1# Makefile for csu code for GNU C library.
2# Copyright (C) 1995-2022 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
25subdir := csu
26
27include ../Makeconfig
28
29routines = init-first libc-start $(libc-init) sysdep version check_fds \
30	   libc-tls dso_handle
31aux	 = errno
32elide-routines.os = libc-tls
33csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
34extra-objs = start.o \
35	     $(start-installed-name) g$(start-installed-name) $(csu-dummies) \
36	     S$(start-installed-name)
37omit-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))
42install-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.
46tests =
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.
55ssp-safe.os = static-reloc libc-start
56
57CFLAGS-.o += $(call elide-stack-protector,.o,$(routines))
58CFLAGS-.op += $(call elide-stack-protector,.op,$(routines))
59CFLAGS-.oS += $(call elide-stack-protector,.oS,$(routines))
60CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
61						 $(ssp-safe.os),$(routines)))
62
63ifeq (yes,$(build-shared))
64extra-objs += S$(start-installed-name) gmon-start.os
65ifneq ($(start-installed-name),$(static-start-installed-name))
66extra-objs += gmon-start.o
67endif
68install-lib += S$(start-installed-name)
69generated += start.os
70else
71extra-objs += gmon-start.o
72endif
73
74ifeq (yes,$(enable-static-pie))
75extra-objs += r$(start-installed-name) gr$(start-installed-name)
76install-lib += r$(start-installed-name) gr$(start-installed-name)
77endif
78
79ifneq ($(start-installed-name),$(static-start-installed-name))
80extra-objs += $(static-start-installed-name) g$(static-start-installed-name)
81omit-deps += $(patsubst %.o,%,$(static-start-installed-name) \
82			     g$(static-start-installed-name))
83install-lib += $(static-start-installed-name) g$(static-start-installed-name)
84ifeq (yes,$(enable-static-pie))
85extra-objs += r$(static-start-installed-name) gr$(static-start-installed-name)
86omit-deps += $(patsubst %.o,%,r$(static-start-installed-name) \
87			     gr$(static-start-installed-name))
88install-lib += r$(static-start-installed-name) gr$(static-start-installed-name)
89endif
90endif
91
92before-compile += $(objpfx)abi-tag.h
93generated += abi-tag.h
94
95# Put it here to generate it earlier.
96gen-as-const-headers += rtld-sizes.sym
97
98# These are the special initializer/finalizer files.  They are always the
99# first and last file in the link.  crti.o ... crtn.o define the global
100# "functions" _init and _fini to run the .init and .fini sections.
101crtstuff = crti crtn
102
103install-lib += $(crtstuff:=.o)
104extra-objs += $(crtstuff:=.o)
105
106ifneq ($(multidir),.)
107multilib-extra-objs = $(addprefix $(multidir)/, $(install-lib))
108extra-objs += $(multilib-extra-objs)
109endif
110
111extra-objs += abi-note.o init.o static-reloc.o
112ifeq (yes,$(build-shared))
113extra-objs += static-reloc.os
114endif
115asm-CPPFLAGS += -I$(objpfx).
116
117# Enable unwinding so backtrace unwinds to __libc_start_main
118CFLAGS-libc-start.c += -funwind-tables
119
120include ../Rules
121
122# Make these in the lib pass so they're available in time to link things with.
123subdir_lib: $(extra-objs:%=$(objpfx)%)
124
125define link-relocatable
126$(CC) -nostdlib -nostartfiles -r -o $@ $^
127endef
128
129ifndef start-installed-name-rule
130# We link the ELF startfile along with a SHT_NOTE section indicating
131# the kernel ABI the binaries linked with this library will require.
132$(objpfx)$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
133				  $(objpfx)init.o $(objpfx)static-reloc.o
134	$(link-relocatable)
135$(objpfx)r$(start-installed-name): $(objpfx)start.o $(objpfx)abi-note.o \
136				  $(objpfx)init.o
137	$(link-relocatable)
138$(objpfx)S$(start-installed-name): $(objpfx)start.os $(objpfx)abi-note.o \
139				  $(objpfx)init.o
140	$(link-relocatable)
141endif
142
143# The profiling startfile is made by linking together the normal
144# startfile with gmon-start.o, which defines a constructor function
145# to turn on profiling code at startup.
146ifeq (yes,$(build-shared))
147$(objpfx)g$(start-installed-name): \
148  $(objpfx)g%: $(objpfx)S% $(objpfx)gmon-start.os $(objpfx)static-reloc.os
149	$(link-relocatable)
150$(objpfx)gr$(start-installed-name): \
151  $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
152	$(link-relocatable)
153ifneq ($(start-installed-name),$(static-start-installed-name))
154$(objpfx)g$(static-start-installed-name): \
155  $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
156	$(link-relocatable)
157$(objpfx)gr$(static-start-installed-name): \
158  $(objpfx)gr%: $(objpfx)r% $(objpfx)gmon-start.o
159	$(link-relocatable)
160endif
161else
162$(addprefix $(objpfx),$(sort g$(start-installed-name) \
163			     g$(static-start-installed-name))): \
164  $(objpfx)g%: $(objpfx)% $(objpfx)gmon-start.o
165	$(link-relocatable)
166endif
167
168# These extra files are sometimes expected by system standard linking
169# procedures, but we have nothing for them to do.  So compile empty files.
170$(addprefix $(objpfx),$(filter-out $(start-installed-name), $(csu-dummies))):\
171  $(before-compile)
172	$(COMPILE.c) -o $@ -x c /dev/null
173
174# These headers are used by the startup code.
175$(objpfx)abi-tag.h: $(..)abi-tags
176	$(make-target-directory)
177	rm -f $@.new
178	sed -e 's/#.*$$//' -e '/^[	]*$$/d' $< | \
179	while read conf tagos tagver; do \
180	  test `expr '$(config-machine)-$(config-vendor)-$(config-os)' \
181		     : "$$conf"` != 0 || continue; \
182	  ( echo "$$tagos" | \
183	    sed -e 's/[^0-9xXa-fA-F 	]//' \
184		-e 's/^/#define __ABI_TAG_OS /'; \
185	    echo "#ifndef __ABI_TAG_VERSION"; \
186	    echo "$$tagver" | \
187	    sed -e 's/[^0-9xXa-fA-F]/ /g' -e 's/ *$$//' \
188	      -e 's/ /,/g' -e 's/^/# define __ABI_TAG_VERSION /'; \
189	    echo "#endif" ) > $@.new; \
190	done
191	if test -r $@.new; then mv -f $@.new $@; \
192	else echo >&2 'This configuration not matched in $<'; exit 1; fi
193
194ifneq ($(multidir),.)
195$(addprefix $(objpfx)$(multidir)/, $(install-lib)): $(addprefix $(objpfx), $(install-lib))
196	$(make-link-multidir)
197endif
198