Kconfig: clean up the "#if defined(arch)" list for exception-trace sysctl entry

Introduce SYSCTL_EXCEPTION_TRACE config option and selec it in the
architectures requiring support for the "exception-trace" debug_table
entry in kernel/sysctl.c.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm64/Kconfig

@@ -28,6 +28,7 @@ config ARM64
 	select PERF_USE_VMALLOC
 	select RTC_LIB
 	select SPARSE_IRQ
+	select SYSCTL_EXCEPTION_TRACE
 	help
 	  ARM 64-bit (AArch64) Linux support.
 

arch/powerpc/Kconfig

@@ -99,6 +99,7 @@ config PPC
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
+	select SYSCTL_EXCEPTION_TRACE
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT

arch/s390/Kconfig

@@ -68,6 +68,7 @@ config S390
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_SYSCALL_TRACEPOINTS
+	select SYSCTL_EXCEPTION_TRACE
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_REGS_AND_STACK_ACCESS_API

arch/sparc/Kconfig

@@ -18,6 +18,7 @@ config SPARC
 	select HAVE_OPROFILE
 	select HAVE_ARCH_KGDB if !SMP || SPARC64
 	select HAVE_ARCH_TRACEHOOK
+	select SYSCTL_EXCEPTION_TRACE
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select RTC_CLASS
 	select RTC_DRV_M48T59

arch/tile/Kconfig

@@ -7,6 +7,7 @@ config TILE
 	select HAVE_DMA_API_DEBUG
 	select HAVE_KVM if !TILEGX
 	select GENERIC_FIND_FIRST_BIT
+	select SYSCTL_EXCEPTION_TRACE
 	select USE_GENERIC_SMP_HELPERS
 	select CC_OPTIMIZE_FOR_SIZE
 	select HAVE_DEBUG_KMEMLEAK

arch/x86/Kconfig

@@ -47,6 +47,7 @@ config X86
 	select HAVE_FUNCTION_GRAPH_FP_TEST
 	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	select HAVE_SYSCALL_TRACEPOINTS
+	select SYSCTL_EXCEPTION_TRACE
 	select HAVE_KVM
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK

init/Kconfig

@@ -1152,6 +1152,11 @@ config SYSCTL_SYSCALL
 
 	  If unsure say N here.
 
+config SYSCTL_EXCEPTION_TRACE
+	bool
+	help
+	  Enable support for /proc/sys/debug/exception-trace.
+
 config KALLSYMS
 	 bool "Load all symbols for debugging/ksymoops" if EXPERT
 	 default y

kernel/sysctl.c

@@ -1549,8 +1549,7 @@ static struct ctl_table fs_table[] = {
 };
 
 static struct ctl_table debug_table[] = {
-#if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_SPARC) || \
-    defined(CONFIG_S390) || defined(CONFIG_TILE) || defined(CONFIG_ARM64)
+#ifdef CONFIG_SYSCTL_EXCEPTION_TRACE
 	{
 		.procname	= "exception-trace",
 		.data		= &show_unhandled_signals,