Re: Regression: graceful unwind termination when we'd need unavailable/uncollect memory or registers to unwind further

[Pedro Alves <pedro at codesourcery dot com>]

Thanks Jan.  I'll take a look as soon as possible.

-- 
Pedro Alves

On Sunday 20 March 2011 18:48:45, Jan Kratochvil wrote:
> Hi Pedro,
> 
> on a testfile from the Fedora patchset there is a regression, IMO a valid one:
> 
> e67dca4a095f4db1022fd0753ef0bda3873dc1bc is the first bad commit
> commit e67dca4a095f4db1022fd0753ef0bda3873dc1bc
> Author: Pedro Alves <pedro@codesourcery.com>
> Date:   Fri Mar 18 18:52:28 2011 +0000
> 
>     	gdb/
>     	* frame.c (frame_unwind_register): Throw an error if unwinding the
>     	register failed.
> [...]
> :040000 040000 6bdd3071cc91073d64ffd2a1030c44ce2b1956b9 a4487e736a1087aee5d5b5207cee5a56ae936f42 M	gdb
> bisect run success
> 
> http://pkgs.fedoraproject.org/gitweb/?p=gdb.git;a=blob_plain;f=gdb-6.8-bz457187-largefile-test.patch;hb=f15/master
>  = This file is included in this mail.
> 
> (gdb) x/i 0x400078
>    0x400078:    hlt    
> PASS: gdb.arch/i386-biarch-core.exp: .text is readable
> ->
> (gdb) x/i 0x400078
> PC not available
> FAIL: gdb.arch/i386-biarch-core.exp: .text is readable
> 
> The core file does not have accessible registers.  It was not a goal of the
> testcase, it tests something else.  But it has found this unrelated
> regression.  I believe one should be able to evaluate PC-indepenent
> expressions even if PC is not available.
> 
> 
> Even the first part is regressing (although it stays PASS->PASS):
> (gdb) core-file gdb.arch/i386-biarch-core.core
> [New LWP 6901]
> warning: Couldn't recognize general-purpose registers in core file.
> Core was generated by `./bad'.
> Program terminated with signal 11, Segmentation fault.
> warning: Couldn't recognize general-purpose registers in core file.
> #0  0x00000000 in ?? ()
> ->
> (gdb) core-file gdb.arch/i386-biarch-core.core
> [New LWP 6901]
> warning: Couldn't recognize general-purpose registers in core file.
> PC register is not available
> 
> The core file reason is not displayed while it could be, I have tried the
> following patch does not help in this case:
> 	[patch 3/3] Display core reasons even during thread error
> 	http://sourceware.org/ml/gdb-patches/2011-02/msg00675.html
> 
> 
> Thanks,
> Jan
> 
> 
> --- /dev/null	2009-04-19 14:49:00.974648389 +0200
> +++ gdb-6.8/gdb/testsuite/gdb.arch/i386-biarch-core.exp	2009-04-19 16:30:12.000000000 +0200
> @@ -0,0 +1,61 @@
> +# This testcase is part of GDB, the GNU debugger.
> +
> +# Copyright 2009 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 2 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write to the Free Software
> +# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
> +
> +# Test ability to load an elf64-i386 core file.  The provided core file was
> +# elf64-x8664 one but it got binary patched to i386:
> +# Elf32_Ehdr.e_machine @0x12..0x13
> +# Elf64_Ehdr.e_machine @0x12..0x13
> +# #define EM_386           3              /* Intel 80386 */
> +# #define EM_X86_64       62              /* AMD x86-64 architecture */
> +# patch @0x12: 0x3E -> 0x03
> +
> +if { ![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"] } then {
> +    verbose "Skipping i386-biarch-core test."
> +    return
> +}
> +
> +set testfile "i386-biarch-core"
> +set corebz2uufile ${srcdir}/${subdir}/${testfile}.core.bz2.uu
> +set corefile ${objdir}/${subdir}/${testfile}.core
> +# Entry point of the original executable.
> +set address 0x400078
> +
> +if {[catch "system \"uudecode -o - ${corebz2uufile} | bzip2 -dc >${corefile}\""] != 0} {
> +    untested "failed uudecode or bzip2"
> +    return -1
> +}
> +file stat ${corefile} corestat
> +if {$corestat(size) != 102400} {
> +    untested "uudecode or bzip2 produce invalid result"
> +    return -1
> +}
> +
> +gdb_exit
> +gdb_start
> +gdb_reinitialize_dir $srcdir/$subdir
> +
> +# Wrongly built GDB complains by:
> +# "..." is not a core dump: File format not recognized
> +# As the provided test core has 64bit PRSTATUS i386 built GDB cannot parse it.
> +# This is just a problem of the test care, real-world elf64-i386 file will have
> +# 32bit PRSTATUS.  One cannot prepare elf64-i386 core file from elf32-i386 by
> +# objcopy as it corrupts the core file beyond all recognition.
> +# "\r\nCore was generated by `\[^\r\n\]*'\\.\r\nProgram terminated with signal 11, Segmentation fault\\.\r\n.*"
> +gdb_test "core-file ${corefile}"
> +
> +gdb_test "x/i $address" "\r\n\[ \t\]*$address:\[ \t\]*hlt\[ \t\]*" ".text is readable"
> --- /dev/null	2009-04-19 14:49:00.974648389 +0200
> +++ gdb-6.8/gdb/testsuite/gdb.arch/i386-biarch-core.S	2009-04-19 14:52:28.000000000 +0200
> @@ -0,0 +1,22 @@
> +/* This testcase is part of GDB, the GNU debugger.
> +
> +   Copyright 2009 Free Software Foundation, Inc.
> +  
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 2 of the License, or
> +   (at your option) any later version.
> +  
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +  
> +   You should have received a copy of the GNU General Public License
> +   along with this program; if not, write to the Free Software
> +   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
> + */
> +
> +	.globl _start
> +_start:
> +	hlt
> --- /dev/null	2009-04-19 14:49:00.974648389 +0200
> +++ gdb-6.8/gdb/testsuite/gdb.arch/i386-biarch-core.core.bz2.uu	2009-04-19 15:02:12.000000000 +0200
> @@ -0,0 +1,13 @@
> +begin 600 i386-biarch-core.core.bz2
> +M0EIH.3%!629361`P1\P`!)?_____\9'@"8Q)6P380'9@'&#`0D@``"``%(``
> +M@`#`"!<(L`%F"(:$GH13::F-)M&D&U,AD:`--#)M0&FT0XR9--,)D9`P(Q-&
> +M",(-&F``02)%38HT]0T`&AH```'H@``T^>9T*(,("&)SE`>`9@+GP=[,N)KB
> +M'I8BL(L]N5TCY\%V]/?DB.BN*UZ'U@]TN7-]UJ5\_%0QTT<*086#%MHT7XVJ
> +M9D"+C!"2*L:8D1XPD!`--M@*XT1H5RFYN&)(!0P0#:`I:;2;$5M&\*9"0@%:
> +MK@X[T()M)9N7`D$VA!^63)%,;@8LT`(7\K&[7G;U:"B6'!GG+46ALOZF.2F-
> +M!@>C*%86X$-]C2`KE;HG)UL(913VR2G]0BD:J=Z_`G@S,`W%.8RMS-#5P:J0
> +MAJ2\8&X?@DE;UF68QHM<,D`('::J65/S:PAG*R-09["8DBI)'V]Y.[(/AM*L
> +M"X_O^V;%FY.S6Q]FM=D37>5F,%4-F1ZF#,CFJVU;H*^IT<(%<V`.32$`JU["
> +/G`68?\7<D4X4)`0,$?,`
> +`
> +end
>