tree 05733ac23e08a6a8a9b3bc2283912a28b7a1afbf
parent e8f897f4afef0031fe618a8e94127a0934896aba
author André Rösti <an.roesti@gmail.com> 1710191824 +0000
committer Thomas Gleixner <tglx@linutronix.de> 1710246212 +0100

entry: Respect changes to system call number by trace_sys_enter()

When a probe is registered at the trace_sys_enter() tracepoint, and that
probe changes the system call number, the old system call still gets
executed.  This worked correctly until commit b6ec41346103 ("core/entry:
Report syscall correctly for trace and audit"), which removed the
re-evaluation of the syscall number after the trace point.

Restore the original semantics by re-evaluating the system call number
after trace_sys_enter(). 

The performance impact of this re-evaluation is minimal because it only
takes place when a trace point is active, and compared to the actual trace
point overhead the read from a cache hot variable is negligible.

Fixes: b6ec41346103 ("core/entry: Report syscall correctly for trace and audit")
Signed-off-by: André Rösti <an.roesti@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240311211704.7262-1-an.roesti@gmail.com