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[Bug tapsets/13454] nd_syscall tapset needs to handle sys_pipe2 and pipe0/pipe1


http://sourceware.org/bugzilla/show_bug.cgi?id=13454

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsmith at redhat dot com
         Depends on|                            |11424

--- Comment #1 from David Smith <dsmith at redhat dot com> 2011-11-30 18:38:48 UTC ---
>From syscalls2.stp:

----
# pipe _______________________________________________________                  
#                                                                               
# asmlinkage int                                                                
# sys_pipe(unsigned long __user * fildes)                                       
#                                                                               
# SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)                      
# pipe2() was added to Linux in version 2.6.27.                                 
probe syscall.pipe = kernel.function("sys_pipe2").call !,                       
                     kernel.function("sys_ia64_pipe").call ?,                   
                     kernel.function("sys_pipe").call                           
----

The reason why it is done this way is that in the kernel
sys_pipe is just a wrapper around sys_pipe2.  This way we
ignore the sys_pipe call, and only catch the sys_pipe2 call on
kernels with sys_pipe2.

Unfortunately, as bug #11424 notes, '!' (optional and sufficient) doesn't work
for kprobe.function probes.  So, the above logic will be difficult to duplicate
in tapset/nd_syscalls2.stp.

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