[PATCH v4 5/8] gdb: Introduce is_address_tagged target hook

[Gustavo Romero <gustavo.romero@linaro.org>]

This commit introduces a new target hook, target_is_address_tagged,
which is used instead of the gdbarch_tagged_address_p gdbarch hook in
the upper layer (printcmd.c).

This change enables easy specialization of memory tagging address
check per target in the future. As target_is_address_tagged continues
to utilize the gdbarch_tagged_address_p hook, there is no change in
behavior for all the targets that use the new target hook (i.e., the
remote.c, aarch64-linux-nat.c, and corelow.c targets).

Just the gdbarch_tagged_address_p signature is changed for convenience,
since target_is_address_tagged takes the address to be checked as a
CORE_ADDR type.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
---
 gdb/aarch64-linux-nat.c   | 15 +++++++++++++++
 gdb/aarch64-linux-tdep.c  | 10 +++-------
 gdb/arch-utils.c          |  2 +-
 gdb/arch-utils.h          |  2 +-
 gdb/corelow.c             | 10 ++++++++++
 gdb/gdbarch-gen.h         |  4 ++--
 gdb/gdbarch.c             |  2 +-
 gdb/gdbarch_components.py |  2 +-
 gdb/printcmd.c            | 26 ++++++++++++++------------
 gdb/remote.c              | 10 ++++++++++
 gdb/target-delegates.c    | 30 ++++++++++++++++++++++++++++++
 gdb/target.c              |  6 ++++++
 gdb/target.h              |  6 ++++++
 13 files changed, 100 insertions(+), 25 deletions(-)

diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index 3face34ce79..297f56cdbf1 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -110,6 +110,8 @@ class aarch64_linux_nat_target final
   /* Write allocation tags to memory via PTRACE.  */
   bool store_memtags (CORE_ADDR address, size_t len,
 		      const gdb::byte_vector &tags, int type) override;
+  /* Check if an address is tagged.  */
+  bool is_address_tagged (gdbarch *gdbarch, CORE_ADDR address) override;
 };
 
 static aarch64_linux_nat_target the_aarch64_linux_nat_target;
@@ -1071,6 +1073,19 @@ aarch64_linux_nat_target::store_memtags (CORE_ADDR address, size_t len,
   return false;
 }
 
+bool
+aarch64_linux_nat_target::is_address_tagged (gdbarch *gdbarch, CORE_ADDR address)
+{
+  /* Here we take a detour going to linux-tdep layer to read the smaps file,
+     because currently there isn't a better way to get that information to
+     check if a given address is tagged or not.
+
+     In the future, if this check is made, for instance, available via PTRACE,
+     it will be possible to drop the smaps path in favor of a PTRACE one for
+     this check.  */
+  return gdbarch_tagged_address_p (gdbarch, address);
+}
+
 void _initialize_aarch64_linux_nat ();
 void
 _initialize_aarch64_linux_nat ()
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index fc60e602748..35979875907 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -2451,17 +2451,13 @@ aarch64_mte_get_atag (CORE_ADDR address)
 /* Implement the tagged_address_p gdbarch method.  */
 
 static bool
-aarch64_linux_tagged_address_p (struct gdbarch *gdbarch, struct value *address)
+aarch64_linux_tagged_address_p (struct gdbarch *gdbarch, CORE_ADDR address)
 {
-  gdb_assert (address != nullptr);
-
-  CORE_ADDR addr = value_as_address (address);
-
   /* Remove the top byte for the memory range check.  */
-  addr = gdbarch_remove_non_address_bits (gdbarch, addr);
+  address = gdbarch_remove_non_address_bits (gdbarch, address);
 
   /* Check if the page that contains ADDRESS is mapped with PROT_MTE.  */
-  if (!linux_address_in_memtag_page (addr))
+  if (!linux_address_in_memtag_page (address))
     return false;
 
   /* We have a valid tag in the top byte of the 64-bit address.  */
diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index 456bfe971ff..cb149c36bc9 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -102,7 +102,7 @@ default_memtag_to_string (struct gdbarch *gdbarch, struct value *tag)
 /* See arch-utils.h */
 
 bool
-default_tagged_address_p (struct gdbarch *gdbarch, struct value *address)
+default_tagged_address_p (struct gdbarch *gdbarch, CORE_ADDR address)
 {
   /* By default, assume the address is untagged.  */
   return false;
diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
index 2dcd8f6dc53..467be40c688 100644
--- a/gdb/arch-utils.h
+++ b/gdb/arch-utils.h
@@ -141,7 +141,7 @@ extern std::string default_memtag_to_string (struct gdbarch *gdbarch,
 					     struct value *tag);
 
 /* Default implementation of gdbarch_tagged_address_p.  */
-bool default_tagged_address_p (struct gdbarch *gdbarch, struct value *address);
+bool default_tagged_address_p (struct gdbarch *gdbarch, CORE_ADDR address);
 
 /* Default implementation of gdbarch_memtag_matches_p.  */
 extern bool default_memtag_matches_p (struct gdbarch *gdbarch,
diff --git a/gdb/corelow.c b/gdb/corelow.c
index f4e8273d962..bdda742ef59 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -109,6 +109,10 @@ class core_target final : public process_stratum_target
   bool fetch_memtags (CORE_ADDR address, size_t len,
 		      gdb::byte_vector &tags, int type) override;
 
+  /* If the architecture supports it, check if ADDRESS is within a memory range
+     mapped with tags.  For example,  MTE tags for AArch64.  */
+  bool is_address_tagged (gdbarch *gdbarch, CORE_ADDR address) override;
+
   x86_xsave_layout fetch_x86_xsave_layout () override;
 
   /* A few helpers.  */
@@ -1410,6 +1414,12 @@ core_target::fetch_memtags (CORE_ADDR address, size_t len,
   return false;
 }
 
+bool
+core_target::is_address_tagged (gdbarch *gdbarch, CORE_ADDR address)
+{
+  return gdbarch_tagged_address_p (gdbarch, address);
+}
+
 /* Implementation of the "fetch_x86_xsave_layout" target_ops method.  */
 
 x86_xsave_layout
diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index ebcff80bb9e..63fab26987f 100644
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -707,8 +707,8 @@ extern void set_gdbarch_memtag_to_string (struct gdbarch *gdbarch, gdbarch_memta
 /* Return true if ADDRESS contains a tag and false otherwise.  ADDRESS
    must be either a pointer or a reference type. */
 
-typedef bool (gdbarch_tagged_address_p_ftype) (struct gdbarch *gdbarch, struct value *address);
-extern bool gdbarch_tagged_address_p (struct gdbarch *gdbarch, struct value *address);
+typedef bool (gdbarch_tagged_address_p_ftype) (struct gdbarch *gdbarch, CORE_ADDR address);
+extern bool gdbarch_tagged_address_p (struct gdbarch *gdbarch, CORE_ADDR address);
 extern void set_gdbarch_tagged_address_p (struct gdbarch *gdbarch, gdbarch_tagged_address_p_ftype *tagged_address_p);
 
 /* Return true if the tag from ADDRESS matches the memory tag for that
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 9319571deba..2d92f604c49 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -3232,7 +3232,7 @@ set_gdbarch_memtag_to_string (struct gdbarch *gdbarch,
 }
 
 bool
-gdbarch_tagged_address_p (struct gdbarch *gdbarch, struct value *address)
+gdbarch_tagged_address_p (struct gdbarch *gdbarch, CORE_ADDR address)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->tagged_address_p != NULL);
diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py
index 7d913ade621..24e979431b6 100644
--- a/gdb/gdbarch_components.py
+++ b/gdb/gdbarch_components.py
@@ -1267,7 +1267,7 @@ must be either a pointer or a reference type.
 """,
     type="bool",
     name="tagged_address_p",
-    params=[("struct value *", "address")],
+    params=[("CORE_ADDR", "address")],
     predefault="default_tagged_address_p",
     invalid=False,
 )
diff --git a/gdb/printcmd.c b/gdb/printcmd.c
index 4edbd458e4d..c9689a29f74 100644
--- a/gdb/printcmd.c
+++ b/gdb/printcmd.c
@@ -1132,7 +1132,7 @@ do_examine (struct format_data fmt, struct gdbarch *gdbarch, CORE_ADDR addr)
 	    = value_from_ulongest (builtin_type (gdbarch)->builtin_data_ptr,
 				   tag_laddr);
 
-	  if (gdbarch_tagged_address_p (gdbarch, v_addr))
+	  if (target_is_address_tagged (gdbarch, value_as_address (v_addr)))
 	    {
 	      /* Fetch the allocation tag.  */
 	      struct value *tag
@@ -1268,7 +1268,7 @@ print_value (value *val, const value_print_options &opts)
 /* Returns true if memory tags should be validated.  False otherwise.  */
 
 static bool
-should_validate_memtags (struct value *value)
+should_validate_memtags (gdbarch *gdbarch, struct value *value)
 {
   gdb_assert (value != nullptr && value->type () != nullptr);
 
@@ -1289,7 +1289,7 @@ should_validate_memtags (struct value *value)
     return false;
 
   /* We do.  Check whether it includes any tags.  */
-  return gdbarch_tagged_address_p (current_inferior ()->arch  (), value);
+  return target_is_address_tagged (gdbarch, value_as_address (value));
 }
 
 /* Helper for parsing arguments for print_command_1.  */
@@ -1346,7 +1346,7 @@ print_command_1 (const char *args, int voidprint)
 	    {
 	      gdbarch *arch = current_inferior ()->arch ();
 
-	      if (should_validate_memtags (val)
+	      if (should_validate_memtags (arch, val)
 		  && !gdbarch_memtag_matches_p (arch, val))
 		{
 		  /* Fetch the logical tag.  */
@@ -2946,9 +2946,10 @@ memory_tag_print_tag_command (const char *args, enum memtag_type tag_type)
      flag, it is no use trying to access/manipulate its allocation tag.
 
      It is OK to manipulate the logical tag though.  */
+  CORE_ADDR addr = value_as_address (val);
   if (tag_type == memtag_type::allocation
-      && !gdbarch_tagged_address_p (arch, val))
-    show_addr_not_tagged (value_as_address (val));
+      && !target_is_address_tagged (arch, addr))
+    show_addr_not_tagged (addr);
 
   value *tag_value = gdbarch_get_memtag (arch, val, tag_type);
   std::string tag = gdbarch_memtag_to_string (arch, tag_value);
@@ -3124,8 +3125,9 @@ memory_tag_set_allocation_tag_command (const char *args, int from_tty)
 
   /* If the address is not in a region memory-mapped with a memory tagging
      flag, it is no use trying to manipulate its allocation tag.  */
-  if (!gdbarch_tagged_address_p (current_inferior ()->arch (), val))
-    show_addr_not_tagged (value_as_address (val));
+  CORE_ADDR addr = value_as_address (val);
+  if (!target_is_address_tagged (current_inferior ()-> arch(), addr))
+    show_addr_not_tagged (addr);
 
   if (!gdbarch_set_memtags (current_inferior ()->arch (), val, length, tags,
 			    memtag_type::allocation))
@@ -3152,12 +3154,12 @@ memory_tag_check_command (const char *args, int from_tty)
   struct value *val = process_print_command_args (args, &print_opts, true);
   gdbarch *arch = current_inferior ()->arch ();
 
+  CORE_ADDR addr = value_as_address (val);
+
   /* If the address is not in a region memory mapped with a memory tagging
      flag, it is no use trying to access/manipulate its allocation tag.  */
-  if (!gdbarch_tagged_address_p (arch, val))
-    show_addr_not_tagged (value_as_address (val));
-
-  CORE_ADDR addr = value_as_address (val);
+  if (!target_is_address_tagged (current_inferior ()->arch (), addr))
+    show_addr_not_tagged (addr);
 
   /* Check if the tag is valid.  */
   if (!gdbarch_memtag_matches_p (arch, val))
diff --git a/gdb/remote.c b/gdb/remote.c
index e278711df7b..9717db55e27 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -1084,6 +1084,8 @@ class remote_target : public process_stratum_target
   bool store_memtags (CORE_ADDR address, size_t len,
 		      const gdb::byte_vector &tags, int type) override;
 
+  bool is_address_tagged (gdbarch *gdbarch, CORE_ADDR address) override;
+
 public: /* Remote specific methods.  */
 
   void remote_download_command_source (int num, ULONGEST addr,
@@ -15573,6 +15575,14 @@ remote_target::store_memtags (CORE_ADDR address, size_t len,
   return packet_check_result (rs->buf).status () == PACKET_OK;
 }
 
+/* Implement the "is_address_tagged" target_ops method.  */
+
+bool
+remote_target::is_address_tagged (gdbarch *gdbarch, CORE_ADDR address)
+{
+  return gdbarch_tagged_address_p (gdbarch, address);
+}
+
 /* Return true if remote target T is non-stop.  */
 
 bool
diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
index 59ea70458ad..e322bbbe481 100644
--- a/gdb/target-delegates.c
+++ b/gdb/target-delegates.c
@@ -197,6 +197,7 @@ struct dummy_target : public target_ops
   bool supports_memory_tagging () override;
   bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
   bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
+  bool is_address_tagged (gdbarch *arg0, CORE_ADDR arg1) override;
   x86_xsave_layout fetch_x86_xsave_layout () override;
 };
 
@@ -373,6 +374,7 @@ struct debug_target : public target_ops
   bool supports_memory_tagging () override;
   bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
   bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
+  bool is_address_tagged (gdbarch *arg0, CORE_ADDR arg1) override;
   x86_xsave_layout fetch_x86_xsave_layout () override;
 };
 
@@ -4562,6 +4564,34 @@ debug_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector
   return result;
 }
 
+bool
+target_ops::is_address_tagged (gdbarch *arg0, CORE_ADDR arg1)
+{
+  return this->beneath ()->is_address_tagged (arg0, arg1);
+}
+
+bool
+dummy_target::is_address_tagged (gdbarch *arg0, CORE_ADDR arg1)
+{
+  tcomplain ();
+}
+
+bool
+debug_target::is_address_tagged (gdbarch *arg0, CORE_ADDR arg1)
+{
+  gdb_printf (gdb_stdlog, "-> %s->is_address_tagged (...)\n", this->beneath ()->shortname ());
+  bool result
+    = this->beneath ()->is_address_tagged (arg0, arg1);
+  gdb_printf (gdb_stdlog, "<- %s->is_address_tagged (", this->beneath ()->shortname ());
+  target_debug_print_gdbarch_p (arg0);
+  gdb_puts (", ", gdb_stdlog);
+  target_debug_print_CORE_ADDR (arg1);
+  gdb_puts (") = ", gdb_stdlog);
+  target_debug_print_bool (result);
+  gdb_puts ("\n", gdb_stdlog);
+  return result;
+}
+
 x86_xsave_layout
 target_ops::fetch_x86_xsave_layout ()
 {
diff --git a/gdb/target.c b/gdb/target.c
index 107a84b3ca1..5c3c1a57dbd 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -796,6 +796,12 @@ target_store_memtags (CORE_ADDR address, size_t len,
   return current_inferior ()->top_target ()->store_memtags (address, len, tags, type);
 }
 
+bool
+target_is_address_tagged (gdbarch *gdbarch, CORE_ADDR address)
+{
+  return current_inferior ()->top_target ()->is_address_tagged (gdbarch, address);
+}
+
 x86_xsave_layout
 target_fetch_x86_xsave_layout ()
 {
diff --git a/gdb/target.h b/gdb/target.h
index c9eaff16346..486a0a687b0 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1334,6 +1334,10 @@ struct target_ops
 				const gdb::byte_vector &tags, int type)
       TARGET_DEFAULT_NORETURN (tcomplain ());
 
+    /* Returns true if ADDRESS is tagged, otherwise returns false.  */
+    virtual bool is_address_tagged (gdbarch *gdbarch, CORE_ADDR address)
+      TARGET_DEFAULT_NORETURN (tcomplain ());
+
     /* Return the x86 XSAVE extended state area layout.  */
     virtual x86_xsave_layout fetch_x86_xsave_layout ()
       TARGET_DEFAULT_RETURN (x86_xsave_layout ());
@@ -2317,6 +2321,8 @@ extern bool target_fetch_memtags (CORE_ADDR address, size_t len,
 extern bool target_store_memtags (CORE_ADDR address, size_t len,
 				  const gdb::byte_vector &tags, int type);
 
+extern bool target_is_address_tagged (gdbarch *gdbarch, CORE_ADDR address);
+
 extern x86_xsave_layout target_fetch_x86_xsave_layout ();
 
 /* Command logging facility.  */
-- 
2.34.1