Re: Infinite backtrace on arm

[Jon Ringle <jon dot ringle at comdial dot com>(by way of Jon Ringle <jon dot ringle at comdial dot com>)]

On Monday 27 October 2003 10:23 am, Daniel Jacobowitz wrote:
> On Mon, Oct 27, 2003 at 10:21:54AM -0500, Andrew Cagney wrote:
> > >The problem is that there's not much GDB can do with hand-coded
> > >assembly functions.
> > >
> > >However, GDB ought to be able to detect and stop that loop without any
> > >of this.  It seems to me that the problem is not two frames with the
> > >same PC, but two frames with their PC "saved" in the same place - i.e.
> > >GDB failing to figure out where the PC is saved.  This is made a little
> > >tricky in current versions of GDB, because the PC is normally unwound
> > >using frame_pc_unwind (which doesn't tell us where it was saved, since
> > >the interface doesn't assume it's a single normal register), and the
> > >core code doesn't have a concept of a "PC register" any more.
> > >
> > >Andrew, any idea on how to do this?
> >
> > Before anything else, find out what a current GDB does - its code to
> > detect a "corrupt stack" is now much improved.
>
> I'll check - I don't have my test for this problem handy any more but I
> know as of a month or two ago the problem still existed.

Here is a debug session debugging gdb 2003-10-27-cvs. I enabled frame_debug
which I hope will contain useful information:

Jon


GNU gdb 5.3-22mdk (Mandrake Linux)
Copyright 2002 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 "i586-mandrake-linux-gnu"...
Setting up the environment for debugging gdb.
Breakpoint 1 at 0x811e895: file ../../src/gdb/utils.c, line 805.
Breakpoint 2 at 0x8079c48: file ../../src/gdb/cli/cli-cmds.c, line 190.
(top-gdb) b get_prev_frame 
Breakpoint 3 at 0x8124700: file ../../src/gdb/frame.c, line 1743.
(top-gdb) run -b 115200 -x ~/sp/sandbox/WipSoundpipe/linux/.gdbinit ~/sp/sandbox/WipSoundpipe/linux/vmlinux 
Starting program: /home/eringlej/gdb-cvs/gdb-6.0-arm-build/gdb/gdb -b 115200 -x ~/sp/sandbox/WipSoundpipe/linux/.gdbinit ~/sp/sandbox/WipSoundpipe/linux/vmlinux
GNU gdb 2003-10-27-cvs
Copyright 2003 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 "--host=i686-pc-linux-gnu --target=arm-linux"...
Setting up the environment for debugging gdb.
.gdbinit:5: Error in sourced command file:
Function "internal_error" not defined.
(gdb) open-extended-debug 
During symbol reading, struct/union type gets multiply defined: struct dentry.

Breakpoint 3, get_prev_frame (this_frame=0x82a8f70)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) set frame_debug = 1
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=-1) { frame_register_unwind (frame=-1,regnum="pc",...) -> *optimizedp=0 *lvalp=2 *addrp=0x3c *bufferp=[c0310110] }
{ frame_pc_unwind (this_frame=-1) -> 0x100131c0 }
-> {level=0,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x100131c0,id=<unknown>,func=<unknown>} }
{ deprecated_update_frame_pc_hack (frame=0,pc=0x100131c0) }
breakpoint () at kgdb-stub.c:1148
1148	}
warning: shared library handler failed to enable breakpoint
(gdb) b dimutl.c:247
Breakpoint 1 at 0x1005e2f0: file common/micro/dim/dimutl.c, line 247.
(gdb) c
{ frame_register_unwind (frame=-1,regnum="sp",...) -> *optimizedp=0 *lvalp=2 *addrp=0x34 *bufferp=[f0ffff10] }
{ frame_register_unwind (frame=-1,regnum="sp",...) -> *optimizedp=0 *lvalp=2 *addrp=0x34 *bufferp=[f0ffff10] }
Continuing.
<<< lots of output from program suppressed >>>
{ flush_cached_frames () }
{ frame_id_p (l={stack=0x0,code=0x0,special=0x0}) -> 0 }
{ create_sentinel_frame (...) -> {level=-1,type=NORMAL_FRAME,unwind=0x824a3c0,pc=<unknown>,id={stack=0x0,code=0x0,special=0x0},func=<unknown>} }

Breakpoint 3, get_prev_frame (this_frame=0x82a8f70)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=-1) { frame_register_unwind (frame=-1,regnum="pc",...) -> *optimizedp=0 *lvalp=2 *addrp=0x3c *bufferp=[f0e20510] }
{ frame_pc_unwind (this_frame=-1) -> 0x1005e2f0 }
-> {level=0,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1005e2f0,id=<unknown>,func=<unknown>} }
{ deprecated_update_frame_pc_hack (frame=0,pc=0x1005e2f0) }
{ frame_register_unwind (frame=-1,regnum="sp",...) -> *optimizedp=0 *lvalp=2 *addrp=0x34 *bufferp=[f0ffff10] }
{ frame_register_unwind (frame=-1,regnum="r6",...) -> *optimizedp=0 *lvalp=2 *addrp=0x18 *bufferp=[00dc2210] }
{ frame_register_unwind (frame=-1,regnum="r11",...) -> *optimizedp=0 *lvalp=2 *addrp=0x2c *bufferp=[04dfff10] }

Breakpoint 1, dimp_proc_bring_dsp_down (p_dsp=0x1022dc00, reason=7) at common/micro/dim/dimutl.c:247
247		    dim_mcb.a_dim_tcids[p_channel->p_dim_tcid->tcid].p_channel = NULL;
(gdb) bt
{ frame_register_unwind (frame=-1,regnum="r6",...) -> *optimizedp=0 *lvalp=2 *addrp=0x18 *bufferp=[00dc2210] }
#0  dimp_proc_bring_dsp_down (p_dsp=0x1022dc00, reason=7) at common/micro/dim/dimutl.c:247

Breakpoint 3, get_prev_frame (this_frame=0x82a8fc4)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=0) { get_frame_id (fi=0) { frame_func_unwind (fi=-1) -> 0x1005e17c }
-> {stack=0x10ffdf08,code=0x1005e17c,special=0x0} }
{ frame_id_p (l={stack=0x10ffdf08,code=0x1005e17c,special=0x0}) -> 1 }
{ frame_register_unwind (frame=0,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf00 *bufferp=[f4df0510] }
{ frame_pc_unwind (this_frame=0) -> 0x1005dff4 }
-> {level=1,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1005dff4,id=<unknown>,func=<unknown>} }
{ frame_register_unwind (frame=0,regnum="r4",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdedc *bufferp=[00dc2210] }
{ frame_register_unwind (frame=0,regnum="r1",...) { frame_register_unwind (frame=-1,regnum="r1",...) -> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
#1  0x1005dff4 in dimp_bring_dsp_down (p_dsp=0x1022dc00, reason=DIM_DSP_ERR_OK) at common/micro/dim/dimutl.c:74

Breakpoint 3, get_prev_frame (this_frame=0x82a9160)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=1) { get_frame_id (fi=1) { frame_register_unwind (frame=0,regnum="r11",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdef8 *bufferp=[1cdfff10] }
{ frame_func_unwind (fi=0) -> 0x1005df78 }
{ frame_id_eq (l={stack=0x10ffdf08,code=0x1005e17c,special=0x0},r={stack=0x10ffdf20,code=0x1005df78,special=0x0}) -> 0 }
-> {stack=0x10ffdf20,code=0x1005df78,special=0x0} }
{ frame_id_p (l={stack=0x10ffdf20,code=0x1005df78,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdf20,code=0x1005df78,special=0x0},r={stack=0x10ffdf08,code=0x1005e17c,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdf20,code=0x1005df78,special=0x0},r={stack=0x10ffdf08,code=0x1005e17c,special=0x0}) -> 0 }
{ frame_register_unwind (frame=1,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf18 *bufferp=[20ae0510] }
{ frame_pc_unwind (this_frame=1) -> 0x1005ae20 }
-> {level=2,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1005ae20,id=<unknown>,func=<unknown>} }
#2  0x1005ae20 in dimp_check_dsp_msgs () at common/micro/dim/dimdsp.c:1831

Breakpoint 3, get_prev_frame (this_frame=0x82a92fc)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=2) { get_frame_id (fi=2) { frame_register_unwind (frame=1,regnum="r11",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf10 *bufferp=[54dfff10] }
{ frame_func_unwind (fi=1) -> 0x1005a5e4 }
{ frame_id_eq (l={stack=0x10ffdf20,code=0x1005df78,special=0x0},r={stack=0x10ffdf58,code=0x1005a5e4,special=0x0}) -> 0 }
-> {stack=0x10ffdf58,code=0x1005a5e4,special=0x0} }
{ frame_id_p (l={stack=0x10ffdf58,code=0x1005a5e4,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdf58,code=0x1005a5e4,special=0x0},r={stack=0x10ffdf20,code=0x1005df78,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdf58,code=0x1005a5e4,special=0x0},r={stack=0x10ffdf20,code=0x1005df78,special=0x0}) -> 0 }
{ frame_register_unwind (frame=2,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf50 *bufferp=[a8570510] }
{ frame_pc_unwind (this_frame=2) -> 0x100557a8 }
-> {level=3,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x100557a8,id=<unknown>,func=<unknown>} }
#3  0x100557a8 in dim_process_poll () at common/micro/dim/dimcomm.c:107

Breakpoint 3, get_prev_frame (this_frame=0x82a9498)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=3) { get_frame_id (fi=3) { frame_register_unwind (frame=2,regnum="r11",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf48 *bufferp=[68dfff10] }
{ frame_func_unwind (fi=2) -> 0x100556e4 }
{ frame_id_eq (l={stack=0x10ffdf58,code=0x1005a5e4,special=0x0},r={stack=0x10ffdf6c,code=0x100556e4,special=0x0}) -> 0 }
-> {stack=0x10ffdf6c,code=0x100556e4,special=0x0} }
{ frame_id_p (l={stack=0x10ffdf6c,code=0x100556e4,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdf6c,code=0x100556e4,special=0x0},r={stack=0x10ffdf58,code=0x1005a5e4,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdf6c,code=0x100556e4,special=0x0},r={stack=0x10ffdf58,code=0x1005a5e4,special=0x0}) -> 0 }
{ frame_register_unwind (frame=3,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf64 *bufferp=[787d0610] }
{ frame_pc_unwind (this_frame=3) -> 0x10067d78 }
-> {level=4,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x10067d78,id=<unknown>,func=<unknown>} }
{ frame_register_unwind (frame=3,regnum="r0",...) { frame_register_unwind (frame=2,regnum="r0",...) { frame_register_unwind (frame=1,regnum="r0",...) { frame_register_unwind (frame=0,regnum="r0",...) { frame_register_unwind (frame=-1,regnum="r0",...) -> *optimizedp=0 *lvalp=2 *addrp=0x0 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x0 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x0 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x0 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x0 *bufferp=[00000000] }
{ frame_register_unwind (frame=3,regnum="r1",...) { frame_register_unwind (frame=2,regnum="r1",...) { frame_register_unwind (frame=1,regnum="r1",...) { frame_register_unwind (frame=0,regnum="r1",...) { frame_register_unwind (frame=-1,regnum="r1",...) -> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
-> *optimizedp=0 *lvalp=2 *addrp=0x4 *bufferp=[00000000] }
{ frame_register_unwind (frame=3,regnum="r2",...) { frame_register_unwind (frame=2,regnum="r2",...) { frame_register_unwind (frame=1,regnum="r2",...) { frame_register_unwind (frame=0,regnum="r2",...) { frame_register_unwind (frame=-1,regnum="r2",...) -> *optimizedp=0 *lvalp=2 *addrp=0x8 *bufferp=[20a81810] }
-> *optimizedp=0 *lvalp=2 *addrp=0x8 *bufferp=[20a81810] }
-> *optimizedp=0 *lvalp=2 *addrp=0x8 *bufferp=[20a81810] }
-> *optimizedp=0 *lvalp=2 *addrp=0x8 *bufferp=[20a81810] }
-> *optimizedp=0 *lvalp=2 *addrp=0x8 *bufferp=[20a81810] }
#4  0x10067d78 in dsp_timer1intHandler (irq=0x0, dev_id=0x0, regs=0x1018a820) at dspdriver.c:169

Breakpoint 3, get_prev_frame (this_frame=0x82a9634)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=4) { get_frame_id (fi=4) { frame_register_unwind (frame=3,regnum="r11",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf5c *bufferp=[7cdfff10] }
{ frame_func_unwind (fi=3) -> 0x10067d28 }
{ frame_id_eq (l={stack=0x10ffdf6c,code=0x100556e4,special=0x0},r={stack=0x10ffdf80,code=0x10067d28,special=0x0}) -> 0 }
-> {stack=0x10ffdf80,code=0x10067d28,special=0x0} }
{ frame_id_p (l={stack=0x10ffdf80,code=0x10067d28,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdf80,code=0x10067d28,special=0x0},r={stack=0x10ffdf6c,code=0x100556e4,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdf80,code=0x10067d28,special=0x0},r={stack=0x10ffdf6c,code=0x100556e4,special=0x0}) -> 0 }
{ frame_register_unwind (frame=4,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf78 *bufferp=[04c00010] }
{ frame_pc_unwind (this_frame=4) -> 0x1000c004 }
-> {level=5,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1000c004,id=<unknown>,func=<unknown>} }
{ frame_register_unwind (frame=4,regnum="r7",...) { frame_register_unwind (frame=3,regnum="r7",...) { frame_register_unwind (frame=2,regnum="r7",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf40 *bufferp=[01000000] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf40 *bufferp=[01000000] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf40 *bufferp=[01000000] }
{ frame_register_unwind (frame=4,regnum="r8",...) { frame_register_unwind (frame=3,regnum="r8",...) { frame_register_unwind (frame=2,regnum="r8",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf44 *bufferp=[a8dfff10] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf44 *bufferp=[a8dfff10] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf44 *bufferp=[a8dfff10] }
#5  0x1000c004 in do_IRQ (irq=0x1, regs=0x10ffdfa8) at irq.c:247

Breakpoint 3, get_prev_frame (this_frame=0x82a97d0)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=5) { get_frame_id (fi=5) { frame_register_unwind (frame=4,regnum="r11",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdf70 *bufferp=[a4dfff10] }
{ frame_func_unwind (fi=4) -> 0x1000bf68 }
{ frame_id_eq (l={stack=0x10ffdf80,code=0x10067d28,special=0x0},r={stack=0x10ffdfa8,code=0x1000bf68,special=0x0}) -> 0 }
-> {stack=0x10ffdfa8,code=0x1000bf68,special=0x0} }
{ frame_id_p (l={stack=0x10ffdfa8,code=0x1000bf68,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdfa8,code=0x1000bf68,special=0x0},r={stack=0x10ffdf80,code=0x10067d28,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdfa8,code=0x1000bf68,special=0x0},r={stack=0x10ffdf80,code=0x10067d28,special=0x0}) -> 0 }
{ frame_register_unwind (frame=5,regnum="pc",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
{ frame_pc_unwind (this_frame=5) -> 0x1000b200 }
-> {level=6,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1000b200,id=<unknown>,func=<unknown>} }
#6  0x1000b200 in linux_VECTOR_IRQ ()

Breakpoint 3, get_prev_frame (this_frame=0x82a996c)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=6) { get_frame_id (fi=6) { frame_register_unwind (frame=5,regnum="sp",...) -> *optimizedp=26 *lvalp=0 *addrp=0x82a99d0 *bufferp=[a8dfff10] }
{ frame_func_unwind (fi=5) -> 0x1000b1b8 }
{ frame_id_eq (l={stack=0x10ffdfa8,code=0x1000bf68,special=0x0},r={stack=0x10ffdff0,code=0x1000b1b8,special=0x0}) -> 0 }
-> {stack=0x10ffdff0,code=0x1000b1b8,special=0x0} }
{ frame_id_p (l={stack=0x10ffdff0,code=0x1000b1b8,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffdff0,code=0x1000b1b8,special=0x0},r={stack=0x10ffdfa8,code=0x1000bf68,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffdff0,code=0x1000b1b8,special=0x0},r={stack=0x10ffdfa8,code=0x1000bf68,special=0x0}) -> 0 }
{ frame_register_unwind (frame=6,regnum="pc",...) { frame_register_unwind (frame=5,regnum="lr",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
{ frame_pc_unwind (this_frame=6) -> 0x1000b200 }
-> {level=7,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1000b200,id=<unknown>,func=<unknown>} }
#7  0x1000b200 in linux_VECTOR_IRQ ()

Breakpoint 3, get_prev_frame (this_frame=0x82a9b08)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) c
Continuing.
{ get_prev_frame (this_frame=7) { get_frame_id (fi=7) { frame_register_unwind (frame=6,regnum="sp",...) -> *optimizedp=26 *lvalp=0 *addrp=0x82a9b6c *bufferp=[f0dfff10] }
{ frame_func_unwind (fi=6) -> 0x1000b1b8 }
{ frame_id_eq (l={stack=0x10ffdff0,code=0x1000b1b8,special=0x0},r={stack=0x10ffe038,code=0x1000b1b8,special=0x0}) -> 0 }
-> {stack=0x10ffe038,code=0x1000b1b8,special=0x0} }
{ frame_id_p (l={stack=0x10ffe038,code=0x1000b1b8,special=0x0}) -> 1 }
{ frame_id_inner (l={stack=0x10ffe038,code=0x1000b1b8,special=0x0},r={stack=0x10ffdff0,code=0x1000b1b8,special=0x0}) -> 0 }
{ frame_id_eq (l={stack=0x10ffe038,code=0x1000b1b8,special=0x0},r={stack=0x10ffdff0,code=0x1000b1b8,special=0x0}) -> 0 }
{ frame_register_unwind (frame=7,regnum="pc",...) { frame_register_unwind (frame=6,regnum="lr",...) { frame_register_unwind (frame=5,regnum="lr",...) -> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
-> *optimizedp=0 *lvalp=1 *addrp=0x10ffdfa0 *bufferp=[00b20010] }
{ frame_pc_unwind (this_frame=7) -> 0x1000b200 }
-> {level=8,type=UNKNOWN_FRAME,unwind=<unknown>,pc=0x1000b200,id=<unknown>,func=<unknown>} }
#8  0x1000b200 in linux_VECTOR_IRQ ()

Breakpoint 3, get_prev_frame (this_frame=0x82a9ca4)
    at ../../src/gdb/frame.c:1743
1743	  if (frame_debug)
(top-gdb) quit
The program is running.  Exit anyway? (y or n)