3a7ea52f17
Compile the linker with -fvisibility=hidden. This reduces the number
of symbols that show up in the .dynsym section of the linker.
These symbols are never exported to other applications.
In particular, this fixes a problem with setting -DLINKER_DEBUG=1
introduced in 468319ce4f.
Because the symbols "debug_verbosity" and "format_log" have not been
resolved before the linker links itself, any attempt to call
PRINT / INFO / TRACE / WARN / ERROR will result in a segfault.
This change allows the static linker to produce a relative reference
to these symbols rather than relying on relocation.
This also has a nice side effect of making the linker slightly smaller
and slightly more optimized.
The following symbols no longer in the .dynsym section of the linker
after this change:
-addr_to_name
-call_constructors_recursi
-calloc
-debugger_init
-debugger_signal_handler
-debug_verbosity
-dladdr
-dlclose
-dlerror
-dl_lock
-dlopen
-dlsym
-dl_unwind_find_exidx
-find_containing_library
-find_containing_symbol
-find_library
-format_buffer
-free
-libdl_info
-linker_env_get
-linker_env_init
-linker_env_secure
-linker_env_unset
-linker_get_error
-__linker_init
-lookup
-lookup_in_library
-malloc
-notify_gdb_of_libraries
-notify_gdb_of_load
-notify_gdb_of_unload
-realloc
-rtld_db_dlactivity
-unload_library
-vsnprintf
Bug: 5827809
Change-Id: I5e8cd7dcf48c1d6831a970a67f63f24916c5e437
70 lines
1.8 KiB
Makefile
70 lines
1.8 KiB
Makefile
LOCAL_PATH:= $(call my-dir)
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include $(CLEAR_VARS)
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LOCAL_SRC_FILES:= \
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arch/$(TARGET_ARCH)/begin.S \
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linker.c \
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linker_environ.c \
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linker_format.c \
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rt.c \
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dlfcn.c \
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debugger.c
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LOCAL_LDFLAGS := -shared
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LOCAL_CFLAGS += -fno-stack-protector \
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-Wstrict-overflow=5 \
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-fvisibility=hidden
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# Set LINKER_DEBUG to either 1 or 0
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#
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LOCAL_CFLAGS += -DLINKER_DEBUG=0
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# we need to access the Bionic private header <bionic_tls.h>
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# in the linker; duplicate the HAVE_ARM_TLS_REGISTER definition
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# from the libc build
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ifeq ($(TARGET_ARCH)-$(ARCH_ARM_HAVE_TLS_REGISTER),arm-true)
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LOCAL_CFLAGS += -DHAVE_ARM_TLS_REGISTER
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endif
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LOCAL_CFLAGS += -I$(LOCAL_PATH)/../libc/private
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ifeq ($(TARGET_ARCH),arm)
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LOCAL_CFLAGS += -DANDROID_ARM_LINKER
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else
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ifeq ($(TARGET_ARCH),x86)
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LOCAL_CFLAGS += -DANDROID_X86_LINKER
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endif
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endif
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LOCAL_MODULE:= linker
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LOCAL_STATIC_LIBRARIES := libc_nomalloc
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#LOCAL_FORCE_STATIC_EXECUTABLE := true # not necessary when not including BUILD_EXECUTABLE
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#
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# include $(BUILD_EXECUTABLE)
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#
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# Instead of including $(BUILD_EXECUTABLE), we execute the steps to create an executable by
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# hand, as we want to insert an extra step that is not supported by the build system, and
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# is probably specific the linker only, so there's no need to modify the build system for
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# the purpose.
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LOCAL_MODULE_CLASS := EXECUTABLES
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LOCAL_MODULE_SUFFIX := $(TARGET_EXECUTABLE_SUFFIX)
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# we don't want crtbegin.o (because we have begin.o), so unset it
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# just for this module
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LOCAL_NO_CRT := true
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include $(BUILD_SYSTEM)/dynamic_binary.mk
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$(linked_module): $(TARGET_CRTBEGIN_STATIC_O) $(all_objects) $(all_libraries) $(TARGET_CRTEND_O)
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$(transform-o-to-static-executable)
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@echo "target PrefixSymbols: $(PRIVATE_MODULE) ($@)"
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$(hide) $(TARGET_OBJCOPY) --prefix-symbols=__dl_ $@
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#
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# end of BUILD_EXECUTABLE hack
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#
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