[PATCH] ARM: ptrace: fix scno of -1 cause SIGILL

[Lecopzer Chen]

> In commit [1], the -1 scno is used as a special scno when the task's
> syscall is traced.

> After commit [2], PTRACE_SET_SYSCALL will always mask syscall with
> __NR_SYSCALL_MASK, this makes the condition `cmp scno, #-1` broken,
> and some test like Android VTS[3] is also failed because SIGILL
> interrupt the test program.

> Let's test with `and` logic with #0x0ff000. Instead of #__NR_SYSCALL_MASK
> because of the constraint of ARM Operand2 rules and avoid conflicting
> with ARM private syscall.

...

Please follow the commit from Kees below and ignore this patch, thanks.

https://lore.kernel.org/all/20230804071045.never.134-kees@kernel.org/