Commit 8cfaf106 authored by Michael Ellerman's avatar Michael Ellerman

powerpc/64s: Fix logic when handling unknown CPU features

In cpufeatures_process_feature(), if a provided CPU feature is unknown and
enable_unknown is false, we erroneously print that the feature is being
enabled and return true, even though no feature has been enabled, and
may also set feature bits based on the last entry in the match table.

Fix this so that we only set feature bits from the match table if we have
actually enabled a feature from that table, and when failing to enable an
unknown feature, always print the "not enabling" message and return false.

Coincidentally, some older gccs (<GCC 7), when invoked with
-fsanitize-coverage=trace-pc, cause a spurious uninitialised variable
warning in this function:

  arch/powerpc/kernel/dt_cpu_ftrs.c: In function ‘cpufeatures_process_feature’:
  arch/powerpc/kernel/dt_cpu_ftrs.c:686:7: warning: ‘m’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    if (m->cpu_ftr_bit_mask)

An upcoming patch will enable support for kcov, which requires this option.
This patch avoids the warning.

Fixes: 5a61ef74 ("powerpc/64s: Support new device tree binding for discovering CPU features")
Reported-by: default avatarSegher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
[ajd: add commit message]
Signed-off-by: default avatarAndrew Donnellan <andrew.donnellan@au1.ibm.com>
parent 6fe243fe
...@@ -666,8 +666,10 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f) ...@@ -666,8 +666,10 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
m = &dt_cpu_feature_match_table[i]; m = &dt_cpu_feature_match_table[i];
if (!strcmp(f->name, m->name)) { if (!strcmp(f->name, m->name)) {
known = true; known = true;
if (m->enable(f)) if (m->enable(f)) {
cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask;
break; break;
}
pr_info("not enabling: %s (disabled or unsupported by kernel)\n", pr_info("not enabling: %s (disabled or unsupported by kernel)\n",
f->name); f->name);
...@@ -675,17 +677,12 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f) ...@@ -675,17 +677,12 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
} }
} }
if (!known && enable_unknown) { if (!known && (!enable_unknown || !feat_try_enable_unknown(f))) {
if (!feat_try_enable_unknown(f)) { pr_info("not enabling: %s (unknown and unsupported by kernel)\n",
pr_info("not enabling: %s (unknown and unsupported by kernel)\n", f->name);
f->name); return false;
return false;
}
} }
if (m->cpu_ftr_bit_mask)
cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask;
if (known) if (known)
pr_debug("enabling: %s\n", f->name); pr_debug("enabling: %s\n", f->name);
else else
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment