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

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);