csu/Makefile

   1 # Makefile for csu code for GNU C library.
   2 # Copyright (C) 1995-2024 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 = \
  30   $(libc-init) \
  31   check_fds \
  32   dso_handle \
  33   init-first \
  34   libc-start \
  35   libc-tls \
  36   sysdep \
  37   version \
  38   # routines
  39 aux      = errno
  40 elide-routines.os = libc-tls
  41 csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
  42 extra-objs = \
  43   $(csu-dummies) \
  44   $(start-installed-name) \
  45   $(start-name-2.0) \
  46   S$(start-installed-name) \
  47   g$(start-installed-name) \
  48   start.o \
  49   # extra-objs
  50 omit-deps = $(patsubst %.o,%,$(start-installed-name) g$(start-installed-name) \
  51                              b$(start-installed-name) $(csu-dummies) \
  52                              S$(start-installed-name) \
  53                              r$(start-installed-name) \
  54                              gr$(start-installed-name))
  55 install-lib = \
  56   $(csu-dummies) \
  57   $(start-installed-name) \
  58   g$(start-installed-name) \
  59   # install-lib
  60
  61 # No tests are allowed in the csu/ subdirectory because the startup
  62 # code is compiled with special flags.
  63 tests =
  64
  65 # static-reloc.os is a dummy object not actually used for anything.  It is
  66 # linked into crt1.o nevertheless, which in turn is statically linked into
  67 # applications, so that build flags matter.
  68 # See <https://sourceware.org/ml/libc-alpha/2018-07/msg00101.html>.
  69 #
  70 # The function is called prior the thread pointer setup, and if stack
  71 # protector is enabled the compiler might still generate the stack check
  72 # (which requires the thread pointer correctly set).
  73 extra-no-ssp = static-reloc
  74
  75 # libc-start.os is safe to be built with stack protector since
  76 # __libc_start_main is called after stack canary setup is done.
  77 ssp-safe.os = libc-start
  78
  79 CFLAGS-.o += $(call elide-stack-protector,.o,$(routines) $(extra-no-ssp))
  80 CFLAGS-.op += $(call elide-stack-protector,.op,$(routines) $(extra-no-ssp))
  81 CFLAGS-.oS += $(call elide-stack-protector,.oS,$(routines) $(extra-no-ssp))
  82 CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
  83                                                  $(ssp-safe.os), \
  84                                                  $(routines) $(extra-no-ssp)))
  85
  86 ifeq (yes,$(build-shared))
  87 extra-objs += \
  88   S$(start-installed-name) \
  89   gmon-start.os \
  90   # extra-objs
  91 ifneq ($(start-installed-name),$(static-start-installed-name))
  92 extra-objs += gmon-start.o
  93 endif
  94 install-lib += S$(start-installed-name)
  95 generated += start.os
  96 else
  97 extra-objs += gmon-start.o
  98 endif
  99
 100 ifeq (yes,$(enable-static-pie))
 101 extra-objs += \
 102   gr$(start-installed-name) \
 103   r$(start-installed-name) \
 104   # extra-objs
 105 install-lib += \
 106   gr$(start-installed-name) \
 107   r$(start-installed-name) \
 108   # install-lib
 109 endif
 110
 111 ifneq ($(start-installed-name),$(static-start-installed-name))
 112 extra-objs += \
 113   $(static-start-installed-name) \
 114   g$(static-start-installed-name) \
 115   # extra-objs
 116 omit-deps += $(patsubst %.o,%,$(static-start-installed-name) \
 117                              g$(static-start-installed-name))
 118 install-lib += \
 119   $(static-start-installed-name) \
 120   g$(static-start-installed-name) \
 121   # install-lib
 122 ifeq (yes,$(enable-static-pie))
 123 extra-objs += \
 124   gr$(static-start-installed-name) \
 125   r$(static-start-installed-name) \
 126   # extra-objs
 127 omit-deps += $(patsubst %.o,%,r$(static-start-installed-name) \
 128                              gr$(static-start-installed-name))
 129 install-lib += \
 130   gr$(static-start-installed-name) \
 131   r$(static-start-installed-name) \
 132   # install-lib
 133 endif
 134 endif
 135
 136 before-compile += $(objpfx)abi-tag.h
 137 generated += abi-tag.h
 138
 139 # Put it here to generate it earlier.
 140 gen-as-const-headers += rtld-sizes.sym
 141
 142 # These are the special initializer/finalizer files.  They are always the
 143 # first and last file in the link.  crti.o ... crtn.o define the global
 144 # "functions" _init and _fini to run the .init and .fini sections.
 145 crtstuff = \
 146   crti \
 147   crtn \
 148   # crtstuff
 149
 150 install-lib += $(crtstuff:=.o)
 151 extra-objs += $(crtstuff:=.o)
 152
 153 ifneq ($(multidir),.)
 154 multilib-extra-objs = $(addprefix $(multidir)/, $(install-lib))
 155 extra-objs += $(multilib-extra-objs)
 156 endif
 157
 158 extra-objs += \
 159   abi-note.o \
 160   init.o \
 161   static-reloc.o \
 162   # extra-objs
 163 ifeq (yes,$(build-shared))
 164 extra-objs += static-reloc.os
 165 endif
 166 asm-CPPFLAGS += -I$(objpfx).
 167
 168 # Enable unwinding so backtrace unwinds to __libc_start_main
 169 CFLAGS-libc-start.c += -funwind-tables
 170
 171 include ../Rules
 172
 173 # Make these in the lib pass so they're available in time to link things with.
 174 subdir_lib: $(extra-objs:%=$(objpfx)%)
 175
 176 define link-relocatable
 177 $(CC) -nostdlib -nostartfiles -r -o $@ $^
 178 endef
 179
 180 ifndef start-installed-name-rule
 181 # We link the ELF startfile along with a SHT_NOTE section indicating
 182 # the kernel ABI the binaries linked with this library will require.
 183 $(objpfx)$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 184                                   $(objpfx)init.o $(objpfx)static-reloc.o
 185         $(link-relocatable)
 186 $(objpfx)$(start-name-2.0): $(objpfx)start.o $(objpfx)abi-note.o \
 187                             $(objpfx)static-reloc.o
 188         $(link-relocatable)
 189 $(objpfx)r$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
 190                                   $(objpfx)init.o
 191         $(link-relocatable)
 192 $(objpfx)S$(start-installed-name): $(objpfx)start.os $(objpfx)abi-note.o \
 193                                   $(objpfx)init.o
 194         $(link-relocatable)
 195 endif
 196
 197 # The profiling startfile is made by linking together the normal
 198 # startfile with gmon-start.o, which defines a constructor function
 199 # to turn on profiling code at startup.
 200 ifeq (yes,$(build-shared))
 201 $(objpfx)g$(start-installed-name): \
 202   $(objpfx)g%: $(objpfx)S% $(objpfx)gmon-start.os $(objpfx)static-reloc.os
 203         $(link-relocatable)
 204 $(objpfx)gr$(start-installed-name): \
 205   $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
 206         $(link-relocatable)
 207 ifneq ($(start-installed-name),$(static-start-installed-name))
 208 $(objpfx)g$(static-start-installed-name): \
 209   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 210         $(link-relocatable)
 211 $(objpfx)gr$(static-start-installed-name): \
 212   $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
 213         $(link-relocatable)
 214 endif
 215 else
 216 $(addprefix $(objpfx),$(sort g$(start-installed-name) \
 217                              g$(static-start-installed-name))): \
 218   $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
 219         $(link-relocatable)
 220 endif
 221
 222 # These extra files are sometimes expected by system standard linking
 223 # procedures, but we have nothing for them to do.  So compile empty files.
 224 $(addprefix $(objpfx),$(filter-out $(start-installed-name), $(csu-dummies))):\
 225   $(before-compile)
 226         $(COMPILE.c) -o $@ -x c /dev/null
 227
 228 # These headers are used by the startup code.
 229 $(objpfx)abi-tag.h: $(..)abi-tags
 230         $(make-target-directory)
 231         rm -f $@.new
 232         sed -e 's/#.*$$//' -e '/^[      ]*$$/d' $< | \
 233         while read conf tagos tagver; do \
 234           test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
 235                      : "$$conf"` != 0 || continue; \
 236           ( echo "$$tagos" | \
 237             sed -e 's/[^0-9xXa-fA-F     ]//' \
 238                 -e 's/^/#define __ABI_TAG_OS /'; \
 239             echo "#ifndef __ABI_TAG_VERSION"; \
 240             echo "$$tagver" | \
 241             sed -e 's/[^0-9xXa-fA-F]/ /g' -e 's/ *$$//' \
 242               -e 's/ /,/g' -e 's/^/# define __ABI_TAG_VERSION /'; \
 243             echo "#endif" ) > $@.new; \
 244         done
 245         if test -r $@.new; then mv -f $@.new $@; \
 246         else echo >&2 'This configuration not matched in $<'; exit 1; fi
 247
 248 ifneq ($(multidir),.)
 249 $(addprefix $(objpfx)$(multidir)/, $(install-lib)): $(addprefix $(objpfx), $(install-lib))
 250         $(make-link-multidir)
 251 endif