On Fri, Nov 3, 2017 at 11:52 AM, Mark Rutland [off-list ref] wrote:

On Fri, Nov 03, 2017 at 06:31:56PM +0000, Mark Rutland wrote:

quoted

On Fri, Nov 03, 2017 at 10:11:52AM -0700, Sami Tolvanen wrote:

quoted

From: Greg Hackmann <redacted>

LLVM bug 30792 causes clang's AArch64 backend to crash compiling
arch/arm64/crypto/aes-ce-cipher.c.  Replacing -mgeneral-regs-only with
-mno-implicit-float is the suggested workaround.

Signed-off-by: Greg Hackmann <redacted>
Cc: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Just to check, what happens if you pass both to clang?

Apparently not. However, we can do:

-KBUILD_CFLAGS  += -mgeneral-regs-only $(lseinstr) $(brokengasinst)
+KBUILD_CFLAGS  += $(lseinstr) $(brokengasinst)
+# Clang workaround for https://bugs.llvm.org/show_bug.cgi?id=30792
+KBUILD_CFLAGS  += $(call cc-option, -mno-implicit-float, -mgeneral-regs-only)

Should a clang version test be included, since we know at least 5.0 is
need (with this fix)? There are distros with much earlier versions of
clang, for example...

-Kees

-- 
Kees Cook
Pixel Security