Re: [patch 06/18] riscv/syscall: Use syscall_enter_from_user_mode_randomize_stack()

On Tue, Jul 07, 2026 at 09:06:19PM +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 <[email protected]>
> Cc: Paul Walmsley <[email protected]>
> Cc: Palmer Dabbelt <[email protected]>
> Cc: [email protected]
> ---
>  arch/riscv/kernel/traps.c |    5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -7,7 +7,6 @@
>  #include <linux/kernel.h>
>  #include <linux/init.h>
>  #include <linux/irqflags.h>
> -#include <linux/randomize_kstack.h>
>  #include <linux/sched.h>
>  #include <linux/sched/debug.h>
>  #include <linux/sched/signal.h>
> @@ -333,9 +332,7 @@ void do_trap_ecall_u(struct pt_regs *reg
>  
>  		riscv_v_vstate_discard(regs);
>  
> -		syscall = syscall_enter_from_user_mode(regs, syscall);
> -
> -		add_random_kstack_offset();
> +		syscall = syscall_enter_from_user_mode_randomize_stack(regs, syscall);
>  
>  		if (syscall >= 0 && syscall < NR_syscalls) {
>  			syscall = array_index_nospec(syscall, NR_syscalls);
> 
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <[email protected]>

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