419 lines
13 KiB
Diff
419 lines
13 KiB
Diff
http://sourceware.org/ml/gdb-patches/2010-09/msg00519.html
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Subject: [patch] Fix inferior execl of new PIE x86_64
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Hi,
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gcc -o 1 1.c -Wall -g -fPIE -pie; gdb -nx ./1 -ex 'b main' -ex r -ex c
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Starting program: .../gdb/1
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Breakpoint 1, main (argc=1, argv=0x7fffffffdff8) at 1.c:7
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7 setbuf (stdout, NULL);
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Continuing.
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re-exec
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process 28056 is executing new program: .../gdb/1
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Error in re-setting breakpoint 1: Cannot access memory at address 0x80c
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exit
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Program exited normally.
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(gdb) _
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while it should be:
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re-exec
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process 28095 is executing new program: .../gdb/1
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Breakpoint 1, main (argc=2, argv=0x7fffffffe008) at 1.c:7
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7 setbuf (stdout, NULL);
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(gdb) _
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The error comes from:
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throw_error <- memory_error <- read_memory <- read_memory_unsigned_integer <-
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amd64_analyze_prologue <- amd64_skip_prologue <- gdbarch_skip_prologue <-
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skip_prologue_sal <- find_function_start_sal <- symbol_found <- decode_variable
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<- decode_line_1 <- breakpoint_re_set_one <- catch_errors <- breakpoint_re_set
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<- clear_symtab_users <- new_symfile_objfile <-
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symbol_file_add_with_addrs_or_offsets <- symbol_file_add_from_bfd <-
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symbol_file_add <- symbol_file_add_main_1 <- symbol_file_add_main <-
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follow_exec
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I understand this hack is not nice, the correct way would be to unify more
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follow_exec with post_create_inferior. But I could break it for non-GNU/Linux
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targets a lot.
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No regressions on {x86_64,x86_64-m32,i686}-fedora14snapshot-linux-gnu.
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Thanks,
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Jan
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for the demo above:
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------------------------------------------------------------------------------
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#include <unistd.h>
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#include <assert.h>
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#include <stdio.h>
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int
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main (int argc, char **argv)
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{
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setbuf (stdout, NULL);
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if (argc == 1)
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{
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puts ("re-exec");
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execl ("/proc/self/exe", argv[0], "foo", NULL);
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assert (0);
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}
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puts ("exit");
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return 0;
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}
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------------------------------------------------------------------------------
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gdb/
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2010-09-30 Jan Kratochvil <jan.kratochvil@redhat.com>
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* infrun.c (follow_exec): Replace symbol_file_add_main by
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symbol_file_add with SYMFILE_DEFER_BP_RESET, set_initial_language and
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breakpoint_re_set.
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* m32r-rom.c (m32r_load, m32r_upload_command): Use parameter 0 for
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clear_symtab_users.
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* objfiles.c (free_all_objfiles): Likewise.
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* remote-m32r-sdi.c (m32r_load): Likewise.
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* solib-som.c (som_solib_create_inferior_hook): Likewise.
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* symfile.c (new_symfile_objfile): New comment for add_flags. Call
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clear_symtab_users with ADD_FLAGS.
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(reread_symbols): Use parameter 0 for clear_symtab_users.
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(clear_symtab_users): New parameter add_flags. Do not call
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breakpoint_re_set if SYMFILE_DEFER_BP_RESET.
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(clear_symtab_users_cleanup): Use parameter 0 for clear_symtab_users.
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* symtab.h (clear_symtab_users): New parameter add_flags.
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gdb/testsuite/
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2010-09-30 Jan Kratochvil <jan.kratochvil@redhat.com>
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* gdb.base/pie-execl.exp: New file.
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* gdb.base/pie-execl.c: New file.
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Index: gdb-7.2/gdb/infrun.c
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===================================================================
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--- gdb-7.2.orig/gdb/infrun.c 2010-10-12 18:27:58.000000000 +0200
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+++ gdb-7.2/gdb/infrun.c 2010-10-12 18:29:24.000000000 +0200
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@@ -840,8 +840,15 @@ follow_exec (ptid_t pid, char *execd_pat
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/* That a.out is now the one to use. */
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exec_file_attach (execd_pathname, 0);
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- /* Load the main file's symbols. */
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- symbol_file_add_main (execd_pathname, 0);
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+ /* SYMFILE_DEFER_BP_RESET is used as the proper displacement for PIE
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+ (Position Independent Executable) main symbol file will get applied by
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+ solib_create_inferior_hook below. breakpoint_re_set would fail to insert
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+ the breakpoints with the zero displacement. */
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+
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+ symbol_file_add (execd_pathname, SYMFILE_MAINLINE | SYMFILE_DEFER_BP_RESET,
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+ NULL, 0);
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+
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+ set_initial_language ();
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#ifdef SOLIB_CREATE_INFERIOR_HOOK
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SOLIB_CREATE_INFERIOR_HOOK (PIDGET (inferior_ptid));
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@@ -851,6 +858,8 @@ follow_exec (ptid_t pid, char *execd_pat
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jit_inferior_created_hook ();
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+ breakpoint_re_set ();
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+
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/* Reinsert all breakpoints. (Those which were symbolic have
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been reset to the proper address in the new a.out, thanks
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to symbol_file_command...) */
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Index: gdb-7.2/gdb/m32r-rom.c
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===================================================================
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--- gdb-7.2.orig/gdb/m32r-rom.c 2010-01-01 08:31:37.000000000 +0100
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+++ gdb-7.2/gdb/m32r-rom.c 2010-10-12 18:29:24.000000000 +0200
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@@ -188,7 +188,7 @@ m32r_load (char *filename, int from_tty)
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the stack may not be valid, and things would get horribly
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confused... */
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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}
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static void
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@@ -551,7 +551,7 @@ m32r_upload_command (char *args, int fro
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the stack may not be valid, and things would get horribly
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confused... */
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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}
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/* Provide a prototype to silence -Wmissing-prototypes. */
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Index: gdb-7.2/gdb/objfiles.c
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===================================================================
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--- gdb-7.2.orig/gdb/objfiles.c 2010-10-12 18:27:56.000000000 +0200
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+++ gdb-7.2/gdb/objfiles.c 2010-10-12 18:29:39.000000000 +0200
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@@ -699,7 +699,7 @@ free_all_objfiles (void)
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{
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free_objfile (objfile);
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}
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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}
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/* Relocate OBJFILE to NEW_OFFSETS. There should be OBJFILE->NUM_SECTIONS
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Index: gdb-7.2/gdb/remote-m32r-sdi.c
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===================================================================
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--- gdb-7.2.orig/gdb/remote-m32r-sdi.c 2010-07-07 18:15:16.000000000 +0200
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+++ gdb-7.2/gdb/remote-m32r-sdi.c 2010-10-12 18:29:24.000000000 +0200
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@@ -1377,7 +1377,7 @@ m32r_load (char *args, int from_tty)
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might be to call normal_stop, except that the stack may not be valid,
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and things would get horribly confused... */
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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if (!nostart)
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{
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Index: gdb-7.2/gdb/solib-som.c
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===================================================================
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--- gdb-7.2.orig/gdb/solib-som.c 2010-05-17 01:49:58.000000000 +0200
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+++ gdb-7.2/gdb/solib-som.c 2010-10-12 18:29:24.000000000 +0200
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@@ -354,7 +354,7 @@ keep_going:
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/* Make the breakpoint at "_start" a shared library event breakpoint. */
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create_solib_event_breakpoint (target_gdbarch, anaddr);
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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}
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static void
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Index: gdb-7.2/gdb/symfile.c
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===================================================================
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--- gdb-7.2.orig/gdb/symfile.c 2010-10-12 18:27:57.000000000 +0200
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+++ gdb-7.2/gdb/symfile.c 2010-10-12 18:29:24.000000000 +0200
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@@ -1036,7 +1036,7 @@ syms_from_objfile (struct objfile *objfi
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/* Perform required actions after either reading in the initial
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symbols for a new objfile, or mapping in the symbols from a reusable
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- objfile. */
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+ objfile. ADD_FLAGS is a bitmask of enum symfile_add_flags. */
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void
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new_symfile_objfile (struct objfile *objfile, int add_flags)
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@@ -1049,7 +1049,7 @@ new_symfile_objfile (struct objfile *obj
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/* OK, make it the "real" symbol file. */
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symfile_objfile = objfile;
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- clear_symtab_users ();
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+ clear_symtab_users (add_flags);
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}
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else if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0)
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{
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@@ -2527,7 +2527,7 @@ reread_symbols (void)
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/* Notify objfiles that we've modified objfile sections. */
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objfiles_changed ();
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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/* At least one objfile has changed, so we can consider that
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the executable we're debugging has changed too. */
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observer_notify_executable_changed ();
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@@ -2745,10 +2745,10 @@ allocate_symtab (char *filename, struct
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/* Reset all data structures in gdb which may contain references to symbol
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- table data. */
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+ table data. ADD_FLAGS is a bitmask of enum symfile_add_flags. */
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void
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-clear_symtab_users (void)
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+clear_symtab_users (int add_flags)
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{
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/* Someday, we should do better than this, by only blowing away
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the things that really need to be blown. */
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@@ -2758,7 +2758,8 @@ clear_symtab_users (void)
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clear_current_source_symtab_and_line ();
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clear_displays ();
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- breakpoint_re_set ();
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+ if ((add_flags & SYMFILE_DEFER_BP_RESET) == 0)
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+ breakpoint_re_set ();
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set_default_breakpoint (0, NULL, 0, 0, 0);
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clear_pc_function_cache ();
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observer_notify_new_objfile (NULL);
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@@ -2777,7 +2778,7 @@ clear_symtab_users (void)
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static void
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clear_symtab_users_cleanup (void *ignore)
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{
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- clear_symtab_users ();
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+ clear_symtab_users (0);
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}
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/* OVERLAYS:
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Index: gdb-7.2/gdb/symtab.h
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===================================================================
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--- gdb-7.2.orig/gdb/symtab.h 2010-10-12 18:27:56.000000000 +0200
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+++ gdb-7.2/gdb/symtab.h 2010-10-12 18:29:24.000000000 +0200
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@@ -1170,7 +1170,7 @@ extern void skip_prologue_sal (struct sy
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/* symfile.c */
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-extern void clear_symtab_users (void);
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+extern void clear_symtab_users (int add_flags);
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extern enum language deduce_language_from_filename (const char *);
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Index: gdb-7.2/gdb/testsuite/gdb.base/pie-execl.c
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===================================================================
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--- /dev/null 1970-01-01 00:00:00.000000000 +0000
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+++ gdb-7.2/gdb/testsuite/gdb.base/pie-execl.c 2010-10-12 18:29:24.000000000 +0200
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@@ -0,0 +1,51 @@
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+/* This testcase is part of GDB, the GNU debugger.
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+
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+ Copyright 2010 Free Software Foundation, Inc.
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+
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+ This program is free software; you can redistribute it and/or modify
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+ it under the terms of the GNU General Public License as published by
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+ the Free Software Foundation; either version 3 of the License, or
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+ (at your option) any later version.
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+
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+ This program is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ GNU General Public License for more details.
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+
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+ You should have received a copy of the GNU General Public License
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+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
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+
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+#include <stdio.h>
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+#include <unistd.h>
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+#include <assert.h>
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+
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+static void pie_execl_marker (void);
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+
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+int
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+main (int argc, char **argv)
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+{
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+ setbuf (stdout, NULL);
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+
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+#if BIN == 1
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+ if (argc == 2)
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+ {
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+ printf ("pie-execl: re-exec: %s\n", argv[1]);
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+ execl (argv[1], argv[1], NULL);
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+ assert (0);
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+ }
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+#endif
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+
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+ pie_execl_marker ();
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+
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+ return 0;
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+}
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+
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+/* pie_execl_marker must be on a different address than in `pie-execl2.c'. */
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+
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+volatile int v;
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+
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+static void
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+pie_execl_marker (void)
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+{
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+ v = 1;
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+}
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Index: gdb-7.2/gdb/testsuite/gdb.base/pie-execl.exp
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===================================================================
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--- /dev/null 1970-01-01 00:00:00.000000000 +0000
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+++ gdb-7.2/gdb/testsuite/gdb.base/pie-execl.exp 2010-10-12 18:29:24.000000000 +0200
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@@ -0,0 +1,94 @@
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+# Copyright 2010 Free Software Foundation, Inc.
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+
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+# This program is free software; you can redistribute it and/or modify
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+# it under the terms of the GNU General Public License as published by
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+# the Free Software Foundation; either version 3 of the License, or
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+# (at your option) any later version.
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+#
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+# This program is distributed in the hope that it will be useful,
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+# but WITHOUT ANY WARRANTY; without even the implied warranty of
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+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+# GNU General Public License for more details.
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+#
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+# You should have received a copy of the GNU General Public License
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+# along with this program. If not, see <http://www.gnu.org/licenses/>.
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+
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+# The problem was due to amd64_skip_prologue attempting to access inferior
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+# memory before the PIE (Position Independent Executable) gets relocated.
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+
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+if { ![istarget *-linux*]} {
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+ continue
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+}
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+
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+set testfile "pie-execl"
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+set srcfile ${testfile}.c
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+set executable1 ${testfile}1
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+set executable2 ${testfile}2
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+set binfile1 ${objdir}/${subdir}/${executable1}
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+set binfile2 ${objdir}/${subdir}/${executable2}
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+
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+# Use conditional compilation according to `BIN' as GDB remembers the source
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+# file name of the breakpoint.
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+
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+set opts [list debug {additional_flags=-fPIE -pie}]
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+if {[build_executable ${testfile}.exp $executable1 $srcfile [concat $opts {additional_flags=-DBIN=1}]] == ""
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+ || [build_executable ${testfile}.exp $executable2 $srcfile [concat $opts {additional_flags=-DBIN=2}]] == ""} {
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+ return -1
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+}
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+
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+clean_restart ${executable1}
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+
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+gdb_test_no_output "set args ${binfile2}"
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+
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+if ![runto_main] {
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+ return -1
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+}
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+
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+# Do not stop on `main' after re-exec.
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+delete_breakpoints
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+
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+gdb_breakpoint "pie_execl_marker"
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+gdb_test "info breakpoints" ".*" ""
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+
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+set addr1 ""
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+set test "pie_execl_marker address first"
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+gdb_test_multiple "p/x &pie_execl_marker" $test {
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+ -re " = (0x\[0-9a-f\]+)\r\n$gdb_prompt $" {
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+ set addr1 $expect_out(1,string)
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+ pass $test
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+ }
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+}
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+verbose -log "addr1 is $addr1"
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+
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+set test "continue"
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+gdb_test_multiple $test $test {
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+ -re "Error in re-setting breakpoint" {
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+ fail $test
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+ }
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+ -re "Cannot access memory" {
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+ fail $test
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+ }
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+ -re "pie-execl: re-exec.*executing new program.*\r\nBreakpoint \[0-9\]+,\[^\r\n\]* pie_execl_marker .*\r\n$gdb_prompt $" {
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+ pass $test
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+ }
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+}
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+
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+gdb_test "info breakpoints" ".*" ""
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+
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+set addr2 ""
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+set test "pie_execl_marker address second"
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+gdb_test_multiple "p/x &pie_execl_marker" $test {
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+ -re " = (0x\[0-9a-f\]+)\r\n$gdb_prompt $" {
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+ set addr2 $expect_out(1,string)
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+ pass $test
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+ }
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+}
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+verbose -log "addr2 is $addr2"
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+
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+# Ensure we cannot get a false PASS and the inferior has really changed.
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+set test "pie_execl_marker address has changed"
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+if [string equal $addr1 $addr2] {
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+ fail $test
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+} else {
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+ pass $test
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+}
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