From 193b2822035263a2c4bb5118a470fc1d0281eb84 Mon Sep 17 00:00:00 2001 From: Luis Machado Date: Fri, 19 Jun 2020 17:31:23 -0300 Subject: New target methods for memory tagging support 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 1 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 1, which indicates an error. This should only be called if memory tagging is supported. It also adds a control option for enabling/disabling memory tagging manually: set memory-tagging on/off. The default is "on", with GDB making its use conditional to the architecture supporting memory tagging. gdb/ChangeLog: YYYY-MM-DD Luis Machado * printcmd.c (memtag): New static global. (show_memtag): New function. (_initialize_printcmd): Add set/show memory-tagging command. * remote.c (remote_target) : New method override. : New method override. : 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 (dummy_target) : New method override. : New method override. : New method override. (debug_target) : New method override. : New method override. : New method override. (target_ops::supports_memory_tagging): New method. (target_ops::fetch_memtags): New method. (target_ops::store_memtags): New method. (dummy_target::supports_memory_tagging): New method. (dummy_target::fetch_memtags): New method. (dummy_target::store_memtags): New method. (debug_target::supports_memory_tagging): New method. (debug_target::fetch_memtags): New method. (debug_target::store_memtags): New method. * target.h (struct target_ops) : New virtual method. : New virtual method. (target_supports_memory_tagging): Define. (target_fetch_memtags): Define. (target_store_memtags): Define. --- gdb/printcmd.c | 28 +++++++++++++++++ gdb/remote.c | 36 ++++++++++++++++++++++ gdb/target-delegates.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++ gdb/target.h | 25 +++++++++++++++ 4 files changed, 173 insertions(+) diff --git a/gdb/printcmd.c b/gdb/printcmd.c index 388a0b2..a422e0c 100644 --- a/gdb/printcmd.c +++ b/gdb/printcmd.c @@ -84,6 +84,24 @@ static CORE_ADDR last_examine_address; static value_ref_ptr last_examine_value; +/* If TRUE (default), and the architecture supports it, GDB will attempt to use + the memory tagging infrastructure to validate certain memory accesses. It + will also report memory tag violations alongside a SIGSEGV signal. + + If FALSE, GDB will not use memory tagging in any way, and debugging will work + in the standard way. */ +static bool memtag = true; + +static void +show_memtag (struct ui_file *file, int from_tty, + struct cmd_list_element *c, + const char *value) +{ + fprintf_filtered (file, + _("Use of memory tagging infrastructure is \"%s\".\n"), + value); +} + /* Largest offset between a symbolic value and an address, that will be printed as `0x1234 '. */ @@ -2883,4 +2901,14 @@ Construct a GDB command and then evaluate it.\n\ Usage: eval \"format string\", ARG1, ARG2, ARG3, ..., ARGN\n\ Convert the arguments to a string as \"printf\" would, but then\n\ treat this string as a command line, and evaluate it.")); + + add_setshow_boolean_cmd ("memory-tagging", class_support, + &memtag, _("\ +Set whether the debugger should use memory tagging infrastructure."), _("\ +Show whether the debugger should use memory tagging infrastructure."), _("\ +If on, gdb will attempt to validate memory tags and will warn the user if\n\ +certain operations have illegal tags."), + NULL, + show_memtag, + &setlist, &showlist); } diff --git a/gdb/remote.c b/gdb/remote.c index d560c69..de594ec 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -685,6 +685,16 @@ public: int remove_exec_catchpoint (int) override; enum exec_direction_kind execution_direction () override; + bool supports_memory_tagging () override; + + /* Read memory tags via the qMemTags packet */ + int fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) override; + + /* Write allocation tags via the QMemTags packet. */ + int store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) override; + public: /* Remote specific methods. */ void remote_download_command_source (int num, ULONGEST addr, @@ -14366,6 +14376,32 @@ set_range_stepping (const char *ignore_args, int from_tty, } } +/* Implement the "supports_memory_tagging" target_ops method. */ + +bool +remote_target::supports_memory_tagging () +{ + return false; +} + +/* Implement the "fetch_memtags" target_ops method. */ + +int +remote_target::fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) +{ + return 0; +} + +/* Implement the "store_memtags" target_ops method. */ + +int +remote_target::store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) +{ + return 0; +} + void _initialize_remote (); void _initialize_remote () diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c index c28af09..2fa945f 100644 --- a/gdb/target-delegates.c +++ b/gdb/target-delegates.c @@ -171,6 +171,11 @@ 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; + int fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) override; + int store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) override; }; struct debug_target : public target_ops @@ -340,6 +345,11 @@ 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; + int fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) override; + int store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) override; }; void @@ -4363,3 +4373,77 @@ debug_target::done_generating_core () fputs_unfiltered (")\n", gdb_stdlog); } +bool +target_ops::supports_memory_tagging () +{ + return this->beneath ()->supports_memory_tagging (); +} + +int +target_ops::fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) +{ + return this->beneath ()->fetch_memtags (address, len, tags); +} + +int +target_ops::store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) +{ + return this->beneath ()->store_memtags (address, len, tags); +} + +bool +dummy_target::supports_memory_tagging () +{ + return false; +} + +int +dummy_target::fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) +{ + return 0; +} + +int +dummy_target::store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) +{ + return 0; +} + +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; +} + +int +debug_target::fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) +{ + fprintf_unfiltered (gdb_stdlog, "-> %s->fetch_memtags (...)\n", this->beneath ()->shortname ()); + int result = this->beneath ()->fetch_memtags (address, len, tags); + fprintf_unfiltered (gdb_stdlog, "<- %s->fetch_memtags (", this->beneath ()->shortname ()); + fputs_unfiltered (")\n", gdb_stdlog); + return result; +} + +int +debug_target::store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) +{ + fprintf_unfiltered (gdb_stdlog, "-> %s->store_memtags (...)\n", this->beneath ()->shortname ()); + int result = this->beneath ()->store_memtags (address, len, tags); + fprintf_unfiltered (gdb_stdlog, "<- %s->store_memtags (", this->beneath ()->shortname ()); + fputs_unfiltered (")\n", gdb_stdlog); + return result; +} diff --git a/gdb/target.h b/gdb/target.h index 4e8d4cc..df2c7ca 100644 --- a/gdb/target.h +++ b/gdb/target.h @@ -1252,6 +1252,22 @@ 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. */ + virtual bool supports_memory_tagging () + TARGET_DEFAULT_RETURN (false); + + /* Return the allocated memory tags associated with + [ADDRESS, ADDRESS + LEN) in TAGS. */ + virtual int fetch_memtags (CORE_ADDR address, size_t len, + gdb::byte_vector &tags) + TARGET_DEFAULT_IGNORE (); + + /* Write the allocation tags contained in TAGS to the memory range + [ADDRESS, ADDRESS + LEN). */ + virtual int store_memtags (CORE_ADDR address, size_t len, + const gdb::byte_vector &tags) + TARGET_DEFAULT_IGNORE (); }; /* Deleter for std::unique_ptr. See comments in @@ -2308,6 +2324,15 @@ extern gdb::unique_xmalloc_ptr 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) \ + (current_top_target ()->fetch_memtags) ((address), (len), (tags)) + +#define target_store_memtags(address, len, tags) \ + (current_top_target ()->store_memtags) ((address), (len), (tags)) + /* Command logging facility. */ #define target_log_command(p) \ -- cgit v1.1