Re: Additional info on modpost segfault

[Alan <alan@clueserver.org>]

On Tue, 2010-06-08 at 13:51 +0800, Américo Wang wrote: 
> On Mon, Jun 07, 2010 at 09:59:39AM -0700, Alan wrote:
> >On Fri, 2010-06-04 at 09:22 +0200, Michal Marek wrote: 
> >> On 4.6.2010 06:51, Américo Wang wrote:
> >> > On Thu, Jun 03, 2010 at 08:10:30PM -0700, alan wrote:
> >> >> Missed adding the actual segfault message:
> >> >>
> >> >>  LD      drivers/usb/built-in.o
> >> >>  LD      drivers/built-in.o
> >> >>  LD      vmlinux.o
> >> >>  MODPOST vmlinux.o
> >> >> /bin/sh: line 1: 20665 Segmentation fault      (core dumped)
> >> >> scripts/mod/modpost -o
> >> >> /home/alan/GitTrees/linux-2.6-mid-ref/Module.symvers -S vmlinux.o
> >> >> make[1]: *** [vmlinux.o] Error 139
> >> >> make: *** [vmlinux.o] Error 2
> >> >>
> >> >> I have looked at the gcc 4.4.4 changelog and I can't see anything
> >> >> that should cause this.
> >> >>
> >> > 
> >> > Hmm, you need to find which program segfaults here.
> >> 
> >> It's the modpost command run on vmlinux.o. Alan, can you try
> >> $ gdb --args scripts/mod/modpost -o Module.symvers -S vmlinux.o
> >> (gdb) r
> >> (wait for the segfault)
> >> (gdb) bt full
> >> 
> >> and post the backtrace?
> >
> >Don't know if this will help much.
> >
> >This GDB was configured as "x86_64-redhat-linux-gnu".
> >For bug reporting instructions, please see:
> ><http://www.gnu.org/software/gdb/bugs/>...
> >Reading symbols
> >from /home/alan/GitTrees/linux-2.6-mid-ref/scripts/mod/modpost...(no
> >debugging symbols found)...done.
> >(gdb) r
> >Starting
> >program: /home/alan/GitTrees/linux-2.6-mid-ref/scripts/mod/modpost -o
> >Module.symvers -S vmlinux.o
> >
> >Program received signal SIGSEGV, Segmentation fault.
> >0x0000000000403711 in main ()
> >(gdb) bt full
> >#0  0x0000000000403711 in main ()
> >No symbol table info available.
> >
> >Trying to get it to compile with debugging info.
> >
> 
> Try to append "-g" to HOSTCFLAGS in the top Makefile. ;)

Thanks. Tried CFLAGS and that did not work...

Here is the backtrace:
(gdb) bt full
#0  read_symbols (argc=5, argv=0x7fffffffe198) at
scripts/mod/modpost.c:1564
        license = <value optimized out>
        info = {size = 209695023, hdr = 0x7fffeb263000, 
          sechdrs = 0x7ffff48fcc2c, symtab_start = 0x7ffff7863e2c, 
          symtab_stop = 0x7ffff794341c, export_sec = 37, 
          export_unused_sec = 0, export_gpl_sec = 48, 
          export_unused_gpl_sec = 0, export_gpl_future_sec = 0, 
          strtab = 0x7ffff794341c "", modinfo = 0x0, modinfo_len = 0}
        sym = <value optimized out>
        symname = <value optimized out>
        version = <value optimized out>
        mod = 0x610010
#1  main (argc=5, argv=0x7fffffffe198) at scripts/mod/modpost.c:1999
        mod = <value optimized out>
        buf = {p = 0x0, pos = 0, size = 0}
        kernel_read = <value optimized out>
        module_read = <value optimized out>
        dump_write = 0x7fffffffe4ed "Module.symvers"
        opt = <value optimized out>
        err = <value optimized out>
        extsym_iter = <value optimized out>
        extsym_start = <value optimized out>

The line is does not like is:

  read_symbols(argv[optind++]);

Not certain why...