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 <ananth@in.ibm.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/Kconfig

@@ -27,5 +27,12 @@ config KPROBES
 	  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

@@ -12,6 +12,7 @@ config ARM
 	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

@@ -18,6 +18,7 @@ config IA64
 	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

@@ -90,6 +90,7 @@ config PPC
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config EARLY_PRINTK
 	bool

arch/s390/Kconfig

@@ -61,6 +61,7 @@ config S390
 	def_bool y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 source "init/Kconfig"
 

arch/sparc64/Kconfig

@@ -10,6 +10,7 @@ config SPARC
 	default y
 	select HAVE_OPROFILE
 	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config SPARC64
 	bool

arch/x86/Kconfig

@@ -21,6 +21,7 @@ config X86
 	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

@@ -20,7 +20,6 @@
 #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

@@ -82,7 +82,6 @@ struct kprobe_ctlblk {
 	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

@@ -80,7 +80,6 @@ typedef unsigned int kprobe_opcode_t;
 #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

@@ -46,7 +46,6 @@ typedef u16 kprobe_opcode_t;
 	? (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

@@ -14,8 +14,6 @@ typedef u32 kprobe_opcode_t;
 
 #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

@@ -42,7 +42,6 @@ typedef u8 kprobe_opcode_t;
 	: (((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

@@ -125,11 +125,11 @@ struct jprobe {
 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)
 {
@@ -138,7 +138,7 @@ static inline int arch_trampoline_kprobe(struct kprobe *p)
 {
 	return 0;
 }
-#endif /* ARCH_SUPPORTS_KRETPROBES */
+#endif /* CONFIG_KRETPROBES */
 /*
  * Function-return probe -
  * Note:

kernel/kprobes.c

@@ -678,8 +678,7 @@ void __kprobes unregister_jprobe(struct jprobe *jp)
 	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.
@@ -769,8 +768,7 @@ int __kprobes register_kretprobe(struct kretprobe *rp)
 	return ret;
 }
 
-#else /* ARCH_SUPPORTS_KRETPROBES */
+#else /* CONFIG_KRETPROBES */
-
 int __kprobes register_kretprobe(struct kretprobe *rp)
 {
 	return -ENOSYS;
@@ -781,8 +779,7 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 {
 	return 0;
 }
-
+#endif /* CONFIG_KRETPROBES */
-#endif /* ARCH_SUPPORTS_KRETPROBES */
 
 void __kprobes unregister_kretprobe(struct kretprobe *rp)
 {