Kprobes: indicate kretprobe support in Kconfig

Add CONFIG_HAVE_KRETPROBES to the arch/<arch>/Kconfig file for relevant
architectures with kprobes support. This facilitates easy handling of
in-kernel modules (like samples/kprobes/kretprobe_example.c) that depend on
kretprobes being present in the kernel.

Thanks to Sam Ravnborg for helping make the patch more lean.

Per Mathieu's suggestion, added CONFIG_KRETPROBES and fixed up dependencies.

Signed-off-by: Ananth N Mavinakayanahalli <[e-mail]>
Acked-by: Mathieu Desnoyers <[e-mail]>
Acked-by: Ingo Molnar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/Kconfig

···
 	  for kernel debugging, non-intrusive instrumentation and testing.
 	  If in doubt, say "N".
 
+config KRETPROBES
+	def_bool y
+	depends on KPROBES && HAVE_KRETPROBES
+
 config HAVE_KPROBES
+	def_bool n
+
+config HAVE_KRETPROBES
 	def_bool n

arch/arm/Kconfig

···
 	select SYS_SUPPORTS_APM_EMULATION
 	select HAVE_OPROFILE
 	select HAVE_KPROBES if (!XIP_KERNEL)
+	select HAVE_KRETPROBES if (HAVE_KPROBES)
 	help
 	  The ARM series is a line of low-power-consumption RISC chip designs
 	  licensed by ARM Ltd and targeted at embedded applications and

arch/ia64/Kconfig

···
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 	default y
 	help
 	  The Itanium Processor Family is Intel's 64-bit successor to

arch/powerpc/Kconfig

···
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config EARLY_PRINTK
 	bool

arch/s390/Kconfig

···
 	def_bool y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 source "init/Kconfig"
 

arch/sparc64/Kconfig

···
 	default y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config SPARC64
 	bool

arch/x86/Kconfig

···
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 	select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
 
 

include/asm-arm/kprobes.h

···
 #include <linux/ptrace.h>
 #include <linux/percpu.h>
 
-#define ARCH_SUPPORTS_KRETPROBES
 #define __ARCH_WANT_KPROBES_INSN_SLOT
 #define MAX_INSN_SIZE			2
 #define MAX_STACK_SIZE			64	/* 32 would probably be OK */

include/asm-ia64/kprobes.h

···
 	struct prev_kprobe prev_kprobe[ARCH_PREV_KPROBE_SZ];
 };
 
-#define ARCH_SUPPORTS_KRETPROBES
 #define kretprobe_blacklist_size 0
 
 #define SLOT0_OPCODE_SHIFT	(37)

include/asm-powerpc/kprobes.h

···
 #define is_trap(instr)	(IS_TW(instr) || IS_TWI(instr))
 #endif
 
-#define ARCH_SUPPORTS_KRETPROBES
 #define flush_insn_slot(p)	do { } while (0)
 #define kretprobe_blacklist_size 0
 

include/asm-s390/kprobes.h

···
 	? (MAX_STACK_SIZE) \
 	: (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR)))
 
-#define ARCH_SUPPORTS_KRETPROBES
 #define kretprobe_blacklist_size 0
 
 #define KPROBE_SWAP_INST	0x10

include/asm-sparc64/kprobes.h

···
 
 #define arch_remove_kprobe(p)	do {} while (0)
 
-#define ARCH_SUPPORTS_KRETPROBES
-
 #define flush_insn_slot(p)		\
 do { 	flushi(&(p)->ainsn.insn[0]);	\
 	flushi(&(p)->ainsn.insn[1]);	\

include/asm-x86/kprobes.h

···
 	: (((unsigned long)current_thread_info()) + THREAD_SIZE \
 	   - (unsigned long)(ADDR)))
 
-#define ARCH_SUPPORTS_KRETPROBES
 #define flush_insn_slot(p)	do { } while (0)
 
 extern const int kretprobe_blacklist_size;

include/linux/kprobes.h

···
 DECLARE_PER_CPU(struct kprobe *, current_kprobe);
 DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
-#ifdef ARCH_SUPPORTS_KRETPROBES
+#ifdef CONFIG_KRETPROBES
 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				   struct pt_regs *regs);
 extern int arch_trampoline_kprobe(struct kprobe *p);
-#else /* ARCH_SUPPORTS_KRETPROBES */
+#else /* CONFIG_KRETPROBES */
 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 					struct pt_regs *regs)
 {
···
 {
 	return 0;
 }
-#endif /* ARCH_SUPPORTS_KRETPROBES */
+#endif /* CONFIG_KRETPROBES */
 /*
  * Function-return probe -
  * Note:

kernel/kprobes.c

···
 	unregister_kprobe(&jp->kp);
 }
 
-#ifdef ARCH_SUPPORTS_KRETPROBES
-
+#ifdef CONFIG_KRETPROBES
 /*
  * This kprobe pre_handler is registered with every kretprobe. When probe
  * hits it will set up the return probe.
···
 	return ret;
 }
 
-#else /* ARCH_SUPPORTS_KRETPROBES */
-
+#else /* CONFIG_KRETPROBES */
 int __kprobes register_kretprobe(struct kretprobe *rp)
 {
 	return -ENOSYS;
···
 {
 	return 0;
 }
-
-#endif /* ARCH_SUPPORTS_KRETPROBES */
+#endif /* CONFIG_KRETPROBES */
 
 void __kprobes unregister_kretprobe(struct kretprobe *rp)
 {