Re: [PATCH] Linux Kernel Markers 0.7 for 2.6.17 (with type checking!)

[Jeremy Fitzhardinge]

Mathieu Desnoyers wrote:
> * Jeremy Fitzhardinge (jeremy@xxxxxxxx) wrote:
>   
> > Mathieu Desnoyers wrote:
> >     
> > > #define MARK_SYM(name) \
> > >        do { \
> > >                __label__ here; \
> > >                volatile static void *__mark_kprobe_##name \
> > >                        asm (MARK_CALL_PREFIX#name) \
> > >                        __attribute__((unused)) = &&here; \
> > > here: \
> > >                do { } while(0); \
> > >        } while(0)
> > >
> > > Which fixes the problem. Some tests showed me that the compiler does not 
> > > unroll
> > > an otherwise unrolled loop when this specific macro is called. (test done 
> > > with
> > > -funroll-all-loops).
> > >       
> > Eh?  I thought you wanted to avoid changing the generated code?  
> > Inhibiting loop unrolling could be a pretty large change...
> >
> >     
>
> Yes, if possible. But letting gcc duplicate those symbols brings many questions,
> such as : how can we name each of them differently ? Is there any way to
> automatically increment an "identifier" counter in assembly ?

Use a section instead:

struct marker {
	const char *name;
	const void *location;
};

#define MARKER_SYM(name)
	do {
		__label__ here;
	here:	asm volatile(".section \".markers\"; .long %0, %1; .previous" : : "m" (#name), "m" (*&&here));\
	} while(0);

Not a linker symbol, but it does let you find all the places containing 
a particular mark.

   J
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