Dear gdb authors:
I am the de-facto leader of a small group of programmers who maintain
the gdb kernel stub patch for Linux. This patch allows remote debugging
of the Linux kernel via gdb running on a second machine with a serial
line connecting the two.
Amit Kale is one of the other contributors from whom you may have heard
already.
I have been testing gdb 4.18 (April 7 version) against Linux
2.3.99-pre3. I am experiencing difficulties with loadable modules. The
problem is not the one that you may have heard from Amit about (global
data symbols). This is a different problem.
On the target machine I do "insmod -m streams >streams.map" to load my
module. I am enclosing the file streams.map that is the result of this
operation.
Back on the gdb machine I attach to the symbols using some gdb macros
that end up using add-symbol-file. The problem, then, is that gdb does
not seem to be able to obtain the correct address and line number
information about routines in this loaded module.
Knowing that the module loads at 0xc281004c and that the relocatable
offset for the routine "lis_i_link" is 0x2d5c, you can calculate that
the correct address for this routine is 0xc2812da8. This is in
agreement with the streams.map file. "lis_i_link" was chosen
more-or-less at random as a symbol name to use to illustrate the
problem.
The attached typescript file from the gdb session shows several
different "looks" at this routine name and address. I don't know if
this is enough for you to go on, but if you need anything more just let
me know what to do and I will gather information for you. I realize
that this could be especially difficult for you to reproduce yourselves.
One other relevant fact: gdb 4.17 does _not_ suffer from this problem.
Thanks,
Dave
Script started on Wed Apr 12 15:27:17 2000
[root@linux-dev2 linux-kgdb]# gdb vmlinux
GNU gdb 4.18
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...
(gdb) rmt
breakpoint () at gdbstub.c:1241
1241 }
(gdb) c
Continuing.
Program received signal SIGTRAP, Trace/breakpoint trap.
breakpoint () at gdbstub.c:1241
1241 }
(gdb) mod-list
0xc2810000 streams
(gdb) mod-add-lis 0xc2810000
(gdb) info addr lis_i_link
Symbol "lis_i_link" is a function at address 0xc28128b0.
(gdb) # above does not match map file
(gdb) info sym 0xc2812da8
lis_i_link in section .text
(gdb) # matches map file
(gdb) info func lis_i_link
All functions matching regular expression "lis_i_link":
File /usr/src/LiS/head/head.c:
int lis_i_link(struct inode *, struct file *, stdata_t *, int, int, cred_t *);
(gdb) list lis_il _l;ink ink
256 *
257 * Get a new muxid. Ensure that it is not in use already.
258 */
259 static int
260 new_muxid(void)
261 {
262 static int muxid ;
263 stdata_t *hd ;
264 int n ;
265
(gdb) # incorrect line number information, file info is correct
(gdb) i x/i lis_i_link
0xc28128b0 <lis_terminate_head>: push %ebp
(gdb) info sym 0xc281292c
new_muxid in section .text
(gdb) # the memory address of the routine that printed as "list lis-i _i_link"
(gdb) list 561
556 * However, if the stream does get closed then the stdata structure
557 * will be laying around in memory with refcnt==1 and nothing holding
558 * onto it. It will be their until the next reboot. Hopefully,
559 * this multiplexor can take care of itself until then.
560 */
561 int lis_i_link(struct inode *i,
562 struct file *f,
563 stdata_t *hd,
564 int muxfd,
565 int cmd,
(gdb) c
Continuing.
[1]+ Stopped gdb vmlinux
[root@linux-dev2 linux-kgdb]# kill %1
[1]+ Stopped gdb vmlinux
[root@linux-dev2 linux-kgdb]#
[1]+ Terminated gdb vmlinux
[root@linux-dev2 linux-kgdb]# exit
Script done on Wed Apr 12 15:59:35 2000
Sections: Size Address Align
.this 0000004c c2810000 2**2
.text 0001223c c281004c 2**2
.text.lock 000001ba c2822288 2**0
.fixup 000000f0 c2822442 2**0
.rodata 0000566f c2822532 2**0
__ex_table 000000a0 c2827ba4 2**2
.data 00000614 c2827c44 2**2
.kstrtab 00001353 c2828258 2**0
.bss 00028398 c28295b0 2**4
__ksymtab 00000a18 c2851948 2**2
Symbols:
00000000 a loop.c
00000000 a safe.c
00000000 a errmsg.c
00000000 a buffcall.c
00000000 a msgutl.c
00000000 a dki.c
00000000 a msg.c
00000000 a mdep.c
00000000 a mod.c
00000000 a queue.c
00000000 a Space.c
00000000 a events.c
00000000 a syscalls.c
00000000 a relay.c
00000000 a ip_strm_mod.c
00000000 a clone.c
00000000 a stats.c
00000000 a slog.c
00000000 a wait.c
00000000 a printk.c
00000000 a sputbuf.c
00000000 a strmdbg.c
00000000 a cmn_err.c
00000000 a head.c
00000000 a minimux.c
00000000 a poll.c
00000000 a osif.c
00000000 a version.c
00000000 a stream.c
c2810000 d __this_module
c281004c t relay_open
c281004c t .text
c2810064 t relay_wput
c2810080 t relay_rput
c281009c t relay_close
c28100a4 t clone_open
c2810118 t clone_close
c2810120 T sloop_init
c2810130 t loop_open
c28101ec t loop_timeout
c2810238 t loop_bufcall
c281025c t loop_concat
c2810294 T loop_request_copyio
c2810304 T loop_iocdata
c28105d4 t loop_wput
c2810ae8 t loop_wsrv
c2810ba8 t loop_rsrv
c2810bd4 t loop_close
c2810ce4 t new_mux
c2810d2c t mux_open
c2810df4 T mux_ioctl
c28110ac t mux_wput
c2811218 t mux_messenger_service
c2811274 t mux_rsrv
c2811284 t mux_close
c2811384 t mux_lrput
c28114e4 t mux_lwsrv
c28114f4 t printk_open
c28114fc t printk_close
c2811504 t printk_wput
c2811558 T ip_to_streams_open
c2811648 T ip_to_streams_close
c2811708 T ip_to_streams_ioctl
c28118a8 T ip_to_streams_wput
c2811b58 T ip_to_streams_allocb
c2811ba8 T ip_to_streams_m_error
c2811c98 T ip_to_streams_error_ack
c2811d8c T ip_to_streams_ok_ack
c2811eac T ip_to_streams_rsrv
c2811f44 T ip_to_streams_wsrv
c28120a8 T ip_to_streams_proto
c281212c T ip_to_streams_rput
c2812318 T convert_to_skbuf
c2812488 t ip_strm_xmit
c2812734 T ip_strm_ioctl
c2812740 t get_stats
c2812758 T ip_strm_open
c28127f8 T ip_strm_close
c281281c T ip_strm_init
c28128b0 T lis_sem_init
c281292c t new_muxid
c2812988 t str_link_mux
c28129c8 t lis_i_unlink
c2812cd4 t lis_unlink_all
c2812da8 T lis_i_link
c2813130 t lis_dismantle
c28131b0 t set_readopt
c281320c t add_to_scanl
c2813284 t start_scanl_timer
c28132b0 t alloc_stdata
c2813400 t free_stdata
c28134c0 T lis_check_ino
c2813520 t copyin_msgpart
c281367c t copyin_msg
c2813744 t copyout_msgpart
c2813960 t copyout_msg
c28139a8 T lis_qdetach
c2813d8c t lis_qattach
c2813f58 t push_mod
c2813fac t pop_mod
c2813ff0 t set_options
c2814190 t lis_wake_up_poll
c28141e0 t lis_deallocate_polllist
c281422c t kill_procs
c2814300 t signalusr
c2814330 t snd_mread
c2814394 t lis_snd_mflush
c2814420 t snd_iocnak
c2814474 t bad_ioc_seq
c2814490 t open_mods
c281455c T lis_strrput
c2814ecc T lis_strwsrv
c2815098 t lis_do_tmout
c2815118 t lis_wait_for_wiocing
c28151e0 t copyout_blks
c2815284 t lis_strdoioctl
c2815bf4 t lis_lookup_stdata
c2815c34 T lis_stropen
c28163b4 T lis_strwrite
c2816988 t lis_requeue
c2816a0c T lis_strread
c2817198 T lis_strputpmsg
c28175fc T lis_strgetpmsg
c2818118 T lis_strioctl
c281a6a8 T lis_poll_bits
c281a7dc T lis_wakeup_close
c281a848 t lis_doclose
c281abb8 T lis_strclose
c281ad68 T lis_init_head
c281adc8 T lis_terminate_head
c281ade8 T lis_timeout_fcn
c281af30 T untimeout
c281afac T lis_terminate_dki
c281b054 t allochdr
c281b144 t freehdr
c281b20c T lis_terminate_msg
c281b244 t allocdb
c281b320 t initb
c281b3f0 T lis_allocb_physreq
c281b408 T lis_allocb
c281b4c8 T lis_testb
c281b4f8 T lis_esballoc
c281b538 T lis_freedb
c281b714 T lis_freeb
c281b724 T lis_freemsg
c281b74c T lis_getint
c281b760 T lis_putbyte
c281b774 T find_mod_objname
c281b780 T find_dev_objname
c281b78c T find_dev_by_major
c281b798 T find_drv_objname
c281b7a4 t apush_free
c281b8b0 t apush_free_major
c281b90c t apush_free_all
c281b95c t apush_drop_mod
c281ba34 t apush_validate
c281ba74 t apush_conf
c281be28 t find_apush_entry
c281bee4 T lis_register_strmod
c281c028 T lis_unregister_strmod
c281c0f0 T lis_findmod
c281c13c T lis_enable_intr
c281c204 T lis_register_strdev
c281c2e4 T lis_unregister_strdev
c281c3dc T lis_find_strdev
c281c408 T lis_apushm
c281c528 T lis_apush_set
c281c724 T lis_apush_get
c281c8e4 T lis_valid_mod_list
c281c96c T lis_init_mod
c281ca74 T lis_terminate_mod
c281cb1c t bc_timeout
c281cb30 t bc_link
c281cc98 t bc_ulink
c281cd0c T lis_bufcall
c281cd5c T lis_esbbcall
c281cda8 T lis_unbufcall
c281ce3c T lis_dobufcall
c281cf80 T lis_init_bufcall
c281d018 T lis_terminate_bufcall
c281d058 T lis_assert_fail
c281d074 T lis_memfree
c281d07c T lis_copyin_str
c281d104 T lis_errmsg
c281d14c T lis_tmout
c281d188 T lis_untmout
c281d198 T lis_time_till
c281d1b0 T lis_target_time
c281d1c4 T lis_fd2str
c281d204 T lis_pick_inode
c281d27c T lis_init_module
c281d2f4 t init_module
c281d300 t cleanup_module
c281d330 T lis_print_trace_func
c281d344 T streams_init
c281d350 T lis_inc_mod_cnt
c281d368 T lis_dec_mod_cnt
c281d380 T lis_hitime
c281d3b0 T lis_splstr
c281d458 T lis_splx
c281d4e8 T lis_print_spl_track
c281d590 T lis_thread_runqueues
c281d770 T lis_start_qsched
c281d894 T lis_setqsched
c281d934 T lis_kill_qsched
c281d99c t lis_do_panic
c281d9a8 T lis_error
c281da30 T lis_get_elist_ent
c281da6c T lis_add_to_elist
c281db64 T lis_del_from_elist
c281dbe8 T lis_free_elist
c281dc24 t tmsgsize
c281dc84 T lis_msgsize
c281dcb0 T lis_msgdsize
c281dcdc T lis_xmsgsize
c281dd24 T lis_adjmsg
c281ddd0 T lis_copyb
c281de2c T lis_copymsg
c281de80 T lis_dupb
c281dec8 T lis_dupmsg
c281df20 T lis_linkb
c281df48 T lis_unlinkb
c281df64 T lis_pullupmsg
c281e12c T lis_msgpullup
c281e304 T lis_rmvb
c281e354 t find_qband
c281e3f8 t updatequeue
c281e4c4 t find_q_spot_head
c281e530 t find_q_spot_tail
c281e5bc t ins_before
c281e634 t rmv_msg
c281e7bc T lis_check_q_magic
c281e7f0 T lis_backq
c281e838 T lis_backenable
c281e8b4 T lis_getq
c281e914 T lis_putq
c281e9a4 T lis_putbq
c281ea2c T lis_insq
c281eb04 T lis_rmvq
c281eba8 T lis_qenable
c281ec48 T lis_setq
c281ed24 T lis_flushband
c281ee0c T lis_flushq
c281ef60 T lis_putctl
c281efdc T lis_putnextctl
c281f004 T lis_putctl1
c281f088 T lis_putnextctl1
c281f0b4 T lis_qsize
c281f11c T lis_strqget
c281f2b4 T lis_strqset
c281f418 T lis_allocq
c281f49c T lis_freeq
c281f590 T lis_appq
c281f5e0 T lis_bcanput
c281f6d0 T lis_bcanputnext
c281f714 T lis_bcanputnext_anyband
c281f7e8 T lis_qcountstrm
c281f870 T lis_qprocson
c281f878 T lis_qprocsoff
c281f880 T safe_noenable
c281f8e8 T safe_enableok
c281f950 T safe_canenable
c281f994 T safe_OTHERQ
c281fa14 T safe_RD
c281fa94 T safe_WR
c281fb10 T safe_SAMESTR
c281fb80 T safe_putnext
c281fc9c T safe_qreply
c281fd4c T lis_stat_neg
c281fd58 T LisUpCounter
c281fd88 T LisSetCounter
c281fdb0 t queuerun
c281ff80 T lis_run_queues
c282001c T lis_scantmout_handler
c2820028 T lis_malloc
c2820124 T lis_check_guard
c2820170 T lis_free
c2820250 T lis_terminate_mem
c28202a0 T lis_check_mem
c28202e4 T lis_mark_mem
c28202fc T lis_print_block
c2820474 T lis_print_mem
c28204b8 T lis_print_queues
c2820528 T lis_strm_name
c282055c T lis_queue_name
c2820588 T lis_msg_type_name
c2820704 T lis_maj_min_name
c2820774 T lis_print_queue
c2820974 t strm_print
c2820a94 T lis_print_stream
c2820aa4 T lis_print_data
c2820bb8 T lis_print_msg
c2820c8c T lis_poll_events
c2820e80 T lis_sleep_on_wopen
c2820ee0 T lis_sleep_on_wioc
c2820f38 T lis_sleep_on_wwrite
c2820fcc T lis_wake_up_wwrite
c2821058 T lis_wake_up_all_wwrite
c28210f4 T lis_sleep_on_wread
c282118c T lis_wake_up_wread
c282121c T lis_wake_up_all_wread
c28212b8 T lis_sleep_on_wiocing
c2821310 T cmn_err
c28213d4 T lis_strm_trace
c2821404 T lis_strm_log
c2821434 T lis_strm_print_trace
c2821548 T lis_strm_putc
c2821568 T lis_strm_readbuf
c2821658 T lis_strm_init
c282174c T sys_putpmsg
c2821a2c T sys_getpmsg
c2821d10 T hook_syscalls
c2821d40 T restore_syscalls
c2821d70 T lis_pcibios_present
c2821d7c T lis_pcibios_init
c2821d84 T lis_pcibios_find_class
c2821d9c T lis_pcibios_find_device
c2821dbc T lis_pcibios_read_config_byte
c2821e10 T lis_pcibios_read_config_word
c2821e2c T lis_pcibios_read_config_dword
c2821e48 T lis_pcibios_write_config_byte
c2821e68 T lis_pcibios_write_config_word
c2821e88 T lis_pcibios_write_config_dword
c2821ea4 T lis_pcibios_strerror
c2821f34 T lis_pci_find_device
c2821f48 T lis_pci_find_class
c2821f58 T lis_pci_find_slot
c2821f68 T lis_pci_read_config_byte
c2821f80 T lis_pci_read_config_word
c2821f98 T lis_pci_read_config_dword
c2821fb0 T lis_pci_write_config_byte
c2821fc8 T lis_pci_write_config_word
c2821fe0 T lis_pci_write_config_dword
c2821ff8 T lis_pci_set_master
c2822008 T lis_request_irq
c2822024 T lis_free_irq
c2822034 T lis_enable_irq
c2822044 T lis_disable_irq
c2822054 T lis_ioremap
c2822068 T lis_ioremap_nocache
c282207c T lis_iounmap
c282208c T lis_vremap
c28220a0 T lis_virt_to_phys
c28220b0 T lis_phys_to_virt
c28220c0 T lis_check_region
c28220d8 T lis_request_region
c28220f0 T lis_release_region
c2822108 T lis_kmalloc
c2822118 T lis_kfree
c2822128 T lis_vmalloc
c2822138 T lis_vfree
c2822148 T lis_request_dma
c2822158 T lis_free_dma
c2822168 T lis_udelay
c2822178 T lis_jiffies
c2822184 T lis_printk
c28221b4 T lis_sprintf
c28221c8 T lis_vsprintf
c28221dc T lis_sleep_on
c28221ec T lis_interruptible_sleep_on
c28221fc T lis_wake_up
c2822210 T lis_wake_up_interruptible
c2822224 T lis_poll_2_1
c2822288 t .text.lock
c2822442 t .fixup
c2822532 r .rodata
c2827ba4 r __ex_table
c2827c44 d relay_minfo
c2827c44 d .data
c2827c5c d relay2_minfo
c2827c74 d relay_rinit
c2827c90 d relay_winit
c2827cac D relay_info
c2827cbc d relay2_rinit
c2827cd8 d relay2_winit
c2827cf4 D relay2_info
c2827d04 d clone_minfo
c2827d1c d clone_rinit
c2827d38 d clone_winit
c2827d54 D clone_info
c2827d64 d loop_minfo
c2827d7c d loop_rinit
c2827d98 d loop_winit
c2827db4 D sloop_info
c2827dc4 d loop_cnt
c2827dc8 d mux_minfo
c2827de0 d mux_rinit
c2827dfc d mux_winit
c2827e18 d mux_lminfo
c2827e30 d mux_lrinit
c2827e4c d mux_lwinit
c2827e68 D mux_info
c2827e78 d printk_minfo
c2827e90 d printk_rinit
c2827eac d printk_winit
c2827ec8 D printk_info
c2827ed8 D ip_to_streams_minfo
c2827ef0 D ip_to_streams_rinit
c2827f0c D ip_to_streams_winit
c2827f28 D ip_to_streams_info
c2827f38 D ip_to_streamsdevflag
c2827f3c D ip_to_streams_debug_mask
c2827f40 D strmhd_rdminfo
c2827f58 D strmhd_wrminfo
c2827f70 D strmhd_rdinit
c2827f8c D strmhd_wrinit
c2827fa8 D lis_mdbfreelist
c2827fac D lis_driver_config
c282810c D lis_device_config
c282810c D lis_module_config
c28281e4 D lis_apush_init
c28281e4 D lis_stropts_file
c28281e8 D lis_streams_fops
c2828224 D lis_kernel_version
c2828230 D lis_mem_head
c2828244 D lis_debug_mask
c2828248 D lis_version
c282824c D lis_date
c2828254 D lis_poll_file
c28295b0 d .bss
c28295b0 d loop_loop
c28297f0 d muxid.516
c28297f4 d mb_zero.522
c2829818 d frtn_zero.523
c2829820 d apush
c2829c1c d apush_nref
c282a018 d id_num.516
c282a01c d lis_strbctimer
c282a020 d cnt.636
c282a024 d lis_major
c282a028 d disableinx
c282a02c d disabletim
c282a030 d disablestate
c282a034 d name.538
c282a0b4 d index.539
c282a0b8 d event_names.552
c282a310 d index.553
c282a314 d total_bytes.518
c282a318 d lis_strm_in
c282a31c d lis_strm_out
c282a320 d lis_strm_buf
c282a324 d lis_strm_end
c282a328 d lis_strm_size
c282a32c d lis_strm_max_bytes
c282a330 d p_sem
c282a354 d msg.618
c282a3b8 D proto_space_filler
c282a3b9 D lis_strbcflag
c282a3bc D lis_putnext_flag
c282a3c0 D lis_strmsgsz
c282a3c4 D lis_runq_open_flag
c282a3c8 D lis_scanqtail
c282a3cc D lis_bc_cnt
c282a3d0 D lis_nstrpush
c282a3d4 D lis_spl_track_inx
c282a3d8 D lis_print_trace
c282a3dc D lis_runq_pid
c282a3e0 D lis_qhead
c282a3e4 D lis_runq_sched
c282a3e8 D lis_bcfreel
c282a3ec D lis_mem_alloced
c282a3f0 D lis_strthresh
c282a3f4 D lis_iocseq
c282a3f8 D lis_global_major
c282a3fc D lis_close_cnt
c282a400 D lis_max_mem
c282a404 D lis_strcount
c282a408 D lis_stdata_head
c282a40c D lis_tlist_head
c282a410 D lis_fmodcnt
c282a414 D lis_sefreelist
c282a418 D lis_qtail
c282a41c D lis_secachep
c282a420 D lis_tlist_handle
c282a424 D lis_queues_running
c282a428 D mux_head
c282a42c D lis_max_msg_mem
c282a430 D lis_strhold
c282a434 D lis_poll_sleeping
c282a438 D lis_scanqhead
c282a43c D lis_negstat
c282a440 D lis_stdata_cnt
c282a444 D lis_open_cnt
c282a448 D lis_bctl
c282a460 D lis_runq_sem
c282a484 D lis_runq_kill_sem
c282a4a8 D lis_sem_template
c282a4cc D lis_strstats
c282a64c D mux_minors
c282a7e0 D lis_strm_print_trace_buf
c282abe0 D lis_bchash
c282b1e0 D lis_cmn_err_buf
c282c1e0 D lis_fmod_sw
c2830d94 D lis_fstr_sw
c2835948 D lis_spl_track
