Re: [patch 01/18] powerpc: Move stack randomization after syscall_enter_from_user_mode()

[Jinjie Ruan]

On 7/8/2026 3:05 AM, Thomas Gleixner wrote:
> add_random_kstack_offset() is invoked before syscall_enter_from_user_mode()
> establishes state. That's wrong because add_random_kstack_offset() calls
> into instrumentable code.
> 
> Move it after syscall_enter_from_user_mode() to ensure that state is
> correctly established.
> 
> Signed-off-by: Thomas Gleixner <t...@kernel.org>
> Cc: Michael Ellerman <m...@ellerman.id.au>
> Cc: Shrikanth Hegde <sshe...@linux.ibm.com>
> Cc: linuxppc-...@lists.ozlabs.org
> ---
>  arch/powerpc/kernel/syscall.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -19,8 +19,8 @@ notrace long system_call_exception(struc
>       long ret;
>       syscall_fn f;
>  
> -     add_random_kstack_offset();
>       r0 = syscall_enter_from_user_mode(regs, r0);
> +     add_random_kstack_offset();

Reviewed-by: Jinjie Ruan <ruanjin...@huawei.com>

>  
>       if (unlikely(r0 >= NR_syscalls)) {
>               if (unlikely(trap_is_unsupported_scv(regs))) {
>