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

  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(-)
  

On 4/16/24 15:07, Gustavo Romero wrote:
> 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))


You can use arch instead of current_inferior ()->arch () since we already have
a local variable that saved this information.

> +    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.  */

Otherwise LGTM.

Approved-By: Luis Machado <luis.machado@arm.com>
Tested-By: Luis Machado <luis.machado@arm.com>