[Bug gdb/13989] New: gdb invalid search order for shared libraries by cross debuging

[Bug gdb/13989] New: gdb invalid search order for shared libraries by cross debuging

[Daniel.Lehne@amk-drives.bg]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

             Bug #: 13989
           Summary: gdb invalid search order for shared libraries by cross
                    debuging
           Product: gdb
           Version: 7.4
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
        AssignedTo: unassigned@sourceware.org
        ReportedBy: Daniel.Lehne@amk-drives.bg
    Classification: Unclassified


Hello,

i think the order to search libraries:

1st sysroot
2nd host-sysroot (absolute path of lib on host)
3rd solib-search-path 

for cross debugging is not usable. In this case libraries of the host-sysroot
replace the libraries for cross target in solib-search-path, and debugging
becomes impossible.
I configured GDB with --with-sysroot, declared additional set sysroot, set
solib-search-path, set solib-absolute-path (nevermind alias of set sysroot). 

Example:
Simple Hello world project, additional lib freetype and jpeg (they should
exists host-sysroot), linked to binary. Gdb session started with init:
set sysroot <TOOLCHAIN>
set solib-search-path <SPECIAL LIBS>

#include "stdio.h"

int main(int argc, char **argv) {
    printf("test");
}

Invoking: Cross GCC Compiler
arm-1136jfs-linux-gnueabi-gcc -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP
-MF"main.d" -MT"main.d" -o "main.o" "../main.c"
../main.c: In function 'main':
../main.c:5:1: warning: control reaches end of non-void function
Finished building: ../main.c

Building target: gdb_bug_sysroot
Invoking: Cross GCC Linker
arm-1136jfs-linux-gnueabi-gcc -L/home/opt/amklibs/arm-1136jfs -o
"gdb_bug_sysroot"  ./main.o   -lz -ljpeg -lfreetype
Finished building target: gdb_bug_sysroot

GDB-Session:

...
252,189
=library-loaded,id="/usr/lib/libz.so.1",target-name="/usr/lib/libz.so.1",host-name="/home/opt/libs/arm-1136jfs/libz.so.1",symbols-loaded="0",thread-group="i1"
252,190 &"warning: `/usr/lib/libjpeg.so.8': Shared library architecture unknown
is not compatible with target architecture arm.\n"
252,190
=library-loaded,id="/usr/lib/libjpeg.so.8",target-name="/usr/lib/libjpeg.so.8",host-name="/usr/lib/libjpeg.so.8",symbols-loaded="0",thread-group="i1"
252,190
=library-loaded,id="/lib/libc.so.6",target-name="/lib/libc.so.6",host-name="/home/opt/Toolchain/arm-1136jfs-linux-gnueabi/gcc-4.5.2-glibc-2.13-binutils-2.21-kernel-2.6.36-sanitized/sysroot-arm-1136jfs-linux-gnueabi/lib/libc.so.6",symbols-loaded="0",thread-group="i1"
252,190 &"warning: `/lib/libgcc_s.so.1': Shared library architecture unknown is
not compatible with target architecture arm.\n"
252,190
=library-loaded,id="/lib/libgcc_s.so.1",target-name="/lib/libgcc_s.so.1",host-name="/lib/libgcc_s.so.1",symbols-loaded="0",thread-group="i1"
...

The library libz loaded correctly from solib-search-path. The library libc.so.6
loaded correctly from Toolchain by sysroot. 

The libjpeg and libfreetype (cut out of log) loaded incorrectly from host
rootfs instead of solib-search-path.

Thanks for a request.

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[palves at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

Pedro Alves <palves at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |palves at redhat dot com

--- Comment #1 from Pedro Alves <palves at redhat dot com> 2012-04-18 11:45:16 UTC ---
I'm guessing this use case wasn't originally considered, because it doesn't
look like how set sysroot/solib-search-path are meant to be used.

(gdb) help set solib-search-path 
Set the search path for loading non-absolute shared library symbol files.
                                ^^^^^^^^^^^^
This takes precedence over the environment variables PATH and LD_LIBRARY_PATH.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This command is there mostly to help targets like Windows that don't report to
the debugger the full path to the shared library.  GNU/Linux always works with
full patchs, such as "/usr/lib/libjpeg.so.8".

The normal use of "set sysroot" is to point that at a directory that contains
_all_ the libraries the target reports as loaded (or simply, the copy of the
target's whole root filesystem).  IOW, make the sysroot wholly self contained
(you can use symlinks though), and forget about solib-search-path.

Or, with GDB >= 7.0, point the sysroot at "remote:", and GDB will fetch the
libraries from the target automatically (but won't work in the end if you strip
the copies of the libraries on the target, as GDB will work with the stripped
copies then).

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[Daniel.Lehne@amk-drives.bg]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

--- Comment #2 from Daniel <Daniel.Lehne@amk-drives.bg> 2012-04-18 12:31:59 UTC ---
I've got this information from 

http://sourceware.org/gdb/onlinedocs/gdb/Files.html. 
"... `solib-search-path' is used after `sysroot' fails to locate the library,
OR if the path to the library is relative instead of absolute."

I've got a cross-toolchain (must stay untouched) as sysroot, which is not
serving all libraries (additional jpeg, ...). So i could give a hint to GDB to
a special folder(solib-search-path) _after_ sysroot. That was my idea to use
solib-search-path, but pity it isn't available.

So this is not a bug, rather unprecise points in the online documentation of
solib-search-path.

Thanks for the advices.

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[Daniel.Lehne@amk-drives.bg]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

--- Comment #3 from Daniel <Daniel.Lehne@amk-drives.bg> 2012-04-18 12:57:57 UTC ---
I'm still confused, because of your answer:

Set the search path for loading non-absolute shared library symbol files.
This takes precedence over the environment variables PATH and LD_LIBRARY_PATH.
GNU/Linux always works with full paths, such as "/usr/lib/libjpeg.so.8"

and this print:

252,189=library-loaded,id="/usr/lib/libz.so.1",target-name="/usr/lib/libz.so.1",host-name="/home/opt/libs/arm-1136jfs/libz.so.1",symbols-loaded="0",thread-group="i1"

Here i see the search order, once Linux reports absolute "/usr/lib/libz.so.1"
and it is not available on sysroot(1st), PATH(2nd) and LD_LIBRARY_PATH(3rd). It
will cut off "/usr/lib/" and replace with _solib-search-path_(4th) to
"/home/opt/libs/arm-1136jfs/libz.so.1".

Both are absolute:
libz.so.1 => /usr/lib/libz.so.1 (0x40026000)
libjpeg.so.8 => /usr/lib/libjpeg.so.8 (0x40041000)

Why he do this stripping for libz.so.1 and not for libjpeg.so.8?

Can anyone tell me the source file/function, where it is implemented?

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[palves at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

--- Comment #4 from Pedro Alves <palves at redhat dot com> 2012-05-10 14:31:20 UTC ---
solib.c:solib_find

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[palves at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

--- Comment #5 from Pedro Alves <palves at redhat dot com> 2012-09-28 19:50:41 UTC ---
The issue has been identified now, and a patch should land on mainline soon.
Sorry for not having clearly understood the issue sooner.

http://sourceware.org/ml/gdb-patches/2012-09/msg00665.html

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[cvs-commit at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

--- Comment #6 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> 2012-09-28 20:20:15 UTC ---
CVSROOT:    /cvs/src
Module name:    src
Changes by:    emachado@sourceware.org    2012-09-28 20:20:10

Modified files:
    gdb            : ChangeLog solib.c 

Log message:
    2012-09-28  Nathan Miller  <nathanm2@us.ibm.com>
    Edjunior Machado  <emachado@linux.vnet.ibm.com>

    PR gdb/13989
    * solib.c (solib_find): Prevent GDB from loading native libraries when
    debugging a cross-target corefile.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.14722&r2=1.14723
http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/solib.c.diff?cvsroot=src&r1=1.166&r2=1.167

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[Bug gdb/13989] gdb invalid search order for shared libraries by cross debuging

[palves at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=13989

Pedro Alves <palves at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |7.6

--- Comment #7 from Pedro Alves <palves at redhat dot com> 2012-09-28 21:10:51 UTC ---
Fix is in.

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