From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v2] Check alignment of PT_LOAD segment only if possible
Date: Fri, 10 Dec 2021 14:02:13 -0800 [thread overview]
Message-ID: <20211210220213.3285838-1-hjl.tools@gmail.com> (raw)
Add a configure check for 2MB variable alignment and check alignment of
PT_LOAD segment only if 2MB variable alignment is supported.
Tested with cross build to glibcs-alpha-linux-gnu.
---
configure | 26 ++++++++++++++++++++++++++
configure.ac | 11 +++++++++++
elf/Makefile | 15 ++++++++++-----
3 files changed, 47 insertions(+), 5 deletions(-)
diff --git a/configure b/configure
index e4d013907c..37259efce7 100755
--- a/configure
+++ b/configure
@@ -6817,6 +6817,32 @@ if test $libc_cv_builtin_trap = yes; then
fi
+# Check target support for 2MB variable alignment.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for 2MB variable alignment" >&5
+$as_echo_n "checking for 2MB variable alignment... " >&6; }
+if ${libc_cv_have_2MB_alignment+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int foo __attribute__((aligned(0x200000))) = 1;
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ libc_cv_have_2MB_alignment=yes
+else
+ libc_cv_have_2MB_alignment=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_have_2MB_alignment" >&5
+$as_echo "$libc_cv_have_2MB_alignment" >&6; }
+config_vars="$config_vars
+have-2MB-alignment = $libc_cv_have_2MB_alignment"
+
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
diff --git a/configure.ac b/configure.ac
index a91a7f399c..57d4572c26 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1726,6 +1726,17 @@ if test $libc_cv_builtin_trap = yes; then
AC_DEFINE([HAVE_BUILTIN_TRAP])
fi
+# Check target support for 2MB variable alignment.
+AC_CACHE_CHECK([for 2MB variable alignment],
+ libc_cv_have_2MB_alignment, [
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+int foo __attribute__((aligned(0x200000))) = 1;
+])],
+ [libc_cv_have_2MB_alignment=yes],
+ [libc_cv_have_2MB_alignment=no])
+])
+LIBC_CONFIG_VAR([have-2MB-alignment], [$libc_cv_have_2MB_alignment])
+
dnl C++ feature tests.
AC_LANG_PUSH([C++])
diff --git a/elf/Makefile b/elf/Makefile
index fe42caeb0e..1bf77bc5ac 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -207,7 +207,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-tls4 tst-tls5 \
tst-tls10 tst-tls11 tst-tls12 tst-tls13 tst-tls14 tst-tls15 \
tst-tls16 tst-tls17 tst-tls18 tst-tls19 tst-tls-dlinfo \
- tst-align tst-align2 tst-align3 \
+ tst-align tst-align2 \
tst-dlmodcount tst-dlopenrpath tst-deep1 \
tst-dlmopen1 tst-dlmopen3 tst-dlmopen4 \
unload3 unload4 unload5 unload6 unload7 unload8 tst-global1 order2 \
@@ -241,9 +241,6 @@ tests-internal += loadtest unload unload2 circleload1 \
tests-container += tst-pldd tst-dlopen-tlsmodid-container \
tst-dlopen-self-container tst-preload-pthread-libc
test-srcs = tst-pathopt
-ifeq (yes,$(have-fpie))
-tests-pie += tst-align3
-endif
selinux-enabled := $(shell cat /selinux/enforce 2> /dev/null)
ifneq ($(selinux-enabled),1)
tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
@@ -305,7 +302,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
circlemod3 circlemod3a \
reldep8mod1 reldep8mod2 reldep8mod3 \
reldep9mod1 reldep9mod2 reldep9mod3 \
- tst-alignmod tst-alignmod2 tst-alignmod3 \
+ tst-alignmod tst-alignmod2 \
$(modules-execstack-$(have-z-execstack)) \
tst-dlopenrpathmod tst-deep1mod1 tst-deep1mod2 tst-deep1mod3 \
tst-dlmopen1mod tst-auditmod1 \
@@ -418,6 +415,14 @@ endif
modules-execstack-yes = tst-execstack-mod
extra-test-objs += $(addsuffix .os,$(strip $(modules-names)))
+ifeq (yes,$(have-2MB-alignment))
+tests += tst-align3
+modules-names += tst-alignmod3
+ifeq (yes,$(have-fpie))
+tests-pie += tst-align3
+endif
+endif
+
# filtmod1.so, tst-big-note-lib.so, tst-ro-dynamic-mod.so have special
# rules.
modules-names-nobuild := filtmod1 tst-big-note-lib tst-ro-dynamic-mod
--
2.33.1
next reply other threads:[~2021-12-10 22:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 22:02 H.J. Lu [this message]
2021-12-12 3:54 ` Rongwei Wang
2021-12-12 16:04 ` H.J. Lu
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