On Tue, Oct 14, 2008 at 10:10:20AM -0700, Anatoli wrote:
> Hi, All
> I have run onto inability to trace (long long) return values - please
> see details below. Is there a way to get it correctly ?
> Thanks in advance
>
...
> Here is what I am getting:
>
> # isainfo -b
> 64
> # dtrace -n "pid`pgrep ret_ll`::ret_ll:return{trace(arg1)}"
> dtrace: description 'pid5633::ret_ll:return' matched 1 probe
> CPU ID FUNCTION:NAME
> 0 47874 ret_ll:return 4294967295 <-- it is
> definately not a (long long)
>
> PS: have tried as well:
> # dtrace -n "pid`pgrep ret_ll`::ret_ll:return{printf(\"%lld\", (long
> long)arg1)}"
> dtrace: description 'pid13837::ret_ll:return' matched 1 probe
> CPU ID FUNCTION:NAME
> 1 47874 ret_ll:return 4294967295 <-- more like
> just (int)
With 32-bit userland binaries, the pid provider's argn probes are only 32-bits
wide. The bits are available in arg2; modifying your code:
% cat > tmpc.c <<\EOF
#include <unistd.h>
unsigned long long ret_ll(void)
{
return (0x0123456789abcdefULL);
}
int
main(int argc, char *argv[])
{
while (1) {
ret_ll();
sleep(1);
}
}
EOF
% cc -o tmpc tmpc.c
%
On SPARC:
#dtrace -qn 'pid$target::ret_ll:return{printf("%08x %08x\n", arg1, arg2)}' \
-c ./tmpc
01234567 89abcdef
01234567 89abcdef
01234567 89abcdef
^C
89abcdef 01234567
#
On x86:
#dtrace -qn 'pid$target::ret_ll:return{printf("%08x %08x\n", arg1, arg2)}' -c
./tmpc-s
89abcdef 01234567
89abcdef 01234567
^C
89abcdef 01234567
#
So unfortunately, endianness does matter.
Cheers,
- jonathan
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