lkml.org 
[lkml]   [2021]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCHv4 2/2] arm64/io: Add a header for mmio access instrumentation
On Mon, Nov 22, 2021 at 3:19 PM Sai Prakash Ranjan
<quic_saipraka@quicinc.com> wrote:
> On 11/22/2021 7:29 PM, Arnd Bergmann wrote:
> >
> > I think this would be a lot less confusing to readers, as it is implemented
> > exactly in the place that has the normal definition, and it can also have
> > somewhat more logical semantics by only instrumenting the
> > normal/relaxed/ioport accessors but not the __raw_* versions that
> > are meant to be little more than a pointer dereference.
>
> But how is this different from logic in atomic-instrumented.h which also
> has asm-generic version?
> Initial review few years back mentioned about having something similar
> to atomic instrumentation
> and hence it was implemented with the similar approach keeping
> instrumentation out of arch specific details.

This is only a cosmetic difference. I usually prefer fewer indirections,
and I like the way that include/asm-generic/io.h only has all the
normal 'static inline' definitions spelled out, and calling the __raw_*
versions. Your version adds an extra layer with the arch_raw_readl(),
which I'd prefer to avoid.

> And if we do move this instrumentation to asm-generic/io.h, how will
> that be executed since
> the arch specifc read{b,w,l,q} overrides this generic version?

As I understand it, your version also requires architecture specific
changes, so that would be the same: it only works for architectures
that get the definition of readl()/readl_relaxed()/inl()/... from
include/asm-generic/io.h and only override the __raw version.

Arnd

\
 
 \ /
  Last update: 2021-11-22 15:31    [W:0.081 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site