On Wed, 2021-09-15 at 16:31 +0200, Christophe Leroy wrote: > dcbz instruction shouldn't be used on non-cached memory. Using > it on non-cached memory can result in alignment exception and > implies a heavy handling. > > Instead of silentely emulating the instruction and resulting in high > performance degradation, warn whenever an alignment exception is > taken due to dcbz, so that the user is made aware that dcbz > instruction has been used unexpectedly. > > Reported-by: Stan Johnson <user...@yahoo.com> > Cc: Finn Thain <fth...@linux-m68k.org> > Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu> > --- > arch/powerpc/kernel/align.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/powerpc/kernel/align.c > b/arch/powerpc/kernel/align.c > index bbb4181621dd..adc3a4a9c6e4 100644 > --- a/arch/powerpc/kernel/align.c > +++ b/arch/powerpc/kernel/align.c > @@ -349,6 +349,7 @@ int fix_alignment(struct pt_regs *regs) > if (op.type != CACHEOP + DCBZ) > return -EINVAL; > PPC_WARN_ALIGNMENT(dcbz, regs); > + WARN_ON_ONCE(1);
This is heavy handed ... It will be treated as an oops by various things uselessly spit out a kernel backtrace. Isn't PPC_WARN_ALIGNMENT enough ? Ben.
