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About issue #3571 (Error in re-setting breakpoint 1: No source file named...)
- From: Pedro Alves <pedro at codesourcery dot com>
- To: gdb-patches at sourceware dot org
- Cc: Daniel Jacobowitz <dan at codesourcery dot com>, Sandra Loosemore <sandra at codesourcery dot com>
- Date: Tue, 19 Aug 2008 15:52:20 +0100
- Subject: About issue #3571 (Error in re-setting breakpoint 1: No source file named...)
Sorry for the long email below, This is mostly GDB logs with comments,
promise. :-)
With my latest change in the tree, we're now *not* discarding and
refetching the list of shared libraries when we attach/detach to/from
processes. The list is now only fetched on connection, or when the user
does "info sharedlibraries".
This prevents the error reported on issue #3571 from triggering on
the common attach/detach case.
Let me go through what is was again:
Issue #3571's error is triggered due to breakpoint_re_set being
called on every object file loaded.
Since "attach" got rid of the previous list of SOs,
attach 1
&"attach 1\n"
~"Attached to process 1\n"
=thread-group-created,id="1"
=thread-created,id="1",group-id="1"
^running
*running,thread-id="1"
&"Error while mapping shared library sections:\n"
&"ProcessSupport.LM_AXG425.elf.R7T01.i686: No such file or directory.\n"
~"Reading symbols from
/local/home/lmckhou/TSP/CodeSourcery/STUB/src/dicos_stub/DicosKernel_LM/bin/DicosKernel.LM_AXG561.elf.R7S01_ECHO.i686..."
~"done.\n"
&"Error in re-setting breakpoint 1: No source file named
/local/home/lmckhou/TSP/TADE/Test_OU/src/test.cc.\n"
... and this breakpoint was set at in an SO whose symbols are only loaded
afterwards, below, we get this error above, on the first SO loaded.
~"Loaded symbols for
/local/home/lmckhou/TSP/CodeSourcery/STUB/src/dicos_stub/DicosKernel_LM/bin/DicosKernel.LM_AXG561.elf.R7S01_ECHO.i686\n"
~"Symbol file not found for ProcessSupport.LM_AXG425.elf.R7T01.i686\n"
~"Reading symbols from
/local/home/lmckhou/TSP/TADE/Test_LM/bin/Test.LM_Test1.elf.R1A01.i686..."
~"done.\n"
~"Loaded symbols for
/local/home/lmckhou/TSP/TADE/Test_LM/bin/Test.LM_Test1.elf.R1A01.i686\n"
(gdb)
Now that we don't get rid of the solist so often, we don't trip on
this as much. We do still trip on it on disconnect/reconnect:
(gdb) b test.cc:123
Breakpoint 2 at 0xe3f6468: file /scratch/pedro/dicos/build/Test_OU/src/test.cc, line 123.
(gdb) info sharedlibrary
From To Syms Read Shared Object Library
0x0916b730 0x0a2f3d23 Yes /net/daisy/scratch/pedro/dicos/build/DicosKernel_LM/bin/DicosKernel.LM_AXG561.elf.R7S01_ECHO.i686
No ProcessSupport.LM_AXG425.elf.R7T01.i686
0x0e267944 0x0e3f68bf Yes /net/daisy/scratch/pedro/dicos/build/Test_LM/bin/Test.LM_Test1.elf.R1A01.i686
(gdb) info breakpoints
Num Type Disp Enb Address What
2 breakpoint keep y 0x0e3f6468 in aBlockingCapsule() at /scratch/pedro/dicos/build/Test_OU/src/test.cc:123
(gdb) disconnect
Ending remote debugging.
(gdb) info sharedlibrary
No shared libraries loaded at this time.
(gdb) info breakpoints
Num Type Disp Enb Address What
2 breakpoint keep y 0x0e3f6468 /scratch/pedro/dicos/build/Test_OU/src/test.cc:123
(gdb) disable 2
(gdb) enable 2
(gdb) info breakpoints
Num Type Disp Enb Address What
2 breakpoint keep y 0x0e3f6468 /scratch/pedro/dicos/build/Test_OU/src/test.cc:123
(gdb) tar extended-remote :10019
Remote debugging using :10019
Error while mapping shared library sections:
ProcessSupport.LM_AXG425.elf.R7T01.i686: No such file or directory.
Reading symbols from /net/daisy/scratch/pedro/dicos/build/DicosKernel_LM/bin/DicosKernel.LM_AXG561.elf.R7S01_ECHO.i686...done.
Error in re-setting breakpoint 2: No source file named test.cc.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Loaded symbols for /net/daisy/scratch/pedro/dicos/build/DicosKernel_LM/bin/DicosKernel.LM_AXG561.elf.R7S01_ECHO.i686
Symbol file not found for ProcessSupport.LM_AXG425.elf.R7T01.i686
Reading symbols from /net/daisy/scratch/pedro/dicos/build/Test_LM/bin/Test.LM_Test1.elf.R1A01.i686...done.
Loaded symbols for /net/daisy/scratch/pedro/dicos/build/Test_LM/bin/Test.LM_Test1.elf.R1A01.i686
^^ test.cc is found in this library.
(gdb) info breakpoints
Num Type Disp Enb Address What
2 breakpoint keep n 0x0e3f6468 in aBlockingCapsule() at /scratch/pedro/dicos/build/Test_OU/src/test.cc:123
^^^
^^^
breakpoint is now disabled.
The error is almost OK to ignore, if it weren't for the fact, that
when enough symbols to resolve the breakpoint are loaded, the breakpoint
is left disabled, when it was enabled before disconnect.
I've spent a bit trying to change this behaviour, but I couldn't
get it 100% solved.
Here's what I've done:
Check this sequence, showing how to reproduce this easilly
on linux:
Setting a breakpoint, when we have symbols:
>gdb ./gdb
(top-gdb) b main
Breakpoint 3 at 0x44f1a7: file ../../src/gdb/gdb.c, line 28.
Running to it:
(top-gdb) r
Starting program: /home/pedro/gdb/multi_process/build/gdb/gdb
[Thread debugging using libthread_db enabled]
[New Thread 0x7fbdca1fb6e0 (LWP 26651)]
[Switching to Thread 0x7fbdca1fb6e0 (LWP 26651)]
Breakpoint 3, main (argc=1, argv=0x7fffd2220688) at ../../src/gdb/gdb.c:28
28 memset (&args, 0, sizeof args);
Setting another breakpoint:
(top-gdb) b gdb_main
Breakpoint 4 at 0x450288: file ../../src/gdb/main.c, line 839.
Let's take a look at the breakpoints state:
(top-gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y 0x0000000000459ca6 in internal_error at ../../src/gdb/utils.c:893
2 breakpoint keep y 0x000000000049f6d2 in info_command at ../../src/gdb/cli/cli-cmds.c:199
silent
return
3 breakpoint keep y 0x000000000044f1a7 in main at ../../src/gdb/gdb.c:28
breakpoint already hit 1 time
4 breakpoint keep y 0x0000000000450288 in gdb_main at ../../src/gdb/main.c:839
Let's now discard the loaded symbols:
(top-gdb) file
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
No executable file now.
Discard symbol table from `/home/pedro/gdb/multi_process/build/gdb/gdb'? (y or n) y
Error in re-setting breakpoint 1: No symbol table is loaded. Use the "file" command.
Error in re-setting breakpoint 2: No symbol table is loaded. Use the "file" command.
Error in re-setting breakpoint 3: No symbol table is loaded. Use the "file" command.
Error in re-setting breakpoint 4: No symbol table is loaded. Use the "file" command.
No symbol file now.
Hmmm, a bunch of weird looking errors. What happened to the breakpoints?
(top-gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep n 0x00459ca6 ../../src/gdb/utils.c:893
2 breakpoint keep n 0x0049f6d2 ../../src/gdb/cli/cli-cmds.c:199
silent
return
3 breakpoint keep n 0x0044f1a7 ../../src/gdb/gdb.c:28
breakpoint already hit 1 time
4 breakpoint keep n 0x00450288 ../../src/gdb/main.c:839
Oh, right, no symbol table is loaded, so the breakpoints are gone. And,
they are marked as not enabled.
Ok, let's fix what GDB suspected was the reason --- let's load a symbol
table:
(top-gdb) file gdb
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
Reading symbols from /home/pedro/gdb/multi_process/build/gdb/gdb...done.
So, at this point, breakpoint should have been enabled, shouldn't they?:
(top-gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep n 0x0000000000459ca6 in internal_error at ../../src/gdb/utils.c:893
2 breakpoint keep n 0x000000000049f6d2 in info_command at ../../src/gdb/cli/cli-cmds.c:199
silent
return
3 breakpoint keep n 0x000000000044f1a7 in main at ../../src/gdb/gdb.c:28
breakpoint already hit 1 time
4 breakpoint keep n 0x0000000000450288 in gdb_main at ../../src/gdb/main.c:839
(top-gdb)
Bummer, they're still disabled...
-------------------------
Patch 001 (submitted upstream a few months back already), in combination
with patch 002, changes GDB's behaviour so instead of throwing an error
when reparsing a breakpoint failed, we set it to pending.
So now, you'd get:
>./gdb --quiet --args ./gdb --quiet
Setting up the environment for debugging gdb.
Breakpoint 1 at 0x459ce6: file ../../src/gdb/utils.c, line 893.
Breakpoint 2 at 0x49f756: file ../../src/gdb/cli/cli-cmds.c, line 199.
(top-gdb) b main
Breakpoint 3 at 0x44f1e7: file ../../src/gdb/gdb.c, line 28.
(top-gdb) r
Starting program: /home/pedro/gdb/multi_process/build/gdb/gdb --quiet
[Thread debugging using libthread_db enabled]
Breakpoint 3, main (argc=2, argv=0x7fffffffe448) at ../../src/gdb/gdb.c:28
28 memset (&args, 0, sizeof args);
(top-gdb) b gdb_main
Breakpoint 4 at 0x4502c8: file ../../src/gdb/main.c, line 839.
(top-gdb) file
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
No executable file now.
Discard symbol table from `/home/pedro/gdb/multi_process/build/gdb/gdb'? (y or n) y
warning: Leaving breakpoint #1 pending
warning: Leaving breakpoint #2 pending
warning: Leaving breakpoint #3 pending
warning: Leaving breakpoint #4 pending
No symbol file now.
(top-gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y <PENDING> ../../src/gdb/utils.c:893
2 breakpoint keep y <PENDING> ../../src/gdb/cli/cli-cmds.c:199
silent
return
3 breakpoint keep y <PENDING> ../../src/gdb/gdb.c:28
breakpoint already hit 1 time
4 breakpoint keep y <PENDING> ../../src/gdb/main.c:839
(top-gdb) file gdb
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
Reading symbols from /home/pedro/gdb/multi_process/build/gdb/gdb...done.
(top-gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y 0x0000000000459ce6 in internal_error at ../../src/gdb/utils.c:893
2 breakpoint keep y 0x000000000049f756 in info_command at ../../src/gdb/cli/cli-cmds.c:199
silent
return
3 breakpoint keep y 0x000000000044f1e7 in main at ../../src/gdb/gdb.c:28
breakpoint already hit 1 time
4 breakpoint keep y 0x00000000004502c8 in gdb_main at ../../src/gdb/main.c:839
(top-gdb)
Ahh, now they're left enabled.
This looks promising, but when shared libraries are involved,
things don't look so great. I've added a hack so that
if we're fetching the solist from the inferior/target, breakpoint resetting
is blocked until after loading the whole list. That's patch 003.
Unfortunatelly, on linux, behaviour still isn't the best:
(gdb) b main
Breakpoint 1 at 0x40066c: file ../../../src/gdb/testsuite/gdb.base/solib-symbol-main.c, line 25.
(gdb) r
Starting program: /home/pedro/gdb/multi_process/build/gdb/testsuite/gdb.base/solib-symbol-main
Breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.base/solib-symbol-main.c:25
25 printf ("in main\n");
(gdb) b foo
Breakpoint 2 at 0x7ffff7bdf570: file ../../../src/gdb/testsuite/gdb.base/solib-symbol-lib.c, line 22.
(gdb) file
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
No executable file now.
Discard symbol table from `/home/pedro/gdb/multi_process/build/gdb/testsuite/gdb.base/solib-symbol-main'? (y or n) y
warning: Leaving breakpoint #1 pending
warning: Leaving breakpoint #2 pending
No symbol file now.
(gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y <PENDING> ../../../src/gdb/testsuite/gdb.base/solib-symbol-main.c:25
breakpoint already hit 1 time
2 breakpoint keep y <PENDING> ../../../src/gdb/testsuite/gdb.base/solib-symbol-lib.c:22
(gdb) file /home/pedro/gdb/multi_process/build/gdb/testsuite/gdb.base/solib-symbol-main
A program is being debugged already.
Are you sure you want to change the file? (y or n) y
Reading symbols from /home/pedro/gdb/multi_process/build/gdb/testsuite/gdb.base/solib-symbol-main...done.
(gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y 0x000000000040066c in main
at ../../../src/gdb/testsuite/gdb.base/solib-symbol-main.c:25
breakpoint already hit 1 time
2 breakpoint keep y 0x00000000004005a0 <foo@plt>
^^^^^^^
(gdb)
Oh, the pending breakpoint at foo is now resolved to the plt in
the main binary... This happens because there are still calls to
breakpoint_re_set in several places, before we get to load the symbols
of the SO where foo is defined in. Specifically in this case,
this happens when we load the symbols for the main executable, the
expression finds the foo@plt symbol and is happy with it. So subsequent
loads of SO's symbols don't change the breakpoint anymore. At
the point in the code, where the symbols for the main executable
are loaded, it isn't possible to know if the user or the target is
going to add more symbols afterwards, which means, that we
can't remove the breakpoint_re_set call...
I'm much inclined to punt on this at this point, as the reported
"error" will only trigger across a disconnect/reconnect, and that
is not the use case Marc was reporting.
What do you think?
--
Pedro Alves
2008-08-18 Pedro Alves <pedro@codesourcery.com>
gdb/
* linespec.c (symtab_from_filename): Also throw NOT_FOUND_ERROR if
there are no symbols loaded, instead of throwing a generic error.
(decode_variable): Likewise.
gdb/testsuite/
* gdb.base/pending.exp: Test pending breakpoints without symbols
loaded.
---
gdb/linespec.c | 15 +++++++++------
gdb/testsuite/gdb.base/pending.exp | 26 ++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 6 deletions(-)
Index: src/gdb/linespec.c
===================================================================
--- src.orig/gdb/linespec.c 2008-08-18 21:42:42.000000000 +0100
+++ src/gdb/linespec.c 2008-08-18 21:43:30.000000000 +0100
@@ -1556,10 +1556,11 @@ symtab_from_filename (char **argptr, cha
file_symtab = lookup_symtab (copy);
if (file_symtab == 0)
{
- if (!have_full_symbols () && !have_partial_symbols ())
- error (_("No symbol table is loaded. Use the \"file\" command."));
if (not_found_ptr)
*not_found_ptr = 1;
+ if (!have_full_symbols () && !have_partial_symbols ())
+ throw_error (NOT_FOUND_ERROR,
+ _("No symbol table is loaded. Use the \"file\" command."));
throw_error (NOT_FOUND_ERROR, _("No source file named %s."), copy);
}
@@ -1760,12 +1761,14 @@ decode_variable (char *copy, int funfirs
if (msymbol != NULL)
return minsym_found (funfirstline, msymbol);
- if (!have_full_symbols () &&
- !have_partial_symbols () && !have_minimal_symbols ())
- error (_("No symbol table is loaded. Use the \"file\" command."));
-
if (not_found_ptr)
*not_found_ptr = 1;
+
+ if (!have_full_symbols ()
+ && !have_partial_symbols ()
+ && !have_minimal_symbols ())
+ throw_error (NOT_FOUND_ERROR,
+ _("No symbol table is loaded. Use the \"file\" command."));
throw_error (NOT_FOUND_ERROR, _("Function \"%s\" not defined."), copy);
}
Index: src/gdb/testsuite/gdb.base/pending.exp
===================================================================
--- src.orig/gdb/testsuite/gdb.base/pending.exp 2008-08-18 21:42:42.000000000 +0100
+++ src/gdb/testsuite/gdb.base/pending.exp 2008-08-18 21:43:30.000000000 +0100
@@ -54,6 +54,32 @@ if { [gdb_compile_shlib $libsrc $lib_sl
gdb_exit
gdb_start
gdb_reinitialize_dir $srcdir/$subdir
+
+gdb_test_multiple "break pendfunc1" "set pending breakpoint" {
+ -re ".*Make breakpoint pending.*y or \\\[n\\\]. $" {
+ gdb_test "y" "Breakpoint.*pendfunc1.*pending." "set pending breakpoint (without symbols)"
+ }
+}
+
+gdb_test "info break" \
+ "Num Type\[ \]+Disp Enb Address\[ \]+What.*
+\[0-9\]+\[\t \]+breakpoint keep y.*PENDING.*pendfunc1.*" \
+"single pending breakpoint info (without symbols)"
+
+gdb_load ${binfile}
+gdb_load_shlibs $lib_sl
+
+set pendfunc1_loc [gdb_get_line_number "y = x + 4" ${libfile}.c]
+gdb_test "run" \
+".*Breakpoint.*pendfunc1.*at.*pendshr.c:$pendfunc1_loc.*y = x \\+ 4.*" \
+"run to resolved breakpoint 1 (without symbols)"
+
+# Restart with a fresh gdb.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+
gdb_load ${binfile}
gdb_load_shlibs $lib_sl
2008-08-19 Pedro Alves <pedro@codesourcery.com>
* breakpoint.c (breakpoint_re_set_one): If parsing failed, and the
breakpoint had been inserted before, set it to pending state.
(sharedlibrary_command): Disable breakpoints set in solibs,
effectively setting them to the pending state.
---
gdb/breakpoint.c | 19 +++++++++++++++----
gdb/solib.c | 1 +
2 files changed, 16 insertions(+), 4 deletions(-)
Index: src/gdb/breakpoint.c
===================================================================
--- src.orig/gdb/breakpoint.c 2008-08-19 12:35:52.000000000 +0100
+++ src/gdb/breakpoint.c 2008-08-19 15:00:02.000000000 +0100
@@ -7485,15 +7485,26 @@ breakpoint_re_set_one (void *bint)
if (e.reason < 0)
{
int not_found_and_ok = 0;
+
+ /* If this breakpoint had been inserted before, but we
+ cannot parse where to place it anymore, set it to
+ pending. */
+ if (not_found && b->loc && !b->loc->shlib_disabled)
+ {
+ warning (_("Leaving breakpoint #%d pending"),
+ b->number);
+ b->loc->shlib_disabled = 1;
+ }
+
/* For pending breakpoints, it's expected that parsing
will fail until the right shared library is loaded.
User has already told to create pending breakpoints and
don't need extra messages. If breakpoint is in bp_shlib_disabled
state, then user already saw the message about that breakpoint
being disabled, and don't want to see more errors. */
- if (not_found
- && (b->condition_not_parsed
- || (b->loc && b->loc->shlib_disabled)
+ if (not_found
+ && (b->condition_not_parsed
+ || b->loc
|| b->enable_state == bp_disabled))
not_found_and_ok = 1;
@@ -7512,7 +7523,7 @@ breakpoint_re_set_one (void *bint)
if (not_found)
break;
-
+
gdb_assert (sals.nelts == 1);
resolve_sal_pc (&sals.sals[0]);
if (b->condition_not_parsed && s && s[0])
Index: src/gdb/solib.c
===================================================================
--- src.orig/gdb/solib.c 2008-08-19 12:35:52.000000000 +0100
+++ src/gdb/solib.c 2008-08-19 15:00:02.000000000 +0100
@@ -950,6 +950,7 @@ sharedlibrary_command (char *args, int f
void
no_shared_libraries (char *ignored, int from_tty)
{
+ disable_breakpoints_in_shlibs ();
objfile_purge_solibs ();
clear_solib ();
}
2008-08-18 Pedro Alves <pedro@codesourcery.com>
* breakpoint.c (defer_breakpoint_re_setting): New.
(breakpoint_re_set): Check it.
(solib_add, reload_shared_libraries): Mask breakpoint_re_set.
---
gdb/breakpoint.c | 8 ++++++++
gdb/solib.c | 19 +++++++++++++++++++
2 files changed, 27 insertions(+)
Index: src/gdb/breakpoint.c
===================================================================
--- src.orig/gdb/breakpoint.c 2008-08-19 12:17:03.000000000 +0100
+++ src/gdb/breakpoint.c 2008-08-19 12:21:04.000000000 +0100
@@ -7616,6 +7616,8 @@ breakpoint_re_set_one (void *bint)
return 0;
}
+int defer_breakpoint_re_setting = 0;
+
/* Re-set all breakpoints after symbols have been re-loaded. */
void
breakpoint_re_set (void)
@@ -7624,6 +7626,12 @@ breakpoint_re_set (void)
enum language save_language;
int save_input_radix;
+ if (defer_breakpoint_re_setting)
+ /* When we're adding symbol files in batch, we defer doing
+ breakpoint re-setting until all symbols files are loaded --
+ e.g., we're loading shared libraries. */
+ return;
+
save_language = current_language->la_language;
save_input_radix = input_radix;
ALL_BREAKPOINTS_SAFE (b, temp)
Index: src/gdb/solib.c
===================================================================
--- src.orig/gdb/solib.c 2008-08-19 12:17:15.000000000 +0100
+++ src/gdb/solib.c 2008-08-19 12:25:43.000000000 +0100
@@ -668,10 +668,18 @@ libpthread_solib_p (struct so_list *so)
FROM_TTY and TARGET are as described for update_solib_list, above. */
+extern int defer_breakpoint_re_setting;
+
void
solib_add (char *pattern, int from_tty, struct target_ops *target, int readsyms)
{
struct so_list *gdb;
+ struct cleanup *old_chain;
+
+ /* Defer reparsing breakpoints until after loading all
+ libraries. */
+ old_chain = make_cleanup_restore_integer (&defer_breakpoint_re_setting);
+ defer_breakpoint_re_setting = 1;
if (pattern)
{
@@ -721,6 +729,8 @@ solib_add (char *pattern, int from_tty,
ops->special_symbol_handling ();
}
}
+
+ do_cleanups (old_chain);
}
@@ -959,8 +969,17 @@ static void
reload_shared_libraries (char *ignored, int from_tty,
struct cmd_list_element *e)
{
+ struct cleanup *old_chain;
+
no_shared_libraries (NULL, from_tty);
+
+ /* Defer reparsing breakpoints until loading all libraries. */
+ old_chain = make_cleanup_restore_integer (&defer_breakpoint_re_setting);
+ defer_breakpoint_re_setting = 1;
+
solib_add (NULL, from_tty, NULL, auto_solib_add);
+
+ do_cleanups (old_chain);
}
static void