Can we dump function arguments for user space functions just like for functions
in kernel space? Can FBT provider dump arguments for user space functions if we
do dtrace -l -f <function name> -v?
I was DTrace'ing "top" utility, (the "top" utility has both
the CTF and the Dwarf debug sections built in the object file)
I am trying to inspect get_system_info function called by "top", I
confirm it is present to be probed
root% dtrace -l | grep get_system_info
55154 pid8488 top get_system_info entry
But I cannot dump the arguments to the function...
root% dtrace -l -f get_system_info -v
ID PROVIDER MODULE FUNCTION NAME
55154 pid8488 top get_system_info entry
Probe Description Attributes
Identifier Names: Private
Data Semantics: Private
Dependency Class: Unknown
Argument Attributes
Identifier Names: Private
Data Semantics: Private
Dependency Class: Unknown
Argument Types
None
Testing with a simple script,
pid8488::get_system_info:entry
{
this->info = (struct system_info *)copyin(args[0],
sizeof(struct system_info));
...
}
...if I use the args[0] notation it says the following,
dtrace: failed to compile script top_d.d: line 17: index 0 is out of
range for pid8488::get_system_info:entry args[ ]
Instead if I replace with arg0, it compiles but the values are not
neccesarily sane.
Example the ncpus member of struct system_info shows a garbage value.
The complete script is
pid8488::get_system_info:entry
{
this->info = (struct system_info *)copyin(arg0, sizeof(struct system_info));
printf("last pid [%d] \n", this->info->last_pid);
}
pid8488::get_process_info:entry
{
this->info = (struct system_info *)copyin(arg0, sizeof(struct system_info));
printf("ncpus [%d] \n", this->info->ncpus);
}
Running this
55154 get_system_info:entry last pid [8513]
55155 get_process_info:entry ncpus [134558720]
Supposed to be showing number of cpus? Anything wrong with the scripting?
_______________________________________________
freebsd-hackers@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
