csu/Makefile

   1 # Makefile for csu code for GNU C library.
   2 # Copyright (C) 1995-2020 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 elf-init dso_handle
  31 aux      = errno
  32 elide-routines.os = libc-tls
  33 static-only-routines = elf-init
  34 csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
  35 extra-objs = start.o \
  36              $(start-installed-name) g$(start-installed-name) $(csu-dummies) \
  37              S$(start-installed-name)
  38 omit-deps = $(patsubst %.o,%,$(start-installed-name) g$(start-installed-name) \
  39                              b$(start-installed-name) $(csu-dummies) \
  40                              S$(start-installed-name) \
  41                              r$(start-installed-name) \
  42                              gr$(start-installed-name))
  43 install-lib = $(start-installed-name) g$(start-installed-name) $(csu-dummies)
  44
  45 # No tests are allowed in the csu/ subdirectory because the startup
  46 # code is compiled with special flags.
  47 tests =
  48
  49 CFLAGS-.o += $(no-stack-protector)
  50 CFLAGS-.op += $(no-stack-protector)
  51 CFLAGS-.os += $(no-stack-protector)
  52
  53 # Dummy object not actually used for anything.  It is linked into
  54 # crt1.o nevertheless, which in turn is statically linked into
  55 # applications, so that build flags matter.
  56 # See <https://sourceware.org/ml/libc-alpha/2018-07/msg00101.html>.
  57 # NB: Using $(stack-protector) in this way causes a wrong definition
  58 # STACK_PROTECTOR_LEVEL due to the preceding $(no-stack-protector),
  59 # but it does not matter for this source file.
  60 CFLAGS-static-reloc.os += $(stack-protector)
  61
  62 # This file is not actually part of the startup code in the nonshared
  63 # case and statically linked into applications.  See
  64 # <https://sourceware.org/bugzilla/show_bug.cgi?id=23323>,
  65 # <https://sourceware.org/ml/libc-alpha/2018-06/msg00717.html>.
  66 # Also see the note above regarding STACK_PROTECTOR_LEVEL.
  67 CFLAGS-elf-init.oS += $(stack-protector)
  68
  69 ifeq (yes,$(build-shared))
  70 extra-objs += S$(start-installed-name) gmon-start.os
  71 ifneq ($(start-installed-name),$(static-start-installed-name))
  72 extra-objs += gmon-start.o
  73 endif
  74 install-lib += S$(start-installed-name)
  75 generated += start.os
  76 else
  77 extra-objs += gmon-start.o
  78 endif
  79
  80 ifneq ($(start-installed-name),$(static-start-installed-name))
  81 # FIXME: Only Hurd defines static-start-installed-name.  Hurd needs to
  82 # provide special rules to support static PIE.
  83 extra-objs += $(static-start-installed-name) g$(static-start-installed-name)
  84 omit-deps += $(patsubst %.o,%,$(static-start-installed-name) \
  85                              g$(static-start-installed-name))
  86 install-lib += $(static-start-installed-name) g$(static-start-installed-name)
  87 else
  88 ifeq (yes,$(enable-static-pie))
  89 extra-objs += r$(start-installed-name) gr$(start-installed-name)
  90 install-lib += r$(start-installed-name) gr$(start-installed-name)
  91 endif
  92 endif
  93
  94 before-compile += $(objpfx)abi-tag.h
  95 generated += abi-tag.h
  96
  97 # These are the special initializer/finalizer files.  They are always the
  98 # first and last file in the link.  crti.o ... crtn.o define the global
  99 # "functions" _init and _fini to run the .init and .fini sections.
 100 crtstuff = crti crtn
 101
 102 install-lib += $(crtstuff:=.o)
 103 extra-objs += $(crtstuff:=.o)
 104
 105 ifneq ($(multidir),.)
 106 multilib-extra-objs = $(addprefix $(multidir)/, $(install-lib))
 107 extra-objs += $(multilib-extra-objs)
 108 endif
 109
 110 extra-objs += abi-note.o init.o static-reloc.o
 111 ifeq (yes,$(build-shared))
 112 extra-objs += static-reloc.os
 113 endif
 114 asm-CPPFLAGS += -I$(objpfx).
 115
 116 # Enable unwinding so backtrace unwinds to __libc_start_main
 117 CFLAGS-libc-start.c += -funwind-tables
 118
 119 include ../Rules
 120
 121 # Make these in the lib pass so they're available in time to link things with.
 122 subdir_lib: $(extra-objs:%=$(objpfx)%)
 123
 124 define link-relocatable
 125 $(CC) -nostdlib -nostartfiles -r -o $@ $^
 126 endef
 127
 128 ifndef start-installed-name-rule
 129 # We link the ELF startfile along with a SHT_NOTE section indicating
 130 # the kernel ABI the binaries linked with this library will require.
 131 $(objpfx)$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 132                                   $(objpfx)init.o $(objpfx)static-reloc.o
 133         $(link-relocatable)
 134 $(objpfx)r$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 135                                   $(objpfx)init.o
 136         $(link-relocatable)
 137 $(objpfx)S$(start-installed-name): $(objpfx)start.os $(objpfx)abi-note.o \
 138                                   $(objpfx)init.o
 139         $(link-relocatable)
 140 endif
 141
 142 # The profiling startfile is made by linking together the normal
 143 # startfile with gmon-start.o, which defines a constructor function
 144 # to turn on profiling code at startup.
 145 ifeq (yes,$(build-shared))
 146 $(objpfx)g$(start-installed-name): \
 147   $(objpfx)g%: $(objpfx)S% $(objpfx)gmon-start.os $(objpfx)static-reloc.os
 148         $(link-relocatable)
 149 $(objpfx)gr$(start-installed-name): \
 150   $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
 151         $(link-relocatable)
 152 ifneq ($(start-installed-name),$(static-start-installed-name))
 153 $(objpfx)g$(static-start-installed-name): \
 154   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 155         $(link-relocatable)
 156 endif
 157 else
 158 $(addprefix $(objpfx),$(sort g$(start-installed-name) \
 159                              g$(static-start-installed-name))): \
 160   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 161         $(link-relocatable)
 162 endif
 163
 164 # These extra files are sometimes expected by system standard linking
 165 # procedures, but we have nothing for them to do.  So compile empty files.
 166 $(addprefix $(objpfx),$(filter-out $(start-installed-name), $(csu-dummies))):\
 167   $(before-compile)
 168         $(COMPILE.c) -o $@ -x c /dev/null
 169
 170 # These headers are used by the startup code.
 171 $(objpfx)abi-tag.h: $(..)abi-tags
 172         $(make-target-directory)
 173         rm -f $@.new
 174         sed -e 's/#.*$$//' -e '/^[      ]*$$/d' $< | \
 175         while read conf tagos tagver; do \
 176           test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
 177                      : "$$conf"` != 0 || continue; \
 178           ( echo "$$tagos" | \
 179             sed -e 's/[^0-9xXa-fA-F     ]//' \
 180                 -e 's/^/#define __ABI_TAG_OS /'; \
 181             echo "#ifndef __ABI_TAG_VERSION"; \
 182             echo "$$tagver" | \
 183             sed -e 's/[^0-9xXa-fA-F]/ /g' -e 's/ *$$//' \
 184               -e 's/ /,/g' -e 's/^/# define __ABI_TAG_VERSION /'; \
 185             echo "#endif" ) > $@.new; \
 186         done
 187         if test -r $@.new; then mv -f $@.new $@; \
 188         else echo >&2 'This configuration not matched in $<'; exit 1; fi
 189
 190 ifneq ($(multidir),.)
 191 $(addprefix $(objpfx)$(multidir)/, $(install-lib)): $(addprefix $(objpfx), $(install-lib))
 192         $(make-link-multidir)
 193 endif