Re: [PATCH] Handle absence of DT_DEBUG while debugging ld.so

[Luis Machado <luisgpm@linux.vnet.ibm.com>]

On Tue, 2008-07-29 at 08:12 -0400, Daniel Jacobowitz wrote:
> On Mon, Jul 28, 2008 at 11:57:15PM -0300, Luis Machado wrote:
> > Yes, this specific address seems broken somehow. This is the first
> > _r_debug entry GDB gets:
> 
> Looks like the section offsets are not set yet.
> 
> > And this is the next _r_debug minimal symbol entry GDB gets:
> 
> What do you mean by "next"?  What commands did you use to get this
> output?

"Next" as in the entry GDB locates in the next time it calls
elf_locate_base(...), this time solib_create_inferior_hook(...) is in
the code path after post_create_inferior(...):

#0  elf_locate_base () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:494
#1  0x00000000100af30c in locate_base () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:570
#2  0x00000000100af9a4 in svr4_current_sos () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:760
#3  0x00000000100ad208 in update_solib_list (from_tty=0, target=0x108fd990) at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib.c:494
#4  0x00000000100ad630 in solib_add (pattern=0x0, from_tty=0, target=0x108fd990, readsyms=1)
    at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib.c:677
#5  0x00000000100b0058 in enable_break () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:989
#6  0x00000000100b0a94 in svr4_solib_create_inferior_hook () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:1408
#7  0x00000000100adc60 in solib_create_inferior_hook () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib.c:884
#8  0x00000000101973e8 in post_create_inferior (target=0x108fd990, from_tty=0) at /home/luis/src/gdb/gdb-head/HEAD3/gdb/infcmd.c:441

... whereas the first time it was called:

#0  elf_locate_base () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:494
#1  0x00000000100af30c in locate_base () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:570
#2  0x00000000100af9a4 in svr4_current_sos () at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib-svr4.c:760
#3  0x00000000100ad208 in update_solib_list (from_tty=0, target=0x108fd990) at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib.c:494
#4  0x00000000100ad630 in solib_add (pattern=0x0, from_tty=0, target=0x108fd990, readsyms=1)
    at /home/luis/src/gdb/gdb-head/HEAD3/gdb/solib.c:677
#5  0x00000000101973e0 in post_create_inferior (target=0x108fd990, from_tty=0) at /home/luis/src/gdb/gdb-head/HEAD3/gdb/infcmd.c:433


> Also, with GDB 6.8 I can "continue" after this error.  With HEAD:
> 
> Continuing.
> Cannot execute this command while the selected thread is running.
> 
> Hey, Pedro?  Cleanup trouble?

Yes, i discussed this with Pedro yesterday and he's aware of the
problem.

Luis