x86/entry: Fix ptrace regression

The recent rework of the syscall entry code missed the historical detail of
the abuse of syscall number -1L to abort a syscall and keep modifications
by tracers to the return value, while a rewrite of the syscall number to an
invalid value undoes eventual tracer modification to the return value and
overwrite it with -ENOSYS.

Restore the original behaviour.

Fixes: 1b1f3b3e1b39 ("x86/entry: Get rid of the sys_ni_syscall() indirection")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/87ecd4xwlr.ffs@fw13
Closes: https://lore.kernel.org/all/20261022142425.3Wx-RrU5@linutronix.de

0 files changed, 0 insertions, 0 deletions