Messages in this thread | | | From | Arvind Sankar <> | Date | Sat, 14 Dec 2019 14:46:27 -0500 | Subject | Re: [PATCH 05/10] efi/libstub: distinguish between native/mixed not 32/64 bit |
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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?
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