On 02-09-19, 15:27, Mark Rutland wrote:
> On Thu, Aug 29, 2019 at 05:03:57PM +0530, Viresh Kumar wrote:
> > From: James Morse <james.morse@xxxxxxx>
> >
> > commit 644c2ae198412c956700e55a2acf80b2541f6aa5 upstream.
> >
> > CPU feature code uses the desc field as a test to find the end of the list,
> > this means every entry must have a description. This generates noise for
> > entries in the list that aren't really features, but combinations of them.
> > e.g.
> > > CPU features: detected feature: Privileged Access Never
> > > CPU features: detected feature: PAN and not UAO
> >
> > These combination features are needed for corner cases with alternatives,
> > where cpu features interact.
> >
> > Change all walkers of the arm64_features[] and arm64_hwcaps[] lists to test
> > 'matches' not 'desc', and only print 'desc' if it is non-NULL.
> >
> > Signed-off-by: James Morse <james.morse@xxxxxxx>
> > Reviewed-by : Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> > ---
> > arch/arm64/kernel/cpufeature.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
>
> >From looking at my 4.9.y/{meltdown,spectre} banches on kernel.org [1,2],
> and chasing the history v4.4..v4.9, there are a number of patches I'd
> expect to have alongside this that I don't spot in this series:
>
> * e3661b128e53ee281e1e7c589a5b647890bd6d7c ("arm64: Allow a capability to be checked on a single CPU")
> * 8f4137588261d7504f4aa022dc9d1a1fd1940e8e ("arm64: Allow checking of a CPU-local erratum")
> * 67948af41f2e6818edeeba5182811c704d484949 ("arm64: capabilities: Handle duplicate entries for a capability")
> * edf298cfce47ab7279d03b5203ae2ef3a58e49db ("arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early")
I also had to pick this one for cleaner rebase:
752835019c15 arm64: HWCAP: Split COMPAT HWCAP table entries
>
> ... which IIUC are necessary for big.LITTLE to work correctly.
I have pushed the changes to my branch again with above 5 patches and
some more reordering to match 4.9 log.
> Have you verified this for big.LITTLE?
Not sure if we ever talked about this earlier, but here is the
situation which I explained to Julien earlier.
I don't have access to the test-suite to verify that these patches
indeed fix the spectre mitigations and I was asked to backport these
and then ask for help from ARM to get these tested through the
test-suite. I was expecting Julien to do that earlier.
Julien did ask me to verify few things earlier, which can be done
without the test suite and was about checking that the new code paths
are getting hit now or not, which I did.
I haven't tested these on big LITTLE, though I can get the branch
through LAVA to get it tested on big LITTLE but I have no clue on what
I should be looking for in results :)
If there is some testing that can be done on my side for this, I sure
can do it. But I would need help from you on that to know what exactly
I need to check.
Thanks for the reviews Mark.
--
viresh
