From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5457 invoked by alias); 17 Oct 2010 17:55:23 -0000 Received: (qmail 5158 invoked by uid 22791); 17 Oct 2010 17:55:17 -0000 X-SWARE-Spam-Status: No, hits=-6.1 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,TW_BJ,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 17 Oct 2010 17:55:04 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o9HHstTK009166 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 17 Oct 2010 13:54:55 -0400 Received: from host1.dyn.jankratochvil.net (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id o9HHsqD0013607 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 17 Oct 2010 13:54:54 -0400 Received: from host1.dyn.jankratochvil.net (localhost [127.0.0.1]) by host1.dyn.jankratochvil.net (8.14.4/8.14.4) with ESMTP id o9HHsqDH009112; Sun, 17 Oct 2010 19:54:52 +0200 Received: (from jkratoch@localhost) by host1.dyn.jankratochvil.net (8.14.4/8.14.4/Submit) id o9HHspQp009100; Sun, 17 Oct 2010 19:54:51 +0200 Date: Sun, 17 Oct 2010 17:55:00 -0000 From: Jan Kratochvil To: Pedro Alves Cc: gdb-patches@sourceware.org Subject: Re: [patch] Fix inferior execl of new PIE x86_64 Message-ID: <20101017175451.GA5936@host1.dyn.jankratochvil.net> References: <20100930185257.GA1245@host1.dyn.jankratochvil.net> <201010160020.45818.pedro@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201010160020.45818.pedro@codesourcery.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2010-10/txt/msg00274.txt.bz2 On Sat, 16 Oct 2010 01:20:45 +0200, Pedro Alves wrote: > Hmm. I'm looking at clear_symtab_users, and noticing that varobj_invalidate > also appears to recreate varobj's, thus, it ends up using the unrelocated > symbols, and thus may manage to not trigger an exception and end up with > varobj's with the wrong values. (If an exception is triggered, say a memory > error, it appears that is caught and swallowed, and the varobjs ends > up with no value.) OK... I agree there is a problem. time T+0: FE did -var-update, stopped. time T+1: inferior did exec, GDB did follow-exec. time T+2: FE did -var-update, stopped. IMO the goal is to report at time T+2 the changes of types/values between T+0 and T+2. Even if we would call varobj_invalidate after relocations from follow_exec still MI would report only changes between T+1 and T+2. Changes between T+0 and T+1 would still get lost. There is IMO already a problem in the defined API of varobj_invalidate. The invalidation has been made more fine grained by (never checked-in): [patch 8/8] Types GC [varobj] http://sourceware.org/ml/gdb-patches/2009-05/msg00551.html (Part of the types garbage collector as a preprequisite for VLA (Variable Length Arrays, for var[variable] and/or Fortran.) Therefore currently postponing that part of the problem till the resubmit of GC/VLA. > Your patch looks like an improvement already, so it is okay as is with me. Checked-in. > Please make the test be skipped against remote targets though, since > there's no support for following execs in the remote protocol. if [is_remote target] { Thanks, Jan http://sourceware.org/ml/gdb-cvs/2010-10/msg00101.html --- src/gdb/ChangeLog 2010/10/17 08:43:45 1.12265 +++ src/gdb/ChangeLog 2010/10/17 17:45:16 1.12266 @@ -1,5 +1,23 @@ 2010-10-17 Jan Kratochvil + * infrun.c (follow_exec): Replace symbol_file_add_main by + symbol_file_add with SYMFILE_DEFER_BP_RESET, set_initial_language and + breakpoint_re_set. + * m32r-rom.c (m32r_load, m32r_upload_command): Use parameter 0 for + clear_symtab_users. + * objfiles.c (free_all_objfiles): Likewise. + * remote-m32r-sdi.c (m32r_load): Likewise. + * solib-som.c (som_solib_create_inferior_hook): Likewise. + * symfile.c (new_symfile_objfile): New comment for add_flags. Call + clear_symtab_users with ADD_FLAGS. + (reread_symbols): Use parameter 0 for clear_symtab_users. + (clear_symtab_users): New parameter add_flags. Do not call + breakpoint_re_set if SYMFILE_DEFER_BP_RESET. + (clear_symtab_users_cleanup): Use parameter 0 for clear_symtab_users. + * symtab.h (clear_symtab_users): New parameter add_flags. + +2010-10-17 Jan Kratochvil + Fix GCC false warning. * varobj.c (value_get_print_value) : Initialize it. --- src/gdb/testsuite/ChangeLog 2010/10/15 17:48:47 1.2481 +++ src/gdb/testsuite/ChangeLog 2010/10/17 17:45:17 1.2482 @@ -1,3 +1,8 @@ +2010-10-17 Jan Kratochvil + + * gdb.base/pie-execl.exp: New file. + * gdb.base/pie-execl.c: New file. + 2010-10-13 Doug Evans Jan Kratochvil --- src/gdb/infrun.c 2010/09/24 18:35:27 1.451 +++ src/gdb/infrun.c 2010/10/17 17:45:16 1.452 @@ -835,8 +835,15 @@ /* That a.out is now the one to use. */ exec_file_attach (execd_pathname, 0); - /* Load the main file's symbols. */ - symbol_file_add_main (execd_pathname, 0); + /* SYMFILE_DEFER_BP_RESET is used as the proper displacement for PIE + (Position Independent Executable) main symbol file will get applied by + solib_create_inferior_hook below. breakpoint_re_set would fail to insert + the breakpoints with the zero displacement. */ + + symbol_file_add (execd_pathname, SYMFILE_MAINLINE | SYMFILE_DEFER_BP_RESET, + NULL, 0); + + set_initial_language (); #ifdef SOLIB_CREATE_INFERIOR_HOOK SOLIB_CREATE_INFERIOR_HOOK (PIDGET (inferior_ptid)); @@ -846,6 +853,8 @@ jit_inferior_created_hook (); + breakpoint_re_set (); + /* Reinsert all breakpoints. (Those which were symbolic have been reset to the proper address in the new a.out, thanks to symbol_file_command...) */ --- src/gdb/m32r-rom.c 2010/09/14 08:01:12 1.41 +++ src/gdb/m32r-rom.c 2010/10/17 17:45:16 1.42 @@ -188,7 +188,7 @@ the stack may not be valid, and things would get horribly confused... */ - clear_symtab_users (); + clear_symtab_users (0); } static void @@ -551,7 +551,7 @@ the stack may not be valid, and things would get horribly confused... */ - clear_symtab_users (); + clear_symtab_users (0); } /* Provide a prototype to silence -Wmissing-prototypes. */ --- src/gdb/objfiles.c 2010/09/22 20:00:53 1.122 +++ src/gdb/objfiles.c 2010/10/17 17:45:16 1.123 @@ -692,7 +692,7 @@ { free_objfile (objfile); } - clear_symtab_users (); + clear_symtab_users (0); } /* A helper function for objfile_relocate1 that relocates a single --- src/gdb/remote-m32r-sdi.c 2010/09/14 08:01:12 1.53 +++ src/gdb/remote-m32r-sdi.c 2010/10/17 17:45:16 1.54 @@ -1377,7 +1377,7 @@ might be to call normal_stop, except that the stack may not be valid, and things would get horribly confused... */ - clear_symtab_users (); + clear_symtab_users (0); if (!nostart) { --- src/gdb/solib-som.c 2010/05/16 23:49:58 1.29 +++ src/gdb/solib-som.c 2010/10/17 17:45:16 1.30 @@ -354,7 +354,7 @@ /* Make the breakpoint at "_start" a shared library event breakpoint. */ create_solib_event_breakpoint (target_gdbarch, anaddr); - clear_symtab_users (); + clear_symtab_users (0); } static void --- src/gdb/symfile.c 2010/10/01 20:26:11 1.297 +++ src/gdb/symfile.c 2010/10/17 17:45:16 1.298 @@ -1038,7 +1038,7 @@ /* Perform required actions after either reading in the initial symbols for a new objfile, or mapping in the symbols from a reusable - objfile. */ + objfile. ADD_FLAGS is a bitmask of enum symfile_add_flags. */ void new_symfile_objfile (struct objfile *objfile, int add_flags) @@ -1051,7 +1051,7 @@ /* OK, make it the "real" symbol file. */ symfile_objfile = objfile; - clear_symtab_users (); + clear_symtab_users (add_flags); } else if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0) { @@ -2530,7 +2530,7 @@ /* Notify objfiles that we've modified objfile sections. */ objfiles_changed (); - clear_symtab_users (); + clear_symtab_users (0); /* At least one objfile has changed, so we can consider that the executable we're debugging has changed too. */ observer_notify_executable_changed (); @@ -2748,10 +2748,10 @@ /* Reset all data structures in gdb which may contain references to symbol - table data. */ + table data. ADD_FLAGS is a bitmask of enum symfile_add_flags. */ void -clear_symtab_users (void) +clear_symtab_users (int add_flags) { /* Someday, we should do better than this, by only blowing away the things that really need to be blown. */ @@ -2761,7 +2761,8 @@ clear_current_source_symtab_and_line (); clear_displays (); - breakpoint_re_set (); + if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0) + breakpoint_re_set (); set_default_breakpoint (0, NULL, 0, 0, 0); clear_pc_function_cache (); observer_notify_new_objfile (NULL); @@ -2780,7 +2781,7 @@ static void clear_symtab_users_cleanup (void *ignore) { - clear_symtab_users (); + clear_symtab_users (0); } /* OVERLAYS: --- src/gdb/symtab.h 2010/09/08 17:17:42 1.163 +++ src/gdb/symtab.h 2010/10/17 17:45:16 1.164 @@ -1186,7 +1186,7 @@ /* symfile.c */ -extern void clear_symtab_users (void); +extern void clear_symtab_users (int add_flags); extern enum language deduce_language_from_filename (const char *); --- src/gdb/testsuite/gdb.base/pie-execl.c +++ src/gdb/testsuite/gdb.base/pie-execl.c 2010-10-17 17:45:47.138149000 +0000 @@ -0,0 +1,51 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2010 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 3 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, see . */ + +#include +#include +#include + +static void pie_execl_marker (void); + +int +main (int argc, char **argv) +{ + setbuf (stdout, NULL); + +#if BIN == 1 + if (argc == 2) + { + printf ("pie-execl: re-exec: %s\n", argv[1]); + execl (argv[1], argv[1], NULL); + assert (0); + } +#endif + + pie_execl_marker (); + + return 0; +} + +/* pie_execl_marker must be on a different address than in `pie-execl2.c'. */ + +volatile int v; + +static void +pie_execl_marker (void) +{ + v = 1; +} --- src/gdb/testsuite/gdb.base/pie-execl.exp +++ src/gdb/testsuite/gdb.base/pie-execl.exp 2010-10-17 17:45:47.456930000 +0000 @@ -0,0 +1,100 @@ +# Copyright 2010 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 3 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, see . + +# The problem was due to amd64_skip_prologue attempting to access inferior +# memory before the PIE (Position Independent Executable) gets relocated. + +if ![istarget *-linux*] { + continue +} + +# Remote protocol does not support follow-exec notifications. + +if [is_remote target] { + continue +} + +set testfile "pie-execl" +set srcfile ${testfile}.c +set executable1 ${testfile}1 +set executable2 ${testfile}2 +set binfile1 ${objdir}/${subdir}/${executable1} +set binfile2 ${objdir}/${subdir}/${executable2} + +# Use conditional compilation according to `BIN' as GDB remembers the source +# file name of the breakpoint. + +set opts [list debug {additional_flags=-fPIE -pie}] +if {[build_executable ${testfile}.exp $executable1 $srcfile [concat $opts {additional_flags=-DBIN=1}]] == "" + || [build_executable ${testfile}.exp $executable2 $srcfile [concat $opts {additional_flags=-DBIN=2}]] == ""} { + return -1 +} + +clean_restart ${executable1} + +gdb_test_no_output "set args ${binfile2}" + +if ![runto_main] { + return -1 +} + +# Do not stop on `main' after re-exec. +delete_breakpoints + +gdb_breakpoint "pie_execl_marker" +gdb_test "info breakpoints" ".*" "" + +set addr1 "" +set test "pie_execl_marker address first" +gdb_test_multiple "p/x &pie_execl_marker" $test { + -re " = (0x\[0-9a-f\]+)\r\n$gdb_prompt $" { + set addr1 $expect_out(1,string) + pass $test + } +} +verbose -log "addr1 is $addr1" + +set test "continue" +gdb_test_multiple $test $test { + -re "Error in re-setting breakpoint" { + fail $test + } + -re "Cannot access memory" { + fail $test + } + -re "pie-execl: re-exec.*executing new program.*\r\nBreakpoint \[0-9\]+,\[^\r\n\]* pie_execl_marker .*\r\n$gdb_prompt $" { + pass $test + } +} + +gdb_test "info breakpoints" ".*" "" + +set addr2 "" +set test "pie_execl_marker address second" +gdb_test_multiple "p/x &pie_execl_marker" $test { + -re " = (0x\[0-9a-f\]+)\r\n$gdb_prompt $" { + set addr2 $expect_out(1,string) + pass $test + } +} +verbose -log "addr2 is $addr2" + +# Ensure we cannot get a false PASS and the inferior has really changed. +set test "pie_execl_marker address has changed" +if [string equal $addr1 $addr2] { + fail $test +} else { + pass $test +}