kern/127440: Dtrace arg0/arg1 variables don't contain return value of syscall:::return

[Henri Hennebert]

>Number:         127440
>Category:       kern
>Synopsis:       Dtrace arg0/arg1 variables don't contain return value of syscall:::return
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Sep 17 14:00:14 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Henri Hennebert
>Release:        7.1-PRERELEASE
>Organization:
>Environment:
FreeBSD morzine.restart.bel 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #0: Sun Sep 14 17:24:37 CEST 2008     root at morzine.restart.bel:/usr/obj/usr/src/sys/MORZINE  i386

>Description:
I am reading the 'Solaris Dynamic tracing guide' and using FreeBSD for the practical test.

In this D program:

syscall::read:entry,
syscall::write:entry
/pid == $1/
{
        printf("%s(%d, 0x%x, %4d)", probefunc, arg0, arg1, arg2);
}

syscall::read:return,
syscall::write:return
/pid == $1/
{
 	printf("\t\t = %d\n", arg1);
}

in syscall::read:return, syscall::write:return
argO/arg1 has respectively the value of arg0/arg1 at the corresponding syscall:::entry instead of the return value of the syscall.

Anyway, thanks for this great port

Henri
>How-To-Repeat:
running the previous D program under 7.1-PRERELEASE

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: