On Fri, Sep 04, 2020 at 03:55:10AM +0100, Al Viro wrote: > On Thu, Sep 03, 2020 at 04:22:40PM +0200, Christoph Hellwig wrote: > > > diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S > > index c8a85b512796e1..94f7be4971ed04 100644 > > --- a/arch/x86/lib/getuser.S > > +++ b/arch/x86/lib/getuser.S > > @@ -35,10 +35,19 @@ > > #include <asm/smap.h> > > #include <asm/export.h> > > > > +#ifdef CONFIG_X86_5LEVEL > > +#define LOAD_TASK_SIZE_MINUS_N(n) \ > > + ALTERNATIVE "mov $((1 << 47) - 4096 - (n)),%rdx", \ > > + "mov $((1 << 56) - 4096 - (n)),%rdx", X86_FEATURE_LA57 > > +#else > > +#define LOAD_TASK_SIZE_MINUS_N(n) \ > > + mov $(TASK_SIZE_MAX - (n)),%_ASM_DX > > +#endif > > Wait a sec... how is that supposed to build with X86_5LEVEL? Do you mean > > #define LOAD_TASK_SIZE_MINUS_N(n) \ > ALTERNATIVE __stringify(mov $((1 << 47) - 4096 - (n)),%rdx), \ > __stringify(mov $((1 << 56) - 4096 - (n)),%rdx), > X86_FEATURE_LA57 > > there?
Don't ask me about the how, but it builds and works with X86_5LEVEL, and the style is copied from elsewhere..
