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