powerpc: add a define for the user interrupt frame size

The user interrupt frame is a different size from the kernel frame, so
give it its own name.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-11-npiggin@gmail.com

arch/powerpc/include/asm/ptrace.h

@@ -122,8 +122,7 @@ struct pt_regs
 
 #define STACK_FRAME_OVERHEAD	112	/* size of minimum stack frame */
 #define STACK_FRAME_LR_SAVE	2	/* Location of LR in stack frame */
-#define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + \
-				 STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
+#define STACK_USER_INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
 #define STACK_INT_FRAME_REGS	STACK_FRAME_OVERHEAD
 #define STACK_INT_FRAME_MARKER	(STACK_FRAME_OVERHEAD - 16)
 
@@ -143,7 +142,7 @@ struct pt_regs
 #define KERNEL_REDZONE_SIZE	0
 #define STACK_FRAME_OVERHEAD	16	/* size of minimum stack frame */
 #define STACK_FRAME_LR_SAVE	1	/* Location of LR in stack frame */
-#define STACK_INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
+#define STACK_USER_INT_FRAME_SIZE	(sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
 #define STACK_INT_FRAME_REGS	STACK_FRAME_OVERHEAD
 #define STACK_INT_FRAME_MARKER	(STACK_FRAME_OVERHEAD - 8)
 #define STACK_FRAME_MIN_SIZE	STACK_FRAME_OVERHEAD
@@ -153,6 +152,7 @@ struct pt_regs
 
 #endif /* __powerpc64__ */
 
+#define STACK_INT_FRAME_SIZE	(KERNEL_REDZONE_SIZE + STACK_USER_INT_FRAME_SIZE)
 #define STACK_INT_FRAME_MARKER_LONGS	(STACK_INT_FRAME_MARKER/sizeof(long))
 
 #ifndef __ASSEMBLY__

arch/powerpc/kernel/process.c

@@ -1756,15 +1756,15 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 	klp_init_thread_info(p);
 
 	/* Create initial stack frame. */
-	sp -= (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD);
+	sp -= STACK_USER_INT_FRAME_SIZE;
 	((unsigned long *)sp)[0] = 0;
 
 	/* Copy registers */
-	childregs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
+	childregs = (struct pt_regs *)(sp + STACK_INT_FRAME_REGS);
 	if (unlikely(args->fn)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
-		childregs->gpr[1] = sp + (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD);
+		childregs->gpr[1] = sp + STACK_USER_INT_FRAME_SIZE;
 		/* function */
 		if (args->fn)
 			childregs->gpr[14] = ppc_function_entry((void *)args->fn);

arch/powerpc/kernel/stacktrace.c

@@ -77,7 +77,7 @@ int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consum
 		/*
 		 * For user tasks, this is the SP value loaded on
 		 * kernel entry, see "PACAKSAVE(r13)" in _switch() and
-		 * system_call_common()/EXCEPTION_PROLOG_COMMON().
+		 * system_call_common().
 		 *
 		 * Likewise for non-swapper kernel threads,
 		 * this also happens to be the top of the stack
@@ -88,7 +88,7 @@ int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consum
 		 * an unreliable stack trace until it's been
 		 * _switch()'ed to for the first time.
 		 */
-		stack_end -= STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
+		stack_end -= STACK_USER_INT_FRAME_SIZE;
 	} else {
 		/*
 		 * idle tasks have a custom stack layout,