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

Luis Machado via Gdb-patches
2021-01-27T20:21:27Z

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;
+
public: /* Remote specific methods. */

void remote_download_command_source (int num, ULONGEST addr,
@@ -14472,6 +14480,32 @@ show_remote_timeout (struct ui_file *file, int from_tty,
value);
}

+/* Implement the "supports_memory_tagging" target_ops method. */
+
+bool
+remote_target::supports_memory_tagging ()
+{
+ return false;
+}
+
+/* Implement the "fetch_memtags" target_ops method. */
+
+bool
+remote_target::fetch_memtags (CORE_ADDR address, size_t len,
+ gdb::byte_vector &tags, int type)
+{
+ return 0;
+}
+
+/* Implement the "store_memtags" target_ops method. */
+
+bool
+remote_target::store_memtags (CORE_ADDR address, size_t len,
+ const gdb::byte_vector &tags, int type)
+{
+ return 0;
+}
+
void _initialize_remote ();
void
_initialize_remote ()
diff --git a/gdb/target-debug.h b/gdb/target-debug.h
index 6910338865..5bc384a39a 100644
--- a/gdb/target-debug.h
+++ b/gdb/target-debug.h
@@ -212,4 +212,28 @@ target_debug_print_signals (gdb::array_view<const unsigned char> sigs)
fputs_unfiltered (" }", gdb_stdlog);
}

+static void
+target_debug_print_size_t (size_t size)
+{
+ fprintf_unfiltered (gdb_stdlog, "%s", pulongest (size));
+}
+
+static void
+target_debug_print_const_gdb_byte_vector_r (const gdb::byte_vector &vector)
+{
+ fputs_unfiltered ("{", gdb_stdlog);
+
+ for (size_t i = 0; i < vector.size (); i++)
+ {
+ fprintf_unfiltered (gdb_stdlog, " %s",
+ phex_nz (vector[i], 1));
+ }
+ fputs_unfiltered (" }", gdb_stdlog);
+}
+
+static void
+target_debug_print_gdb_byte_vector_r (gdb::byte_vector &vector)
+{
+ target_debug_print_gdb_byte_vector_r (vector);
+}
#endif /* TARGET_DEBUG_H */
diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
index 437b19b858..e4563e4dac 100644
--- a/gdb/target-delegates.c
+++ b/gdb/target-delegates.c
@@ -173,6 +173,9 @@ struct dummy_target : public target_ops
const struct frame_unwind *get_tailcall_unwinder () override;
void prepare_to_generate_core () override;
void done_generating_core () override;
+ 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;
};

struct debug_target : public target_ops
@@ -344,6 +347,9 @@ struct debug_target : public target_ops
const struct frame_unwind *get_tailcall_unwinder () override;
void prepare_to_generate_core () override;
void done_generating_core () override;
+ 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;
};

void
@@ -4413,3 +4419,92 @@ debug_target::done_generating_core ()
fputs_unfiltered (")\n", gdb_stdlog);
}

+bool
+target_ops::supports_memory_tagging ()
+{
+ return this->beneath ()->supports_memory_tagging ();
+}
+
+bool
+dummy_target::supports_memory_tagging ()
+{
+ return false;
+}
+
+bool
+debug_target::supports_memory_tagging ()
+{
+ bool result;
+ fprintf_unfiltered (gdb_stdlog, "-> %s->supports_memory_tagging (...)\n", this->beneath ()->shortname ());
+ result = this->beneath ()->supports_memory_tagging ();
+ fprintf_unfiltered (gdb_stdlog, "<- %s->supports_memory_tagging (", this->beneath ()->shortname ());
+ fputs_unfiltered (") = ", gdb_stdlog);
+ target_debug_print_bool (result);
+ fputs_unfiltered ("\n", gdb_stdlog);
+ return result;
+}
+
+bool
+target_ops::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+ return this->beneath ()->fetch_memtags (arg0, arg1, arg2, arg3);
+}
+
+bool
+dummy_target::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+ tcomplain ();
+}
+
+bool
+debug_target::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+ bool result;
+ fprintf_unfiltered (gdb_stdlog, "-> %s->fetch_memtags (...)\n", this->beneath ()->shortname ());
+ result = this->beneath ()->fetch_memtags (arg0, arg1, arg2, arg3);
+ fprintf_unfiltered (gdb_stdlog, "<- %s->fetch_memtags (", this->beneath ()->shortname ());
+ target_debug_print_CORE_ADDR (arg0);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_size_t (arg1);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_gdb_byte_vector_r (arg2);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_int (arg3);
+ fputs_unfiltered (") = ", gdb_stdlog);
+ target_debug_print_bool (result);
+ fputs_unfiltered ("\n", gdb_stdlog);
+ return result;
+}
+
+bool
+target_ops::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+ return this->beneath ()->store_memtags (arg0, arg1, arg2, arg3);
+}
+
+bool
+dummy_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+ tcomplain ();
+}
+
+bool
+debug_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+ bool result;
+ fprintf_unfiltered (gdb_stdlog, "-> %s->store_memtags (...)\n", this->beneath ()->shortname ());
+ result = this->beneath ()->store_memtags (arg0, arg1, arg2, arg3);
+ fprintf_unfiltered (gdb_stdlog, "<- %s->store_memtags (", this->beneath ()->shortname ());
+ target_debug_print_CORE_ADDR (arg0);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_size_t (arg1);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_const_gdb_byte_vector_r (arg2);
+ fputs_unfiltered (", ", gdb_stdlog);
+ target_debug_print_int (arg3);
+ fputs_unfiltered (") = ", gdb_stdlog);
+ target_debug_print_bool (result);
+ fputs_unfiltered ("\n", gdb_stdlog);
+ return result;
+}
+
diff --git a/gdb/target.h b/gdb/target.h
index 917476d16a..19395f1258 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1260,6 +1260,38 @@ struct target_ops
/* Cleanup after generating a core file. */
virtual void done_generating_core ()
TARGET_DEFAULT_IGNORE ();
+
+ /* Returns true if the target supports memory tagging, false otherwise. */
+ virtual bool supports_memory_tagging ()
+ TARGET_DEFAULT_RETURN (false);
+
+ /* Return the allocated memory tags of type TYPE associated with
+ [ADDRESS, ADDRESS + LEN) in TAGS.
+
+ LEN is the number of bytes in the memory range. TAGS is a vector of
+ bytes containing the tags found in the above memory range.
+
+ It is up to the architecture/target to interpret the bytes in the TAGS
+ vector and read the tags appropriately.
+
+ Returns true if fetching the tags succeeded and false otherwise. */
+ virtual bool fetch_memtags (CORE_ADDR address, size_t len,
+ gdb::byte_vector &tags, int type)
+ TARGET_DEFAULT_NORETURN (tcomplain ());
+
+ /* Write the allocation tags of type TYPE contained in TAGS to the memory
+ range [ADDRESS, ADDRESS + LEN).
+
+ LEN is the number of bytes in the memory range. TAGS is a vector of
+ bytes containing the tags to be stored to the memory range.
+
+ It is up to the architecture/target to interpret the bytes in the TAGS
+ vector and store them appropriately.
+
+ Returns true if storing the tags succeeded and false otherwise. */
+ virtual bool store_memtags (CORE_ADDR address, size_t len,
+ const gdb::byte_vector &tags, int type)
+ TARGET_DEFAULT_NORETURN (tcomplain ());
};

/* Deleter for std::unique_ptr. See comments in
@@ -2312,6 +2344,15 @@ extern gdb::unique_xmalloc_ptr<char> target_fileio_read_stralloc
#define target_augmented_libraries_svr4_read() \
(current_top_target ()->augmented_libraries_svr4_read) ()

+#define target_supports_memory_tagging() \
+ ((current_top_target ()->supports_memory_tagging) ())
+
+#define target_fetch_memtags(address, len, tags, type) \
+ (current_top_target ()->fetch_memtags) ((address), (len), (tags), (type))
+
+#define target_store_memtags(address, len, tags, type) \
+ (current_top_target ()->store_memtags) ((address), (len), (tags), (type))
+
/* Command logging facility. */

#define target_log_command(p) \
--
2.25.1