arm64: cpufeature: Test 'matches' pointer to find the end of the list

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>
(cherry picked from commit 644c2ae198412c956700e55a2acf80b2541f6aa5)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index ae22edf9d3c904dcbad2e86028e92080d39a1a3b..9cc8186cd14b467e857255b3405cbcf240e4f3d6 100644 (file)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -771,7 +771,7 @@ static void __init 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]);
 }
@@ -781,11 +781,11 @@ 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);
                cpus_set_cap(caps[i].capability);
        }
@@ -800,7 +800,7 @@ 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))
                        on_each_cpu(caps[i].enable, NULL, true);
 }
@@ -907,7 +907,7 @@ 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;
                /*
@@ -920,7 +920,7 @@ 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]))