Re: [patch 05/18] powerpc/syscall: Use syscall_enter_from_user_mode_randomize_stack()

[Radu Rendec]

On Tue, 2026-07-07 at 21:06 +0200, Thomas Gleixner wrote:
> syscall_enter_from_user_mode_randomize_stack() replaces
> syscall_enter_from_user_mode() and the subsequent invocation of
> add_random_kstack_offset().
> 
> The advantage is that it applies the stack randomization right after
> enter_from_user_mode() and thereby avoids the overhead of get/put_cpu_var()
> as that code is invoked with interrupts disabled.
> 
> No functional change.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> ---
>  arch/powerpc/kernel/syscall.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> --- a/arch/powerpc/kernel/syscall.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -2,7 +2,6 @@
>  
>  #include <linux/compat.h>
>  #include <linux/context_tracking.h>
> -#include <linux/randomize_kstack.h>
>  #include <linux/entry-common.h>
>  
>  #include <asm/interrupt.h>
> @@ -19,8 +18,7 @@ notrace long system_call_exception(struc
>  	long ret;
>  	syscall_fn f;
>  
> -	r0 = syscall_enter_from_user_mode(regs, r0);
> -	add_random_kstack_offset();
> +	r0 = syscall_enter_from_user_mode_randomize_stack(regs, r0);
>  
>  	if (unlikely(r0 >= NR_syscalls)) {
>  		if (unlikely(trap_is_unsupported_scv(regs))) {

Reviewed-by: Radu Rendec <radu@xxxxxxxxxx>