Re: [PATCH] refreshed patch for PR 11804 and PR 9904

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi Jean-Marc,

On Sun, 29 Jul 2012 19:11:12 +0200, Jean-Marc Saffroy wrote:
> I'm not sure what kind you expect, so I'll let you write them. :-)

OK, done.

On Sun, 29 Jul 2012 19:35:00 +0200, Jean-Marc Saffroy wrote:
> Of course I forgot to add a ChangeLog entry, so here it is:

Updated it.  Also sorry but I am still the primary author of this patch.

No regressions on {x86_64,x86_64-m32,i686}-fedorarawhide-linux-gnu and with
gdbserver.  I will check it in in some time.  While it would be nice for 7.5
I think it is too late for it.


Thanks,
Jan


2012-07-31  Jan Kratochvil  <jan.kratochvil@redhat.com>
	    Jean-Marc Saffroy  <saffroy@gmail.com>

	PR 11804
	* defs.h (find_memory_region_ftype): New comment.  New arg modified.
	* fbsd-nat.c (fbsd_find_memory_regions): Add the passed modified value.
	* gcore.c (gcore_create_callback): New function comment.  Add modified
	parameter.  Only write modified regions.  Set SEC_READONLY exactly
	according to MODIFIED.
	(objfile_find_memory_regions): Ignore separate debug info files.  Ass
	the passed modified value to FUNC.
	* gnu-nat.c (gnu_find_memory_regions): Add the passed modified value.
	* linux-tdep.c (linux_find_memory_regions): Try to reads smaps file
	first.  New variables modified and has_anonymous.  Parse the lines of
	smaps file.  Add the passed MODIFIED value to FUNC.
	* procfs.c (find_memory_regions_callback): Add the passed modified
	value.

gdb/testsuite/
2012-07-31  Jan Kratochvil  <jan.kratochvil@redhat.com>
	    Jean-Marc Saffroy  <saffroy@gmail.com>

	PR 11804
	* gdb.base/gcore-relro.exp: New file.
	* gdb.base/gcore-relro-main.c: New file.
	* gdb.base/gcore-relro-lib.c: New file.

diff --git a/gdb/defs.h b/gdb/defs.h
index 7be99a2..de34740 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -362,9 +362,14 @@ extern void init_source_path (void);
 
 /* From exec.c */
 
+/* Process memory area starting at ADDR with length SIZE.  Area is readable iff
+   READ is non-zero, writable if WRITE is non-zero, executable if EXEC is
+   non-zero.  Area is possibly changed against its original file based copy if
+   MODIFIED is non-zero.  DATA is passed without changes from a caller.  */
+
 typedef int (*find_memory_region_ftype) (CORE_ADDR addr, unsigned long size,
 					 int read, int write, int exec,
-					 void *data);
+					 int modified, void *data);
 
 /* Take over the 'find_mapped_memory' vector from exec.c.  */
 extern void exec_set_find_memory_regions
diff --git a/gdb/fbsd-nat.c b/gdb/fbsd-nat.c
index b3e4fab..4a8a509 100644
--- a/gdb/fbsd-nat.c
+++ b/gdb/fbsd-nat.c
@@ -131,8 +131,9 @@ fbsd_find_memory_regions (find_memory_region_ftype func, void *obfd)
 			    exec ? 'x' : '-');
 	}
 
-      /* Invoke the callback function to create the corefile segment.  */
-      func (start, size, read, write, exec, obfd);
+      /* Invoke the callback function to create the corefile segment.
+	 Pass MODIFIED as true, we do not know the real modification state.  */
+      func (start, size, read, write, exec, 1, obfd);
     }
 
   do_cleanups (cleanup);
diff --git a/gdb/gcore.c b/gdb/gcore.c
index a45e787..3c8e2f4 100644
--- a/gdb/gcore.c
+++ b/gdb/gcore.c
@@ -379,9 +379,12 @@ make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
   bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
 }
 
+/* find_memory_region_ftype implementation.  DATA is 'bfd *' for the core file
+   GDB is creating.  */
+
 static int
-gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
-		       int read, int write, int exec, void *data)
+gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read,
+		       int write, int exec, int modified, void *data)
 {
   bfd *obfd = data;
   asection *osec;
@@ -390,7 +393,7 @@ gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
   /* If the memory segment has no permissions set, ignore it, otherwise
      when we later try to access it for read/write, we'll get an error
      or jam the kernel.  */
-  if (read == 0 && write == 0 && exec == 0)
+  if (read == 0 && write == 0 && exec == 0 && modified == 0)
     {
       if (info_verbose)
         {
@@ -401,7 +404,7 @@ gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
       return 0;
     }
 
-  if (write == 0 && !solib_keep_data_in_core (vaddr, size))
+  if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size))
     {
       /* See if this region of memory lies inside a known file on disk.
 	 If so, we can avoid copying its contents by clearing SEC_LOAD.  */
@@ -433,10 +436,12 @@ gcore_create_callback (CORE_ADDR vaddr, unsigned long size,
 	    }
 	}
 
-    keep:
-      flags |= SEC_READONLY;
+    keep:;
     }
 
+  if (write == 0)
+    flags |= SEC_READONLY;
+
   if (exec)
     flags |= SEC_CODE;
   else
@@ -477,6 +482,10 @@ objfile_find_memory_regions (find_memory_region_ftype func, void *obfd)
       asection *isec = objsec->the_bfd_section;
       flagword flags = bfd_get_section_flags (ibfd, isec);
 
+      /* Separate debug info files are irrelevant for gcore.  */
+      if (objfile->separate_debug_objfile_backlink != NULL)
+	continue;
+
       if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
 	{
 	  int size = bfd_section_size (ibfd, isec);
@@ -486,6 +495,7 @@ objfile_find_memory_regions (find_memory_region_ftype func, void *obfd)
 			 1, /* All sections will be readable.  */
 			 (flags & SEC_READONLY) == 0, /* Writable.  */
 			 (flags & SEC_CODE) != 0, /* Executable.  */
+			 1, /* MODIFIED is unknown, pass it as true.  */
 			 obfd);
 	  if (ret != 0)
 	    return ret;
@@ -498,6 +508,7 @@ objfile_find_memory_regions (find_memory_region_ftype func, void *obfd)
 	     1, /* Stack section will be readable.  */
 	     1, /* Stack section will be writable.  */
 	     0, /* Stack section will not be executable.  */
+	     1, /* Stack section will be modified.  */
 	     obfd);
 
   /* Make a heap segment.  */
@@ -506,6 +517,7 @@ objfile_find_memory_regions (find_memory_region_ftype func, void *obfd)
 	     1, /* Heap section will be readable.  */
 	     1, /* Heap section will be writable.  */
 	     0, /* Heap section will not be executable.  */
+	     1, /* Heap section will be modified.  */
 	     obfd);
 
   return 0;
diff --git a/gdb/gnu-nat.c b/gdb/gnu-nat.c
index 0c45f20..5a653cf 100644
--- a/gdb/gnu-nat.c
+++ b/gdb/gnu-nat.c
@@ -2558,6 +2558,7 @@ gnu_find_memory_regions (find_memory_region_ftype func, void *data)
 		     last_protection & VM_PROT_READ,
 		     last_protection & VM_PROT_WRITE,
 		     last_protection & VM_PROT_EXECUTE,
+		     1, /* MODIFIED is unknown, pass it as true.  */
 		     data);
 	  last_region_address = region_address;
 	  last_region_end = region_address += region_length;
@@ -2571,6 +2572,7 @@ gnu_find_memory_regions (find_memory_region_ftype func, void *data)
 	     last_protection & VM_PROT_READ,
 	     last_protection & VM_PROT_WRITE,
 	     last_protection & VM_PROT_EXECUTE,
+	     1, /* MODIFIED is unknown, pass it as true.  */
 	     data);
 
   return 0;
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index b6f2efb..65f5f97 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -547,19 +547,28 @@ linux_find_memory_regions (struct gdbarch *gdbarch,
     return 1;
 
   xsnprintf (filename, sizeof filename,
-	     "/proc/%d/maps", current_inferior ()->pid);
+	     "/proc/%d/smaps", current_inferior ()->pid);
   data = target_fileio_read_stralloc (filename);
+  if (data == NULL)
+    {
+      /* Older Linux kernels did not support /proc/PID/smaps.  */
+      xsnprintf (filename, sizeof filename,
+		 "/proc/%d/maps", current_inferior ()->pid);
+      data = target_fileio_read_stralloc (filename);
+    }
   if (data)
     {
       struct cleanup *cleanup = make_cleanup (xfree, data);
       char *line;
 
-      for (line = strtok (data, "\n"); line; line = strtok (NULL, "\n"))
+      line = strtok (data, "\n");
+      while (line)
 	{
 	  ULONGEST addr, endaddr, offset, inode;
 	  const char *permissions, *device, *filename;
 	  size_t permissions_len, device_len;
 	  int read, write, exec;
+	  int modified = 0, has_anonymous = 0;
 
 	  read_mapping (line, &addr, &endaddr, &permissions, &permissions_len,
 			&offset, &device, &device_len, &inode, &filename);
@@ -569,8 +578,35 @@ linux_find_memory_regions (struct gdbarch *gdbarch,
 	  write = (memchr (permissions, 'w', permissions_len) != 0);
 	  exec = (memchr (permissions, 'x', permissions_len) != 0);
 
+	  /* Try to detect if region was modified by parsing smaps counters.  */
+	  for (line = strtok (NULL, "\n");
+	       line && line[0] >= 'A' && line[0] <= 'Z';
+	       line = strtok (NULL, "\n"))
+	    {
+	      char keyword[64 + 1];
+	      unsigned long number;
+
+	      if (sscanf (line, "%64s%lu kB\n", keyword, &number) != 2)
+		{
+		  warning (_("Error parsing {s,}maps file '%s'"), filename);
+		  break;
+		}
+	      if (strcmp (keyword, "Anonymous:") == 0)
+		has_anonymous = 1;
+	      if (number != 0 && (strcmp (keyword, "Shared_Dirty:") == 0
+				  || strcmp (keyword, "Private_Dirty:") == 0
+				  || strcmp (keyword, "Swap:") == 0
+				  || strcmp (keyword, "Anonymous:") == 0))
+		modified = 1;
+	    }
+
+	  /* Older Linux kernels did not support the "Anonymous:" counter.
+	     If it is missing, we can't be sure - dump all the pages.  */
+	  if (!has_anonymous)
+	    modified = 1;
+
 	  /* Invoke the callback function to create the corefile segment.  */
-	  func (addr, endaddr - addr, read, write, exec, obfd);
+	  func (addr, endaddr - addr, read, write, exec, modified, obfd);
 	}
 
       do_cleanups (cleanup);
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 4409e5b..ee2b123 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -5074,6 +5074,7 @@ find_memory_regions_callback (struct prmap *map,
 		  (map->pr_mflags & MA_READ) != 0,
 		  (map->pr_mflags & MA_WRITE) != 0,
 		  (map->pr_mflags & MA_EXEC) != 0,
+		  1, /* MODIFIED is unknown, pass it as true.  */
 		  data);
 }
 
diff --git a/gdb/testsuite/gdb.base/gcore-relro-lib.c b/gdb/testsuite/gdb.base/gcore-relro-lib.c
new file mode 100644
index 0000000..d74b690
--- /dev/null
+++ b/gdb/testsuite/gdb.base/gcore-relro-lib.c
@@ -0,0 +1,21 @@
+/* Copyright 2010 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 <http://www.gnu.org/licenses/>.  */
+
+void
+lib (void)
+{
+}
diff --git a/gdb/testsuite/gdb.base/gcore-relro-main.c b/gdb/testsuite/gdb.base/gcore-relro-main.c
new file mode 100644
index 0000000..46b9dfe
--- /dev/null
+++ b/gdb/testsuite/gdb.base/gcore-relro-main.c
@@ -0,0 +1,25 @@
+/* Copyright 2010 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   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 <http://www.gnu.org/licenses/>.  */
+
+extern void lib (void);
+
+int
+main (void)
+{
+  lib ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/gcore-relro.exp b/gdb/testsuite/gdb.base/gcore-relro.exp
new file mode 100644
index 0000000..5b8d6c7
--- /dev/null
+++ b/gdb/testsuite/gdb.base/gcore-relro.exp
@@ -0,0 +1,78 @@
+# Copyright 2012 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 <http://www.gnu.org/licenses/>.
+
+if {[skip_shlib_tests]} {
+    return 0
+}
+
+standard_testfile gcore-relro-main.c
+set libfile gcore-relro-lib
+set srcfile_lib ${libfile}.c
+set binfile_lib [standard_output_file ${libfile}.so]
+set gcorefile ${binfile}.gcore
+set objfile [standard_output_file ${testfile}.o]
+
+ if { [gdb_compile_shlib ${srcdir}/${subdir}/${srcfile_lib} ${binfile_lib} {debug}] != ""
+      || [gdb_compile ${srcdir}/${subdir}/${srcfile} ${objfile} object {debug}] != "" } {
+      untested ${testfile}.exp
+      return -1
+ }
+ set opts [list debug shlib=${binfile_lib} additional_flags=-Wl,-z,relro]
+ if { [gdb_compile ${objfile} ${binfile} executable $opts] != "" } {
+      unsupported "-Wl,-z,relro compilation failed"
+      return -1
+ }
+
+clean_restart ${binfile}
+gdb_load_shlibs ${binfile_lib}
+
+# Does this gdb support gcore?
+set test "help gcore"
+gdb_test_multiple $test $test {
+    -re "Undefined command: .gcore.*\r\n$gdb_prompt $" {
+	# gcore command not supported -- nothing to test here.
+	unsupported "gdb does not support gcore on this target"
+	return -1;
+    }
+    -re "Save a core file .*\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
+if ![runto lib] {
+    return -1
+}
+
+set escapedfilename [string_to_regexp ${gcorefile}]
+
+set test "save a corefile"
+gdb_test_multiple "gcore ${gcorefile}" $test {
+    -re "Saved corefile ${escapedfilename}\r\n$gdb_prompt $" {
+	pass $test
+    }
+    -re "Can't create a corefile\r\n$gdb_prompt $" {
+	unsupported $test
+	return -1
+    }
+}
+
+# Now restart gdb and load the corefile.
+
+clean_restart ${binfile}
+gdb_load_shlibs ${binfile_lib}
+
+gdb_test "core ${gcorefile}" "Core was generated by .*" "re-load generated corefile"
+
+gdb_test "frame" "#0 \[^\r\n\]* lib .*" "library got loaded"