csu/Makefile

   1 # Makefile for csu code for GNU C library.
   2 # Copyright (C) 1995-2021 Free Software Foundation, Inc.
   3 # This file is part of the GNU C Library.
   4
   5 # The GNU C Library is free software; you can redistribute it and/or
   6 # modify it under the terms of the GNU Lesser General Public
   7 # License as published by the Free Software Foundation; either
   8 # version 2.1 of the License, or (at your option) any later version.
   9
  10 # The GNU C Library is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 # Lesser General Public License for more details.
  14
  15 # You should have received a copy of the GNU Lesser General Public
  16 # License along with the GNU C Library; if not, see
  17 # <https://www.gnu.org/licenses/>.
  18
  19 # This directory contains the C startup code (that which calls main).  This
  20 # consists of the startfile, built from start.c and installed as crt0.o
  21 # (traditionally) or crt1.o (for ELF).  In ELF we also install crti.o and
  22 # crtn.o, special "initializer" and "finalizer" files used in the link
  23 # to make the .init and .fini sections work right.
  24
  25 subdir := csu
  26
  27 include ../Makeconfig
  28
  29 routines = init-first libc-start $(libc-init) sysdep version check_fds \
  30            libc-tls dso_handle
  31 aux      = errno
  32 elide-routines.os = libc-tls
  33 csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
  34 extra-objs = start.o \
  35              $(start-installed-name) g$(start-installed-name) $(csu-dummies) \
  36              S$(start-installed-name)
  37 omit-deps = $(patsubst %.o,%,$(start-installed-name) g$(start-installed-name) \
  38                              b$(start-installed-name) $(csu-dummies) \
  39                              S$(start-installed-name) \
  40                              r$(start-installed-name) \
  41                              gr$(start-installed-name))
  42 install-lib = $(start-installed-name) g$(start-installed-name) $(csu-dummies)
  43
  44 # No tests are allowed in the csu/ subdirectory because the startup
  45 # code is compiled with special flags.
  46 tests =
  47
  48 # static-reloc.os is a dummy object not actually used for anything.  It is
  49 # linked into crt1.o nevertheless, which in turn is statically linked into
  50 # applications, so that build flags matter.
  51 # See <https://sourceware.org/ml/libc-alpha/2018-07/msg00101.html>.
  52 #
  53 # libc-start.os is safe to be built with stack protector since
  54 # __libc_start_main is called after stack canary setup is done.
  55 ssp-safe.os = static-reloc libc-start
  56
  57 CFLAGS-.o += $(call elide-stack-protector,.o,$(routines))
  58 CFLAGS-.op += $(call elide-stack-protector,.op,$(routines))
  59 CFLAGS-.oS += $(call elide-stack-protector,.oS,$(routines))
  60 CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
  61                                                  $(ssp-safe.os),$(routines)))
  62
  63 ifeq (yes,$(build-shared))
  64 extra-objs += S$(start-installed-name) gmon-start.os
  65 ifneq ($(start-installed-name),$(static-start-installed-name))
  66 extra-objs += gmon-start.o
  67 endif
  68 install-lib += S$(start-installed-name)
  69 generated += start.os
  70 else
  71 extra-objs += gmon-start.o
  72 endif
  73
  74 ifneq ($(start-installed-name),$(static-start-installed-name))
  75 # FIXME: Only Hurd defines static-start-installed-name.  Hurd needs to
  76 # provide special rules to support static PIE.
  77 extra-objs += $(static-start-installed-name) g$(static-start-installed-name)
  78 omit-deps += $(patsubst %.o,%,$(static-start-installed-name) \
  79                              g$(static-start-installed-name))
  80 install-lib += $(static-start-installed-name) g$(static-start-installed-name)
  81 else
  82 ifeq (yes,$(enable-static-pie))
  83 extra-objs += r$(start-installed-name) gr$(start-installed-name)
  84 install-lib += r$(start-installed-name) gr$(start-installed-name)
  85 endif
  86 endif
  87
  88 before-compile += $(objpfx)abi-tag.h
  89 generated += abi-tag.h
  90
  91 # These are the special initializer/finalizer files.  They are always the
  92 # first and last file in the link.  crti.o ... crtn.o define the global
  93 # "functions" _init and _fini to run the .init and .fini sections.
  94 crtstuff = crti crtn
  95
  96 install-lib += $(crtstuff:=.o)
  97 extra-objs += $(crtstuff:=.o)
  98
  99 ifneq ($(multidir),.)
 100 multilib-extra-objs = $(addprefix $(multidir)/, $(install-lib))
 101 extra-objs += $(multilib-extra-objs)
 102 endif
 103
 104 extra-objs += abi-note.o init.o static-reloc.o
 105 ifeq (yes,$(build-shared))
 106 extra-objs += static-reloc.os
 107 endif
 108 asm-CPPFLAGS += -I$(objpfx).
 109
 110 # Enable unwinding so backtrace unwinds to __libc_start_main
 111 CFLAGS-libc-start.c += -funwind-tables
 112
 113 include ../Rules
 114
 115 # Make these in the lib pass so they're available in time to link things with.
 116 subdir_lib: $(extra-objs:%=$(objpfx)%)
 117
 118 define link-relocatable
 119 $(CC) -nostdlib -nostartfiles -r -o $@ $^
 120 endef
 121
 122 ifndef start-installed-name-rule
 123 # We link the ELF startfile along with a SHT_NOTE section indicating
 124 # the kernel ABI the binaries linked with this library will require.
 125 $(objpfx)$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 126                                   $(objpfx)init.o $(objpfx)static-reloc.o
 127         $(link-relocatable)
 128 $(objpfx)r$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 129                                   $(objpfx)init.o
 130         $(link-relocatable)
 131 $(objpfx)S$(start-installed-name): $(objpfx)start.os $(objpfx)abi-note.o \
 132                                   $(objpfx)init.o
 133         $(link-relocatable)
 134 endif
 135
 136 # The profiling startfile is made by linking together the normal
 137 # startfile with gmon-start.o, which defines a constructor function
 138 # to turn on profiling code at startup.
 139 ifeq (yes,$(build-shared))
 140 $(objpfx)g$(start-installed-name): \
 141   $(objpfx)g%: $(objpfx)S% $(objpfx)gmon-start.os $(objpfx)static-reloc.os
 142         $(link-relocatable)
 143 $(objpfx)gr$(start-installed-name): \
 144   $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
 145         $(link-relocatable)
 146 ifneq ($(start-installed-name),$(static-start-installed-name))
 147 $(objpfx)g$(static-start-installed-name): \
 148   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 149         $(link-relocatable)
 150 endif
 151 else
 152 $(addprefix $(objpfx),$(sort g$(start-installed-name) \
 153                              g$(static-start-installed-name))): \
 154   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 155         $(link-relocatable)
 156 endif
 157
 158 # These extra files are sometimes expected by system standard linking
 159 # procedures, but we have nothing for them to do.  So compile empty files.
 160 $(addprefix $(objpfx),$(filter-out $(start-installed-name), $(csu-dummies))):\
 161   $(before-compile)
 162         $(COMPILE.c) -o $@ -x c /dev/null
 163
 164 # These headers are used by the startup code.
 165 $(objpfx)abi-tag.h: $(..)abi-tags
 166         $(make-target-directory)
 167         rm -f $@.new
 168         sed -e 's/#.*$$//' -e '/^[      ]*$$/d' $< | \
 169         while read conf tagos tagver; do \
 170           test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
 171                      : "$$conf"` != 0 || continue; \
 172           ( echo "$$tagos" | \
 173             sed -e 's/[^0-9xXa-fA-F     ]//' \
 174                 -e 's/^/#define __ABI_TAG_OS /'; \
 175             echo "#ifndef __ABI_TAG_VERSION"; \
 176             echo "$$tagver" | \
 177             sed -e 's/[^0-9xXa-fA-F]/ /g' -e 's/ *$$//' \
 178               -e 's/ /,/g' -e 's/^/# define __ABI_TAG_VERSION /'; \
 179             echo "#endif" ) > $@.new; \
 180         done
 181         if test -r $@.new; then mv -f $@.new $@; \
 182         else echo >&2 'This configuration not matched in $<'; exit 1; fi
 183
 184 ifneq ($(multidir),.)
 185 $(addprefix $(objpfx)$(multidir)/, $(install-lib)): $(addprefix $(objpfx), $(install-lib))
 186         $(make-link-multidir)
 187 endif