sh: Add kprobes support.

Initial support for kprobes/kretprobes for 32-bit SH platforms.

[ General cleanup and some rework for the kretprobe hash lock. -- PFM ]
Signed-off-by: Chris Smith <chris.smith@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -20,6 +20,8 @@ config SUPERH
 
 config SUPERH32
 	def_bool !SUPERH64
+	select HAVE_KPROBES
+	select HAVE_KRETPROBES
 
 config SUPERH64
 	def_bool y if CPU_SH5

arch/sh/include/asm/kprobes.h

+#ifndef __ASM_SH_KPROBES_H
+#define __ASM_SH_KPROBES_H
+
+#ifdef CONFIG_KPROBES
+
+#include <linux/types.h>
+#include <linux/ptrace.h>
+
+struct pt_regs;
+
+typedef u16 kprobe_opcode_t;
+#define BREAKPOINT_INSTRUCTION	0xc3ff
+
+#define MAX_INSN_SIZE 16
+#define MAX_STACK_SIZE 64
+#define MIN_STACK_SIZE(ADDR) (((MAX_STACK_SIZE) < \
+	(((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR))) \
+	? (MAX_STACK_SIZE) \
+	: (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR)))
+
+#define regs_return_value(regs)		((regs)->regs[0])
+#define flush_insn_slot(p)		do { } while (0)
+#define kretprobe_blacklist_size	0
+
+struct kprobe;
+
+void arch_remove_kprobe(struct kprobe *);
+void kretprobe_trampoline(void);
+void jprobe_return_end(void);
+
+/* Architecture specific copy of original instruction*/
+struct arch_specific_insn {
+	/* copy of the original instruction */
+	kprobe_opcode_t insn[MAX_INSN_SIZE];
+};
+
+struct prev_kprobe {
+	struct kprobe *kp;
+	unsigned long status;
+};
+
+/* per-cpu kprobe control block */
+struct kprobe_ctlblk {
+	unsigned long kprobe_status;
+	unsigned long jprobe_saved_r15;
+	struct pt_regs jprobe_saved_regs;
+	kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
+	struct prev_kprobe prev_kprobe;
+};
+
+extern int kprobe_exceptions_notify(struct notifier_block *self,
+				    unsigned long val, void *data);
+extern int kprobe_handle_illslot(unsigned long pc);
+#else
+
+#define kprobe_handle_illslot(pc)	(-1)
+
+#endif /* CONFIG_KPROBES */
+#endif /* __ASM_SH_KPROBES_H */

arch/sh/kernel/Makefile_32

@@ -23,5 +23,6 @@ obj-$(CONFIG_PM)		+= pm.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_ELF_CORE)		+= dump_task.o
 obj-$(CONFIG_IO_TRAPPED)	+= io_trapped.o
+obj-$(CONFIG_KPROBES)		+= kprobes.o
 
 EXTRA_CFLAGS += -Werror

arch/sh/kernel/traps_32.c

@@ -26,6 +26,7 @@
 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <asm/fpu.h>
+#include <asm/kprobes.h>
 
 #ifdef CONFIG_SH_KGDB
 #include <asm/kgdb.h>
@@ -743,6 +744,10 @@ asmlinkage void do_illegal_slot_inst(unsigned long r4, unsigned long r5,
 	struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 	unsigned long error_code;
 	struct task_struct *tsk = current;
+
+	if (kprobe_handle_illslot(regs->pc) == 0)
+		return;
+
 #ifdef CONFIG_SH_FPU_EMU
 	unsigned short inst = 0;