[tip: core/entry] powerpc: Move stack randomization after syscall_enter_from_user_mode()

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     89d163dd9dacb028773244dba0a2c86f3a6b74b7
Gitweb:        https://git.kernel.org/tip/89d163dd9dacb028773244dba0a2c86f3a6b74b7
Author:        Thomas Gleixner <tglx@xxxxxxxxxx>
AuthorDate:    Tue, 07 Jul 2026 21:05:58 +02:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Sun, 12 Jul 2026 12:38:00 +02:00

powerpc: Move stack randomization after syscall_enter_from_user_mode()

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 <tglx@xxxxxxxxxx>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@xxxxxxxxx>
Reviewed-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Reviewed-by: Radu Rendec <radu@xxxxxxxxxx>
Reviewed-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxxxxxxxx>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@xxxxxxxxx>
Link: https://patch.msgid.link/20260707190253.718191130@xxxxxxxxxx
---
 arch/powerpc/kernel/syscall.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index a9da2af..ee07b2e 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -19,8 +19,8 @@ notrace long system_call_exception(struct pt_regs *regs, unsigned long r0)
 	long ret;
 	syscall_fn f;
 
-	add_random_kstack_offset();
 	r0 = syscall_enter_from_user_mode(regs, r0);
+	add_random_kstack_offset();
 
 	if (unlikely(r0 >= NR_syscalls)) {
 		if (unlikely(trap_is_unsupported_scv(regs))) {