Messages in this thread | | | Date | Thu, 21 Sep 2006 22:01:19 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH] Linux Kernel Markers 0.7 for 2.6.17 (with type checking!) |
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* Jeremy Fitzhardinge (jeremy@goop.org) wrote: > Mathieu Desnoyers wrote: > >+#ifdef CONFIG_MARK_SYMBOL > >+#define MARK_SYM(name) \ > >+ do { \ > >+ __label__ here; \ > >+ here: asm volatile \ > >+ (MARK_KPROBE_PREFIX#name " = %0" : : "m" (*&&here)); > >\ > >+ } while(0) > >+#else > >+#define MARK_SYM(name) > >+#endif > > BTW, this won't work if you put the MARK_SYM in a loop which gcc > unrolls; you'll only get the mark in the last unrolled iteration > (because the symbol assignments will override each other). > > Do make this work properly, you really need to put the mark entries into > a separate section, so that if gcc duplicates the code, you get > duplicated markers too. >
Good point, I will change it to :
#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).
Regards,
Mathieu
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