[PATCH] gcore registers storing fix

Daniel Gutson
2009-11-06T22:37:11Z

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The attached patch attempts to solve a bug that caused the gcore command
to produce core files containing incorrect registers information. The
problem caused incomplete backtraces when the files were read back into GDB.

I tested this patch with the gdb testsuite, and my addition to the
gcore-thread.exp test case.

If OK, please commit it for me since I don't have write access.

Thanks,
Daniel.

2009-11-06 Daniel Gutson <dgutson@codesourcery.com>

gdb/
* procfs.c (procfs_do_thread_registers): Added a call to fetch
register values before saving them in the core file
through the gcore command.
(procfs_corefile_thread_callback): removed the backup of
inferior_ptid before calling procfs_do_thread_registers since
the function already saves and restores it before returning.

gdb/testsuite/gdb.threads/
* gcore-thread.exp: Added a test case in order to check
if the core dump contains the registers values, and symbol
lookup is working properly.

--
Daniel Gutson
CodeSourcery
www.codesourcery.com

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Index: gdb/procfs.c
===================================================================
RCS file: /cvs/src/src/gdb/procfs.c,v
retrieving revision 1.119
diff -u -p -r1.119 procfs.c
--- gdb/procfs.c 21 Oct 2009 08:27:25 -0000 1.119
+++ gdb/procfs.c 6 Nov 2009 22:30:54 -0000
@@ -6060,9 +6060,19 @@ procfs_do_thread_registers (bfd *obfd, p
gdb_gregset_t gregs;
gdb_fpregset_t fpregs;
unsigned long merged_pid;
+ struct cleanup *old_chain;

merged_pid = TIDGET (ptid) << 16 | PIDGET (ptid);

+ /* This part is the old method for fetching registers.
+ It should be replaced by the newer one using regsets
+ once it is implemented in this platform:
+ gdbarch_regset_from_core_section() and regset->collect_regset(). */
+
+ old_chain = save_inferior_ptid ();
+ inferior_ptid = ptid;
+ target_fetch_registers (regcache, -1);
+
fill_gregset (regcache, &gregs, -1);
#if defined (UNIXWARE)
note_data = (char *) elfcore_write_lwpstatus (obfd,
@@ -6085,6 +6095,9 @@ procfs_do_thread_registers (bfd *obfd, p
note_size,
&fpregs,
sizeof (fpregs));
+
+ do_cleanups (old_chain);
+
return note_data;
}

@@ -6102,13 +6115,11 @@ procfs_corefile_thread_callback (procinf

if (pi != NULL)
{
- ptid_t saved_ptid = inferior_ptid;
- inferior_ptid = MERGEPID (pi->pid, thread->tid);
- args->note_data = procfs_do_thread_registers (args->obfd, inferior_ptid,
+ ptid_t ptid = MERGEPID (pi->pid, thread->tid);
+ args->note_data = procfs_do_thread_registers (args->obfd, ptid,
args->note_data,
args->note_size,
args->stop_signal);
- inferior_ptid = saved_ptid;
}
return 0;
}
Index: gdb/testsuite/gdb.threads/gcore-thread.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.threads/gcore-thread.exp,v
retrieving revision 1.13
diff -u -p -r1.13 gcore-thread.exp
--- gdb/testsuite/gdb.threads/gcore-thread.exp 3 Jan 2009 05:58:07 -0000 1.13
+++ gdb/testsuite/gdb.threads/gcore-thread.exp 6 Nov 2009 22:30:54 -0000
@@ -154,11 +154,7 @@ gdb_expect {
}
}

-# FIXME: now what can we test about the thread state?
-# We do not know for certain that there should be at least
-# three threads, because who knows what kind of many-to-one
-# mapping various OS's may do? Let's assume that there must
-# be at least two threads:
+# There must be at least two threads.

gdb_test "info threads" ".*${nl} 2 ${horiz}${nl}\\* 1 .*" \
"corefile contains at least two threads"
@@ -173,3 +169,16 @@ gdb_test "info threads" ".* thread2 .*"
gdb_test "info threads" ".*${nl}\\* ${horiz} thread2 .*" \
"thread2 is current thread in corefile"

+# The threads should be standing at a known function, rather than ??.
+
+gdb_test_multiple "info threads" \
+ "corefile contains good register values and enables symbols lookup" \
+{
+ -re ".* in \\?\\? .*" {
+ fail "corefile contains good register values and enables symbols lookup"
+ }
+ -re ".* in \[_a-zA-Z0-9]+ \\(.*" {
+ pass "corefile contains good register values and enables symbols lookup"
+ }
+}
+