diff mbox series

[RFC,v10,4/7] Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (bug 22745)

Message ID 20210322154111.24798-5-vivek@collabora.com
State New
Delegated to: Adhemerval Zanella Netto
Headers show
Series Implementation of RTLD_SHARED for dlmopen | expand

Commit Message

Vivek Das Mohapatra March 22, 2021, 3:41 p.m. UTC
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).
---
 Makeconfig                |  3 +++
 Makerules                 | 19 +++++++++++++-
 config.make.in            |  1 +
 configure                 | 54 ++++++++++++++++++++++++++++++++++++---
 configure.ac              | 32 +++++++++++++++++++++--
 dynamic-notes.c           |  4 +++
 elf/Makefile              |  3 +++
 extra-lib.mk              |  3 +++
 htl/Makefile              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 +++
 nptl/Makefile             |  3 +++
 12 files changed, 126 insertions(+), 6 deletions(-)
 create mode 100644 dynamic-notes.c
diff mbox series

Patch

diff --git a/Makeconfig b/Makeconfig
index 01f8638c2e..7e1116163f 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 ca9885436e..d54767f3a6 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 +637,17 @@  build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+%/dynamic-notes.os: dynamic-notes.c
+
+ifeq ($(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 +718,11 @@  $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/config.make.in b/config.make.in
index 7f47f0caa4..c2d818681b 100644
--- a/config.make.in
+++ b/config.make.in
@@ -72,6 +72,7 @@  have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
 fno-unit-at-a-time = @fno_unit_at_a_time@
 bind-now = @bindnow@
 have-hash-style = @libc_cv_hashstyle@
+ld-zunique = @ld_zunique@
 use-default-link = @use_default_link@
 have-cxx-thread_local = @libc_cv_cxx_thread_local@
 have-loop-to-function = @libc_cv_cc_loop_to_function@
diff --git a/configure b/configure
index 37cef37413..1040130d6c 100755
--- a/configure
+++ b/configure
@@ -685,6 +685,7 @@  hardcoded_path_in_tests
 enable_timezone_tools
 extra_nonshared_cflags
 use_default_link
+ld_zunique
 sysheaders
 ac_ct_CXX
 CXXFLAGS
@@ -731,6 +732,7 @@  infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -843,6 +845,7 @@  datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1095,6 +1098,15 @@  do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1232,7 +1244,7 @@  fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1385,6 +1397,7 @@  Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -3331,6 +3344,7 @@  fi
 
 
 
+
 # Check whether --with-default-link was given.
 if test "${with_default_link+set}" = set; then :
   withval=$with_default_link; use_default_link=$withval
@@ -5976,6 +5990,34 @@  fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+{ $as_echo "$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 ${libc_cv_ld_zunique+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.ld.c <<\EOF
+int x (void) { return 0; }
+EOF
+libc_cv_ld_zunique=no;
+if { ac_try='${CC-cc} -Wl,--fatal-warnings -Wl,-z,unique -shared -o conftest.ld.so conftest.ld.c'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  libc_cv_ld_zunique=yes
+else
+  echo >&5 "\
+${CC-cc} does not support -Wl,-z,unique from:
+$ac_try"
+fi;
+ld_zunique=$libc_cv_ld_zunique
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ld_zunique" >&5
+$as_echo "$libc_cv_ld_zunique" >&6; }
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
 # all allocated NOTE sections come first.
@@ -6021,10 +6063,16 @@  EOF
       esac
       shift 2
     done
-    case "$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 anyway"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 16b15b6f90..178874aa12 100644
--- a/configure.ac
+++ b/configure.ac
@@ -148,6 +148,7 @@  AC_ARG_WITH([headers],
 	    [sysheaders=''])
 AC_SUBST(sysheaders)
 
+AC_SUBST(ld_zunique)
 AC_SUBST(use_default_link)
 AC_ARG_WITH([default-link],
 	    AS_HELP_STRING([--with-default-link],
@@ -1352,6 +1353,27 @@  fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1/ DF_GNU_1_UNIQUE support],
+                libc_cv_ld_zunique, [dnl
+cat > conftest.ld.c <<\EOF
+int x (void) { return 0; }
+EOF
+libc_cv_ld_zunique=no;
+dnl FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME
+dnl THIS IS DELIBERATELY WRONG SO WE CAN TEST BUILDING WITH A TOO-OLD LINKER
+dnl FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME
+if AC_TRY_COMMAND([dnl
+${CC-cc} -Wl,--fatal-warnings -Wl,-z,unique -shared -o conftest.ld.so conftest.ld.c])
+then
+  libc_cv_ld_zunique=yes
+else
+  echo >&AS_MESSAGE_LOG_FD "\
+${CC-cc} does not support -Wl,-z,unique from:
+$ac_try"
+fi;
+ld_zunique=$libc_cv_ld_zunique
+rm -f conftest*])
+
 # 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.
@@ -1390,10 +1412,16 @@  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 anyway"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/dynamic-notes.c b/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/dynamic-notes.c
@@ -0,0 +1,4 @@ 
+#include <link.h>
+
+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/elf/Makefile b/elf/Makefile
index 3b8e13e066..22f2a87fcb 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -102,6 +102,9 @@  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/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..4e4a447d5e 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)dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/htl/Makefile b/htl/Makefile
index 895a6f777c..65ddd202a1 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -205,6 +205,9 @@  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 55c527a5f7..2fe2404ade 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..4d81358f19 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: $(common-objpfx)dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif
diff --git a/nptl/Makefile b/nptl/Makefile
index b1948cc47a..dedfe389c0 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -396,6 +396,9 @@  tests-printers-libs := $(static-thread-library)
 endif
 
 LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
+ifeq ($(ld-zunique),yes)
+LDFLAGS-pthread.so += -Wl,-z,unique
+endif
 
 tests += tst-cancelx7 tst-cancelx17 tst-cleanupx4