[PATCH v3 02/24] New gdbarch memory tagging hooks

Luis Machado via Gdb-patches
2020-11-09T17:04:56Z

We need some new gdbarch hooks to help us manipulate memory tags without having
to have GDB calls the target methods directly.

This patch adds the following hooks:

gdbarch_memtag_to_string
--
Returns a printable string corresponding to the tag.

gdbarch_tagged_address_p
--
Checks if a particular address is protected with memory tagging.

gdbarch_memtag_mismatch_p
--
Checks if there is a mismatch between the logical tag of a pointer and the
allocation tag.

gdbarch_set_memtags:
--
Sets either the allocation tag or the logical tag for a particular value.

gdbarch_get_memtag:
--
Gets either the allocation tag or the logical tag for a particular value.

gdbarch_granule_size
--
Sets the memory tag granule size, which represents the number of bytes a
particular allocation tag covers. For example, this is 16 bytes for
AArch64's MTE.

I've used struct value as opposed to straight CORE_ADDR so other architectures
can use the infrastructure without having to rely on fixed types.

gdb/ChangeLog:

YYYY-MM-DD Luis Machado <luis.machado@linaro.org>

* arch-utils.c (default_memtag_to_string, +default_tagged_address_p)
(default_memtag_mismatch_p, default_set_memtags)
(default_get_memtag): New functions.
* arch-utils.h (default_memtag_to_string, default_tagged_address_p)
(default_memtag_mismatch_p, default_set_memtags)
(default_get_memtag): New prototypes.
* gdbarch.c: Regenerate.
* gdbarch.h: Regenerate.
* gdbarch.sh (memtag_to_string, tagged_address_p, memtag_mismatch_p)
(set_memtags, get_memtag, memtag_granule_size): New gdbarch hooks.
(enum memtag_type): New enum.
---
gdb/arch-utils.c | 50 +++++++++++++++++
gdb/arch-utils.h | 23 ++++++++
gdb/gdbarch.c | 137 +++++++++++++++++++++++++++++++++++++++++++++++
gdb/gdbarch.h | 53 ++++++++++++++++++
gdb/gdbarch.sh | 36 +++++++++++++
5 files changed, 299 insertions(+)

diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index e50df82091..10064759b2 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -77,6 +77,56 @@ legacy_register_sim_regno (struct gdbarch *gdbarch, int regnum)
return LEGACY_SIM_REGNO_IGNORE;
}

+
+/* See arch-utils.h */
+
+std::string
+default_memtag_to_string (struct gdbarch *gdbarch, struct value *address,
+ enum memtag_type tag_type)
+{
+ /* By default, assume the address is untagged. */
+ return "";
+}
+
+/* See arch-utils.h */
+
+bool
+default_tagged_address_p (struct gdbarch *gdbarch, struct value *address)
+{
+ /* By default, assume the address is untagged. */
+ return false;
+}
+
+/* See arch-utils.h */
+
+bool
+default_memtag_mismatch_p (struct gdbarch *gdbarch, struct value *address)
+{
+ /* By default, assume there is no mismatch. */
+ return false;
+}
+
+/* See arch-utils.h */
+
+int
+default_set_memtags (struct gdbarch *gdbarch, struct value *address,
+ size_t length, const gdb::byte_vector &tags,
+ enum memtag_type tag_type)
+{
+ /* By default, return 0; */
+ return 0;
+}
+
+/* See arch-utils.h */
+
+struct value *
+default_get_memtag (struct gdbarch *gdbarch, struct value *address,
+ enum memtag_type tag_type)
+{
+ /* By default, return no tag. */
+ return NULL;
+}
+
CORE_ADDR
generic_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
{
diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
index 7eea838ac3..375432e9d5 100644
--- a/gdb/arch-utils.h
+++ b/gdb/arch-utils.h
@@ -132,6 +132,29 @@ extern const struct floatformat **
default_floatformat_for_type (struct gdbarch *gdbarch,
const char *name, int len);

+/* Default implementation of gdbarch_tagged_address_p. */
+extern std::string default_memtag_to_string (struct gdbarch *gdbarch,
+ struct value *address,
+ enum memtag_type tag_type);
+
+/* Default implementation of gdbarch_tagged_address_p. */
+bool default_tagged_address_p (struct gdbarch *gdbarch, struct value *address);
+
+/* Default implementation of gdbarch_memtag_mismatch_p. */
+extern bool default_memtag_mismatch_p (struct gdbarch *gdbarch,
+ struct value *address);
+
+/* Default implementation of gdbarch_set_memtags. */
+int default_set_memtags (struct gdbarch *gdbarch,
+ struct value *address, size_t length,
+ const gdb::byte_vector &tags,
+ enum memtag_type tag_type);
+
+/* Default implementation of gdbarch_get_memtag. */
+struct value *default_get_memtag (struct gdbarch *gdbarch,
+ struct value *address,
+ enum memtag_type tag_type);
+
extern CORE_ADDR generic_skip_trampoline_code (struct frame_info *frame,
CORE_ADDR pc);

diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 0b43ae434e..2f1d835428 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -253,6 +253,12 @@ struct gdbarch
gdbarch_convert_from_func_ptr_addr_ftype *convert_from_func_ptr_addr;
gdbarch_addr_bits_remove_ftype *addr_bits_remove;
int significant_addr_bit;
+ gdbarch_memtag_to_string_ftype *memtag_to_string;
+ gdbarch_tagged_address_p_ftype *tagged_address_p;
+ gdbarch_memtag_mismatch_p_ftype *memtag_mismatch_p;
+ gdbarch_set_memtags_ftype *set_memtags;
+ gdbarch_get_memtag_ftype *get_memtag;
+ CORE_ADDR memtag_granule_size;
gdbarch_software_single_step_ftype *software_single_step;
gdbarch_single_step_through_delay_ftype *single_step_through_delay;
gdbarch_print_insn_ftype *print_insn;
@@ -430,6 +436,11 @@ gdbarch_alloc (const struct gdbarch_info *info,
gdbarch->stabs_argument_has_addr = default_stabs_argument_has_addr;
gdbarch->convert_from_func_ptr_addr = convert_from_func_ptr_addr_identity;
gdbarch->addr_bits_remove = core_addr_identity;
+ gdbarch->memtag_to_string = default_memtag_to_string;
+ gdbarch->tagged_address_p = default_tagged_address_p;
+ gdbarch->memtag_mismatch_p = default_memtag_mismatch_p;
+ gdbarch->set_memtags = default_set_memtags;
+ gdbarch->get_memtag = default_get_memtag;
gdbarch->print_insn = default_print_insn;
gdbarch->skip_trampoline_code = generic_skip_trampoline_code;
gdbarch->skip_solib_resolver = generic_skip_solib_resolver;
@@ -623,6 +634,12 @@ verify_gdbarch (struct gdbarch *gdbarch)
/* Skip verify of convert_from_func_ptr_addr, invalid_p == 0 */
/* Skip verify of addr_bits_remove, invalid_p == 0 */
/* Skip verify of significant_addr_bit, invalid_p == 0 */
+ /* Skip verify of memtag_to_string, invalid_p == 0 */
+ /* Skip verify of tagged_address_p, invalid_p == 0 */
+ /* Skip verify of memtag_mismatch_p, invalid_p == 0 */
+ /* Skip verify of set_memtags, invalid_p == 0 */
+ /* Skip verify of get_memtag, invalid_p == 0 */
+ /* Skip verify of memtag_granule_size, invalid_p == 0 */
/* Skip verify of software_single_step, has predicate. */
/* Skip verify of single_step_through_delay, has predicate. */
/* Skip verify of print_insn, invalid_p == 0 */
@@ -1068,6 +1085,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
fprintf_unfiltered (file,
"gdbarch_dump: get_longjmp_target = <%s>\n",
host_address_to_string (gdbarch->get_longjmp_target));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: get_memtag = <%s>\n",
+ host_address_to_string (gdbarch->get_memtag));
fprintf_unfiltered (file,
"gdbarch_dump: get_pc_address_flags = <%s>\n",
host_address_to_string (gdbarch->get_pc_address_flags));
@@ -1197,6 +1217,15 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
fprintf_unfiltered (file,
"gdbarch_dump: memory_remove_breakpoint = <%s>\n",
host_address_to_string (gdbarch->memory_remove_breakpoint));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: memtag_granule_size = %s\n",
+ core_addr_to_string_nz (gdbarch->memtag_granule_size));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: memtag_mismatch_p = <%s>\n",
+ host_address_to_string (gdbarch->memtag_mismatch_p));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: memtag_to_string = <%s>\n",
+ host_address_to_string (gdbarch->memtag_to_string));
fprintf_unfiltered (file,
"gdbarch_dump: num_pseudo_regs = %s\n",
plongest (gdbarch->num_pseudo_regs));
@@ -1350,6 +1379,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
fprintf_unfiltered (file,
"gdbarch_dump: sdb_reg_to_regnum = <%s>\n",
host_address_to_string (gdbarch->sdb_reg_to_regnum));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: set_memtags = <%s>\n",
+ host_address_to_string (gdbarch->set_memtags));
fprintf_unfiltered (file,
"gdbarch_dump: short_bit = %s\n",
plongest (gdbarch->short_bit));
@@ -1458,6 +1490,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
fprintf_unfiltered (file,
"gdbarch_dump: syscalls_info = %s\n",
host_address_to_string (gdbarch->syscalls_info));
+ fprintf_unfiltered (file,
+ "gdbarch_dump: tagged_address_p = <%s>\n",
+ host_address_to_string (gdbarch->tagged_address_p));
fprintf_unfiltered (file,
"gdbarch_dump: target_desc = %s\n",
host_address_to_string (gdbarch->target_desc));
@@ -3263,6 +3298,108 @@ set_gdbarch_significant_addr_bit (struct gdbarch *gdbarch,
gdbarch->significant_addr_bit = significant_addr_bit;
}

+std::string
+gdbarch_memtag_to_string (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type)
+{
+ gdb_assert (gdbarch != NULL);
+ gdb_assert (gdbarch->memtag_to_string != NULL);
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_memtag_to_string called\n");
+ return gdbarch->memtag_to_string (gdbarch, address, tag_type);
+}
+
+void
+set_gdbarch_memtag_to_string (struct gdbarch *gdbarch,
+ gdbarch_memtag_to_string_ftype memtag_to_string)
+{
+ gdbarch->memtag_to_string = memtag_to_string;
+}
+
+bool
+gdbarch_tagged_address_p (struct gdbarch *gdbarch, struct value *address)
+{
+ gdb_assert (gdbarch != NULL);
+ gdb_assert (gdbarch->tagged_address_p != NULL);
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_tagged_address_p called\n");
+ return gdbarch->tagged_address_p (gdbarch, address);
+}
+
+void
+set_gdbarch_tagged_address_p (struct gdbarch *gdbarch,
+ gdbarch_tagged_address_p_ftype tagged_address_p)
+{
+ gdbarch->tagged_address_p = tagged_address_p;
+}
+
+bool
+gdbarch_memtag_mismatch_p (struct gdbarch *gdbarch, struct value *address)
+{
+ gdb_assert (gdbarch != NULL);
+ gdb_assert (gdbarch->memtag_mismatch_p != NULL);
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_memtag_mismatch_p called\n");
+ return gdbarch->memtag_mismatch_p (gdbarch, address);
+}
+
+void
+set_gdbarch_memtag_mismatch_p (struct gdbarch *gdbarch,
+ gdbarch_memtag_mismatch_p_ftype memtag_mismatch_p)
+{
+ gdbarch->memtag_mismatch_p = memtag_mismatch_p;
+}
+
+int
+gdbarch_set_memtags (struct gdbarch *gdbarch, struct value *address, size_t length, const gdb::byte_vector &tags, enum memtag_type tag_type)
+{
+ gdb_assert (gdbarch != NULL);
+ gdb_assert (gdbarch->set_memtags != NULL);
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_set_memtags called\n");
+ return gdbarch->set_memtags (gdbarch, address, length, tags, tag_type);
+}
+
+void
+set_gdbarch_set_memtags (struct gdbarch *gdbarch,
+ gdbarch_set_memtags_ftype set_memtags)
+{
+ gdbarch->set_memtags = set_memtags;
+}
+
+struct value *
+gdbarch_get_memtag (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type)
+{
+ gdb_assert (gdbarch != NULL);
+ gdb_assert (gdbarch->get_memtag != NULL);
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_get_memtag called\n");
+ return gdbarch->get_memtag (gdbarch, address, tag_type);
+}
+
+void
+set_gdbarch_get_memtag (struct gdbarch *gdbarch,
+ gdbarch_get_memtag_ftype get_memtag)
+{
+ gdbarch->get_memtag = get_memtag;
+}
+
+CORE_ADDR
+gdbarch_memtag_granule_size (struct gdbarch *gdbarch)
+{
+ gdb_assert (gdbarch != NULL);
+ /* Skip verify of memtag_granule_size, invalid_p == 0 */
+ if (gdbarch_debug >= 2)
+ fprintf_unfiltered (gdb_stdlog, "gdbarch_memtag_granule_size called\n");
+ return gdbarch->memtag_granule_size;
+}
+
+void
+set_gdbarch_memtag_granule_size (struct gdbarch *gdbarch,
+ CORE_ADDR memtag_granule_size)
+{
+ gdbarch->memtag_granule_size = memtag_granule_size;
+}
+
bool
gdbarch_software_single_step_p (struct gdbarch *gdbarch)
{
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index b620bb25b9..48228b5169 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -115,6 +115,18 @@ enum function_call_return_method
return_method_struct,
};

+enum memtag_type
+{
+ /* Logical tag, the tag that is stored in unused bits of a pointer to a
+ virtual address. */
+ tag_logical = 0,
+
+ /* Allocation tag, the tag that is associated with every granule of memory in
+ the physical address space. Allocation tags are used to validate memory
+ accesses via pointers containing logical tags. */
+ tag_allocation,
+};
+

/* The following are pre-initialized by GDBARCH. */
@@ -710,6 +722,47 @@ extern void set_gdbarch_addr_bits_remove (struct gdbarch *gdbarch, gdbarch_addr_
extern int gdbarch_significant_addr_bit (struct gdbarch *gdbarch);
extern void set_gdbarch_significant_addr_bit (struct gdbarch *gdbarch, int significant_addr_bit);

+/* Return a string representation of the memory tag TYPE of ADDRESS.
+ If no tag is associated with such an address, return the empty string. */
+
+typedef std::string (gdbarch_memtag_to_string_ftype) (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type);
+extern std::string gdbarch_memtag_to_string (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type);
+extern void set_gdbarch_memtag_to_string (struct gdbarch *gdbarch, gdbarch_memtag_to_string_ftype *memtag_to_string);
+
+/* Return true if ADDRESS contains a tag and false otherwise. */
+
+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);
+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 does not match the memory tag for that
+ particular address. Return false otherwise. */
+
+typedef bool (gdbarch_memtag_mismatch_p_ftype) (struct gdbarch *gdbarch, struct value *address);
+extern bool gdbarch_memtag_mismatch_p (struct gdbarch *gdbarch, struct value *address);
+extern void set_gdbarch_memtag_mismatch_p (struct gdbarch *gdbarch, gdbarch_memtag_mismatch_p_ftype *memtag_mismatch_p);
+
+/* Set the tags for the address range [ADDRESS, ADDRESS + LENGTH) to TAGS
+ Return 0 if successful and non-zero otherwise. */
+
+typedef int (gdbarch_set_memtags_ftype) (struct gdbarch *gdbarch, struct value *address, size_t length, const gdb::byte_vector &tags, enum memtag_type tag_type);
+extern int gdbarch_set_memtags (struct gdbarch *gdbarch, struct value *address, size_t length, const gdb::byte_vector &tags, enum memtag_type tag_type);
+extern void set_gdbarch_set_memtags (struct gdbarch *gdbarch, gdbarch_set_memtags_ftype *set_memtags);
+
+/* Return the tag portion of ADDRESS, assuming ADDRESS is tagged. */
+
+typedef struct value * (gdbarch_get_memtag_ftype) (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type);
+extern struct value * gdbarch_get_memtag (struct gdbarch *gdbarch, struct value *address, enum memtag_type tag_type);
+extern void set_gdbarch_get_memtag (struct gdbarch *gdbarch, gdbarch_get_memtag_ftype *get_memtag);
+
+/* memtag_granule_size is the size of the allocation tag granule, for
+ architectures that support memory tagging.
+ This is 0 for architectures that do not support memory tagging.
+ For a non-zero value, this represents the number of bytes of memory per tag. */
+
+extern CORE_ADDR gdbarch_memtag_granule_size (struct gdbarch *gdbarch);
+extern void set_gdbarch_memtag_granule_size (struct gdbarch *gdbarch, CORE_ADDR memtag_granule_size);
+
/* FIXME/cagney/2001-01-18: This should be split in two. A target method that
indicates if the target needs software single step. An ISA method to
implement it.
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index d27318a757..1fd3b0b4da 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -605,6 +605,30 @@ m;CORE_ADDR;addr_bits_remove;CORE_ADDR addr;addr;;core_addr_identity;;0
# additional data associated with the address.
v;int;significant_addr_bit;;;;;;0

+# Return a string representation of the memory tag TYPE of ADDRESS.
+# If no tag is associated with such an address, return the empty string.
++m;std::string;memtag_to_string;struct value *address, enum memtag_type tag_type;address, tag_type;;default_memtag_to_string;;0
+
+# Return true if ADDRESS contains a tag and false otherwise.
++m;bool;tagged_address_p;struct value *address;address;;default_tagged_address_p;;0
+
+# Return true if the tag from ADDRESS does not match the memory tag for that
+# particular address. Return false otherwise.
++m;bool;memtag_mismatch_p;struct value *address;address;;default_memtag_mismatch_p;;0
+
+# Set the tags for the address range [ADDRESS, ADDRESS + LENGTH) to TAGS
+# Return 0 if successful and non-zero otherwise.
++m;int;set_memtags;struct value *address, size_t length, const gdb::byte_vector \&tags, enum memtag_type tag_type;address, length, tags, tag_type;;default_set_memtags;;0
+
+# Return the tag portion of ADDRESS, assuming ADDRESS is tagged.
++m;struct value *;get_memtag;struct value *address, enum memtag_type tag_type;address, tag_type;;default_get_memtag;;0
+
+# memtag_granule_size is the size of the allocation tag granule, for
+# architectures that support memory tagging.
+# This is 0 for architectures that do not support memory tagging.
+# For a non-zero value, this represents the number of bytes of memory per tag.
+v;CORE_ADDR;memtag_granule_size;;;;;;0
+
# FIXME/cagney/2001-01-18: This should be split in two. A target method that
# indicates if the target needs software single step. An ISA method to
# implement it.
@@ -1354,6 +1378,18 @@ enum function_call_return_method
return_method_struct,
};

+enum memtag_type
+{
+ /* Logical tag, the tag that is stored in unused bits of a pointer to a
+ virtual address. */
+ tag_logical = 0,
+
+ /* Allocation tag, the tag that is associated with every granule of memory in
+ the physical address space. Allocation tags are used to validate memory
+ accesses via pointers containing logical tags. */
+ tag_allocation,
+};
+
EOF

# function typedef's
--
2.17.1