| Message ID | 20191126161255.323992-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: fix comparison of u8 with -1 | expand |
On Tue, Nov 26, 2019 at 8:21 AM Colin King <colin.king@canonical.com> wrote: > > From: Colin Ian King <colin.king@canonical.com> > > The comparison of the u8 value __entry->u with -1 is always > going to be false because a __entry-u can never be negative. > Fix this by casting it to a s8 integer. > > Addresses clang warning: > arch/x86/kvm/./mmutrace.h:360:16: warning: result of comparison > of constant -1 with expression of type 'u8' (aka 'unsigned char') > is always false [-Wtautological-constant-out-of-range-compare] (__entry->u is defined as a u8) > > Fixes: 335e192a3fa4 ("KVM: x86: add tracepoints around __direct_map and FNAME(fetch)") > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > arch/x86/kvm/mmutrace.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h > index 7ca8831c7d1a..3466cd528a67 100644 > --- a/arch/x86/kvm/mmutrace.h > +++ b/arch/x86/kvm/mmutrace.h > @@ -357,7 +357,7 @@ TRACE_EVENT( > __entry->r ? "r" : "-", > __entry->spte & PT_WRITABLE_MASK ? "w" : "-", > __entry->x ? "x" : "-", > - __entry->u == -1 ? "" : (__entry->u ? "u" : "-"), > + (s8)__entry->u == -1 ? "" : (__entry->u ? "u" : "-"), Or could compare against 0xFF instead of -1. Either way, thanks for the patch. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > __entry->level, __entry->sptep > ) > );
diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h index 7ca8831c7d1a..3466cd528a67 100644 --- a/arch/x86/kvm/mmutrace.h +++ b/arch/x86/kvm/mmutrace.h @@ -357,7 +357,7 @@ TRACE_EVENT( __entry->r ? "r" : "-", __entry->spte & PT_WRITABLE_MASK ? "w" : "-", __entry->x ? "x" : "-", - __entry->u == -1 ? "" : (__entry->u ? "u" : "-"), + (s8)__entry->u == -1 ? "" : (__entry->u ? "u" : "-"), __entry->level, __entry->sptep ) );