powerpc: Rename STACK_FRAME_MARKER and derive it from frame offset

This is a count of longs from the stack pointer to the regs marker.
Rename it to make it more distinct from the other byte offsets. It
can be derived from the byte offset definitions just added.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-10-npiggin@gmail.com

arch/powerpc/include/asm/ptrace.h

@@ -126,7 +126,6 @@ struct pt_regs
 				 STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
 #define STACK_INT_FRAME_REGS	STACK_FRAME_OVERHEAD
 #define STACK_INT_FRAME_MARKER	(STACK_FRAME_OVERHEAD - 16)
-#define STACK_FRAME_MARKER	12
 
 #ifdef CONFIG_PPC64_ELF_ABI_V2
 #define STACK_FRAME_MIN_SIZE	32
@@ -147,7 +146,6 @@ struct pt_regs
 #define STACK_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_MARKER	2
 #define STACK_FRAME_MIN_SIZE	STACK_FRAME_OVERHEAD
 
 /* Size of stack frame allocated when calling signal handler. */
@@ -155,6 +153,8 @@ struct pt_regs
 
 #endif /* __powerpc64__ */
 
+#define STACK_INT_FRAME_MARKER_LONGS	(STACK_INT_FRAME_MARKER/sizeof(long))
+
 #ifndef __ASSEMBLY__
 #include <asm/paca.h>
 

arch/powerpc/kernel/process.c

@@ -2263,7 +2263,7 @@ void __no_sanitize_address show_stack(struct task_struct *tsk,
 		 * We look for the "regs" marker in the current frame.
 		 */
 		if (validate_sp(sp, tsk, STACK_FRAME_WITH_PT_REGS)
-		    && stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+		    && stack[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
 			struct pt_regs *regs = (struct pt_regs *)
 				(sp + STACK_INT_FRAME_REGS);
 

arch/powerpc/kernel/stacktrace.c

@@ -136,7 +136,7 @@ int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consum
 
 		/* Mark stacktraces with exception frames as unreliable. */
 		if (sp <= stack_end - STACK_INT_FRAME_SIZE &&
-		    stack[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+		    stack[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
 			return -EINVAL;
 		}
 

arch/powerpc/perf/callchain.c

@@ -62,7 +62,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
 
 		if (next_sp == sp + STACK_INT_FRAME_SIZE &&
 		    validate_sp(sp, current, STACK_INT_FRAME_SIZE) &&
-		    fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
+		    fp[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
 			/*
 			 * This looks like an interrupt frame for an
 			 * interrupt that occurred in the kernel

arch/powerpc/xmon/xmon.c

@@ -1721,7 +1721,6 @@ static void get_function_bounds(unsigned long pc, unsigned long *startp,
 }
 
 #define LRSAVE_OFFSET		(STACK_FRAME_LR_SAVE * sizeof(unsigned long))
-#define MARKER_OFFSET		(STACK_FRAME_MARKER * sizeof(unsigned long))
 
 static void xmon_show_stack(unsigned long sp, unsigned long lr,
 			    unsigned long pc)
@@ -1784,7 +1783,7 @@ static void xmon_show_stack(unsigned long sp, unsigned long lr,
 
 		/* Look for "regs" marker to see if this is
 		   an exception frame. */
-		if (mread(sp + MARKER_OFFSET, &marker, sizeof(unsigned long))
+		if (mread(sp + STACK_INT_FRAME_MARKER, &marker, sizeof(unsigned long))
 		    && marker == STACK_FRAME_REGS_MARKER) {
 			if (mread(sp + STACK_INT_FRAME_REGS, &regs, sizeof(regs)) != sizeof(regs)) {
 				printf("Couldn't read registers at %lx\n",