On 7/2/19 5:37 pm, Segher Boessenkool wrote:
On Thu, Feb 07, 2019 at 04:33:23PM +1100, Andrew Donnellan wrote:
Some older gccs (<GCC 7), when invoked with -fsanitize-coverage=trace-pc,
cause a spurious uninitialised variable warning in dt_cpu_ftrs.c:

   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)

It seems to me the warning is correct?  If enable_unknown is false and no
cpu_feature is found, it will in

        if (m->cpu_ftr_bit_mask)
                cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask;

enable random features (whatever was last in the table), or indeed access
via NULL if the table is length 0?  So maybe this should be

        if (known && m->cpu_ftr_bit_mask)
                cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask;

instead?  (The code would be much clearer if all the known vs. !known
codepath was fully separated here).

The table is never length 0, it's a statically defined array.



Segher


--
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnel...@au1.ibm.com  IBM Australia Limited

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