• Michael Ellerman's avatar
    powerpc/64s: Fix logic when handling unknown CPU features · 8cfaf106
    Michael Ellerman authored
    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>
    8cfaf106
dt_cpu_ftrs.c 25 KB