linker: Re-implement {APP,KERNEL}_INPUT_SECTION

This rewrites the implementation of the APP_INPUT_SECTION and
KERNEL_INPUT_SECTION macros such that an unbounded amount of
kernelspace libraries can be used.

This resolves #7703

The new implementation has a caveat/limitation; the linker script
developer must invoke APP_INPUT_SECTION before KERNEL_INPUT_SECTION.

All in-tree linker scripts happened to already be doing this so no
in-tree porting was necessary.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>

CMakeLists.txt

@@ -618,15 +618,14 @@ if(CONFIG_APPLICATION_MEMORY)
     list(APPEND ks ${fixed_path})
   endforeach()
 
-  # We are done constructing kernel_object_file_list, now we inject this
-  # information into the linker script through -D's
-  list(LENGTH kernel_object_file_list NUM_KERNEL_OBJECT_FILES)
-  list(APPEND LINKER_SCRIPT_DEFINES -DNUM_KERNEL_OBJECT_FILES=${NUM_KERNEL_OBJECT_FILES})
-  set(i 0)
+  # We are done constructing kernel_object_file_list, now we inject
+  # this list into the linker script through the define
+  # KERNELSPACE_OBJECT_FILES
+  set(def -DKERNELSPACE_OBJECT_FILES=)
   foreach(f ${ks})
-    list(APPEND LINKER_SCRIPT_DEFINES -DKERNEL_OBJECT_FILE_${i}=${f})
-    math(EXPR i "${i}+1")
+    set(def "${def} ${f}")
   endforeach()
+  list(APPEND LINKER_SCRIPT_DEFINES ${def})
 endif() # CONFIG_APPLICATION_MEMORY
 
 # Declare MPU userspace dependencies before the linker scripts to make

include/linker/linker-defs.h

@@ -112,34 +112,27 @@
  * their shell commands are automatically initialized by the kernel.
  */
 
+#ifdef CONFIG_APPLICATION_MEMORY
+/*
+ * KERNELSPACE_OBJECT_FILES is a space-separated list of object files
+ * and libraries that belong in kernelspace.
+ */
+#define MAYBE_EXCLUDE_SOME_FILES EXCLUDE_FILE (KERNELSPACE_OBJECT_FILES)
+#else
+#define MAYBE_EXCLUDE_SOME_FILES
+#endif /* CONFIG_APPLICATION_MEMORY */
+
 /*
  * APP_INPUT_SECTION should be invoked on sections that should be in
  * 'app' space. KERNEL_INPUT_SECTION should be invoked on sections
  * that should be in 'kernel' space.
+ *
+ * NB: APP_INPUT_SECTION must be invoked before
+ * KERNEL_INPUT_SECTION. If it is not all sections will end up in
+ * kernelspace.
  */
-#ifdef CONFIG_APPLICATION_MEMORY
-
-#ifndef NUM_KERNEL_OBJECT_FILES
-#error "Expected NUM_KERNEL_OBJECT_FILES to be defined"
-#elif NUM_KERNEL_OBJECT_FILES > 32
-#error "Max supported kernel objects is 32."
-/* TODO: Using the preprocessor to do this was a mistake. Rewrite to
-   scale better. e.g. by aggregating the kernel objects into two
-   archives like KBuild did.*/
-#endif
-
-#define X(i, j) KERNEL_OBJECT_FILE_##i (j)
-#define Y(i, j) KERNEL_OBJECT_FILE_##i
-
-#define KERNEL_INPUT_SECTION(sect) \
-    UTIL_LISTIFY(NUM_KERNEL_OBJECT_FILES, X, sect)
-#define APP_INPUT_SECTION(sect)	\
-    *(EXCLUDE_FILE (UTIL_LISTIFY(NUM_KERNEL_OBJECT_FILES, Y, ~)) sect)
-
-#else
-#define KERNEL_INPUT_SECTION(sect)	*(sect)
-#define APP_INPUT_SECTION(sect)		*(sect)
-#endif /* CONFIG_APPLICATION_MEMORY */
+#define APP_INPUT_SECTION(sect)    *(MAYBE_EXCLUDE_SOME_FILES sect)
+#define KERNEL_INPUT_SECTION(sect) *(sect)
 
 #define APP_SMEM_SECTION() KEEP(*(SORT(data_smem_[_a-zA-Z0-9]*)))