Add ISA test

sdk/include/cheri.hh

@@ -299,6 +299,95 @@ namespace CHERI
 			return this->contains(p) && this->contains(ps...);
 		}
 
+		/**
+		 * Returns a new PermissionSet with the maximum permissions
+		 * representable in the format that the hardware would use if asked to
+		 * represent this PermissionSet. If `this` is representable it will
+		 * return a superset but otherwise there is not necessarily any
+		 * intersection!
+		 */
+		[[nodiscard]] constexpr PermissionSet get_max_format_perms() const
+		{
+			if (this->contains(Permission::Execute,
+			                   Permission::Load,
+			                   Permission::LoadStoreCapability))
+			{
+				// Executable format
+				return PermissionSet{Permission::Global,
+				                     Permission::Execute,
+				                     Permission::Load,
+				                     Permission::LoadStoreCapability,
+				                     Permission::LoadGlobal,
+				                     Permission::LoadMutable,
+				                     Permission::AccessSystemRegisters};
+			}
+			if (this->contains(Permission::Load,
+			                   Permission::Store,
+			                   Permission::LoadStoreCapability))
+			{
+				// cap-rw format
+				return PermissionSet{Permission::Global,
+				                     Permission::Load,
+				                     Permission::Store,
+				                     Permission::LoadStoreCapability,
+				                     Permission::LoadGlobal,
+				                     Permission::LoadMutable,
+				                     Permission::StoreLocal};
+			}
+			if (this->contains(Permission::Load,
+			                   Permission::LoadStoreCapability))
+			{
+				// cap-ro format
+				return PermissionSet{Permission::Global,
+				                     Permission::Load,
+				                     Permission::LoadStoreCapability,
+				                     Permission::LoadGlobal,
+				                     Permission::LoadMutable};
+			}
+			if (this->contains(Permission::Store,
+			                   Permission::LoadStoreCapability))
+			{
+				// cap-wo format
+				return PermissionSet{Permission::Global,
+				                     Permission::Store,
+				                     Permission::LoadStoreCapability};
+			}
+			if (this->contains(Permission::Store) ||
+			    this->contains(Permission::Load))
+			{
+				// data-rw format
+				return PermissionSet{
+				  Permission::Global, Permission::Load, Permission::Store};
+			}
+			// sealing format
+			return PermissionSet{Permission::Global,
+			                     Permission::Seal,
+			                     Permission::Unseal,
+			                     Permission::User0};
+		}
+
+		/**
+		 * Returns a new PermissionSet that is the set of permissions that the
+		 * hardware would return if asked to encode this PermissionSet by
+		 * CAndPerms.
+		 *
+		 * The returned PermissionSet will always be a (possibly empty) subset
+		 * of `this`.
+		 */
+		[[nodiscard]] constexpr PermissionSet to_representable() const
+		{
+			return this->get_max_format_perms() & (*this);
+		}
+
+		/**
+		 * Returns whether this PermissionSet is exactly representable in the
+		 * hardware encodings.
+		 */
+		[[nodiscard]] constexpr bool is_representable() const
+		{
+			return (*this) == this->to_representable();
+		}
+
 		/**
 		 * Returns the raw permission mask as an integer containing a bitfield
 		 * of permissions.
@@ -689,6 +778,10 @@ namespace CHERI
 			 */
 			__always_inline BoundsProxy &set_inexact_at_most(size_t bounds)
 			{
+#if __has_builtin(__builtin_cheri_bounds_set_round_down)
+				set(__builtin_cheri_bounds_set_round_down(ptr(), bounds));
+				return *this;
+#else
 				// Just try to set the requested bounds, first.  If that works,
 				// there's no need for bit-twiddling at all.
 				Capability p = ptr();
@@ -700,6 +793,7 @@ namespace CHERI
 				}
 
 				return set_inexact_at_most_slow(bounds);
+#endif
 			}
 		};
 
@@ -958,6 +1052,14 @@ namespace CHERI
 			return false;
 		}
 
+		/**
+		 * Clears the tag bit indicating whether this is a valid capability.
+		 */
+		void invalidate()
+		{
+			ptr = __builtin_cheri_tag_clear(ptr);
+		}
+
 		/**
 		 * Returns the tag bit indicating whether this is a valid
 		 * capability.

sdk/include/debug.hh

@@ -438,8 +438,7 @@ struct DebugFormatArgumentAdaptor<CHERI::Capability<T, Sealed>>
 	__always_inline static DebugFormatArgument
 	construct(CHERI::Capability<T, Sealed> value)
 	{
-		return {reinterpret_cast<uintptr_t>(
-		          static_cast<const volatile void *>(value)),
+		return {reinterpret_cast<uintptr_t>(value.get()),
 		        DebugFormatArgumentKind::DebugFormatArgumentPointer};
 	}
 };