[Minios-devel] [UNIKRAFT PATCH RFC 3/5] build: Link image for 3 times if backtrace is needed

[Jia He <justin.he@xxxxxxx>]

Changes the linker stages by 3 times linking unikraft image
if backtrace is needed.
1.1st linking: It is to generate the original image
2.2nd linking: Use nm and allsymbol tool to generate all the symbol
  names symbol.S in step 1; Compile and link symbol.o into image2
3.3rd linking: Use nm and allsymbol tool again. It is to avoid text
segment relocation after adding the symbol.o

Signed-off-by: Jia He <justin.he@xxxxxxx>
---
 plat/kvm/Linker.uk | 71 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 70 insertions(+), 1 deletion(-)

diff --git a/plat/kvm/Linker.uk b/plat/kvm/Linker.uk
index 5e42193..610b995 100644
--- a/plat/kvm/Linker.uk
+++ b/plat/kvm/Linker.uk
@@ -4,7 +4,24 @@ else ifeq (arm64,$(CONFIG_UK_ARCH))
 KVM_LDFLAGS-y   += -Wl,-m,aarch64elf
 endif
 
+# allsyms tool settings
+ALLSYMS_TOOL         := $(BUILD_DIR)/allsyms2assembly
+ALLSYMS_TOOL_SRC     := $(CONFIG_UK_BASE)/support/kallsyms/kallsyms.c
 
+ifeq ($(CONFIG_DEBUG_BACK_TRACE),y)
+#todo change to build
+SYMBOL_SRC       := $(BUILD_DIR)/symbol.S
+SYMBOL_OBJ       := $(call src2obj,libkvmplat,$(SYMBOL_SRC))
+endif
+
+$(ALLSYMS_TOOL):$(ALLSYMS_TOOL_SRC)
+ifeq ($(CONFIG_DEBUG_BACK_TRACE),y)
+       $(HOSTCC) $(HOST_EXTRACFLAGS) $(HOSTCFLAGS) $< -o $(ALLSYMS_TOOL)
+endif
+
+allsyms:$(ALLSYMS_TOOL)
+
+.PHONY: allsyms
 ##
 ## Link image
 ##
@@ -17,7 +34,7 @@ KVM_LD_SCRIPT_FLAGS += $(addprefix -Wl$(comma)-T$(comma),\
                        $(KVM_LD_SCRIPT-y) $(EXTRA_LD_SCRIPT-y))
 
 $(KVM_DEBUG_IMAGE): $(KVM_ALIBS) $(KVM_ALIBS-y) $(KVM_OLIBS) $(KVM_OLIBS-y) \
-                   $(UK_ALIBS) $(UK_ALIBS-y) $(UK_OLIBS) $(UK_OLIBS-y)
+                   $(UK_ALIBS) $(UK_ALIBS-y) $(UK_OLIBS) $(UK_OLIBS-y) allsyms
        $(call build_cmd,LD,,$(KVM_IMAGE).ld.o,\
               $(LD) -r $(LIBLDFLAGS) $(LIBLDFLAGS-y) \
                        $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
@@ -36,6 +53,55 @@ $(KVM_DEBUG_IMAGE): $(KVM_ALIBS) $(KVM_ALIBS-y) $(KVM_OLIBS) 
$(KVM_OLIBS-y) \
                     $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
                     $(KVM_LD_SCRIPT_FLAGS) \
                     $(KVM_IMAGE).o -o $@)
+# If dumping backtrace is supported, we should link the image 3 times after
+# getting the symbol name assembly src file.
+ifeq ($(CONFIG_DEBUG_BACK_TRACE),y)
+# 2nd time link
+       $(NM) -n $@ | $(ALLSYMS_TOOL) > $(SYMBOL_SRC)
+       $(HOSTCC) -I$(CONFIG_UK_BASE)/include $(HOST_EXTRACFLAGS) $(HOSTCFLAGS) 
-c $(SYMBOL_SRC) -o $(SYMBOL_OBJ)
+       $(call build_cmd,LD,,$(KVM_IMAGE).ld.2.o,\
+              $(LD) -r $(LIBLDFLAGS) $(LIBLDFLAGS-y) \
+                       $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
+                       $(KVM_OLIBS) $(KVM_OLIBS-y) \
+                       $(UK_OLIBS) $(UK_OLIBS-y) \
+                       -Wl$(comma)--start-group \
+                       $(KVM_ALIBS) $(KVM_ALIBS-y) \
+                       $(UK_ALIBS) $(UK_ALIBS-y) \
+                       $(SYMBOL_OBJ) \
+                       -Wl$(comma)--end-group \
+                       -o $(KVM_IMAGE).ld.2.o)
+       $(call build_cmd,OBJCOPY,,$(KVM_IMAGE).2.o,\
+               $(OBJCOPY) -w -G kvmos_* -G _libkvmplat_entry \
+                       $(KVM_IMAGE).ld.2.o $(KVM_IMAGE).2.o)
+       $(call build_cmd,LD,,$@,\
+              $(LD) $(LDFLAGS) $(LDFLAGS-y) \
+                    $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
+                    $(KVM_LD_SCRIPT_FLAGS) \
+                    $(KVM_IMAGE).2.o -o $@)
+# 3rd time
+       $(NM) -n $@ | $(ALLSYMS_TOOL) > $(SYMBOL_SRC)
+       rm -f $(SYMBOL_OBJ)
+       $(HOSTCC) -I$(CONFIG_UK_BASE)/include $(HOST_EXTRACFLAGS) $(HOSTCFLAGS) 
-c $(SYMBOL_SRC) -o $(SYMBOL_OBJ)
+       $(call build_cmd,LD,,$(KVM_IMAGE).ld.3.o,\
+              $(LD) -r $(LIBLDFLAGS) $(LIBLDFLAGS-y) \
+                       $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
+                       $(KVM_OLIBS) $(KVM_OLIBS-y) \
+                       $(UK_OLIBS) $(UK_OLIBS-y) \
+                       -Wl$(comma)--start-group \
+                       $(KVM_ALIBS) $(KVM_ALIBS-y) \
+                       $(UK_ALIBS) $(UK_ALIBS-y) \
+                       $(SYMBOL_OBJ) \
+                       -Wl$(comma)--end-group \
+                       -o $(KVM_IMAGE).ld.3.o)
+       $(call build_cmd,OBJCOPY,,$(KVM_IMAGE).3.o,\
+               $(OBJCOPY) -w -G kvmos_* -G _libkvmplat_entry \
+                       $(KVM_IMAGE).ld.3.o $(KVM_IMAGE).3.o)
+       $(call build_cmd,LD,,$@,\
+              $(LD) $(LDFLAGS) $(LDFLAGS-y) \
+                    $(KVM_LDFLAGS) $(KVM_LDFLAGS-y) \
+                    $(KVM_LD_SCRIPT_FLAGS) \
+                    $(KVM_IMAGE).3.o -o $@)
+endif
 
 $(KVM_IMAGE): $(KVM_IMAGE).dbg
        $(call build_cmd,SCSTRIP,,$@,\
@@ -62,3 +128,6 @@ endif
 # ...for cleaning:
 LIBKVMPLAT_CLEAN += $(call build_clean,$(KVM_IMAGE).o)
 LIBKVMPLAT_CLEAN += $(call build_clean,$(KVM_IMAGE).ld.o)
+LIBKVMPLAT_CLEAN += $(call build_clean,$(KVM_IMAGE).*.o)
+LIBKVMPLAT_CLEAN += $(call build_clean,$(SYMBOL_OBJ))
+LIBKVMPLAT_CLEAN += $(call build_clean,$(SYMBOL_SRC))
-- 
2.17.1


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