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8b8f13b60d
This does not change the emitted code since __libc_start_main does not return, but is important for formal flags compliance. This also cleans up the cosmetic inconsistency in the stack protector flags in csu, especially the incorrect value of STACK_PROTECTOR_LEVEL. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
188 lines
6.9 KiB
Makefile
188 lines
6.9 KiB
Makefile
# Makefile for csu code for GNU C library.
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# Copyright (C) 1995-2021 Free Software Foundation, Inc.
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# This file is part of the GNU C Library.
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# The GNU C Library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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# The GNU C Library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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# You should have received a copy of the GNU Lesser General Public
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# License along with the GNU C Library; if not, see
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# <https://www.gnu.org/licenses/>.
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# This directory contains the C startup code (that which calls main). This
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# consists of the startfile, built from start.c and installed as crt0.o
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# (traditionally) or crt1.o (for ELF). In ELF we also install crti.o and
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# crtn.o, special "initializer" and "finalizer" files used in the link
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# to make the .init and .fini sections work right.
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subdir := csu
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include ../Makeconfig
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routines = init-first libc-start $(libc-init) sysdep version check_fds \
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libc-tls dso_handle
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aux = errno
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elide-routines.os = libc-tls
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csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
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extra-objs = start.o \
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$(start-installed-name) g$(start-installed-name) $(csu-dummies) \
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S$(start-installed-name)
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omit-deps = $(patsubst %.o,%,$(start-installed-name) g$(start-installed-name) \
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b$(start-installed-name) $(csu-dummies) \
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S$(start-installed-name) \
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r$(start-installed-name) \
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gr$(start-installed-name))
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install-lib = $(start-installed-name) g$(start-installed-name) $(csu-dummies)
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# No tests are allowed in the csu/ subdirectory because the startup
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# code is compiled with special flags.
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tests =
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# static-reloc.os is a dummy object not actually used for anything. It is
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# linked into crt1.o nevertheless, which in turn is statically linked into
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# applications, so that build flags matter.
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# See <https://sourceware.org/ml/libc-alpha/2018-07/msg00101.html>.
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#
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# libc-start.os is safe to be built with stack protector since
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# __libc_start_main is called after stack canary setup is done.
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ssp-safe.os = static-reloc libc-start
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CFLAGS-.o += $(call elide-stack-protector,.o,$(routines))
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CFLAGS-.op += $(call elide-stack-protector,.op,$(routines))
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CFLAGS-.oS += $(call elide-stack-protector,.oS,$(routines))
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CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
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$(ssp-safe.os),$(routines)))
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ifeq (yes,$(build-shared))
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extra-objs += S$(start-installed-name) gmon-start.os
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ifneq ($(start-installed-name),$(static-start-installed-name))
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extra-objs += gmon-start.o
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endif
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install-lib += S$(start-installed-name)
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generated += start.os
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else
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extra-objs += gmon-start.o
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endif
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ifneq ($(start-installed-name),$(static-start-installed-name))
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# FIXME: Only Hurd defines static-start-installed-name. Hurd needs to
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# provide special rules to support static PIE.
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extra-objs += $(static-start-installed-name) g$(static-start-installed-name)
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omit-deps += $(patsubst %.o,%,$(static-start-installed-name) \
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g$(static-start-installed-name))
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install-lib += $(static-start-installed-name) g$(static-start-installed-name)
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else
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ifeq (yes,$(enable-static-pie))
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extra-objs += r$(start-installed-name) gr$(start-installed-name)
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install-lib += r$(start-installed-name) gr$(start-installed-name)
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endif
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endif
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before-compile += $(objpfx)abi-tag.h
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generated += abi-tag.h
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# These are the special initializer/finalizer files. They are always the
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# first and last file in the link. crti.o ... crtn.o define the global
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# "functions" _init and _fini to run the .init and .fini sections.
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crtstuff = crti crtn
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install-lib += $(crtstuff:=.o)
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extra-objs += $(crtstuff:=.o)
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ifneq ($(multidir),.)
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multilib-extra-objs = $(addprefix $(multidir)/, $(install-lib))
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extra-objs += $(multilib-extra-objs)
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endif
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extra-objs += abi-note.o init.o static-reloc.o
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ifeq (yes,$(build-shared))
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extra-objs += static-reloc.os
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endif
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asm-CPPFLAGS += -I$(objpfx).
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# Enable unwinding so backtrace unwinds to __libc_start_main
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CFLAGS-libc-start.c += -funwind-tables
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include ../Rules
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# Make these in the lib pass so they're available in time to link things with.
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subdir_lib: $(extra-objs:%=$(objpfx)%)
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define link-relocatable
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$(CC) -nostdlib -nostartfiles -r -o $@ $^
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endef
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ifndef start-installed-name-rule
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# We link the ELF startfile along with a SHT_NOTE section indicating
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# the kernel ABI the binaries linked with this library will require.
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$(objpfx)$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
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$(objpfx)init.o $(objpfx)static-reloc.o
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$(link-relocatable)
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$(objpfx)r$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
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$(objpfx)init.o
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$(link-relocatable)
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$(objpfx)S$(start-installed-name): $(objpfx)start.os $(objpfx)abi-note.o \
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$(objpfx)init.o
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$(link-relocatable)
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endif
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# The profiling startfile is made by linking together the normal
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# startfile with gmon-start.o, which defines a constructor function
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# to turn on profiling code at startup.
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ifeq (yes,$(build-shared))
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$(objpfx)g$(start-installed-name): \
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$(objpfx)g%: $(objpfx)S% $(objpfx)gmon-start.os $(objpfx)static-reloc.os
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$(link-relocatable)
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$(objpfx)gr$(start-installed-name): \
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$(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
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$(link-relocatable)
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ifneq ($(start-installed-name),$(static-start-installed-name))
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$(objpfx)g$(static-start-installed-name): \
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$(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
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$(link-relocatable)
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endif
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else
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$(addprefix $(objpfx),$(sort g$(start-installed-name) \
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g$(static-start-installed-name))): \
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$(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
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$(link-relocatable)
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endif
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# These extra files are sometimes expected by system standard linking
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# procedures, but we have nothing for them to do. So compile empty files.
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$(addprefix $(objpfx),$(filter-out $(start-installed-name), $(csu-dummies))):\
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$(before-compile)
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$(COMPILE.c) -o $@ -x c /dev/null
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# These headers are used by the startup code.
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$(objpfx)abi-tag.h: $(..)abi-tags
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$(make-target-directory)
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rm -f $@.new
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sed -e 's/#.*$$//' -e '/^[ ]*$$/d' $< | \
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while read conf tagos tagver; do \
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test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
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: "$$conf"` != 0 || continue; \
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( echo "$$tagos" | \
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sed -e 's/[^0-9xXa-fA-F ]//' \
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-e 's/^/#define __ABI_TAG_OS /'; \
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echo "#ifndef __ABI_TAG_VERSION"; \
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echo "$$tagver" | \
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sed -e 's/[^0-9xXa-fA-F]/ /g' -e 's/ *$$//' \
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-e 's/ /,/g' -e 's/^/# define __ABI_TAG_VERSION /'; \
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echo "#endif" ) > $@.new; \
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done
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if test -r $@.new; then mv -f $@.new $@; \
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else echo >&2 'This configuration not matched in $<'; exit 1; fi
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ifneq ($(multidir),.)
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$(addprefix $(objpfx)$(multidir)/, $(install-lib)): $(addprefix $(objpfx), $(install-lib))
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$(make-link-multidir)
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endif
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