Soluzione 1:
Non ho un ~=RHEL5 a portata di mano, quindi l'output mostrato è di Fedora 20, anche se il processo dovrebbe essere sostanzialmente lo stesso (il nome della funzione è cambiato).
Dovresti installare il kernel-debug-debuginfo appropriato pacchetto per il tuo kernel (assumendo RHEL o una distribuzione derivata). Questo pacchetto fornisce un vmlinux image (una versione non compressa del kernel):
# rpm -ql kernel-debug-debuginfo | grep vmlinux
/usr/lib/debug/lib/modules/3.14.7-200.fc20.x86_64+debug/vmlinux
quell'immagine può essere utilizzata direttamente con gdb
# gdb /usr/lib/debug/lib/modules/3.14.7-200.fc20.x86_64+debug/vmlinux
GNU gdb (GDB) Fedora 7.7.1-13.fc20
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
...
Reading symbols from /usr/lib/debug/lib/modules/3.14.7-200.fc20.x86_64+debug/vmlinux...done.
(gdb) disassemble link_path_walk
Dump of assembler code for function link_path_walk:
0xffffffff81243d50 <+0>: callq 0xffffffff817ea840 <__fentry__>
0xffffffff81243d55 <+5>: push %rbp
0xffffffff81243d56 <+6>: mov %rsp,%rbp
0xffffffff81243d59 <+9>: push %r15
0xffffffff81243d5b <+11>: mov %rsi,%r15
0xffffffff81243d5e <+14>: push %r14
0xffffffff81243d60 <+16>: push %r13
0xffffffff81243d62 <+18>: push %r12
0xffffffff81243d64 <+20>: push %rbx
0xffffffff81243d65 <+21>: mov %rdi,%rbx
0xffffffff81243d68 <+24>: sub $0x78,%rsp
0xffffffff81243d6c <+28>: mov %gs:0x28,%rax
0xffffffff81243d75 <+37>: mov %rax,0x70(%rsp)
0xffffffff81243d7a <+42>: xor %eax,%eax
0xffffffff81243d7c <+44>: movzbl (%rdi),%eax
0xffffffff81243d7f <+47>: cmp $0x2f,%al
....
Puoi anche usare objdump(1) sul vmlinux immagine:
# objdump -rDlS /usr/lib/debug/lib/modules/3.14.7-200.fc20.x86_64+debug/vmlinux > vmlinux.out
I flag sono:
-D
--disassemble-all
Like -d, but disassemble the contents of all sections, not just those expected to contain instructions.
-r
--reloc
Print the relocation entries of the file. If used with -d or -D, the relocations are printed interspersed with the
disassembly.
-S
--source
Display source code intermixed with disassembly, if possible. Implies -d.
-l
--line-numbers
Label the display (using debugging information) with the filename and source line numbers corresponding to the object
code or relocs shown. Only useful with -d, -D, or -r.
Puoi cercare la funzione qui:
ffffffff81243d50 <link_path_walk>:
link_path_walk():
/usr/src/debug/kernel-3.14.fc20/linux-3.14.7-200.fc20.x86_64/fs/namei.c:1729
*
* Returns 0 and nd will have valid dentry and mnt on success.
* Returns error and drops reference to input namei data on failure.
*/
static int link_path_walk(const char *name, struct nameidata *nd)
{
ffffffff81243d50: e8 eb 6a 5a 00 callq ffffffff817ea840 <__entry_text_start>
ffffffff81243d55: 55 push %rbp
ffffffff81243d56: 48 89 e5 mov %rsp,%rbp
ffffffff81243d59: 41 57 push %r15
ffffffff81243d5b: 49 89 f7 mov %rsi,%r15
ffffffff81243d5e: 41 56 push %r14
ffffffff81243d60: 41 55 push %r13
ffffffff81243d62: 41 54 push %r12
ffffffff81243d64: 53 push %rbx
ffffffff81243d65: 48 89 fb mov %rdi,%rbx
ffffffff81243d68: 48 83 ec 78 sub $0x78,%rsp
ffffffff81243d6c: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
ffffffff81243d73: 00 00
ffffffff81243d75: 48 89 44 24 70 mov %rax,0x70(%rsp)
ffffffff81243d7a: 31 c0 xor %eax,%eax
/usr/src/debug/kernel-3.14.fc20/linux-3.14.7-200.fc20.x86_64/fs/namei.c:1733
struct path next;
int err;
while (*name=='/')
ffffffff81243d7c: 0f b6 07 movzbl (%rdi),%eax
ffffffff81243d7f: 3c 2f cmp $0x2f,%al
ffffffff81243d81: 75 10 jne ffffffff81243d93 <link_path_walk+0x43>
ffffffff81243d83: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
/usr/src/debug/kernel-3.14.fc20/linux-3.14.7-200.fc20.x86_64/fs/namei.c:1734
name++;
ffffffff81243d88: 48 83 c3 01 add $0x1,%rbx
/usr/src/debug/kernel-3.14.fc20/linux-3.14.7-200.fc20.x86_64/fs/namei.c:1733
static int link_path_walk(const char *name, struct nameidata *nd)
{
struct path next;
int err;
while (*name=='/')
....
e far corrispondere l'offset alla riga di codice effettiva.
Soluzione 2:
Dato un vmlinux non strippato con i simboli di debug (tipicamente inclusi nei pacchetti "linux-devel" o "linux-headers" che corrispondono alla tua versione del kernel), puoi usare il addr2line programma incluso con binutils per tradurre gli indirizzi in righe nei file sorgente.
Considera questa traccia delle chiamate:
Call Trace:
[<ffffffff8107bf5d>] ? finish_task_switch+0x3d/0x120
[<ffffffff815f3130>] __schedule+0x3b0/0x9d0
[<ffffffff815f3779>] schedule+0x29/0x70
[<ffffffff815f2ccc>] schedule_hrtimeout_range_clock.part.24+0xdc/0xf0
[<ffffffff81076440>] ? hrtimer_get_res+0x50/0x50
[<ffffffff815f2c6f>] ? schedule_hrtimeout_range_clock.part.24+0x7f/0xf0
[<ffffffff815f2cf9>] schedule_hrtimeout_range_clock+0x19/0x60
[<ffffffff815f2d53>] schedule_hrtimeout_range+0x13/0x20
[<ffffffff811a8aa9>] poll_schedule_timeout+0x49/0x70
[<ffffffff811aa203>] do_sys_poll+0x423/0x550
[<ffffffff814eaf8c>] ? sock_recvmsg+0x9c/0xd0
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811a8c50>] ? poll_select_copy_remaining+0x140/0x140
[<ffffffff811aa3fe>] SyS_poll+0x5e/0x100
[<ffffffff816015d2>] system_call_fastpath+0x16/0x1b
Quindi l'indirizzo del chiamante in poll_select_copy_remaining può essere trovato con:
$ addr2line -e /tmp/vmlinux ffffffff811a8c50
/tmp/linux-3.15-rc8/fs/select.c:209
Soluzione 3:
-
Installa kernel-debuginfo
-
Scarica decode_stacktrace.sh che si trova nell'albero dei sorgenti del kernel.
-
Rendi di nuovo utile l'output dello stack dump.
# ./decode_stacktrace.sh /usr/lib/debug/lib/modules/`uname -r`/vmlinux /usr/lib/debug/lib/modules/4.1.12-112.14.14.el7uek.x86_64/ < ./trace > out # cat out [102820.087367] Call Trace: [102820.087371] dump_stack (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/lib/dump_stack.c:53) [102820.087375] warn_slowpath_common (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/kernel/panic.c:499) [102820.087378] warn_slowpath_null (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/kernel/panic.c:533) [102820.087380] af_alg_accept (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/include/net/sock.h:1689 /usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/crypto/af_alg.c:287) [102820.087382] alg_accept (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/crypto/af_alg.c:326) [102820.087385] SYSC_accept4 (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/net/socket.c:1485) [102820.087388] ? release_sock (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/net/core/sock.c:2415) [102820.087390] ? alg_setsockopt (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/crypto/af_alg.c:264) [102820.087393] SyS_accept (/usr/src/debug/kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/net/socket.c:1515) [102820.087395] system_call_fastpath (/usr/src/debug////////kernel-4.1.12/linux-4.1.12-112.14.14.el7uek/arch/x86/kernel/entry_64.S:277) [102820.087397] ---[ end trace 1315ff0b8d6ff7d8 ]--- -
Per una manciata di offset di funzioni, prova
faddr2lineche si trova anche nei sorgenti del kernel.$ wget https://raw.githubusercontent.com/torvalds/linux/master/scripts/faddr2line $ bash faddr2line /usr/lib/debug/lib/modules/`uname -r`/vmlinux __do_softirq+0x92/0x320 __do_softirq+0x92/0x320: ffs at arch/x86/include/asm/bitops.h:410 (inlined by) __do_softirq at kernel/softirq.c:261