 \
"The namelist argument supplied in this case is a debuginfo file,\nwhich must be accompanied by the kernel file from which it was derived.\n"
/*
* This routine scours the namelist for kernel text and data symbols,
* sorts, and stores, them in a static table for quick reference.
*/
void
symtab_init(void)
{
char **matching;
long symcount;
void *minisyms;
unsigned int size;
asymbol *sort_x;
asymbol *sort_y;
if ((st->bfd = bfd_openr(pc->namelist, NULL)) == NULL)
error(FATAL, "cannot open object file: %s\n", pc->namelist);
if (!bfd_check_format_matches(st->bfd, bfd_object, &matching))
error(FATAL, "cannot determine object file format: %s\n",
pc->namelist);
/*
* Check whether the namelist is a kerntypes file built by
* dwarfextract, which places a magic number in e_version.
*/
if (file_elf_version(pc->namelist) == EV_DWARFEXTRACT)
pc->flags |= KERNTYPES;
if (pc->flags & SYSMAP) {
bfd_map_over_sections(st->bfd, section_header_info,
VERIFY_SECTIONS);
if ((st->flags & (NO_SEC_LOAD|NO_SEC_CONTENTS)) ==
(NO_SEC_LOAD|NO_SEC_CONTENTS)) {
error(INFO, "%s: no text and data contents\n",
pc->namelist);
error(FATAL, pc->flags & SYSMAP_ARG ?
DEBUGINFO_ERROR_MESSAGE1 :
DEBUGINFO_ERROR_MESSAGE2);
}
store_sysmap_symbols();
return;
} else if (LKCD_KERNTYPES())
error(FATAL, "%s: use of kerntypes requires a system map\n",
pc->namelist);
/*
* Pull a bait-and-switch on st->bfd if we've got a separate
* .gnu_debuglink file that matches the CRC. Not done for kerntypes.
*/
if (!(LKCD_KERNTYPES()) &&
!(bfd_get_file_flags(st->bfd) & HAS_SYMS)) {
if (!check_gnu_debuglink(st->bfd))
no_debugging_data(FATAL);
}
/*
* Gather references to the kernel sections.
*/
if ((st->sections = (struct sec *)
malloc(st->bfd->section_count * sizeof(struct sec *))) == NULL)
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)) ==
(NO_SEC_LOAD|NO_SEC_CONTENTS)) {
if (!pc->namelist_debug && !pc->debuginfo_file) {
error(INFO, "%s: no text and data contents\n",
pc->namelist);
error(FATAL, DEBUGINFO_ERROR_MESSAGE2);
}
}
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");
kaslr_init();
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();
}
/*
* Adapted from gdb's get_debug_link_info()
*
* Look in: current directory
* basename-of-namelist/.debug directory
* /usr/lib/debug/boot (since we know it's a Red Hat kernel)
*/
static int
check_gnu_debuglink(bfd *bfd)
{
int i, exists, found;
asection *sect;
bfd_size_type debuglink_size;
char *contents;
int crc_offset;
unsigned long crc32;
char *dirname;
char *namelist_debug;
char **matching;
sect = bfd_get_section_by_name(bfd, ".gnu_debuglink");
if (!sect) {
error(INFO, "%s: no .gnu_debuglink section\n", pc->namelist);
return FALSE;
}
debuglink_size = bfd_section_size(sect);
contents = GETBUF(debuglink_size);
bfd_get_section_contents(bfd, sect, contents,
(file_ptr)0, (bfd_size_type)debuglink_size);
crc_offset = strlen (contents) + 1;
crc_offset = (crc_offset + 3) & ~3;
crc32 = bfd_get_32(bfd, (bfd_byte *)(contents + crc_offset));
if (CRASHDEBUG(1))
error(NOTE, "gnu_debuglink file: %s\ncrc32: %lx\n",
contents, crc32);
if ((pc->debuginfo_file = (char *)
malloc(((strlen(pc->namelist) + strlen("/.debug/") +
+ strlen(".debug") + strlen(" /usr/lib/debug/boot/ "))*10)
+ strlen(pc->namelist_debug ? pc->namelist_debug : " "))) == NULL)
error(FATAL, "debuginfo file name malloc: %s\n",
strerror(errno));
dirname = GETBUF(strlen(pc->namelist)+1);
strcpy(dirname, pc->namelist);
for (i = strlen(dirname)-1; i >= 0; i--)
{
if (dirname[i] == '/')
break;
}
dirname[i+1] = NULLCHAR;
if (!strlen(dirname))
sprintf(dirname, ".");
namelist_debug = NULL;
if (pc->namelist_debug) {
sprintf(pc->debuginfo_file, "%s", pc->namelist_debug);
if (separate_debug_file_exists(pc->debuginfo_file,
crc32, &exists)) {
if (CRASHDEBUG(1))
fprintf(fp, "%s: CRC matches\n",
pc->debuginfo_file);
st->flags |= CRC_MATCHES;
goto reset_bfd;
} else {
if ((st->flags & FORCE_DEBUGINFO) && exists) {
error(WARNING,
"%s:\n CRC value does not match\n\n",
pc->debuginfo_file);
goto reset_bfd;
} else
error(INFO, "%s:\n CRC value does not match\n\n",
pc->debuginfo_file);
namelist_debug = pc->namelist_debug;
pc->namelist_debug = NULL;
}
}
found = 0;
sprintf(pc->debuginfo_file, "%s/%s", dirname, contents);
if (separate_debug_file_exists(pc->debuginfo_file, crc32, &exists)) {
if (CRASHDEBUG(1))
fprintf(fp, "%s: CRC matches\n", pc->debuginfo_file);
st->flags |= CRC_MATCHES;
goto reset_bfd;
} else {
if (CRASHDEBUG(1))
fprintf(fp, "%s: %s\n", pc->debuginfo_file, exists ?
"CRC does not match" : "not readable/found");
if (exists) {
error(INFO, "%s: CRC does not match\n\n",
pc->debuginfo_file);
found++;
}
}
sprintf(pc->debuginfo_file, "%s/.debug/%s", dirname, contents);
if (separate_debug_file_exists(pc->debuginfo_file, crc32, &exists)) {
if (CRASHDEBUG(1))
fprintf(fp, "%s: CRC matches\n", pc->debuginfo_file);
st->flags |= CRC_MATCHES;
goto reset_bfd;
} else {
if (CRASHDEBUG(1))
fprintf(fp, "%s: %s\n", pc->debuginfo_file, exists ?
"CRC does not match" : "not readable/found");
if (exists) {
error(INFO, "%s: CRC does not match\n\n",
pc->debuginfo_file);
found++;
}
}
sprintf(pc->debuginfo_file, "/usr/lib/debug/boot/%s", contents);
if (separate_debug_file_exists(pc->debuginfo_file, crc32, &exists)) {
if (CRASHDEBUG(1))
fprintf(fp, "%s: CRC matches\n", pc->debuginfo_file);
st->flags |= CRC_MATCHES;
goto reset_bfd;
} else {
if (CRASHDEBUG(1))
fprintf(fp, "%s: %s\n", pc->debuginfo_file, exists ?
"CRC does not match" : "not readable/found");
if (exists) {
error(INFO, "%s: CRC does not match\n\n",
pc->debuginfo_file);
found++;
}
}
if (!found && namelist_debug) {
error(INFO,
"%s:\n use of -f option may suffice, or may fail miserably\n",
namelist_debug);
}
if (!found && !namelist_debug) {
no_debugging_data(INFO);
error(INFO, "%s: debuginfo file not found\n", contents);
error(FATAL,
"either install the appropriate kernel debuginfo package, or\n copy %s to this machine", contents);
}
return FALSE;
reset_bfd:
if ((st->bfd = bfd_openr(pc->debuginfo_file, NULL)) == NULL)
error(FATAL, "cannot open object file: %s\n",
pc->debuginfo_file);
if (!bfd_check_format_matches(st->bfd, bfd_object, &matching))
error(FATAL, "cannot determine object file format: %s\n",
pc->debuginfo_file);
FREEBUF(contents);
FREEBUF(dirname);
return TRUE;
}
/*
* Based upon gdb's separate_debug_file_exists().
*/
static int
separate_debug_file_exists(const char *name, unsigned long crc, int *exists)
{
unsigned long file_crc = 0;
int fd;
char buffer[8*1024];
size_t count;
fd = open(name, O_RDONLY);
if (fd < 0) {
*exists = FALSE;
return 0;
}
*exists = TRUE;
while ((count = read(fd, buffer, sizeof(buffer))) > 0)
#ifdef GDB_5_3
file_crc = calc_crc32(file_crc, buffer, count);
#else
#if defined(GDB_7_6) || defined(GDB_10_2)
file_crc = bfd_calc_gnu_debuglink_crc32(file_crc,
(unsigned char *)buffer, count);
#else
file_crc = gnu_debuglink_crc32(file_crc,
(unsigned char *)buffer, count);
#endif
#endif
close (fd);
return crc == file_crc;
}
/*
* Callback for gdb to use a specified vmlinux.debug file.
*/
char *
check_specified_kernel_debug_file()
{
if (pc->flags & GDB_INIT)
return NULL;
return (pc->namelist_debug ? pc->namelist_debug : NULL);
}
/*
* Common bailout/warning routine when running against non-debug kernels.
*
* INFO: used when this routine should return.
* FATAL: kills function if runtime, or kills program if during init.
* WARNING: called by gdb_session_init() only, in an attempt to at least
* get by with built-in debug data; if not possible the program
* is killed.
*/
void
no_debugging_data(int error_type)
{
switch (error_type)
{
case INFO:
error(INFO, "%s: no debugging data available\n", pc->namelist);
break;
case FATAL:
error(FATAL, "%s%s: no debugging data available\n",
pc->flags & RUNTIME ? "" : "\n", pc->namelist);
clean_exit(1);
case WARNING:
error(FATAL, "\n%s: no debugging data available\n",
pc->namelist);
clean_exit(1);
}
}
/*
* Get the address space formerly used as init-time text. While there
* get the boundaries of the kernel .rodata section so that it won't
* be confused with text.
*
* This is done indirectly by the call-back to section_header_info().
*/
void
get_text_init_space(void)
{
asection *section = NULL;
if (pc->flags & SYSMAP)
return;
if (machine_type("ARM"))
section = get_kernel_section(".init");
if (!section && !(section = get_kernel_section(".text.init")))
section = get_kernel_section(".init.text");
if (!section) {
error(WARNING, "cannot determine text init space\n");
return;
}
kt->stext_init = (ulong)bfd_section_vma(section);
kt->etext_init = kt->stext_init +
(ulong)bfd_section_size(section);
if (kt->relocate) {
kt->stext_init -= kt->relocate;
kt->etext_init -= kt->relocate;
}
}
/*
* Strip gcc-generated cloned text symbol name endings.
*/
static char *
strip_symbol_end(const char *name, char *buf)
{
int i;
char *p;
char *strip[] = {
".isra.",
".part.",
".llvm.",
NULL
};
if (st->flags & NO_STRIP)
return (char *)name;
for (i = 0; strip[i]; i++) {
if ((p = strstr(name, strip[i]))) {
if (buf) {
strcpy(buf, name);
buf[p-name] = NULLCHAR;
return buf;
} else {
*p = NULLCHAR;
return (char *)name;
}
}
}
return (char *)name;
}
/*
* Gather the relevant information from the dumpfile or live system
* and determine whether to derive the KASLR offset.
*
* Setting st->_stext_vmlinux to UNINITIALIZED will trigger the
* search for "_stext" from the vmlinux file during the initial
* symbol sort operation.
*
* Setting RELOC_AUTO will ensure that derive_kaslr_offset() is
* called after the sorting operation has captured the vmlinux
* file's "_stext" symbol value -- which it will compare to the
* relocated "_stext" value found in either a dumpfile's vmcoreinfo
* or in /proc/kallsyms on a live system.
*
* Setting KASLR_CHECK will trigger a search for "module_load_offset"
* during the initial symbol sort operation, and if found, will
* set (RELOC_AUTO|KASLR). On live systems, the search is done
* here by checking /proc/kallsyms.
*/
static void
kaslr_init(void)
{
char *string;
if ((!machine_type("X86_64") && !machine_type("ARM64") && !machine_type("X86") &&
!machine_type("S390X") && !machine_type("RISCV64")) || (kt->flags & RELOC_SET))
return;
if (!kt->vmcoreinfo._stext_SYMBOL &&
(string = pc->read_vmcoreinfo("SYMBOL(_stext)"))) {
kt->vmcoreinfo._stext_SYMBOL = htol(string, RETURN_ON_ERROR, NULL);
free(string);
}
/*
* --kaslr=auto
*/
if ((kt->flags2 & (RELOC_AUTO|KASLR)) == (RELOC_AUTO|KASLR))
st->_stext_vmlinux = UNINITIALIZED;
if (ACTIVE() && /* Linux 3.15 */
(symbol_value_from_proc_kallsyms("module_load_offset") != BADVAL)) {
kt->flags2 |= (RELOC_AUTO|KASLR);
st->_stext_vmlinux = UNINITIALIZED;
}
if (machine_type("S390X")) {
kt->flags2 |= (RELOC_AUTO|KASLR);
st->_stext_vmlinux = UNINITIALIZED;
}
if (QEMU_MEM_DUMP_NO_VMCOREINFO()) {
if (KDUMP_DUMPFILE() && kdump_kaslr_check()) {
kt->flags2 |= KASLR_CHECK;
} else if (DISKDUMP_DUMPFILE() && diskdump_kaslr_check()) {
kt->flags2 |= KASLR_CHECK;
}
} else if (KDUMP_DUMPFILE() || DISKDUMP_DUMPFILE()) {
/* Linux 3.14 */
if ((string = pc->read_vmcoreinfo("KERNELOFFSET"))) {
free(string);
kt->flags2 |= KASLR_CHECK;
st->_stext_vmlinux = UNINITIALIZED;
}
}
if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO() || VMSS_DUMPFILE()) {
/* Need for kaslr_offset and phys_base */
kt->flags2 |= KASLR_CHECK;
st->_stext_vmlinux = UNINITIALIZED;
}
}
/*
* Derives the kernel aslr offset by comparing the _stext symbol from the
* the vmcoreinfo in the dump file to the _stext symbol in the vmlinux file.
*/
static void
derive_kaslr_offset(bfd *abfd, int dynamic, bfd_byte *start, bfd_byte *end,
unsigned int size, asymbol *store)
{
unsigned long relocate;
ulong _stext_relocated;
if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO() || VMSS_DUMPFILE()) {
ulong kaslr_offset = 0;
ulong phys_base = 0;
calc_kaslr_offset(&kaslr_offset, &phys_base);
if (kaslr_offset) {
kt->relocate = kaslr_offset * -1;
kt->flags |= RELOC_SET;
}
if (phys_base) {
if (SADUMP_DUMPFILE())
sadump_set_phys_base(phys_base);
else if (KDUMP_DUMPFILE())
kdump_set_phys_base(phys_base);
else if (DISKDUMP_DUMPFILE())
diskdump_set_phys_base(phys_base);
else if (VMSS_DUMPFILE())
vmware_vmss_set_phys_base(phys_base);
}
return;
}
if (ACTIVE()) {
_stext_relocated = symbol_value_from_proc_kallsyms("_stext");
if (_stext_relocated == BADVAL)
return;
} else {
_stext_relocated = kt->vmcoreinfo._stext_SYMBOL;
if (_stext_relocated == 0)
return;
}
/*
* To avoid mistaking an mismatched kernel version with
* a kaslr offset, we make sure that the offset is
* aligned by 0x1000, as it always will be for kaslr.
*/
if (st->_stext_vmlinux && (st->_stext_vmlinux != UNINITIALIZED)) {
relocate = st->_stext_vmlinux - _stext_relocated;
if (relocate && !(relocate & 0xfff)) {
kt->relocate = relocate;
kt->flags |= RELOC_SET;
}
}
if (CRASHDEBUG(1) && (kt->flags & RELOC_SET)) {
fprintf(fp, "KASLR:\n");
fprintf(fp, " _stext from %s: %lx\n",
basename(pc->namelist), st->_stext_vmlinux);
fprintf(fp, " _stext from %s: %lx\n",
ACTIVE() ? "/proc/kallsyms" : "vmcoreinfo",
_stext_relocated);
fprintf(fp, " relocate: %lx (%ldMB)\n",
kt->relocate * -1, (kt->relocate * -1) >> 20);
}
}
/*
* Store the symbols gathered by symtab_init(). The symbols are stored
* in increasing numerical order.
*/
static void
store_symbols(bfd *abfd, int dynamic, void *minisyms, long symcount,
unsigned int size)
{
asymbol *store;
asymbol *sym;
bfd_byte *from, *fromend;
symbol_info syminfo;
struct syment *sp;
char buf[BUFSIZE];
char *name;
int first;
if ((store = bfd_make_empty_symbol(abfd)) == NULL)
error(FATAL, "bfd_make_empty_symbol() failed\n");
if ((st->symtable = (struct syment *)
calloc(symcount, sizeof(struct syment))) == NULL)
error(FATAL, "symbol table syment space malloc: %s\n",
strerror(errno));
if (!namespace_ctl(NAMESPACE_INIT, &st->kernel_namespace,
(void *)symcount, NULL))
error(FATAL, "symbol table namespace malloc: %s\n",
strerror(errno));
st->syment_size = symcount * sizeof(struct syment);
st->symcnt = 0;
sp = st->symtable;
first = 0;
from = (bfd_byte *) minisyms;
fromend = from + symcount * size;
if (machine_type("X86")) {
if (kt->flags2 & KASLR) {
if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
derive_kaslr_offset(abfd, dynamic, from,
fromend, size, store);
} else if (!(kt->flags & RELOC_SET))
kt->flags |= RELOC_FORCE;
} else if (machine_type("X86_64") || machine_type("ARM64") ||
machine_type("S390X") || machine_type("RISCV64")) {
if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
derive_kaslr_offset(abfd, dynamic, from,
fromend, size, store);
} else
kt->flags &= ~RELOC_SET;
for (; from < fromend; from += size)
{
if ((sym = bfd_minisymbol_to_symbol(abfd, dynamic, from, store))
== NULL)
error(FATAL, "bfd_minisymbol_to_symbol() failed\n");
bfd_get_symbol_info(abfd, sym, &syminfo);
name = strip_symbol_end(syminfo.name, buf);
if (machdep->verify_symbol(name, syminfo.value,
syminfo.type)) {
if (kt->flags & (RELOC_SET|RELOC_FORCE))
sp->value = relocate(syminfo.value,
(char *)syminfo.name, !(first++));
else
sp->value = syminfo.value;
sp->type = syminfo.type;
namespace_ctl(NAMESPACE_INSTALL, &st->kernel_namespace,
sp, name);
sp++;
st->symcnt++;
}
}
st->symend = &st->symtable[st->symcnt];
st->flags |= KERNEL_SYMS;
namespace_ctl(NAMESPACE_COMPLETE, &st->kernel_namespace,
st->symtable, st->symend);
}
/*
* Store the symbols from the designated System.map. The symbols are stored
* in increasing numerical order.
*/
static void
store_sysmap_symbols(void)
{
int c, first;
long symcount;
char buf[BUFSIZE];
char name[BUFSIZE];
FILE *map;
char *mapitems[MAXARGS];
struct syment *sp, syment;
if ((map = fopen(pc->system_map, "r")) == NULL)
error(FATAL, "cannot open %s\n", pc->system_map);
symcount = 0;
while (fgets(buf, BUFSIZE, map))
symcount++;
if ((st->symtable = (struct syment *)
calloc(symcount, sizeof(struct syment))) == NULL)
error(FATAL, "symbol table syment space malloc: %s\n",
strerror(errno));
if (!namespace_ctl(NAMESPACE_INIT, &st->kernel_namespace,
(void *)symcount, NULL))
error(FATAL, "symbol table namespace malloc: %s\n",
strerror(errno));
if (!machine_type("X86") && !machine_type("X86_64") &&
!machine_type("ARM64") && !machine_type("S390X"))
kt->flags &= ~RELOC_SET;
first = 0;
st->syment_size = symcount * sizeof(struct syment);
st->symcnt = 0;
sp = st->symtable;
rewind(map);
while (fgets(buf, BUFSIZE, map)) {
if ((c = parse_line(buf, mapitems)) != 3)
continue;
syment.value = htol(mapitems[0], FAULT_ON_ERROR, NULL);
syment.type = mapitems[1][0];
syment.name = mapitems[2];
strcpy(name, syment.name);
strip_symbol_end(name, NULL);
if (machdep->verify_symbol(name, syment.value,
syment.type)) {
if (kt->flags & RELOC_SET)
sp->value = relocate(syment.value,
syment.name, !(first++));
else
sp->value = syment.value;
sp->type = syment.type;
namespace_ctl(NAMESPACE_INSTALL, &st->kernel_namespace,
sp, name);
sp++;
st->symcnt++;
}
}
fclose(map);
st->symend = &st->symtable[st->symcnt];
st->flags |= KERNEL_SYMS;
namespace_ctl(NAMESPACE_COMPLETE, &st->kernel_namespace,
st->symtable, st->symend);
symname_hash_init();
symval_hash_init();
}
/*
* Handle x86/arm64 kernels configured such that the vmlinux symbols
* are not as loaded into the kernel (not unity-mapped).
*/
static ulong
relocate(ulong symval, char *symname, int first_symbol)
{
if (XEN_HYPER_MODE()) {
kt->flags &= ~(RELOC_SET|RELOC_FORCE);
return symval;
}
switch (kt->flags & (RELOC_SET|RELOC_FORCE))
{
case RELOC_SET:
break;
case RELOC_FORCE:
if (first_symbol && !relocate_force(symval, symname))
kt->flags &= ~RELOC_FORCE;
break;
}
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;
}
/*
* If no --reloc argument was passed, try to figure it out
* by comparing the first vmlinux kernel symbol with the
* first /proc/kallsyms symbol. (should be "_text")
*
* Live system only (at least for now).
*/
static int
relocate_force(ulong symval, char *symname)
{
int count, found;
FILE *kp;
char buf[BUFSIZE];
char *kallsyms[MAXARGS];
ulong kallsym;
if (!ACTIVE() || !file_exists("/proc/kallsyms", NULL)) {
if (CRASHDEBUG(1))
fprintf(fp,
"cannot determine relocation value: %s\n",
!ACTIVE() ? "not a live system" :
"/proc/kallsyms does not exist");
return FALSE;
}
if ((kp = fopen("/proc/kallsyms", "r")) == NULL) {
if (CRASHDEBUG(1))
fprintf(fp,
"cannot open /proc/kallsyms to determine relocation\n");
return FALSE;
}
if (CRASHDEBUG(1))
fprintf(fp,
"relocate from: %s\n"
" %s @ %lx\n"
"relocate to: /proc/kallsyms\n",
pc->namelist, symname, symval);
found = FALSE;
count = kallsym = 0;