* [PATCH] um: Allow builds with Clang
@ 2022-02-17 0:28 Kees Cook
2022-02-17 0:37 ` Nathan Chancellor
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Kees Cook @ 2022-02-17 0:28 UTC (permalink / raw)
To: Jeff Dike
Cc: Kees Cook, Richard Weinberger, Anton Ivanov, Masahiro Yamada,
Nick Desaulniers, Nathan Chancellor, David Gow, linux-um,
linux-kbuild, linux-kselftest, kunit-dev, llvm, linux-kernel,
x86, linux-hardening
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@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: David Gow <davidgow@google.com>
Cc: linux-um@lists.infradead.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: kunit-dev@googlegroups.com
Cc: llvm@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
---
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
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] um: Allow builds with Clang 2022-02-17 0:28 [PATCH] um: Allow builds with Clang Kees Cook @ 2022-02-17 0:37 ` Nathan Chancellor 2022-02-17 2:59 ` David Gow 2022-02-17 4:54 ` Masahiro Yamada 2 siblings, 0 replies; 6+ messages in thread From: Nathan Chancellor @ 2022-02-17 0:37 UTC (permalink / raw) To: Kees Cook Cc: Jeff Dike, Richard Weinberger, Anton Ivanov, Masahiro Yamada, Nick Desaulniers, David Gow, linux-um, linux-kbuild, linux-kselftest, kunit-dev, llvm, linux-kernel, x86, linux-hardening On Wed, Feb 16, 2022 at 04:28:43PM -0800, Kees Cook 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 Clang-friendly assembly? > ("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@addtoit.com> > Cc: Richard Weinberger <richard@nod.at> > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: David Gow <davidgow@google.com> > Cc: linux-um@lists.infradead.org > Cc: linux-kbuild@vger.kernel.org > Cc: linux-kselftest@vger.kernel.org > Cc: kunit-dev@googlegroups.com > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> I am not super familiar with UML but this seems reasonable. Reviewed-by: Nathan Chancellor <nathan@kernel.org> One small nit below if you have to send a v2, not sure it is worth it otherwise. > --- > 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 It might be nice to keep this in alphabetical order. > CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) > > ifeq ($(CROSS_COMPILE),) > -- > 2.30.2 > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] um: Allow builds with Clang 2022-02-17 0:28 [PATCH] um: Allow builds with Clang Kees Cook 2022-02-17 0:37 ` Nathan Chancellor @ 2022-02-17 2:59 ` David Gow 2022-02-17 4:54 ` Masahiro Yamada 2 siblings, 0 replies; 6+ messages in thread From: David Gow @ 2022-02-17 2:59 UTC (permalink / raw) To: Kees Cook Cc: Jeff Dike, Richard Weinberger, Anton Ivanov, Masahiro Yamada, Nick Desaulniers, Nathan Chancellor, linux-um, linux-kbuild, open list:KERNEL SELFTEST FRAMEWORK, KUnit Development, llvm, Linux Kernel Mailing List, x86, linux-hardening On Thu, Feb 17, 2022 at 8:28 AM Kees Cook <keescook@chromium.org> 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@addtoit.com> > Cc: Richard Weinberger <richard@nod.at> > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: David Gow <davidgow@google.com> > Cc: linux-um@lists.infradead.org > Cc: linux-kbuild@vger.kernel.org > Cc: linux-kselftest@vger.kernel.org > Cc: kunit-dev@googlegroups.com > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> > --- 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@google.com> 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 > > -- > You received this message because you are subscribed to the Google Groups "KUnit Development" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kunit-dev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kunit-dev/20220217002843.2312603-1-keescook%40chromium.org. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] um: Allow builds with Clang 2022-02-17 0:28 [PATCH] um: Allow builds with Clang Kees Cook 2022-02-17 0:37 ` Nathan Chancellor 2022-02-17 2:59 ` David Gow @ 2022-02-17 4:54 ` Masahiro Yamada 2022-02-17 17:41 ` Nathan Chancellor 2 siblings, 1 reply; 6+ messages in thread From: Masahiro Yamada @ 2022-02-17 4:54 UTC (permalink / raw) To: Kees Cook Cc: Jeff Dike, Richard Weinberger, Anton Ivanov, Nick Desaulniers, Nathan Chancellor, David Gow, linux-um, Linux Kbuild mailing list, open list:KERNEL SELFTEST FRAMEWORK, kunit-dev, llvm, Linux Kernel Mailing List, X86 ML, linux-hardening On Thu, Feb 17, 2022 at 9:28 AM Kees Cook <keescook@chromium.org> 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@addtoit.com> > Cc: Richard Weinberger <richard@nod.at> > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> > Cc: Masahiro Yamada <masahiroy@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: David Gow <davidgow@google.com> > Cc: linux-um@lists.infradead.org > Cc: linux-kbuild@vger.kernel.org > Cc: linux-kselftest@vger.kernel.org > Cc: kunit-dev@googlegroups.com > Cc: llvm@lists.linux.dev > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > 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 Does this work for the i386 host? UML supports i386 and x86_64 as the host architecture as of now, but this always compiles UML for x86_64? > CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) > > ifeq ($(CROSS_COMPILE),) > -- > 2.30.2 > -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] um: Allow builds with Clang 2022-02-17 4:54 ` Masahiro Yamada @ 2022-02-17 17:41 ` Nathan Chancellor 2022-02-18 2:19 ` Masahiro Yamada 0 siblings, 1 reply; 6+ messages in thread From: Nathan Chancellor @ 2022-02-17 17:41 UTC (permalink / raw) To: Masahiro Yamada Cc: Kees Cook, Jeff Dike, Richard Weinberger, Anton Ivanov, Nick Desaulniers, David Gow, linux-um, Linux Kbuild mailing list, open list:KERNEL SELFTEST FRAMEWORK, kunit-dev, llvm, Linux Kernel Mailing List, X86 ML, linux-hardening On Thu, Feb 17, 2022 at 01:54:58PM +0900, Masahiro Yamada wrote: > On Thu, Feb 17, 2022 at 9:28 AM Kees Cook <keescook@chromium.org> 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@addtoit.com> > > Cc: Richard Weinberger <richard@nod.at> > > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> > > Cc: Masahiro Yamada <masahiroy@kernel.org> > > Cc: Nick Desaulniers <ndesaulniers@google.com> > > Cc: Nathan Chancellor <nathan@kernel.org> > > Cc: David Gow <davidgow@google.com> > > Cc: linux-um@lists.infradead.org > > Cc: linux-kbuild@vger.kernel.org > > Cc: linux-kselftest@vger.kernel.org > > Cc: kunit-dev@googlegroups.com > > Cc: llvm@lists.linux.dev > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > 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 > > > Does this work for the i386 host? > > UML supports i386 and x86_64 as the host architecture as of now, > but this always compiles UML for x86_64? I think the current code will work because arch/x86/Makefile.um includes -m32 for CONFIG_X86_32, which will implicitly change x86_64-linux-gnu into a 32-bit target triple: $ echo | clang --target=x86_64-linux-gnu -x c -c -o test.o - $ file test.o test.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped $ echo | clang --target=x86_64-linux-gnu -m32 -x c -c -o test.o - $ file test.o test.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped In fact, we rely on this for ARCH=i386 LLVM=1 right now, as it uses x86_64-linux-gnu for the target flag. While UML only supports x86, maybe it is worth using SUBARCH instead of hardcoding the triple? No strong opinion around that though. diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang index 51fc23e2e9e5..87285b76adb2 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 := $(CLANG_TARGET_FLAGS_$(SUBARCH)) CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) ifeq ($(CROSS_COMPILE),) > > CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) > > > > ifeq ($(CROSS_COMPILE),) > > -- > > 2.30.2 > > > > > -- > Best Regards > Masahiro Yamada ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] um: Allow builds with Clang 2022-02-17 17:41 ` Nathan Chancellor @ 2022-02-18 2:19 ` Masahiro Yamada 0 siblings, 0 replies; 6+ messages in thread From: Masahiro Yamada @ 2022-02-18 2:19 UTC (permalink / raw) To: Nathan Chancellor Cc: Kees Cook, Jeff Dike, Richard Weinberger, Anton Ivanov, Nick Desaulniers, David Gow, linux-um, Linux Kbuild mailing list, open list:KERNEL SELFTEST FRAMEWORK, kunit-dev, llvm, Linux Kernel Mailing List, X86 ML, linux-hardening On Fri, Feb 18, 2022 at 2:41 AM Nathan Chancellor <nathan@kernel.org> wrote: > > On Thu, Feb 17, 2022 at 01:54:58PM +0900, Masahiro Yamada wrote: > > On Thu, Feb 17, 2022 at 9:28 AM Kees Cook <keescook@chromium.org> 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@addtoit.com> > > > Cc: Richard Weinberger <richard@nod.at> > > > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> > > > Cc: Masahiro Yamada <masahiroy@kernel.org> > > > Cc: Nick Desaulniers <ndesaulniers@google.com> > > > Cc: Nathan Chancellor <nathan@kernel.org> > > > Cc: David Gow <davidgow@google.com> > > > Cc: linux-um@lists.infradead.org > > > Cc: linux-kbuild@vger.kernel.org > > > Cc: linux-kselftest@vger.kernel.org > > > Cc: kunit-dev@googlegroups.com > > > Cc: llvm@lists.linux.dev > > > Signed-off-by: Kees Cook <keescook@chromium.org> > > > --- > > > 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 > > > > > > Does this work for the i386 host? > > > > UML supports i386 and x86_64 as the host architecture as of now, > > but this always compiles UML for x86_64? > > I think the current code will work because arch/x86/Makefile.um includes > -m32 for CONFIG_X86_32, which will implicitly change x86_64-linux-gnu > into a 32-bit target triple: Ah, you are right! > > $ echo | clang --target=x86_64-linux-gnu -x c -c -o test.o - > > $ file test.o > test.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped > > $ echo | clang --target=x86_64-linux-gnu -m32 -x c -c -o test.o - > > $ file test.o > test.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped > > In fact, we rely on this for ARCH=i386 LLVM=1 right now, as it uses > x86_64-linux-gnu for the target flag. > > While UML only supports x86, maybe it is worth using SUBARCH instead of > hardcoding the triple? No strong opinion around that though. > > diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang > index 51fc23e2e9e5..87285b76adb2 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 := $(CLANG_TARGET_FLAGS_$(SUBARCH)) LGTM. I also thought of not passing --target at all for ARCH=um, but we decided to override --target all the time (for reproducibility?). Anyway, Nathan's way is clean, and looks OK to me. > CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) > > ifeq ($(CROSS_COMPILE),) > > > > CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(SRCARCH)) > > > > > > ifeq ($(CROSS_COMPILE),) > > > -- > > > 2.30.2 > > > > > > > > > -- > > Best Regards > > Masahiro Yamada -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-02-18 2:20 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-02-17 0:28 [PATCH] um: Allow builds with Clang Kees Cook 2022-02-17 0:37 ` Nathan Chancellor 2022-02-17 2:59 ` David Gow 2022-02-17 4:54 ` Masahiro Yamada 2022-02-17 17:41 ` Nathan Chancellor 2022-02-18 2:19 ` Masahiro Yamada
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