On Thu, Aug 29, 2019 at 05:03:57PM +0530, Viresh Kumar wrote:
From: James Morse james.morse@arm.com
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@arm.com Reviewed-by : Suzuki K Poulose suzuki.poulose@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
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")
... which IIUC are necessary for big.LITTLE to work correctly.
Have you verified this for big.LITTLE?
Thanks, Mark.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=stable... [2] https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=stable...
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index c1eddc07d996..bdb4cd9ffccf 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -744,7 +744,7 @@ static void setup_cpu_hwcaps(void) int i; const struct arm64_cpu_capabilities *hwcaps = arm64_hwcaps;
- for (i = 0; hwcaps[i].desc; i++)
- for (i = 0; hwcaps[i].matches; i++) if (hwcaps[i].matches(&hwcaps[i])) cap_set_hwcap(&hwcaps[i]);
} @@ -754,11 +754,11 @@ void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps, { int i;
- for (i = 0; caps[i].desc; i++) {
- for (i = 0; caps[i].matches; i++) { if (!caps[i].matches(&caps[i])) continue;
if (!cpus_have_cap(caps[i].capability))
if (!cpus_have_cap(caps[i].capability) && caps[i].desc) pr_info("%s %s\n", info, caps[i].desc);@@ -772,7 +772,7 @@ static void enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps) { int i;
- for (i = 0; caps[i].desc; i++)
- for (i = 0; caps[i].matches; i++) if (caps[i].enable && cpus_have_cap(caps[i].capability)) /* * Use stop_machine() as it schedules the work allowing
@@ -884,7 +884,7 @@ void verify_local_cpu_capabilities(void) return; caps = arm64_features;
- for (i = 0; caps[i].desc; i++) {
- for (i = 0; caps[i].matches; i++) { if (!cpus_have_cap(caps[i].capability) || !caps[i].sys_reg) continue; /*
@@ -897,7 +897,7 @@ void verify_local_cpu_capabilities(void) caps[i].enable(NULL); }
- for (i = 0, caps = arm64_hwcaps; caps[i].desc; i++) {
- for (i = 0, caps = arm64_hwcaps; caps[i].matches; i++) { if (!cpus_have_hwcap(&caps[i])) continue; if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i]))
-- 2.21.0.rc0.269.g1a574e7a288b