lkml.org 
[lkml]   [2019]   [Dec]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 05/10] efi/libstub: distinguish between native/mixed not 32/64 bit
On Sat, Dec 14, 2019 at 02:46:27PM -0500, Arvind Sankar wrote:
> On Sat, Dec 14, 2019 at 06:57:30PM +0100, Ard Biesheuvel wrote:
> > +
> > +#define efi_table_attr(table, attr, instance) ({ \
> > + __typeof__(((table##_t *)0)->attr) __ret; \
> > + if (efi_is_native()) { \
> > + __ret = ((table##_t *)instance)->attr; \
> > + } else { \
> > + __typeof__(((table##_32_t *)0)->attr) at; \
> > + at = (((table##_32_t *)(unsigned long)instance)->attr); \
> > + __ret = (__typeof__(__ret))(unsigned long)at; \
> > + } \
> > + __ret; \
> > +})
>
> The casting of `at' is appropriate if the attr is a pointer type which
> needs to be zero-extended to 64-bit, but for other fields it is
> unnecessary at best and possibly dangerous. There are probably no
> instances currently where it is called for a non-pointer field, but is
> it possible to detect if the type is pointer and avoid the cast if not?

To clarify, I mean the casting via `unsigned long' -- casting to type of
__ret should be ok. We could also use uintptr_t for cleanliness when the
cast is required?

\
 
 \ /
  Last update: 2019-12-14 20:50    [W:0.047 / U:5.868 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site