Le 02/09/2024 à 16:18, Christophe Leroy a écrit :
Le 02/09/2024 à 15:57, Jason A. Donenfeld a écrit :
On Mon, Sep 02, 2024 at 03:23:47PM +0200, Christophe Leroy wrote:
Le 02/09/2024 à 14:37, Mark Brown a écrit :
On Mon, Sep 02, 2024 at 02:22:38PM +0200, Christophe Leroy wrote:
When vdso_test_getcpu doesn't find the vDSO entry point, it prints
an error
text and returns KSFT_SKIP
I thought it would be more correct to have the same behaviour on
vdso_test_getrandom instead of trying to build it only when the
underlying
kernel supports it.
The problem is that the test incorporates assembler code so it simply
won't build for architectures without explicit porting, the issue isn't
if the target kernel supports it but rather that the test won't compile
in the first place.
Yes indeed and that was the purpose of my patch, have a macro in
vdso_config.h to tell where the assembler code is:
diff --git a/tools/testing/selftests/vDSO/vdso_config.h
b/tools/testing/selftests/vDSO/vdso_config.h
index 740ce8c98d2e..693920471160 100644
--- a/tools/testing/selftests/vDSO/vdso_config.h
+++ b/tools/testing/selftests/vDSO/vdso_config.h
@@ -47,6 +47,7 @@
#elif defined(__x86_64__)
#define VDSO_VERSION 0
#define VDSO_NAMES 1
+#define VDSO_GETRANDOM
"../../../../arch/x86/entry/vdso/vgetrandom-chacha.S"
#elif defined(__riscv__) || defined(__riscv)
#define VDSO_VERSION 5
#define VDSO_NAMES 1
And then:
diff --git a/tools/testing/selftests/vDSO/vdso_test_chacha-asm.S
b/tools/testing/selftests/vDSO/vdso_test_chacha-asm.S
new file mode 100644
index 000000000000..8e704165f6f2
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_test_chacha-asm.S
@@ -0,0 +1,7 @@
+#include "vdso_config.h"
+
+#ifdef VDSO_GETRANDOM
+
+#include VDSO_GETRANDOM
+
+#endif
I thought it was a lot easier to handle if through necessary #ifdefs in
vdso_config.h that implementing an additional logic in Makefiles.
Yet it still tripped up the test robot, right?
Yes I need to look at that.
In general I'm not crazy about this approach.
I have the feeling I get things done easier with that approach. But if
you feel better playing up with the makefile, I incline.
Also I thing that one day or another someone will want to implement it a
more performant way on power10 which is one of the latest powerpc CPU,
something similar to arch/powerpc/crypto/chacha-p10le-8x.S
When that happens, we will need a way to tell vdso_test_chacha to build
another vgetrandom-chacha.S and I feel that doing it in the Makefile
will become really tricky.
