[RFC][PATCH 05/24] kernel/task: Add shadow stack to thread structure

[Dave Hansen]

Add a shadow stack member to the stack structure. It is zero-sized
for now. Adding it permits new code to reference it, though.

---

 b/include/linux/sched.h |    4 ++++
 1 file changed, 4 insertions(+)

diff -puN include/linux/sched.h~add-shadow_stack-to-thread_stacks include/linux/sched.h
--- a/include/linux/sched.h~add-shadow_stack-to-thread_stacks	2026-10-21 12:36:34.689874862 -0700
+++ b/include/linux/sched.h	2026-10-21 12:36:34.691874865 -0700
@@ -1986,8 +1986,12 @@ extern void ia64_set_curr_task(int cpu,
 
 void yield(void);
 
+#ifndef TASK_SHADOW_STACK_SIZE
+#define TASK_SHADOW_STACK_SIZE	0
+#endif
 struct thread_stacks {
 	unsigned long stack[THREAD_SIZE/sizeof(long)];
+	u8 shadow_stack[TASK_SHADOW_STACK_SIZE];
 };
 
 union thread_union {
_