| Message ID | 20181107194858.9380-2-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/23] x86/fpu: Use ULL for shift in xfeature_uncompacted_offset() | expand |
On Wed, Nov 07, 2018 at 08:48:36PM +0100, Sebastian Andrzej Siewior wrote: > The xfeature mask is 64bit so a shift from a number to its mask should > have LL prefix or else nr > 31 will be lost. This is not a problem now > but should XFEATURE_MASK_SUPERVISOR gain a bit >31 then this check won't > catch it. > > Add a ULL suffix so >31bit number will be properly shifted. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > arch/x86/kernel/fpu/xstate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index 87a57b7642d36..9dc0a2c8c2755 100644 > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -444,7 +444,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr) > * format. Checking a supervisor state's uncompacted offset is > * an error. > */ > - if (XFEATURE_MASK_SUPERVISOR & (1 << xfeature_nr)) { > + if (XFEATURE_MASK_SUPERVISOR & (1ULL << xfeature_nr)) { Or simply BIT_ULL(xfeature_nr).
On 2018-11-08 12:38:17 [+0100], Borislav Petkov wrote:
> Or simply BIT_ULL(xfeature_nr).
Yes, why not. Updated. Thanks.
Sebastian
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 87a57b7642d36..9dc0a2c8c2755 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -444,7 +444,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr) * format. Checking a supervisor state's uncompacted offset is * an error. */ - if (XFEATURE_MASK_SUPERVISOR & (1 << xfeature_nr)) { + if (XFEATURE_MASK_SUPERVISOR & (1ULL << xfeature_nr)) { WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); return -1; }
The xfeature mask is 64bit so a shift from a number to its mask should have LL prefix or else nr > 31 will be lost. This is not a problem now but should XFEATURE_MASK_SUPERVISOR gain a bit >31 then this check won't catch it. Add a ULL suffix so >31bit number will be properly shifted. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- arch/x86/kernel/fpu/xstate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)