Re: [PATCH v5 01/25] New target methods for memory tagging support

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-01-27 3:20 p.m., Luis Machado via Gdb-patches wrote:
> Updates on v5:
> 
> - Remove the memory_tagging global (in favor of setting a specific print
>   option) and related functions.
> 
> Updates on v4:
> 
> - Updated the return types of fetch/store member functions from int to bool.
> - Implemented target-debug type print helpers.
> - Renamed global memtag to memory_tagging.
> 
> Updates on v3:
> 
> - Updated the code documentation for the fetch_memtags and store_memtags
>   methods.
> 
> Updates on v2:
> 
> - Added type parameter to fetch_memtags/store_memtags hooks.
> 
> --
> 
> This patch starts adding some of the generic pieces to accomodate memory
> tagging.
> 
> We have three new target methods:
> 
> - supports_memory_tagging: Checks if the target supports memory tagging. This
>   defaults to false for targets that don't support memory tagging.
> 
> - fetch_memtags: Fetches the allocation tags associated with a particular
>   memory range [address, address + length).
> 
>   The default is to return 0 without returning any tags. This should only
>   be called if memory tagging is supported.
> 
> - store_memtags: Stores a set of allocation tags for a particular memory
>   range [address, address + length).
> 
>   The default is to return 0. This should only
>   be called if memory tagging is supported.
> 
> gdb/ChangeLog:
> 
> YYYY-MM-DD  Luis Machado  <luis.machado@linaro.org>
> 
> 	* remote.c (remote_target) <supports_memory_tagging>: New method
> 	override.
> 	<fetch_memtags>: New method override.
> 	<store_memtags>: New method override.
> 	(remote_target::supports_memory_tagging): New method.
> 	(remote_target::fetch_memtags): New method.
> 	(remote_target::store_memtags): New method.
> 	* target-delegates.c: Regenerate.
> 	* target.h (struct target_ops) <supports_memory_tagging>: New virtual
> 	method.
> 	<fetch_memtags>: New virtual method.
> 	<store_memtags>: New virtual method.
> 	(target_supports_memory_tagging): Define.
> 	(target_fetch_memtags): Define.
> 	(target_store_memtags): Define.
> 	* target-debug.h (target_debug_print_size_t)
> 	(target_debug_print_const_gdb_byte_vector_r)
> 	(target_debug_print_gdb_byte_vector_r): New functions.
> ---
>  gdb/remote.c           | 34 +++++++++++++++
>  gdb/target-debug.h     | 24 +++++++++++
>  gdb/target-delegates.c | 95 ++++++++++++++++++++++++++++++++++++++++++
>  gdb/target.h           | 41 ++++++++++++++++++
>  4 files changed, 194 insertions(+)
> 
> diff --git a/gdb/remote.c b/gdb/remote.c
> index bc995edc53..b130f1ddae 100644
> --- a/gdb/remote.c
> +++ b/gdb/remote.c
> @@ -690,6 +690,14 @@ class remote_target : public process_stratum_target
>    int remove_exec_catchpoint (int) override;
>    enum exec_direction_kind execution_direction () override;
>  
> +  bool supports_memory_tagging () override;
> +
> +  bool fetch_memtags (CORE_ADDR address, size_t len,
> +		     gdb::byte_vector &tags, int type) override;
> +
> +  bool store_memtags (CORE_ADDR address, size_t len,
> +		     const gdb::byte_vector &tags, int type) override;

The indentation is a bit off here.  Otherwise, LGTM.

Simon