* [EMAIL PROTECTED] ([EMAIL PROTECTED]) wrote:
> On 13 Nov 2007 at 13:46, Mathieu Desnoyers wrote:
>
> > +void *text_poke_early(void *addr, const void *opcode, size_t len)
> > +{
> > + memcpy(addr, opcode, len);
> > + text_sync(addr, len);
> > + return addr;
> > +}
>
> why do you need this function (vs. using text_poke throughout)?
>
Because it's not safe to use read_cr0() in paravirtualization
before the alternatives are set.
> > +#define kernel_wp_save(cr0) \
> > + do { \
> > + preempt_disable(); \
> > + cr0 = read_cr0(); \
> > + if (cpu_data(smp_processor_id()).wp_works_ok) \
>
> why do you need this test? if cr0.wp is ineffective, then it doesn't
> matter whether it's on or off (in fact, at least the intel manual
> says that 386s would not even let you change its value, they'll
> silently ignore attempts of setting the wp bit).
>
Ok.. then this test could go away then. I prefered to use a conservative
approach. Will fix. Thanks for the hint.
Mathieu
> > + write_cr0(cr0 & ~X86_CR0_WP); \
> > + } while (0)
> > +
> > +#define kernel_wp_restore(cr0) \
> > + do { \
> > + if (cpu_data(smp_processor_id()).wp_works_ok) \
>
> ditto...
>
> > + write_cr0(cr0); \
> > + preempt_enable(); \
> > + } while (0)
> >
> > #endif /* _I386_ALTERNATIVE_H */
>
>
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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