On Thu, Feb 11, 2021 at 12:15 AM Ard Biesheuvel <a...@kernel.org> wrote:
>
> On Thu, 11 Feb 2021 at 03:52, Nick Desaulniers <ndesaulni...@google.com>
> wrote:
> >
> > GNU as warns twice for this file:
> > Warning: using r15 results in unpredictable behaviour
> >
> > via the Arm ARM:
> > K1.1.1 Overview of the constraints on Armv7 UNPREDICTABLE behaviors
> >
> > The term UNPREDICTABLE describes a number of cases where the
> > architecture has a feature that software must not use.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/1271
> > Link: https://reviews.llvm.org/D95586
> > Reported-by: kernelci.org bot <b...@kernelci.org>
> > Suggested-by: Peter Smith <peter.sm...@arm.com>
> > Suggested-by: Renato Golin <rengo...@systemcall.eu>
> > Suggested-by: David Spickett <david.spick...@linaro.org>
> > Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
>
> Acked-by: Ard Biesheuvel <a...@kernel.org>
>
> But can we add a bit more context to the commit log, please? It is not
Sure, that's a good idea.
> obvious to the casual reader why it is OK to emit UNPREDICTABLE
> opcodes, i.e., that these are selftests that aim to ensure that kprobe
> never attempts to replace the opcodes in question with a probe, but
> that they are not actually executed, or expected to occur in real
> code.
I'll add:
Ard notes:
These are selftests that aim to ensure that kprobe
never attempts to replace the opcodes in question with a probe, but
they are not actually executed, or expected to occur in real
code.
to the commit message, when submitting to RMK's queue.
Thanks for taking a look and the feedback.
>
> > ---
> > arch/arm/probes/kprobes/test-arm.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm/probes/kprobes/test-arm.c
> > b/arch/arm/probes/kprobes/test-arm.c
> > index 977369f1aa48..2543106a203e 100644
> > --- a/arch/arm/probes/kprobes/test-arm.c
> > +++ b/arch/arm/probes/kprobes/test-arm.c
> > @@ -166,10 +166,10 @@ void kprobe_arm_test_cases(void)
> >
> > /* Data-processing with PC as a target and status registers updated
> > */
> > TEST_UNSUPPORTED("movs pc, r1")
> > - TEST_UNSUPPORTED("movs pc, r1, lsl r2")
> > + TEST_UNSUPPORTED(__inst_arm(0xe1b0f211) " @movs pc, r1, lsl
> > r2")
> > TEST_UNSUPPORTED("movs pc, #0x10000")
> > TEST_UNSUPPORTED("adds pc, lr, r1")
> > - TEST_UNSUPPORTED("adds pc, lr, r1, lsl r2")
> > + TEST_UNSUPPORTED(__inst_arm(0xe09ef211) " @adds pc, lr, r1,
> > lsl r2")
> > TEST_UNSUPPORTED("adds pc, lr, #4")
> >
> > /* Data-processing with SP as target */
> > --
> > 2.30.0.478.g8a0d178c01-goog
> >
--
Thanks,
~Nick Desaulniers
