On Thu, Feb 17, 2022 at 8:28 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> Add x86-64 target for Clang+um and update user-offsets.c to use
> Clang-friendly assembler, similar to the fix from commit cf0c3e68aa81
> ("kbuild: fix asm-offset generation to work with clang").
>
> This lets me run KUnit tests with Clang:
>
> $ ./tools/testing/kunit/kunit.py config --make_options LLVM=1
> ...
> $ ./tools/testing/kunit/kunit.py run --make_options LLVM=1
> ...
>
> Cc: Jeff Dike <jdike@xxxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Anton Ivanov <anton.ivanov@xxxxxxxxxxxxxxxxxx>
> Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
> Cc: David Gow <davidgow@xxxxxxxxxx>
> Cc: linux-um@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kbuild@xxxxxxxxxxxxxxx
> Cc: linux-kselftest@xxxxxxxxxxxxxxx
> Cc: kunit-dev@xxxxxxxxxxxxxxxx
> Cc: llvm@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
Thanks, this worked fine for me, with one small note:
I get the following warning with clang (13.0.1) under UML (but not
under x86_64):
clang: warning: argument unused during compilation:
'-mno-global-merge' [-Wunused-command-line-argument]
It's not really a problem unless -Werror is enabled, though, so this
is still definitely an improvement over clang not working at all.
With that caveat, this is:
Tested-by: David Gow <davidgow@xxxxxxxxxx>
Cheers,
-- David
> arch/x86/um/user-offsets.c | 4 ++--
> scripts/Makefile.clang | 1 +
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
> index bae61554abcc..d9071827b515 100644
> --- a/arch/x86/um/user-offsets.c
> +++ b/arch/x86/um/user-offsets.c
> @@ -10,10 +10,10 @@
> #include <asm/types.h>
>
> #define DEFINE(sym, val) \
> - asm volatile("\n->" #sym " %0 " #val : : "i" (val))
> + asm volatile("\n.ascii \"->" #sym " %0 " #val "\"": : "i" (val))
>
> #define DEFINE_LONGS(sym, val) \
> - asm volatile("\n->" #sym " %0 " #val : : "i" (val/sizeof(unsigned long)))
> + asm volatile("\n.ascii \"->" #sym " %0 " #val "\"": : "i" (val/sizeof(unsigned long)))
>
> void foo(void)
> {
> diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang
> index 51fc23e2e9e5..857b23de51c6 100644
> --- a/scripts/Makefile.clang
> +++ b/scripts/Makefile.clang
> @@ -10,6 +10,7 @@ CLANG_TARGET_FLAGS_powerpc := powerpc64le-linux-gnu
> CLANG_TARGET_FLAGS_riscv := riscv64-linux-gnu
> CLANG_TARGET_FLAGS_s390 := s390x-linux-gnu
> CLANG_TARGET_FLAGS_x86 := x86_64-linux-gnu
> +CLANG_TARGET_FLAGS_um := x86_64-linux-gnu
> CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH))
>
> ifeq ($(CROSS_COMPILE),)
> --
> 2.30.2
>
> --
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