[PATCH] Move [PAC] into a new MI field addr_flags

[Alan Hayward <Alan dot Hayward at arm dot com>]

Add a new print_pc which prints both the PC and a new field addr_flags.
Call this wherever the PC is printed in stack.c.

Add a new gdbarch method get_pc_address_flags to obtain the addr_flag
contents. By default returns an empty string, on AArch64 this returns
PAC if the address has been masked in the frame.

Document this in the manual and NEWS file.

gdb/ChangeLog:

2019-08-12  Alan Hayward  <alan.hayward@arm.com>

	* NEWS (Other MI changes): New subsection.
	* aarch64-tdep.c (aarch64_get_pc_address_flags): New function.
	(aarch64_gdbarch_init): Add aarch64_get_pc_address_flags.
	* arch-utils.c (default_get_pc_address_flags): New function.
	* arch-utils.h (default_get_pc_address_flags): New declaration.
	* gdbarch.sh: Add get_pc_address_flags.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Likewise.
	* stack.c (print_pc): New function.
	(print_frame_info) (print_frame): Call print_pc.

gdb/doc/ChangeLog:

2019-08-12  Alan Hayward  <alan.hayward@arm.com>

	* gdb.texinfo (AArch64 Pointer Authentication)
	(GDB/MI Breakpoint Information) (Frame Information): Document
	addr_field.
---
 gdb/NEWS            |  6 ++++++
 gdb/aarch64-tdep.c  | 13 +++++++++++++
 gdb/arch-utils.c    |  8 ++++++++
 gdb/arch-utils.h    |  4 ++++
 gdb/doc/gdb.texinfo | 18 +++++++++++++++++-
 gdb/gdbarch.c       | 23 +++++++++++++++++++++++
 gdb/gdbarch.h       |  6 ++++++
 gdb/gdbarch.sh      |  3 +++
 gdb/stack.c         | 29 ++++++++++++++++++++---------
 9 files changed, 100 insertions(+), 10 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index fa01adf6e8..42b2ba3d2b 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -287,6 +287,12 @@ maint show test-options-completion-result
   These can be used to catch C++ exceptions in a similar fashion to
   the CLI commands 'catch throw', 'catch rethrow', and 'catch catch'.
 
+* Other MI changes
+
+ ** Backtraces and frames include a new optional field addr_flags which is
+    given after the addr field.  Currently this is only used by AArch64
+    for indicating PAC encyrpted addresses.
+
 * Testsuite
 
   The testsuite now creates the files gdb.cmd (containing the arguments
diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
index 9b6324f0fc..236456399d 100644
--- a/gdb/aarch64-tdep.c
+++ b/gdb/aarch64-tdep.c
@@ -273,6 +273,17 @@ aarch64_frame_unmask_lr (struct gdbarch_tdep *tdep,
   return addr;
 }
 
+/* Implement the "get_pc_address_flags" gdbarch method.  */
+
+static std::string
+aarch64_get_pc_address_flags (frame_info *frame, CORE_ADDR pc)
+{
+  if (pc != 0 && get_frame_pc_masked (frame))
+    return "PAC";
+
+  return "";
+}
+
 /* Analyze a prologue, looking for a recognizable stack frame
    and frame pointer.  Scan until we encounter a store that could
    clobber the stack frame unexpectedly, or an unknown instruction.  */
@@ -3382,6 +3393,8 @@ aarch64_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 
   set_gdbarch_gen_return_address (gdbarch, aarch64_gen_return_address);
 
+  set_gdbarch_get_pc_address_flags (gdbarch, aarch64_get_pc_address_flags);
+
   tdesc_use_registers (gdbarch, tdesc, tdesc_data);
 
   /* Add standard register aliases.  */
diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index bfcb58207a..c61fa6f051 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -995,6 +995,14 @@ default_type_align (struct gdbarch *gdbarch, struct type *type)
   return 0;
 }
 
+/* See arch-utils.h.  */
+
+std::string
+default_get_pc_address_flags (frame_info *frame, CORE_ADDR pc)
+{
+  return "";
+}
+
 void
 _initialize_gdbarch_utils (void)
 {
diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
index 588e7c0762..e5bbcd1f95 100644
--- a/gdb/arch-utils.h
+++ b/gdb/arch-utils.h
@@ -272,4 +272,8 @@ extern bool default_in_indirect_branch_thunk (gdbarch *gdbarch,
 extern ULONGEST default_type_align (struct gdbarch *gdbarch,
 				    struct type *type);
 
+/* Default implementation of gdbarch get_pc_address_flags method.  */
+extern std::string default_get_pc_address_flags (frame_info *frame,
+						 CORE_ADDR pc);
+
 #endif /* ARCH_UTILS_H */
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index c8ca757989..433b7eb260 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -24397,7 +24397,8 @@ When @value{GDBN} is debugging the AArch64 architecture, and the program is
 using the v8.3-A feature Pointer Authentication (PAC), then whenever the link
 register @code{$lr} is pointing to an PAC function its value will be masked.
 When GDB prints a backtrace, any addresses that required unmasking will be
-postfixed with the marker [PAC].
+postfixed with the marker [PAC].  When using the MI, this is printed as part
+of the @code{addr_flags}. field
 
 @node i386
 @subsection x86 Architecture-specific Issues
@@ -28925,6 +28926,11 @@ breakpoint; or the string @samp{<MULTIPLE>}, for a breakpoint with
 multiple locations.  This field will not be present if no address can
 be determined.  For example, a watchpoint does not have an address.
 
+@item addr_flags
+Optional field containing any flags related to the address.  If there
+are any flags defined for the current target then they are documented in
+the @xref{Architectures} section.
+
 @item func
 If known, the function in which the breakpoint appears.
 If not known, this field is not present.
@@ -29025,6 +29031,11 @@ Note that this is not the same as the field @code{enable}.
 @item addr
 The address of this location as an hexidecimal number.
 
+@item addr_flags
+Optional field containing any flags related to the address.  If there
+are any flags defined for the current target then they are documented in
+the @xref{Architectures} section.
+
 @item func
 If known, the function in which the location appears.
 If not known, this field is not present.
@@ -29077,6 +29088,11 @@ be absent if @value{GDBN} is unable to determine the function name.
 @item addr
 The code address for the frame.  This field is always present.
 
+@item addr_flags
+Optional field containing any flags related to the address.  If there
+are any flags defined for the current target then they are documented in
+the @xref{Architectures} section.
+
 @item file
 The name of the source files that correspond to the frame's code
 address.  This field may be absent.
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 725b98fcd9..7b93d003a7 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -358,6 +358,7 @@ struct gdbarch
   char ** disassembler_options;
   const disasm_options_and_args_t * valid_disassembler_options;
   gdbarch_type_align_ftype *type_align;
+  gdbarch_get_pc_address_flags_ftype *get_pc_address_flags;
 };
 
 /* Create a new ``struct gdbarch'' based on information provided by
@@ -473,6 +474,7 @@ gdbarch_alloc (const struct gdbarch_info *info,
   gdbarch->gnu_triplet_regexp = default_gnu_triplet_regexp;
   gdbarch->addressable_memory_unit_size = default_addressable_memory_unit_size;
   gdbarch->type_align = default_type_align;
+  gdbarch->get_pc_address_flags = default_get_pc_address_flags;
   /* gdbarch_alloc() */
 
   return gdbarch;
@@ -721,6 +723,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of disassembler_options, invalid_p == 0 */
   /* Skip verify of valid_disassembler_options, invalid_p == 0 */
   /* Skip verify of type_align, invalid_p == 0 */
+  /* Skip verify of get_pc_address_flags, invalid_p == 0 */
   if (!log.empty ())
     internal_error (__FILE__, __LINE__,
                     _("verify_gdbarch: the following are invalid ...%s"),
@@ -1065,6 +1068,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
   fprintf_unfiltered (file,
                       "gdbarch_dump: get_longjmp_target = <%s>\n",
                       host_address_to_string (gdbarch->get_longjmp_target));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: get_pc_address_flags = <%s>\n",
+                      host_address_to_string (gdbarch->get_pc_address_flags));
   fprintf_unfiltered (file,
                       "gdbarch_dump: gdbarch_get_siginfo_type_p() = %d\n",
                       gdbarch_get_siginfo_type_p (gdbarch));
@@ -5156,6 +5162,23 @@ set_gdbarch_type_align (struct gdbarch *gdbarch,
   gdbarch->type_align = type_align;
 }
 
+std::string
+gdbarch_get_pc_address_flags (struct gdbarch *gdbarch, frame_info *frame, CORE_ADDR pc)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->get_pc_address_flags != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_get_pc_address_flags called\n");
+  return gdbarch->get_pc_address_flags (frame, pc);
+}
+
+void
+set_gdbarch_get_pc_address_flags (struct gdbarch *gdbarch,
+                                  gdbarch_get_pc_address_flags_ftype get_pc_address_flags)
+{
+  gdbarch->get_pc_address_flags = get_pc_address_flags;
+}
+
 
 /* Keep a registry of per-architecture data-pointers required by GDB
    modules.  */
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index c3556d3841..3c6efae895 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -1640,6 +1640,12 @@ typedef ULONGEST (gdbarch_type_align_ftype) (struct gdbarch *gdbarch, struct typ
 extern ULONGEST gdbarch_type_align (struct gdbarch *gdbarch, struct type *type);
 extern void set_gdbarch_type_align (struct gdbarch *gdbarch, gdbarch_type_align_ftype *type_align);
 
+/* Return a string containing any flags for the given PC in the given FRAME. */
+
+typedef std::string (gdbarch_get_pc_address_flags_ftype) (frame_info *frame, CORE_ADDR pc);
+extern std::string gdbarch_get_pc_address_flags (struct gdbarch *gdbarch, frame_info *frame, CORE_ADDR pc);
+extern void set_gdbarch_get_pc_address_flags (struct gdbarch *gdbarch, gdbarch_get_pc_address_flags_ftype *get_pc_address_flags);
+
 extern struct gdbarch_tdep *gdbarch_tdep (struct gdbarch *gdbarch);
 
 
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 2f9fbbc56c..d589b2c49a 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1210,6 +1210,9 @@ v;const disasm_options_and_args_t *;valid_disassembler_options;;;0;0;;0;host_add
 # default rules as laid out in gdbtypes.c:type_align.
 m;ULONGEST;type_align;struct type *type;type;;default_type_align;;0
 
+# Return a string containing any flags for the given PC in the given FRAME.
+f;std::string;get_pc_address_flags;frame_info *frame, CORE_ADDR pc;frame, pc;;default_get_pc_address_flags;;0
+
 EOF
 }
 
diff --git a/gdb/stack.c b/gdb/stack.c
index 49b9100485..06431ea354 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -923,6 +923,23 @@ print_frame_info_to_print_what (const char *print_frame_info)
 		  print_frame_info);
 }
 
+/* Print the PC from FRAME, plus any flags, to UIOUT.  */
+
+static void
+print_pc (struct ui_out *uiout, struct gdbarch *gdbarch, frame_info *frame,
+	  CORE_ADDR pc)
+{
+  uiout->field_core_addr ("addr", gdbarch, pc);
+
+  std::string flags = gdbarch_get_pc_address_flags (gdbarch, frame, pc);
+  if (!flags.empty ())
+  {
+    uiout->text (" [");
+    uiout->field_string ("addr_flags", flags);
+    uiout->text ("]");
+  }
+}
+
 /* See stack.h.  */
 
 void
@@ -980,8 +997,7 @@ print_frame_info (const frame_print_options &fp_opts,
       if (uiout->is_mi_like_p ())
         {
           annotate_frame_address ();
-          uiout->field_core_addr ("addr",
-				  gdbarch, get_frame_pc (frame));
+	  print_pc (uiout, gdbarch, frame, get_frame_pc (frame));
           annotate_frame_address_end ();
         }
 
@@ -1065,8 +1081,7 @@ print_frame_info (const frame_print_options &fp_opts,
 	     ability to decide for themselves if it is desired.  */
 	  if (opts.addressprint && mid_statement)
 	    {
-	      uiout->field_core_addr ("addr",
-				      gdbarch, get_frame_pc (frame));
+	      print_pc (uiout, gdbarch, frame, get_frame_pc (frame));
 	      uiout->text ("\t");
 	    }
 
@@ -1292,11 +1307,7 @@ print_frame (const frame_print_options &fp_opts,
 	{
 	  annotate_frame_address ();
 	  if (pc_p)
-	    {
-	      uiout->field_core_addr ("addr", gdbarch, pc);
-	      if (get_frame_pc_masked (frame))
-		uiout->field_string ("pac", " [PAC]");
-	    }
+	    print_pc (uiout, gdbarch, frame, pc);
 	  else
 	    uiout->field_string ("addr", "<unavailable>",
 				 ui_out_style_kind::ADDRESS);
-- 
2.20.1 (Apple Git-117)