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