xtensa: drop ARCH_WANT_FRAME_POINTERS

ARCH_WANT_FRAME_POINTERS was enabled in the xtensa Kconfig in the commit
8f371c75 ("xtensa: enable lockdep support"), but neither windowed
nor call0 xtensa ABI need frame pointers for stack tracing.
Drop ARCH_WANT_FRAME_POINTERS from the xtensa Kconfig.
Drop ftrace_return_address0 definition as the generic implementation is
correct.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig

@@ -16,7 +16,6 @@ config XTENSA
 	select ARCH_USE_MEMTEST
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
-	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select BUILDTIME_TABLE_SORT
 	select CLONE_BACKWARDS

arch/xtensa/include/asm/ftrace.h

@@ -13,17 +13,8 @@
 #include <asm/processor.h>
 
 #ifndef __ASSEMBLY__
-#define ftrace_return_address0 ({ unsigned long a0, a1; \
-		__asm__ __volatile__ ( \
-			"mov %0, a0\n" \
-			"mov %1, a1\n" \
-			: "=r"(a0), "=r"(a1)); \
-		MAKE_PC_FROM_RA(a0, a1); })
-
-#ifdef CONFIG_FRAME_POINTER
 extern unsigned long return_address(unsigned level);
 #define ftrace_return_address(n) return_address(n)
-#endif
 #endif /* __ASSEMBLY__ */
 
 #ifdef CONFIG_FUNCTION_TRACER

arch/xtensa/kernel/stacktrace.c

@@ -237,8 +237,6 @@ EXPORT_SYMBOL_GPL(save_stack_trace);
 
 #endif
 
-#ifdef CONFIG_FRAME_POINTER
-
 struct return_addr_data {
 	unsigned long addr;
 	unsigned skip;
@@ -271,5 +269,3 @@ unsigned long return_address(unsigned level)
 	return r.addr;
 }
 EXPORT_SYMBOL(return_address);
-
-#endif