Add a method to leave the symbol table in a library.

When LOCAL_STRIP_MODULE := keep_symbols is set, then the normal strip rules
will be modified so that only the .debug_* sections are removed. The original
symbol table is left alone.

This allows the compilation of certain libraries so that libbacktrace library
can provide meaningful names to functions.

Bug: 12958251
Change-Id: I82bdc304a463012e29086325ccb51163464cb4a9

9 files changed, 52 insertions, 38 deletions

diff --git a/core/combo/TARGET_linux-arm.mk b/core/combo/TARGET_linux-arm.mk
index 213cae2..c2e4679 100644
--- a/core/combo/TARGET_linux-arm.mk
+++ b/core/combo/TARGET_linux-arm.mk
@@ -58,13 +58,9 @@ $(combo_2nd_arch_prefix)TARGET_CXX := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PRE
 $(combo_2nd_arch_prefix)TARGET_AR := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_OBJCOPY := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_LD := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+$(combo_2nd_arch_prefix)TARGET_READELF := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_STRIP := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-ifeq ($(TARGET_BUILD_VARIANT),user)
-    $(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@
-else
-    $(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ && \
-        $(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 $(combo_2nd_arch_prefix)TARGET_NO_UNDEFINED_LDFLAGS := -Wl,--no-undefined
 
diff --git a/core/combo/TARGET_linux-arm64.mk b/core/combo/TARGET_linux-arm64.mk
index f130311..c04f2ca 100644
--- a/core/combo/TARGET_linux-arm64.mk
+++ b/core/combo/TARGET_linux-arm64.mk
@@ -60,13 +60,9 @@ TARGET_CXX := $(TARGET_TOOLS_PREFIX)g++$(HOST_EXECUTABLE_SUFFIX)
 TARGET_AR := $(TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 TARGET_OBJCOPY := $(TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 TARGET_LD := $(TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+TARGET_READELF := $(TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 TARGET_STRIP := $(TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-ifeq ($(TARGET_BUILD_VARIANT),user)
-    TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@
-else
-    TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ && \
-        $(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 TARGET_NO_UNDEFINED_LDFLAGS := -Wl,--no-undefined
 
diff --git a/core/combo/TARGET_linux-mips.mk b/core/combo/TARGET_linux-mips.mk
index 31e0b9a..8ba5959 100644
--- a/core/combo/TARGET_linux-mips.mk
+++ b/core/combo/TARGET_linux-mips.mk
@@ -58,13 +58,9 @@ $(combo_2nd_arch_prefix)TARGET_CXX := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PRE
 $(combo_2nd_arch_prefix)TARGET_AR := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_OBJCOPY := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_LD := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+$(combo_2nd_arch_prefix)TARGET_READELF := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_STRIP := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-ifeq ($(TARGET_BUILD_VARIANT),user)
-    $(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@
-else
-    $(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ && \
-        $(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 $(combo_2nd_arch_prefix)TARGET_NO_UNDEFINED_LDFLAGS := -Wl,--no-undefined
 
diff --git a/core/combo/TARGET_linux-mips64.mk b/core/combo/TARGET_linux-mips64.mk
index 099edfa..c617ac1 100644
--- a/core/combo/TARGET_linux-mips64.mk
+++ b/core/combo/TARGET_linux-mips64.mk
@@ -63,13 +63,9 @@ TARGET_CXX := $(TARGET_TOOLS_PREFIX)g++$(HOST_EXECUTABLE_SUFFIX)
 TARGET_AR := $(TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 TARGET_OBJCOPY := $(TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 TARGET_LD := $(TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+TARGET_READELF := $(TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 TARGET_STRIP := $(TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-ifeq ($(TARGET_BUILD_VARIANT),user)
-    TARGET_STRIP_COMMAND = $(TARGET_STRIP) --strip-all $< -o $@
-else
-    TARGET_STRIP_COMMAND = $(TARGET_STRIP) --strip-all $< -o $@ && \
-        $(TARGET_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 TARGET_NO_UNDEFINED_LDFLAGS := -Wl,--no-undefined
 
diff --git a/core/combo/TARGET_linux-x86.mk b/core/combo/TARGET_linux-x86.mk
index 37795ff..c471e21 100644
--- a/core/combo/TARGET_linux-x86.mk
+++ b/core/combo/TARGET_linux-x86.mk
@@ -51,14 +51,9 @@ $(combo_2nd_arch_prefix)TARGET_CXX := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PRE
 $(combo_2nd_arch_prefix)TARGET_AR := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_OBJCOPY := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_LD := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+$(combo_2nd_arch_prefix)TARGET_READELF := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 $(combo_2nd_arch_prefix)TARGET_STRIP := $($(combo_2nd_arch_prefix)TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-
-ifeq ($(TARGET_BUILD_VARIANT),user)
-$(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@
-else
-$(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ && \
-    $(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 ifneq ($(wildcard $($(combo_2nd_arch_prefix)TARGET_CC)),)
 $(combo_2nd_arch_prefix)TARGET_LIBGCC := \
diff --git a/core/combo/TARGET_linux-x86_64.mk b/core/combo/TARGET_linux-x86_64.mk
index 8e6a653..fbc0056 100644
--- a/core/combo/TARGET_linux-x86_64.mk
+++ b/core/combo/TARGET_linux-x86_64.mk
@@ -53,14 +53,9 @@ TARGET_CXX := $(TARGET_TOOLS_PREFIX)g++$(HOST_EXECUTABLE_SUFFIX)
 TARGET_AR := $(TARGET_TOOLS_PREFIX)ar$(HOST_EXECUTABLE_SUFFIX)
 TARGET_OBJCOPY := $(TARGET_TOOLS_PREFIX)objcopy$(HOST_EXECUTABLE_SUFFIX)
 TARGET_LD := $(TARGET_TOOLS_PREFIX)ld$(HOST_EXECUTABLE_SUFFIX)
+TARGET_READELF := $(TARGET_TOOLS_PREFIX)readelf$(HOST_EXECUTABLE_SUFFIX)
 TARGET_STRIP := $(TARGET_TOOLS_PREFIX)strip$(HOST_EXECUTABLE_SUFFIX)
-
-ifeq ($(TARGET_BUILD_VARIANT),user)
-TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@
-else
-TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ && \
-	$(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
-endif
+include $(BUILD_SYSTEM)/strip.mk
 
 ifneq ($(wildcard $(TARGET_CC)),)
 TARGET_LIBGCC := \
diff --git a/core/definitions.mk b/core/definitions.mk
index 9cbd647..d6cd9d1 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -1327,6 +1327,12 @@ define transform-to-stripped
 $(hide) $($(PRIVATE_2ND_ARCH_VAR_PREFIX)TARGET_STRIP_COMMAND)
 endef
 
+define transform-to-stripped-keep-symbols
+@mkdir -p $(dir $@)
+@echo "target Strip (keep symbols): $(PRIVATE_MODULE) ($@)"
+$(hide) $($(PRIVATE_2ND_ARCH_VAR_PREFIX)TARGET_STRIP_KEEP_SYMBOLS_COMMAND)
+endef
+
 
 ###########################################################
 ## Commands for running gcc to link an executable
diff --git a/core/dynamic_binary.mk b/core/dynamic_binary.mk
index 1d3b99e..32f2c91 100644
--- a/core/dynamic_binary.mk
+++ b/core/dynamic_binary.mk
@@ -116,6 +116,14 @@ $(strip_output): PRIVATE_OBJCOPY := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_OBJCOPY
 $(strip_output): $(strip_input) | $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_STRIP)
 	$(transform-to-stripped)
 else
+ifeq ($(my_strip_module),keep_symbols)
+# Strip only the debug frames, but leave the symbol table.
+$(strip_output): PRIVATE_STRIP := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_STRIP)
+$(strip_output): PRIVATE_OBJCOPY := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_OBJCOPY)
+$(strip_output): PRIVATE_READELF := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_READELF)
+$(strip_output): $(strip_input) | $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_STRIP)
+	$(transform-to-stripped-keep-symbols)
+else
 # Don't strip the binary, just copy it.  We can't skip this step
 # because a copy of the binary must appear at LOCAL_BUILT_MODULE.
 #
@@ -130,6 +138,7 @@ $(strip_output): $(strip_input)
 	@echo "target Unstripped: $(PRIVATE_MODULE) ($@)"
 	$(copy-file-to-target-with-cp)
 endif
+endif
 endif # my_strip_module
 
 
diff --git a/core/strip.mk b/core/strip.mk
new file mode 100644
index 0000000..906d90e
--- /dev/null
+++ b/core/strip.mk
@@ -0,0 +1,25 @@
+#
+# Copyright (C) 2014 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+ifneq ($(TARGET_BUILD_VARIANT),user)
+  TARGET_STRIP_EXTRA = && $(PRIVATE_OBJCOPY) --add-gnu-debuglink=$< $@
+  TARGET_STRIP_KEEP_SYMBOLS_EXTRA = --add-gnu-debuglink=$<
+endif
+$(combo_2nd_arch_prefix)TARGET_STRIP_COMMAND = $(PRIVATE_STRIP) --strip-all $< -o $@ $(TARGET_STRIP_EXTRA)
+$(combo_2nd_arch_prefix)TARGET_STRIP_KEEP_SYMBOLS_COMMAND = \
+  $(PRIVATE_OBJCOPY) \
+    `$(PRIVATE_READELF) -S $< | awk '/.debug_/ {print "-R " $$2}' | xargs` \
+    $(TARGET_STRIP_KEEP_SYMBOLS_EXTRA) $< $@