arm-elf-gdb segfault in get_frame_pc

[Shaun Jackman <sjackman at gmail dot com>]

arm-elf-gdb segfaulted as I started single stepping through an inline
assembler macro, start_thread.

Thanks,
Shaun

$ arm-elf-gdb _build/kernel/kernel
GNU gdb 6.4.50.20060206-cvs
...
This GDB was configured as "--host=x86_64-unknown-linux-gnu --target=arm-elf"...
(gdb) target remote bdi:2001
Remote debugging using bdi:2001
0x02080000 in ?? ()
(gdb) load
Loading section .text, size 0xf534 lma 0x2000000
Loading section .rodata, size 0x17b4 lma 0x200f534
Loading section .data, size 0x13a4 lma 0x2010de8
Start address 0x2000000, load size 73868
Transfer rate: 203003 bits/sec, 959 bytes/write.
(gdb) c
Current language:  auto; currently asm
CPSR: 0xdf IRQ FIQ MODE_SYS

Program received signal SIGSTOP, Stopped (signal).
0x02007908 in dcc_read (fd=<value optimized out>, buf=0x20645d0, count=1024)
    at ../../drivers/dcc.c:48
48                              if (n > 0) return n;
Current language:  auto; currently c
(gdb) l load_bflt
...
(gdb) b 28
Breakpoint 1 at 0x2000310: file ../../kernel/bflt.c, line 28.
(gdb) c
Continuing.

Breakpoint 1, load_bflt (src=0x10a4000, n=<value optimized out>)
    at ../../kernel/bflt.c:28
28              if (setjmp(proc.kcontext) == 0)
(gdb) s
setjmp () at ../../../../../../../newlib/libc/machine/arm/setjmp.S:98
98              FUNC_START setjmp
Current language:  auto; currently asm
(gdb)
.arm_start_of.setjmp ()
    at ../../../../../../../newlib/libc/machine/arm/setjmp.S:101
101             stmea           a1!, { v1-v7, fp, ip, sp, lr }
(gdb)
110             mov             a1, #0
(gdb)
112             FUNC_END setjmp
(gdb)
load_bflt (src=0x10a4000, n=<value optimized out>) at ../../kernel/bflt.c:29
29                      start_thread(entry, &proc.ucontext);
Current language:  auto; currently c
(gdb)
Segmentation fault (core dumped)
$ gdb ~/bin/arm-elf-gdb core
GNU gdb 6.3-debian
...
This GDB was configured as "i386-linux"...Using host libthread_db
library "/lib/tls/i686/cmov/libthread_db.so.1".

Core was generated by `arm-elf-gdb _build/kernel/kernel'.
Program terminated with signal 11, Segmentation fault.

warning: current_sos: Can't read pathname for load map: Input/output error

...
#0  0x0813dc99 in get_frame_pc (frame=0x0) at ../../gdb/frame.c:1321
1321      gdb_assert (frame->next != NULL);
(gdb) bt
#0  0x0813dc99 in get_frame_pc (frame=0x0) at ../../gdb/frame.c:1321
#1  0x080bec2c in insert_step_resume_breakpoint_at_frame (return_frame=0x0)
    at ../../gdb/infrun.c:2760
#2  0x080c20ed in handle_inferior_event (ecs=0xbfec8e20)
    at ../../gdb/infrun.c:2531
#3  0x080c27a8 in wait_for_inferior () at ../../gdb/infrun.c:1001
#4  0x080c2a75 in proceed (addr=1, siggnal=TARGET_SIGNAL_DEFAULT, step=1)
    at ../../gdb/infrun.c:826
#5  0x080bc069 in step_1 (skip_subroutines=0, single_inst=0, count_string=0x0)
    at ../../gdb/infcmd.c:757
#6  0x08050803 in execute_command (p=0x8298991 "", from_tty=1)
    at ../../gdb/top.c:448
#7  0x080ccec2 in command_handler (command=0x8298990 "s")
    at ../../gdb/event-top.c:508
#8  0x080cd465 in command_line_handler (rl=0x82bb6b8 "")
    at ../../gdb/event-top.c:799
#9  0x081972a5 in rl_callback_read_char () at ../../readline/callback.c:123
#10 0x080cc83b in rl_callback_read_char_wrapper (client_data=0x0)
    at ../../gdb/event-top.c:174
#11 0x080cc02e in handle_file_event (event_file_desc=0)
    at ../../gdb/event-loop.c:728
#12 0x080cbaf6 in process_event () at ../../gdb/event-loop.c:341
#13 0x080cc365 in gdb_do_one_event (data=0x0) at ../../gdb/event-loop.c:378
#14 0x080c95ac in catch_errors (func=0x80cc240 <gdb_do_one_event>,
    func_args=0x0, errstring=0x81f344f "", mask=6)
    at ../../gdb/exceptions.c:515
#15 0x0807f213 in tui_command_loop (data=0x0) at ../../gdb/tui/tui-interp.c:151
#16 0x080c986c in current_interp_command_loop () at ../../gdb/interps.c:278
#17 0x0804b9eb in captured_command_loop (data=0x0) at ../../gdb/main.c:101
#18 0x080c95ac in catch_errors (func=0x804b9e0 <captured_command_loop>,
    func_args=0x0, errstring=0x81f344f "", mask=6)
    at ../../gdb/exceptions.c:515
#19 0x0804c093 in captured_main (data=0x0) at ../../gdb/main.c:834
#20 0x080c95ac in catch_errors (func=0x804ba20 <captured_main>,
    func_args=0xbfec9300, errstring=0x81f344f "", mask=6)
    at ../../gdb/exceptions.c:515
#21 0x0804c833 in gdb_main (args=0x0) at ../../gdb/main.c:843
#22 0x0804b9cd in main (argc=0, argv=0x0) at ../../gdb/gdb.c:35
(gdb)