Re: [rfc v2][3/3] Remote core file generation: memory map

["Ulrich Weigand" <uweigand at de dot ibm dot com>]

> this patch replaces the earlier attempt to define a <process-map> XML-based
> target object in order to implement find_memory_regions for remote targets.
> 
> Instead, we simply move find_memory_regions to target-dependent code, and
> access /proc via the new TARGET_OBJECT_PROC target object.  /proc/../maps
> parsing code is once again shared with the info_proc implementation which
> is now also in linux-tdep.c.
> 
> For procfs targets, we still fall back to the target method.

Here's the version of the patch I just checked in.  It is basically
unchanged compared to the prior version, execpt it uses target_fileio_...
to access /proc files instead of TARGET_OBJECT_PROC.

Bye,
Ulrich


ChangeLog:

	* gdbarch.sh (find_memory_regions): New callback.
	* gdbarch.c, gdbarch.h: Regenerate.

	* gcore.c (gcore_memory_sections): Try gdbarch find_memory_regions
	callback before falling back to target method.

	* linux-nat.c (read_mapping, linux_nat_find_memory_regions): Remove.
	(linux_target_install_ops): No longer install it.

	* linux-tdep.c (linux_find_memory_regions): New function.
	(linux_init_abi): Install it.


Index: gdb-head/gdb/gcore.c
===================================================================
--- gdb-head.orig/gdb/gcore.c	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/gcore.c	2012-01-19 10:45:59.000000000 +0100
@@ -561,8 +561,14 @@ gcore_copy_callback (bfd *obfd, asection
 static int
 gcore_memory_sections (bfd *obfd)
 {
-  if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
-    return 0;			/* FIXME: error return/msg?  */
+  /* Try gdbarch method first, then fall back to target method.  */
+  if (!gdbarch_find_memory_regions_p (target_gdbarch)
+      || gdbarch_find_memory_regions (target_gdbarch,
+				      gcore_create_callback, obfd) != 0)
+    {
+      if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
+	return 0;			/* FIXME: error return/msg?  */
+    }
 
   /* Record phdrs for section-to-segment mapping.  */
   bfd_map_over_sections (obfd, make_output_phdrs, NULL);
Index: gdb-head/gdb/gdbarch.c
===================================================================
--- gdb-head.orig/gdb/gdbarch.c	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/gdbarch.c	2012-01-19 10:45:59.000000000 +0100
@@ -240,6 +240,7 @@ struct gdbarch
   gdbarch_regset_from_core_section_ftype *regset_from_core_section;
   struct core_regset_section * core_regset_sections;
   gdbarch_make_corefile_notes_ftype *make_corefile_notes;
+  gdbarch_find_memory_regions_ftype *find_memory_regions;
   gdbarch_core_xfer_shared_libraries_ftype *core_xfer_shared_libraries;
   gdbarch_core_pid_to_str_ftype *core_pid_to_str;
   const char * gcore_bfd_target;
@@ -397,6 +398,7 @@ struct gdbarch startup_gdbarch =
   0,  /* regset_from_core_section */
   0,  /* core_regset_sections */
   0,  /* make_corefile_notes */
+  0,  /* find_memory_regions */
   0,  /* core_xfer_shared_libraries */
   0,  /* core_pid_to_str */
   0,  /* gcore_bfd_target */
@@ -686,6 +688,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of fetch_pointer_argument, has predicate.  */
   /* Skip verify of regset_from_core_section, has predicate.  */
   /* Skip verify of make_corefile_notes, has predicate.  */
+  /* Skip verify of find_memory_regions, has predicate.  */
   /* Skip verify of core_xfer_shared_libraries, has predicate.  */
   /* Skip verify of core_pid_to_str, has predicate.  */
   /* Skip verify of gcore_bfd_target, has predicate.  */
@@ -928,6 +931,12 @@ gdbarch_dump (struct gdbarch *gdbarch, s
                       "gdbarch_dump: fetch_tls_load_module_address = <%s>\n",
                       host_address_to_string (gdbarch->fetch_tls_load_module_address));
   fprintf_unfiltered (file,
+                      "gdbarch_dump: gdbarch_find_memory_regions_p() = %d\n",
+                      gdbarch_find_memory_regions_p (gdbarch));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: find_memory_regions = <%s>\n",
+                      host_address_to_string (gdbarch->find_memory_regions));
+  fprintf_unfiltered (file,
                       "gdbarch_dump: float_bit = %s\n",
                       plongest (gdbarch->float_bit));
   fprintf_unfiltered (file,
@@ -3278,6 +3287,30 @@ set_gdbarch_make_corefile_notes (struct 
 }
 
 int
+gdbarch_find_memory_regions_p (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  return gdbarch->find_memory_regions != NULL;
+}
+
+int
+gdbarch_find_memory_regions (struct gdbarch *gdbarch, find_memory_region_ftype func, void *data)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->find_memory_regions != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_find_memory_regions called\n");
+  return gdbarch->find_memory_regions (gdbarch, func, data);
+}
+
+void
+set_gdbarch_find_memory_regions (struct gdbarch *gdbarch,
+                                 gdbarch_find_memory_regions_ftype find_memory_regions)
+{
+  gdbarch->find_memory_regions = find_memory_regions;
+}
+
+int
 gdbarch_core_xfer_shared_libraries_p (struct gdbarch *gdbarch)
 {
   gdb_assert (gdbarch != NULL);
Index: gdb-head/gdb/gdbarch.h
===================================================================
--- gdb-head.orig/gdb/gdbarch.h	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/gdbarch.h	2012-01-19 10:45:59.000000000 +0100
@@ -717,6 +717,14 @@ typedef char * (gdbarch_make_corefile_no
 extern char * gdbarch_make_corefile_notes (struct gdbarch *gdbarch, bfd *obfd, int *note_size);
 extern void set_gdbarch_make_corefile_notes (struct gdbarch *gdbarch, gdbarch_make_corefile_notes_ftype *make_corefile_notes);
 
+/* Find core file memory regions */
+
+extern int gdbarch_find_memory_regions_p (struct gdbarch *gdbarch);
+
+typedef int (gdbarch_find_memory_regions_ftype) (struct gdbarch *gdbarch, find_memory_region_ftype func, void *data);
+extern int gdbarch_find_memory_regions (struct gdbarch *gdbarch, find_memory_region_ftype func, void *data);
+extern void set_gdbarch_find_memory_regions (struct gdbarch *gdbarch, gdbarch_find_memory_regions_ftype *find_memory_regions);
+
 /* Read offset OFFSET of TARGET_OBJECT_LIBRARIES formatted shared libraries list from
    core file into buffer READBUF with length LEN. */
 
Index: gdb-head/gdb/gdbarch.sh
===================================================================
--- gdb-head.orig/gdb/gdbarch.sh	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/gdbarch.sh	2012-01-19 10:45:59.000000000 +0100
@@ -634,6 +634,9 @@ v:struct core_regset_section *:core_regs
 # Create core file notes
 M:char *:make_corefile_notes:bfd *obfd, int *note_size:obfd, note_size
 
+# Find core file memory regions
+M:int:find_memory_regions:find_memory_region_ftype func, void *data:func, data
+
 # Read offset OFFSET of TARGET_OBJECT_LIBRARIES formatted shared libraries list from
 # core file into buffer READBUF with length LEN.
 M:LONGEST:core_xfer_shared_libraries:gdb_byte *readbuf, ULONGEST offset, LONGEST len:readbuf, offset, len
Index: gdb-head/gdb/linux-nat.c
===================================================================
--- gdb-head.orig/gdb/linux-nat.c	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/linux-nat.c	2012-01-19 10:45:59.000000000 +0100
@@ -4396,90 +4396,6 @@ linux_child_pid_to_exec_file (int pid)
     return name1;
 }
 
-/* Service function for corefiles and info proc.  */
-
-static int
-read_mapping (FILE *mapfile,
-	      long long *addr,
-	      long long *endaddr,
-	      char *permissions,
-	      long long *offset,
-	      char *device, long long *inode, char *filename)
-{
-  int ret = fscanf (mapfile, "%llx-%llx %s %llx %s %llx",
-		    addr, endaddr, permissions, offset, device, inode);
-
-  filename[0] = '\0';
-  if (ret > 0 && ret != EOF)
-    {
-      /* Eat everything up to EOL for the filename.  This will prevent
-         weird filenames (such as one with embedded whitespace) from
-         confusing this code.  It also makes this code more robust in
-         respect to annotations the kernel may add after the filename.
-
-         Note the filename is used for informational purposes
-         only.  */
-      ret += fscanf (mapfile, "%[^\n]\n", filename);
-    }
-
-  return (ret != 0 && ret != EOF);
-}
-
-/* Fills the "to_find_memory_regions" target vector.  Lists the memory
-   regions in the inferior for a corefile.  */
-
-static int
-linux_nat_find_memory_regions (find_memory_region_ftype func, void *obfd)
-{
-  int pid = PIDGET (inferior_ptid);
-  char mapsfilename[MAXPATHLEN];
-  FILE *mapsfile;
-  long long addr, endaddr, size, offset, inode;
-  char permissions[8], device[8], filename[MAXPATHLEN];
-  int read, write, exec;
-  struct cleanup *cleanup;
-
-  /* Compose the filename for the /proc memory map, and open it.  */
-  sprintf (mapsfilename, "/proc/%d/maps", pid);
-  if ((mapsfile = fopen (mapsfilename, "r")) == NULL)
-    error (_("Could not open %s."), mapsfilename);
-  cleanup = make_cleanup_fclose (mapsfile);
-
-  if (info_verbose)
-    fprintf_filtered (gdb_stdout,
-		      "Reading memory regions from %s\n", mapsfilename);
-
-  /* Now iterate until end-of-file.  */
-  while (read_mapping (mapsfile, &addr, &endaddr, &permissions[0],
-		       &offset, &device[0], &inode, &filename[0]))
-    {
-      size = endaddr - addr;
-
-      /* Get the segment's permissions.  */
-      read = (strchr (permissions, 'r') != 0);
-      write = (strchr (permissions, 'w') != 0);
-      exec = (strchr (permissions, 'x') != 0);
-
-      if (info_verbose)
-	{
-	  fprintf_filtered (gdb_stdout,
-			    "Save segment, %s bytes at %s (%c%c%c)",
-			    plongest (size), paddress (target_gdbarch, addr),
-			    read ? 'r' : ' ',
-			    write ? 'w' : ' ', exec ? 'x' : ' ');
-	  if (filename[0])
-	    fprintf_filtered (gdb_stdout, " for %s", filename);
-	  fprintf_filtered (gdb_stdout, "\n");
-	}
-
-      /* Invoke the callback function to create the corefile
-	 segment.  */
-      func (addr, size, read, write, exec, obfd);
-    }
-  do_cleanups (cleanup);
-  return 0;
-}
-
 /* Records the thread's register state for the corefile note
    section.  */
 
@@ -4827,7 +4743,6 @@ linux_target_install_ops (struct target_
   t->to_post_startup_inferior = linux_child_post_startup_inferior;
   t->to_post_attach = linux_child_post_attach;
   t->to_follow_fork = linux_child_follow_fork;
-  t->to_find_memory_regions = linux_nat_find_memory_regions;
   t->to_make_corefile_notes = linux_nat_make_corefile_notes;
 
   super_xfer_partial = t->to_xfer_partial;
Index: gdb-head/gdb/linux-tdep.c
===================================================================
--- gdb-head.orig/gdb/linux-tdep.c	2012-01-19 10:45:56.000000000 +0100
+++ gdb-head/gdb/linux-tdep.c	2012-01-19 10:45:59.000000000 +0100
@@ -530,6 +530,53 @@ linux_info_proc (struct gdbarch *gdbarch
     }
 }
 
+/* List memory regions in the inferior for a corefile.  */
+
+static int
+linux_find_memory_regions (struct gdbarch *gdbarch,
+			   find_memory_region_ftype func, void *obfd)
+{
+  char filename[100];
+  gdb_byte *data;
+
+  /* We need to know the real target PID to access /proc.  */
+  if (current_inferior ()->fake_pid_p)
+    return 1;
+
+  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"))
+	{
+	  ULONGEST addr, endaddr, offset, inode;
+	  const char *permissions, *device, *filename;
+	  size_t permissions_len, device_len;
+	  int read, write, exec;
+
+	  read_mapping (line, &addr, &endaddr, &permissions, &permissions_len,
+			&offset, &device, &device_len, &inode, &filename);
+
+	  /* Decode permissions.  */
+	  read = (memchr (permissions, 'r', permissions_len) != 0);
+	  write = (memchr (permissions, 'w', permissions_len) != 0);
+	  exec = (memchr (permissions, 'x', permissions_len) != 0);
+
+	  /* Invoke the callback function to create the corefile segment.  */
+	  func (addr, endaddr - addr, read, write, exec, obfd);
+	}
+
+      do_cleanups (cleanup);
+      return 0;
+    }
+
+  return 1;
+}
+
 /* Determine which signal stopped execution.  */
 
 static int
@@ -807,6 +854,7 @@ linux_init_abi (struct gdbarch_info info
 {
   set_gdbarch_core_pid_to_str (gdbarch, linux_core_pid_to_str);
   set_gdbarch_info_proc (gdbarch, linux_info_proc);
+  set_gdbarch_find_memory_regions (gdbarch, linux_find_memory_regions);
   set_gdbarch_make_corefile_notes (gdbarch, linux_make_corefile_notes_1);
 }
 

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com