Add support for bound table in the Intel MPX context.

Intel(R) Memory protection bound information are located in register
to be tested using the MPX new instructions. Since the number of
bound registers are limited a table is used to provide storage for
bounds during run-time.

In order to investigate the contents of the MPX bound table two new
commands are added to GDB.  "show mpx bound" and "set mpx bound" are
used to display and set values on the MPX bound table.

2015-04-20  Walfred Tedeschi  <walfred.tedeschi@intel.com>
            Mircea Gherzan  <mircea.gherzan@intel.com>

	* i386-tdep.c (MPX_BASE_MASK, MPX_BD_MASK, MPX_BT_MASK, MPX_BD_MASK_32,
	MPX_BT_MASK_32): New macros.
	(i386_mpx_set_bounds): New function that implements
	the command "set-mpx-bound".
	(i386_mpx_enabled) Helper function to test MPX availability.
	(i386_mpx_bd_base) Helper function to calculate the base directory
	address. (i386_mpx_get_bt_entry) Helper function to access a bound
	table entry. (i386_mpx_print_bounds) Effectively display bound
	information. (_initialize_i386_tdep): Qdd new commands
	to commands "set mpx" and "show mpx". (_initialize_i386_tdep):
	Add "bound" to the commands "show mpx" and "set mpx" commands.
	(mpx_set_cmdlist and mpx_show_cmdlist):
	list for the new prefixed "set mpx" and "show mpx" commands.
	* NEWS: List new commands for MPX support.

testsuite:

	* gdb.arch/i386-mpx-map.c: New file.
	* gdb.arch/i386-mpx-map.exp: New File.

doc:
	* gdb.texinfo (i386): Add documentation about "show mpx bound"
	and "set mpx bound".

1 files changed, 273 insertions, 0 deletions

diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index b4ffe1b..6304591 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8619,6 +8619,251 @@ i386_target_description (uint64_t xcr0)
     }
 }
 
+#define MPX_BASE_MASK (~(ULONGEST) 0xfff)
+
+/* Find the bound directory base address.  */
+
+static unsigned long
+i386_mpx_bd_base (void)
+{
+  struct regcache *rcache;
+  struct gdbarch_tdep *tdep;
+  ULONGEST ret;
+  enum register_status regstatus;
+  struct gdb_exception except;
+
+  rcache = get_current_regcache ();
+  tdep = gdbarch_tdep (get_regcache_arch (rcache));
+
+  regstatus = regcache_raw_read_unsigned (rcache, tdep->bndcfgu_regnum, &ret);
+
+  if (regstatus != REG_VALID)
+    error (_("BNDCFGU register invalid, read status %d."), regstatus);
+
+  return ret & MPX_BASE_MASK;
+}
+
+/* Check if the current target is MPX enabled.  */
+
+static int
+i386_mpx_enabled (void)
+{
+  const struct gdbarch_tdep *tdep = gdbarch_tdep (get_current_arch ());
+  const struct target_desc *tdesc = tdep->tdesc;
+
+  return (tdesc_find_feature (tdesc, "org.gnu.gdb.i386.mpx") != NULL);
+}
+
+#define MPX_BD_MASK     0xfffffff00000ULL	/* select bits [47:20]  */
+#define MPX_BT_MASK     0x0000000ffff8	        /* select bits [19:3]   */
+#define MPX_BD_MASK_32  0xfffff000	        /* select bits [31:12]  */
+#define MPX_BT_MASK_32  0x00000ffc	        /* select bits [11:2]   */
+
+/* Find the bound table entry given the pointer location and the base
+   address of the table.  */
+
+static CORE_ADDR
+i386_mpx_get_bt_entry (CORE_ADDR ptr, CORE_ADDR bd_base)
+{
+  CORE_ADDR offset1;
+  CORE_ADDR offset2;
+  CORE_ADDR mpx_bd_mask, bd_ptr_r_shift, bd_ptr_l_shift;
+  CORE_ADDR bt_mask, bt_select_r_shift, bt_select_l_shift;
+  CORE_ADDR bd_entry_addr;
+  CORE_ADDR bt_addr;
+  CORE_ADDR bd_entry;
+  struct gdbarch *gdbarch = get_current_arch ();
+  struct type *data_ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
+
+
+  if (gdbarch_ptr_bit (gdbarch) == 64)
+    {
+      mpx_bd_mask = MPX_BD_MASK;
+      bd_ptr_r_shift = 20;
+      bd_ptr_l_shift = 3;
+      bt_select_r_shift = 3;
+      bt_select_l_shift = 5;
+      bt_mask = MPX_BT_MASK;
+    }
+  else
+    {
+      mpx_bd_mask = MPX_BD_MASK_32;
+      bd_ptr_r_shift = 12;
+      bd_ptr_l_shift = 2;
+      bt_select_r_shift = 2;
+      bt_select_l_shift = 4;
+      bt_mask = MPX_BT_MASK_32;
+    }
+
+  offset1 = ((ptr & mpx_bd_mask) >> bd_ptr_r_shift) << bd_ptr_l_shift;
+  bd_entry_addr = bd_base + offset1;
+  bd_entry = read_memory_typed_address (bd_entry_addr, data_ptr_type);
+
+  if ((bd_entry & 0x1) == 0)
+    error (_("Invalid bounds directory entry at %s."),
+	   paddress (get_current_arch (), bd_entry_addr));
+
+  /* Clearing status bit.  */
+  bd_entry--;
+  bt_addr = bd_entry & ~bt_select_r_shift;
+  offset2 = ((ptr & bt_mask) >> bt_select_r_shift) << bt_select_l_shift;
+
+  return bt_addr + offset2;
+}
+
+/* Print routine for the mpx bounds.  */
+
+static void
+i386_mpx_print_bounds (const CORE_ADDR bt_entry[4])
+{
+  struct ui_out *uiout = current_uiout;
+  long long int size;
+  struct gdbarch *gdbarch = get_current_arch ();
+  CORE_ADDR onecompl = ~((CORE_ADDR) 0);
+  int bounds_in_map = ((~bt_entry[1] == 0 && bt_entry[0] == onecompl) ? 1 : 0);
+
+  if (bounds_in_map == 1)
+    {
+      ui_out_text (uiout, "Null bounds on map:");
+      ui_out_text (uiout, " pointer value = ");
+      ui_out_field_core_addr (uiout, "pointer-value", gdbarch, bt_entry[2]);
+      ui_out_text (uiout, ".");
+      ui_out_text (uiout, "\n");
+    }
+  else
+    {
+      ui_out_text (uiout, "{lbound = ");
+      ui_out_field_core_addr (uiout, "lower-bound", gdbarch, bt_entry[0]);
+      ui_out_text (uiout, ", ubound = ");
+
+      /* The upper bound is stored in 1's complement.  */
+      ui_out_field_core_addr (uiout, "upper-bound", gdbarch, ~bt_entry[1]);
+      ui_out_text (uiout, "}: pointer value = ");
+      ui_out_field_core_addr (uiout, "pointer-value", gdbarch, bt_entry[2]);
+
+      if (gdbarch_ptr_bit (gdbarch) == 64)
+	size = ( (~(int64_t) bt_entry[1]) - (int64_t) bt_entry[0]);
+      else
+	size = ( ~((int32_t) bt_entry[1]) - (int32_t) bt_entry[0]);
+
+      /* In case the bounds are 0x0 and 0xffff... the difference will be -1.
+	 -1 represents in this sense full memory access, and there is no need
+	 one to the size.  */
+
+      size = (size > -1 ? size + 1 : size);
+      ui_out_text (uiout, ", size = ");
+      ui_out_field_fmt (uiout, "size", "%lld", size);
+
+      ui_out_text (uiout, ", metadata = ");
+      ui_out_field_core_addr (uiout, "metadata", gdbarch, bt_entry[3]);
+      ui_out_text (uiout, "\n");
+    }
+}
+
+/* Implement the command "show mpx bound".  */
+
+static void
+i386_mpx_info_bounds (char *args, int from_tty)
+{
+  CORE_ADDR bd_base = 0;
+  CORE_ADDR addr;
+  CORE_ADDR bt_entry_addr = 0;
+  CORE_ADDR bt_entry[4];
+  int i;
+  struct gdbarch *gdbarch = get_current_arch ();
+  struct type *data_ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
+
+  if (!i386_mpx_enabled ())
+    error (_("Intel(R) Memory Protection Extensions not\
+ supported on this target."));
+
+  if (args == NULL)
+    error (_("Address of pointer variable expected."));
+
+  addr = parse_and_eval_address (args);
+
+  bd_base = i386_mpx_bd_base ();
+  bt_entry_addr = i386_mpx_get_bt_entry (addr, bd_base);
+
+  memset (bt_entry, 0, sizeof (bt_entry));
+
+  for (i = 0; i < 4; i++)
+    bt_entry[i] = read_memory_typed_address (bt_entry_addr
+					     + i * data_ptr_type->length,
+					     data_ptr_type);
+
+  i386_mpx_print_bounds (bt_entry);
+}
+
+/* Implement the command "set mpx bound".  */
+
+static void
+i386_mpx_set_bounds (char *args, int from_tty)
+{
+  CORE_ADDR bd_base = 0;
+  CORE_ADDR addr, lower, upper;
+  CORE_ADDR bt_entry_addr = 0;
+  CORE_ADDR bt_entry[2];
+  const char *input = args;
+  int i;
+  struct gdbarch *gdbarch = get_current_arch ();
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  struct type *data_ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
+
+  if (!i386_mpx_enabled ())
+    error (_("Intel(R) Memory Protection Extensions not supported\
+ on this target."));
+
+  if (args == NULL)
+    error (_("Pointer value expected."));
+
+  addr = value_as_address (parse_to_comma_and_eval (&input));
+
+  if (input[0] == ',')
+    ++input;
+  if (input[0] == '\0')
+    error (_("wrong number of arguments: missing lower and upper bound."));
+  lower = value_as_address (parse_to_comma_and_eval (&input));
+
+  if (input[0] == ',')
+    ++input;
+  if (input[0] == '\0')
+    error (_("Wrong number of arguments; Missing upper bound."));
+  upper = value_as_address (parse_to_comma_and_eval (&input));
+
+  bd_base = i386_mpx_bd_base ();
+  bt_entry_addr = i386_mpx_get_bt_entry (addr, bd_base);
+  for (i = 0; i < 2; i++)
+    bt_entry[i] = read_memory_typed_address (bt_entry_addr
+					     + i * data_ptr_type->length,
+					     data_ptr_type);
+  bt_entry[0] = (uint64_t) lower;
+  bt_entry[1] = ~(uint64_t) upper;
+
+  for (i = 0; i < 2; i++)
+    write_memory_unsigned_integer (bt_entry_addr + i * data_ptr_type->length,
+				   data_ptr_type->length, byte_order,
+				   bt_entry[i]);
+}
+
+static struct cmd_list_element *mpx_set_cmdlist, *mpx_show_cmdlist;
+
+/* Helper function for the CLI commands.  */
+
+static void
+set_mpx_cmd (char *args, int from_tty)
+{
+  help_list (mpx_set_cmdlist, "set mpx", all_commands, gdb_stdout);
+}
+
+/* Helper function for the CLI commands.  */
+
+static void
+show_mpx_cmd (char *args, int from_tty)
+{
+  cmd_show_list (mpx_show_cmdlist, from_tty, "");
+}
+
 /* Provide a prototype to silence -Wmissing-prototypes.  */
 void _initialize_i386_tdep (void);
 
@@ -8649,6 +8894,34 @@ is \"default\"."),
 			NULL, /* FIXME: i18n: */
 			&setlist, &showlist);
 
+  /* Add "mpx" prefix for the set commands.  */
+
+  add_prefix_cmd ("mpx", class_support, set_mpx_cmd, _("\
+Set Intel(R) Memory Protection Extensions specific variables."),
+		  &mpx_set_cmdlist, "set tdesc ",
+		  0 /* allow-unknown */, &setlist);
+
+  /* Add "mpx" prefix for the show commands.  */
+
+  add_prefix_cmd ("mpx", class_support, show_mpx_cmd, _("\
+Show Intel(R) Memory Protection Extensions specific variables."),
+		  &mpx_show_cmdlist, "show mpx ",
+		  0 /* allow-unknown */, &showlist);
+
+  /* Add "bound" command for the show mpx commands list.  */
+
+  add_cmd ("bound", no_class, i386_mpx_info_bounds,
+	   "Show the memory bounds for a given array/pointer storage\
+ in the bound table.",
+	   &mpx_show_cmdlist);
+
+  /* Add "bound" command for the set mpx commands list.  */
+
+  add_cmd ("bound", no_class, i386_mpx_set_bounds,
+	   "Set the memory bounds for a given array/pointer storage\
+ in the bound table.",
+	   &mpx_set_cmdlist);
+
   gdbarch_register_osabi_sniffer (bfd_arch_i386, bfd_target_coff_flavour,
 				  i386_coff_osabi_sniffer);