On Wed, Dec 23, 2020 at 06:42:20PM +0100, Borislav Petkov wrote: > From: Borislav Petkov <[email protected]> > > intel_pmu_pebs_fixup_ip() needs only the insn length so use the > appropriate helper instead of a full decode. A full decode differs only > in running insn_complete() on the decoded insn but that is not needed > here. > > Signed-off-by: Borislav Petkov <[email protected]> > --- > arch/x86/events/intel/ds.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c > index 67dbc91bccfe..3786b4e07078 100644 > --- a/arch/x86/events/intel/ds.c > +++ b/arch/x86/events/intel/ds.c > @@ -1265,14 +1265,14 @@ static int intel_pmu_pebs_fixup_ip(struct pt_regs > *regs) > is_64bit = kernel_ip(to) || any_64bit_mode(regs); > #endif > insn_init(&insn, kaddr, size, is_64bit); > - insn_get_length(&insn); > + > /* > * Make sure there was not a problem decoding the > * instruction and getting the length. This is > * doubly important because we have an infinite > * loop if insn.length=0. > */ > - if (!insn.length) > + if (insn_get_length(&insn) || !insn.length)
Do we really still need the !insn.length? That is, it *should* be impossible to not fail insn_get_length() and still have a 0 length, seeing how x86 doesn't have 0 length instructions.
