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* [glibc/maskray/clang] x86_64: Improve Intel MPX check to reject incomplete Clang support
@ 2021-10-10 23:34 Fangrui Song
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From: Fangrui Song @ 2021-10-10 23:34 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b97388ab52adf4b53a5b40f65321fb40241c2f9b
commit b97388ab52adf4b53a5b40f65321fb40241c2f9b
Author: Fangrui Song <maskray@google.com>
Date: Sat Sep 25 23:36:15 2021 -0700
x86_64: Improve Intel MPX check to reject incomplete Clang support
LLVM integrated assembler has incomplete MPX support, e.g.
bnd is not supported while bndmov is supported:
error: invalid instruction mnemonic 'bnd'
Improve the configure check so that HAVE_MPX_SUPPORT code can be
properly skipped.
Diff:
---
sysdeps/x86_64/configure | 2 ++
sysdeps/x86_64/configure.ac | 2 ++
2 files changed, 4 insertions(+)
diff --git a/sysdeps/x86_64/configure b/sysdeps/x86_64/configure
index 585279f83d..c3145e6030 100755
--- a/sysdeps/x86_64/configure
+++ b/sysdeps/x86_64/configure
@@ -30,6 +30,8 @@ if ${libc_cv_asm_mpx+:} false; then :
else
cat > conftest.s <<\EOF
bndmov %bnd0,(%rsp)
+ bnd
+ jmp *%r11
EOF
if { ac_try='${CC-cc} -c $ASFLAGS conftest.s 1>&5'
{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
diff --git a/sysdeps/x86_64/configure.ac b/sysdeps/x86_64/configure.ac
index 29e14033c0..3c935d66e1 100644
--- a/sysdeps/x86_64/configure.ac
+++ b/sysdeps/x86_64/configure.ac
@@ -14,6 +14,8 @@ dnl Check whether asm supports Intel MPX
AC_CACHE_CHECK(for Intel MPX support, libc_cv_asm_mpx, [dnl
cat > conftest.s <<\EOF
bndmov %bnd0,(%rsp)
+ bnd
+ jmp *%r11
EOF
if AC_TRY_COMMAND(${CC-cc} -c $ASFLAGS conftest.s 1>&AS_MESSAGE_LOG_FD); then
libc_cv_asm_mpx=yes
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