Re: [PATCH v2 16/22] arm64/debug: Make use of the system wide safe value

[Suzuki K. Poulose]

On 08/10/15 16:08, Catalin Marinas wrote:
> On Thu, Oct 08, 2015 at 12:56:28PM +0100, Suzuki K. Poulose wrote:
> > On 08/10/15 12:11, Catalin Marinas wrote:
> > > On Mon, Oct 05, 2015 at 06:02:05PM +0100, Suzuki K. Poulose wrote:
> > > > @@ -137,13 +138,17 @@ extern struct pmu perf_ops_bp;
> > > >   /* Determine number of BRP registers available. */
> > > >   static inline int get_num_brps(void)
> > > >   {
> > > > -	return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;
> > > > +	return 1 +
> > > > +		cpuid_feature_extract_field(read_system_reg(SYS_ID_AA64DFR0_EL1),
> > > > +						ID_AA64DFR0_BRPS_SHIFT);
> > > >   }
> > >
> > > cpuid_feature_extract_field() is fine but we should we bother with
> > > read_system_reg vs just read_cpuid?
> > > Similar question for patch 17/22.
> >
> > Well, we would have already TAINTed the kernel, if these fields are different.
> > It is just the matter of, whether we want to provide the safer value on a tainted
> > kernel or not. I am open to suggestions.
>
> Ah, sorry, I mixed read_system_reg() with read_cpu_sysreg(). I think we

Oh, ok. I think we should rename it as you suggest below to avoid the
confusion.

> need to rename the latter as it gets confusing. Maybe something like
> read_native_sys_reg() or __raw_read_system_reg().


Thanks
Suzuki



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/