Integration DTrace problems

[Adam Leventhal]

Hey Mark,

I'd go so far as to suggest you remove the #ifdef sun stuff and just
have your new logic replace what was there. As the original author of
that code (I think), it is more kludgy than clever in retrospect -- as
so many things are...

Thanks.

Adam

On Sun, Oct 20, 2013 at 6:52 PM, Mark Johnston <markj at freebsd.org> wrote:
> On Wed, Oct 09, 2013 at 01:54:14AM +0400, Veniamin Gvozdikov wrote:
>> Hello,
>>
>> I have problems with integration DTrace:
>>
>> * Wildcard bug
>> * USDT at runtime works only with probes with arguments less than 5
>
> The patch below should partly address this issue (which exists for the
> pid provider too). On amd64, the first six arguments are taken out of the
> trap frame with (roughly) the following line:
>
>     val = regs->r_rdi[argno]
>
> where 0 <= argno <= 5 is the argument index. This works when the six
> argument registers correspond to consecutive of struct reg, which is not
> the case on FreeBSD. This bug only comes up when argno == 5 though,
> since the first _five_ arguments are passed directly to dtrace_probe() by
> the fasttrap trap handler.
>
> Arguments of index > 5 come from the stack and may still be incorrect
> with this patch. I'm not yet sure what the problem is - if the arguments
> are (4-byte) ints, some of the values are wrong, but when I change the
> types to long, the values are correct (up to arg9 at least).
>
>> * USDT depended by base src because need dtrace.h although It exists on OSX and Oracle Linux
>> * Bug with providers position in D file with multi link dtrace objects
>> * Bug with not used probes when all providers unavailable if doesn't use in code
>> * Inconvenient toolchains (need to see DTrace on OSX)
>>
>> For more details go to link http://zlonet.ru/page/dtrace-integration-features/ .
>>
>>
>> Any idea?
>
> diff --git a/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c b/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
> index 65991af..8afc45a 100644
> --- a/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
> +++ b/sys/cddl/contrib/opensolaris/uts/intel/dtrace/fasttrap_isa.c
> @@ -271,8 +271,26 @@ fasttrap_anarg(struct reg *rp, int function_entry, int argno)
>                  * In 64-bit mode, the first six arguments are stored in
>                  * registers.
>                  */
> -               if (argno < 6)
> +               if (argno < 6) {
> +#if !defined(sun)
> +                       switch (argno) {
> +                       case 0:
> +                               return (rp->r_rdi);
> +                       case 1:
> +                               return (rp->r_rsi);
> +                       case 2:
> +                               return (rp->r_rdx);
> +                       case 3:
> +                               return (rp->r_rcx);
> +                       case 4:
> +                               return (rp->r_r8);
> +                       case 5:
> +                               return (rp->r_r9);
> +                       }
> +#else
>                         return ((&rp->r_rdi)[argno]);
> +#endif
> +               }
>
>                 stack = (uintptr_t *)rp->r_rsp;
>                 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
> diff --git a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
> index 34d6f33..b82b77f 100644
> --- a/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
> +++ b/sys/cddl/dev/dtrace/amd64/dtrace_isa.c
> @@ -367,7 +367,31 @@ dtrace_getarg(int arg, int aframes)
>                             sizeof (uintptr_t));
>
>                         if (arg <= inreg) {
> +#if !defined(sun)
> +                               switch (arg) {
> +                               case 0:
> +                                       stack = (uintptr_t *)&rp->r_rdi;
> +                                       break;
> +                               case 1:
> +                                       stack = (uintptr_t *)&rp->r_rsi;
> +                                       break;
> +                               case 2:
> +                                       stack = (uintptr_t *)&rp->r_rdx;
> +                                       break;
> +                               case 3:
> +                                       stack = (uintptr_t *)&rp->r_rcx;
> +                                       break;
> +                               case 4:
> +                                       stack = (uintptr_t *)&rp->r_r8;
> +                                       break;
> +                               case 5:
> +                                       stack = (uintptr_t *)&rp->r_r9;
> +                                       break;
> +                               }
> +                               arg = 0;
> +#else
>                                 stack = (uintptr_t *)&rp->r_rdi;
> +#endif
>                         } else {
>                                 stack = (uintptr_t *)(rp->r_rsp);
>                                 arg -= inreg;
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-- 
Adam Leventhal
CTO, Delphix
http://blog.delphix.com/ahl