From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id C03A73938C25; Mon, 9 Aug 2021 20:17:54 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C03A73938C25 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745) X-Act-Checkin: glibc X-Git-Author: Vivek Das Mohapatra X-Git-Refname: refs/heads/azanella/rtld-shared X-Git-Oldrev: 22b419be4e23df6fead108b7a40ea7b019aa9f13 X-Git-Newrev: 83dc194adfa8e5b0747947806409a4582369da24 Message-Id: <20210809201754.C03A73938C25@sourceware.org> Date: Mon, 9 Aug 2021 20:17:54 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Aug 2021 20:17:54 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=83dc194adfa8e5b0747947806409a4582369da24 commit 83dc194adfa8e5b0747947806409a4582369da24 Author: Vivek Das Mohapatra Date: Thu Jul 8 17:32:51 2021 +0100 elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745) libc.so, libpthread.so etc should have the new unique-dso-by-default flag set to allow dlmopen to work better (libc et al instance shared by default when DSOs dlmopened into a new namespace). Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Adhemerval Zanella Diff: --- Makeconfig | 3 +++ Makerules | 18 +++++++++++++++++- config.make.in | 1 + configure | 48 ++++++++++++++++++++++++++++++++++++++++++++--- configure.ac | 23 ++++++++++++++++++++--- elf/Makefile | 3 +++ elf/dynamic-notes.c | 4 ++++ extra-lib.mk | 3 +++ htl/Makefile | 3 +++ iconvdata/Makefile | 3 +++ iconvdata/extra-module.mk | 4 ++++ 11 files changed, 106 insertions(+), 7 deletions(-) diff --git a/Makeconfig b/Makeconfig index 68663d984e..1046ebb291 100644 --- a/Makeconfig +++ b/Makeconfig @@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now # Extra flags for dynamically linked non-test main programs. link-extra-flags += -Wl,-z,now endif +ifeq ($(ld-zunique),yes) +LDFLAGS-lib.so += -Wl,-z,unique +endif # Command to run after every final link (executable or shared object). # This is invoked with $(call after-link,...), so it should operate on diff --git a/Makerules b/Makerules index 596fa68376..66c1251754 100644 --- a/Makerules +++ b/Makerules @@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules PROVIDE(__start___libc_IO_vtables = .);\ __libc_IO_vtables : { *(__libc_IO_vtables) }\ PROVIDE(__stop___libc_IO_vtables = .);\ - /DISCARD/ : { *(.gnu.glibc-stub.*) }@' + /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \ + -e 's/^.*\*(\.dynamic).*$$/ .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/' test -s $@T mv -f $@T $@ common-generated += shlib.lds @@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \ # Also omits crti.o and crtn.o, which we do not want # since we define our own `.init' section specially. LDFLAGS-c.so = -nostdlib -nostartfiles + +# The stub dynamic-notes.os should not have weak/undefined symbol magic in it. +# It's not really part of the internals, rather it is a vector for linker magic +# which we need when the linker isn't new enough: +%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME + +ifeq ($(ld-zunique),yes) +LDFLAGS-c.so += -Wl,-z,unique +endif + # But we still want to link libc.so against $(libc.so-gnulib). LDLIBS-c.so += $(libc.so-gnulib) # Give libc.so an entry point and make it directly runnable itself. @@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \ $(build-shlib) $(call after-link,$@) +ifneq ($(ld-zunique),yes) +$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os +$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os +endif + ifeq ($(build-shared),yes) $(common-objpfx)libc.so: $(common-objpfx)libc.map endif diff --git a/config.make.in b/config.make.in index cbf59114b0..8755490c13 100644 --- a/config.make.in +++ b/config.make.in @@ -72,6 +72,7 @@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@ fno-unit-at-a-time = @fno_unit_at_a_time@ bind-now = @bindnow@ have-hash-style = @libc_cv_hashstyle@ +ld-zunique = @ld_zunique@ use-default-link = @use_default_link@ have-cxx-thread_local = @libc_cv_cxx_thread_local@ have-loop-to-function = @libc_cv_cc_loop_to_function@ diff --git a/configure b/configure index 9619c10991..3e6d7ffc49 100755 --- a/configure +++ b/configure @@ -625,6 +625,7 @@ libc_cv_cc_nofma libc_cv_mtls_dialect_gnu2 fno_unit_at_a_time libc_cv_has_glob_dat +ld_zunique libc_cv_hashstyle libc_cv_fpie libc_cv_z_execstack @@ -6074,9 +6075,44 @@ fi $as_echo "$libc_cv_hashstyle" >&6; } +old_LDFLAGS="$LDFLAGS" +LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared" +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5 +$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; } +if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +void foo (void) { } +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + libc_cv_ld_zunique=yes +else + libc_cv_ld_zunique=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then : + $as_echo_n "(cached) " >&6 +fi +eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +void foo (void) { } +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + libc_cv_ld_zunique=yes +else + libc_cv_ld_zunique=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5 +$as_echo "$ac_res" >&6; } +LDFLAGS="$old_LDFLAGS" + + # The linker's default -shared behavior is good enough if it # does these things that our custom linker scripts ensure that -# all allocated NOTE sections come first. +# all allocated NOTE sections come first AND it understands +# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE +# sections in its output. if test "$use_default_link" = default; then { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5 $as_echo_n "checking for sufficient default -shared layout... " >&6; } @@ -6119,10 +6155,16 @@ EOF esac shift 2 done - case "$libc_seen_a$libc_seen_b" in - yesyes) + case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in + yesyesyes) libc_cv_use_default_link=yes ;; + yesyesno) + echo >&5 "\ +shared layout from: +$ac_try +is OK but -Wl,-z,unique is unsupported so linker scripts are required" + ;; *) echo >&5 "\ $libc_seen_a$libc_seen_b from: diff --git a/configure.ac b/configure.ac index 34ecbba540..6a443007fe 100644 --- a/configure.ac +++ b/configure.ac @@ -1372,9 +1372,20 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_hashstyle) +old_LDFLAGS="$LDFLAGS" +LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared" +AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support], + AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])], + libc_cv_ld_zunique=yes, + libc_cv_ld_zunique=no)) +LDFLAGS="$old_LDFLAGS" +AC_SUBST(ld_zunique) + # The linker's default -shared behavior is good enough if it # does these things that our custom linker scripts ensure that -# all allocated NOTE sections come first. +# all allocated NOTE sections come first AND it understands +# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE +# sections in its output. if test "$use_default_link" = default; then AC_CACHE_CHECK([for sufficient default -shared layout], libc_cv_use_default_link, [dnl @@ -1410,10 +1421,16 @@ EOF esac shift 2 done - case "$libc_seen_a$libc_seen_b" in - yesyes) + case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in + yesyesyes) libc_cv_use_default_link=yes ;; + yesyesno) + echo >&AS_MESSAGE_LOG_FD "\ +shared layout from: +$ac_try +is OK but -Wl,-z,unique is unsupported so linker scripts are required" + ;; *) echo >&AS_MESSAGE_LOG_FD "\ $libc_seen_a$libc_seen_b from: diff --git a/elf/Makefile b/elf/Makefile index d05f410592..f33a761c93 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -103,6 +103,9 @@ endif ifeq (yes,$(build-shared)) extra-objs = $(all-rtld-routines:%=%.os) sofini.os interp.os +ifneq (yes,$(ld-zunique)) +extra-objs += dynamic-notes.os +endif generated += librtld.os dl-allobjs.os ld.so ldd install-others = $(inst_rtlddir)/$(rtld-installed-name) install-bin-script = ldd diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c new file mode 100644 index 0000000000..d0b487e970 --- /dev/null +++ b/elf/dynamic-notes.c @@ -0,0 +1,4 @@ +#include + +const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) = + { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE }; diff --git a/extra-lib.mk b/extra-lib.mk index 72f8d2e1df..9051958ec0 100644 --- a/extra-lib.mk +++ b/extra-lib.mk @@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \ $(addprefix $(common-objpfx), \ $(filter $(lib).map, \ $(version-maps)))) +ifneq ($(ld-zunique),yes) +$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os +endif endif endif diff --git a/htl/Makefile b/htl/Makefile index cf9d12fc12..c2a25dcd79 100644 --- a/htl/Makefile +++ b/htl/Makefile @@ -203,6 +203,9 @@ libc-link.so = $(common-objpfx)libc.so extra-B-pthread.so = -B$(common-objpfx)htl/ LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst +ifeq ($(ld-zunique),yes) +LDFLAGS-pthread.so += -Wl,-z,unique +endif include ../Rules diff --git a/iconvdata/Makefile b/iconvdata/Makefile index c216f959df..b1b46e5a43 100644 --- a/iconvdata/Makefile +++ b/iconvdata/Makefile @@ -67,6 +67,9 @@ modules := ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5 \ ifeq ($(bind-now),yes) LDFLAGS.so += -Wl,-z,now endif +ifeq ($(ld-zunique),yes) +LDFLAGS.so += -Wl,-z,unique +endif modules.so := $(addsuffix .so, $(modules)) diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk index ecaf507624..92c3ab4d7b 100644 --- a/iconvdata/extra-module.mk +++ b/iconvdata/extra-module.mk @@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\ $(shlib-lds) $(link-libc-deps) $(build-module-asneeded) +ifneq ($(ld-zunique),yes) +$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os +endif + ifneq (,$(extra-modules-left)) include extra-module.mk endif