[v4,10/14] gcore command: Place all file-backed mappings in NT_FILE note

Message ID 20200705225807.2264705-11-kevinb@redhat.com
State Superseded
Headers show
Series
  • Fix BZ 25631 - core file memory access problem
Related show

Commit Message

Shahab Vahedi via Gdb-patches July 5, 2020, 10:58 p.m.
When making a core file with the GDB's gcore command on Linux,
the same criteria used for determining which mappings should be
dumped were also being used for determining which entries should
be placed in the NT_FILE note.  This is wrong; we want to place
all file-backed mappings in this note.

The predicate function, dump_mapping_p, was used to determine whether
or not to dump a mapping from within linux_find_memory_regions_full.
This commit leaves this predicate in place, but adds a new parameter,
should_dump_mapping_p, to linux_find_memory_regions_full.  It then
calls should_dump_mapping_p instead of dump_mapping_p.  dump_mapping_p
is passed to linux_find_memory_regions_full at one call site; at the
other call site, dump_note_entry_p is passed instead.

gdb/ChangeLog:

	* linux-tdep.c (dump_note_entry_p): New function.
	(linux_dump_mapping_p_ftype): New typedef.
	(linux_find_memory_regions_full): Add new parameter,
	should_dump_mapping_p.
	(linux_find_memory_regions): Adjust call to
	linux_find_memory_regions_full.
	(linux_make_mappings_core_file_notes): Use dump_note_entry_p in
	call to linux_find_memory_regions_full.
---
 gdb/linux-tdep.c | 41 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 4 deletions(-)

-- 
2.26.2

Patch

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index fa59b09eec..302e432968 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -726,6 +726,25 @@  dump_mapping_p (filter_flags filterflags, const struct smaps_vmflags *v,
   return dump_p;
 }
 
+/* As above, but return true only when we should dump the NT_FILE
+   entry.  */
+
+static int
+dump_note_entry_p (filter_flags filterflags, const struct smaps_vmflags *v,
+		int maybe_private_p, int mapping_anon_p, int mapping_file_p,
+		const char *filename, ULONGEST addr, ULONGEST offset)
+{
+  /* vDSO and vsyscall mappings will end up in the core file.  Don't
+     put them in the NT_FILE note.  */
+  if (strcmp ("[vdso]", filename) == 0
+      || strcmp ("[vsyscall]", filename) == 0)
+    return 0;
+
+  /* Otherwise, any other file-based mapping should be placed in the
+     note.  */
+  return filename != nullptr;
+}
+
 /* Implement the "info proc" command.  */
 
 static void
@@ -1240,10 +1259,20 @@  typedef int linux_find_memory_region_ftype (ULONGEST vaddr, ULONGEST size,
 					    const char *filename,
 					    void *data);
 
+typedef int linux_dump_mapping_p_ftype (filter_flags filterflags,
+					const struct smaps_vmflags *v,
+					int maybe_private_p,
+					int mapping_anon_p,
+					int mapping_file_p,
+					const char *filename,
+					ULONGEST addr,
+					ULONGEST offset);
+
 /* List memory regions in the inferior for a corefile.  */
 
 static int
 linux_find_memory_regions_full (struct gdbarch *gdbarch,
+				linux_dump_mapping_p_ftype *should_dump_mapping_p,
 				linux_find_memory_region_ftype *func,
 				void *obfd)
 {
@@ -1394,9 +1423,10 @@  linux_find_memory_regions_full (struct gdbarch *gdbarch,
 	    }
 
 	  if (has_anonymous)
-	    should_dump_p = dump_mapping_p (filterflags, &v, priv,
-					    mapping_anon_p, mapping_file_p,
-					    filename, addr, offset);
+	    should_dump_p = should_dump_mapping_p (filterflags, &v, priv,
+					           mapping_anon_p,
+						   mapping_file_p,
+					           filename, addr, offset);
 	  else
 	    {
 	      /* Older Linux kernels did not support the "Anonymous:" counter.
@@ -1460,6 +1490,7 @@  linux_find_memory_regions (struct gdbarch *gdbarch,
   data.obfd = obfd;
 
   return linux_find_memory_regions_full (gdbarch,
+					 dump_mapping_p,
 					 linux_find_memory_regions_thunk,
 					 &data);
 }
@@ -1543,7 +1574,9 @@  linux_make_mappings_corefile_notes (struct gdbarch *gdbarch, bfd *obfd,
   pack_long (buf, long_type, 1);
   obstack_grow (&data_obstack, buf, TYPE_LENGTH (long_type));
 
-  linux_find_memory_regions_full (gdbarch, linux_make_mappings_callback,
+  linux_find_memory_regions_full (gdbarch, 
+				  dump_note_entry_p,
+				  linux_make_mappings_callback,
 				  &mapping_data);
 
   if (mapping_data.file_count != 0)