tests/Makefile.inc: Add function wrapping mechanism

This patch extends mocks functionality to allowing wrapping of mocked
functions. Original function name will be prefixed with `__real_`.
Example:
- Mocked function: cbfs_lookup()
- New function name: __real_cbfs_lookup()
- Mock name: cbfs_lookup()

Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Change-Id: I7cd0d66a17029955cbf75c8b155a7ebb7f5513aa
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56719
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

tests/Makefile.inc

@@ -18,6 +18,7 @@ CMOCKA_LIB := $(cmockaobj)/src/libcmocka.so
 
 CMAKE:= cmake
 OBJCOPY?= objcopy
+OBJDUMP?= objdump
 
 TEST_DEFAULT_CONFIG = $(top)/configs/config.emulation_qemu_x86_i440fx
 TEST_DOTCONFIG = $(testobj)/.config
@@ -115,12 +116,28 @@ $$($(1)-config-file): $(TEST_KCONFIG_AUTOHEADER)
 
 $($(1)-objs): TEST_CFLAGS += -I$$(dir $$($(1)-config-file)) \
 	-D__$$(shell echo $$($(1)-stage) | tr '[:lower:]' '[:upper:]')__
+
+# Weaken symbols listed as mocks to enable overriding in the code
 $($(1)-srcobjs): OBJCOPY_FLAGS += $$(foreach mock,$$($(1)-mocks),--globalize-symbol=$$(mock) --weaken-symbol=$$(mock))
+
+# Compile sources and apply mocking/wrapping of selected symbols.
+# For each listed mock add new symbol with prefix `__real_`,
+# and pointing to the same section:address.
 $($(1)-objs): $(testobj)/$(1)/%.o: $$$$*.c $$($(1)-config-file)
 	mkdir -p $$(dir $$@)
 	$(HOSTCC) $(HOSTCFLAGS) $$(TEST_CFLAGS) $($(1)-cflags) -MMD \
 		-MF $$(basename $$@).d -MT $$@ -c $$< -o $$@.orig
-	$(OBJCOPY) $$@.orig $$(OBJCOPY_FLAGS) $$@
+	$(OBJCOPY) $$@.orig $$(OBJCOPY_FLAGS) $$@.orig2
+	objcopy_wrap_flags=''; \
+	for sym in $$($(1)-mocks); do \
+		sym_line="$$$$($(OBJDUMP) -t $$@.orig2 | grep -E "[0-9a-fA-F]+\\s+w\\s+F\\s+.*\\s$$$$sym$$$$")"; \
+		if [ ! -z "$$$$sym_line" ] ; then \
+			addr="$$$$(echo \"$$$$sym_line\" | awk '{ print $$$$1 }')"; \
+			section="$$$$(echo \"$$$$sym_line\" | awk '{ print $$$$(NF - 2) }')"; \
+			objcopy_wrap_flags="$$$$objcopy_wrap_flags --add-symbol __real_$$$${sym}=$$$${section}:0x$$$${addr},function,global"; \
+		fi \
+	done ; \
+	$(OBJCOPY) $$@.orig2 $$$$objcopy_wrap_flags $$@
 
 $($(1)-bin): $($(1)-objs) $(CMOCKA_LIB)
 	$(HOSTCC) $$^ $($(1)-cflags) $$(TEST_LDFLAGS) -o $$@