Re: [PATCH v2 9/9] arm64: Work around systems with mismatched cache line sizes

[Suzuki K Poulose]

On 26/08/16 18:00, Catalin Marinas wrote:
> On Fri, Aug 26, 2016 at 05:16:27PM +0100, Will Deacon wrote:
> > On Fri, Aug 26, 2016 at 02:08:01PM +0100, Suzuki K Poulose wrote:
> > > On 26/08/16 14:04, Suzuki K Poulose wrote:

> > It might be worth looking to see if we can pass the ctr as an extra
> > parameter to the assembly routines that need it. Then you can access it
> > easily from C code, and if you pass it as 0 that could result in the asm
> > code reading it from the h/w register, removing the need for the _raw
> > stuff you add.
>
> How often to we need to access a sanitised sysreg from assembly? AFAICT,
> CTR_EL0 is the first. If we only need it to infer the minimum cache line
> size, we could as well store the latter in a global variable and access
> it directly. If we feel brave, we could patch a "mov \reg, #x"
> instruction in the ?cache_line_size macros (starting with 32 by default,
> though to make it less cumbersome we'd have to improve the run-time
> patching code a bit).


With Ard's patches [1] to refactor the feature array, we can refer to named
CTR_EL0 feature register cleanly. I can rebase this series on top of that
if nobody has any objection.

[1] http://marc.info/?l=linux-arm-kernel&m=147263959504998&w=2


Suzuki