ACPICA: Use original data_table_region pointer for accesses

ACPICA commit d9eb82bd7515989f0b29d79deeeb758db4d6529c

Currently the pointer to the table is cast to acpi_physical_address and
later cast back to a pointer to be dereferenced. Whether or not this is
supported is implementation-defined.

On CHERI, and thus Arm's experimental Morello prototype architecture,
pointers are represented as capabilities, which are unforgeable bounded
pointers, providing always-on fine-grained spatial memory safety. This
means that any pointer cast to a plain integer will lose all its
associated metadata, and when cast back to a pointer it will give a
null-derived pointer (one that has the same metadata as null but an
address equal to the integer) that will trap on any dereference. As a
result, this is an implementation where acpi_physical_address cannot be
used as a hack to store real pointers.

Thus, add a new field to struct acpi_object_region to store the pointer for
table regions, and propagate it to acpi_ex_data_table_space_handler via the
region context, to use a more portable implementation that supports
CHERI.

Link: https://github.com/acpica/acpica/commit/d9eb82bd
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/acpi/actypes.h b/include/acpi/actypes.h
index 248242dca28d..700c2449e85a 100644
--- a/include/acpi/actypes.h
+++ b/include/acpi/actypes.h
@@ -1221,6 +1221,10 @@ struct acpi_mem_space_context {
 	struct acpi_mem_mapping *first_mm;
 };
 
+struct acpi_data_table_space_context {
+	void *pointer;
+};
+
 /*
  * struct acpi_memory_list is used only if the ACPICA local cache is enabled
  */