On Tue, Apr 26, 2016 at 09:14:47PM +0200, Arnd Bergmann wrote:
> On Tuesday 26 April 2016 21:04:42 Rabin Vincent wrote:
> > The support is added via <asm-generic/io.h> and as such is only
> > available on the archs which use that header.
>
> Why that limitation? I think only few architectures use it. Maybe
> at least enable it for x86 as well?
Seems to work to on x86 (and presumably other archs as well, not tested
yet) to insert the include into linux/io.h instead of asm-generic/io.h.
>
> > +/* This part must be outside protection */
> > +#include <trace/define_trace.h>
> > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> > index e45db6b0d878..feca834436c5 100644
> > --- a/kernel/trace/Kconfig
> > +++ b/kernel/trace/Kconfig
> > @@ -372,6 +372,22 @@ config STACK_TRACER
> >
> > Say N if unsure.
> >
> > +config TRACE_MMIO_HELPERS
> > + bool "Support for tracing MMIO helpers"
> > + select GENERIC_TRACER
>
> How about putting a whitelist of architectures here that are including
> the necessary definitions? Or better, a HAVE_TRACE_MMIO_HELPERS
> symbol that gets selected by architectures and that this depends on?
If it works with linux/io.h we won't need to restrict it to specific
archs, otherwise I'll add a symbol as you suggest.
> > +#define DEFINE_MMIO_RW_TRACE(c, type) \
> > +type read ## c ## _trace(const volatile void __iomem *addr, \
> > + const char *addrexp, bool relaxed, \
> > + unsigned long caller) \
> > +{ \
> > + type value; \
> > + \
> > + if (relaxed) \
> > + value = read ## c ## _relaxed_notrace(addr); \
> > + else \
> > + value = read ## c ## _notrace(addr); \
> > + \
> > + trace_mmio_read(addr, addrexp, value, \
> > + sizeof(value), relaxed, caller); \
> > + \
> > + return value; \
> > +} \
> > + \
>
> We have a number of other accessors that are commonly used:
>
> {ioread,iowrite}{8,16,32,64}{,_be}
I'll make the code handle these.
> {in,out}{b,w,l,q}
These are port-mapped IO accesors, aren't they? They don't even take
pointer arguments so mmio:* tracepoints don't seem appropriate for them?
> {hi_lo_,lo_hi_}{read,write}q
There's only a single definition of these and that is in terms of
writel()/readl() so they should be coverd by the readl/writel case.
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