cpu_has_feature() has an optimisation where it maintains a map of possible cpu features. This allows the compiler to determine at compile time that some cpu_has_feature() checks will always return 0, and therefore the code guarded by the check can be elided.
However we have no logic to check whether the set of cpu features in the current cpu spec are in the possible map. Although that should never happen, if it does things are likely to go badly. So add a check and print a warning. Signed-off-by: Michael Ellerman <[email protected]> --- arch/powerpc/kernel/cputable.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index 6c8dd5d..eb31713 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -2255,6 +2255,15 @@ static struct cpu_spec * __init setup_cpu_spec(unsigned long offset, } #endif /* CONFIG_PPC64 || CONFIG_BOOKE */ + /* + * Check that all CPU features are in the possible mask. We don't want + * to WARN() because we're called very early, and doing so will kill + * the machine, so just printk() instead. + */ + if (t->cpu_features != (t->cpu_features & CPU_FTRS_POSSIBLE)) + printk("WARNING: cpu spec contains impossible features! 0x%lx\n", + (t->cpu_features & ~CPU_FTRS_POSSIBLE)); + return t; } -- 1.8.3.2 _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
