sh: Add kprobe-based event tracer.

This follows the x86/ppc changes for kprobe-based event tracing on sh.
While kprobes is only supported on 32-bit sh, we provide the API for
HAVE_REGS_AND_STACK_ACCESS_API for both 32 and 64-bit.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 86 insertions, 3 deletions

diff --git a/arch/sh/include/asm/ptrace.h b/arch/sh/include/asm/ptrace.h
index 2168fde25611..33b3f37dcdbb 100644
--- a/arch/sh/include/asm/ptrace.h
+++ b/arch/sh/include/asm/ptrace.h
@@ -1,6 +1,8 @@
 #ifndef __ASM_SH_PTRACE_H
 #define __ASM_SH_PTRACE_H
 
+#include <linux/stringify.h>
+
 /*
  * Copyright (C) 1999, 2000  Niibe Yutaka
  *
@@ -14,6 +16,13 @@ struct pt_regs {
 	unsigned long long tregs[8];
 	unsigned long long pad[2];
 };
+
+#define MAX_REG_OFFSET		offsetof(struct pt_regs, tregs[7])
+#define regs_return_value(regs)	((regs)->regs[3])
+
+#define TREGS_OFFSET_NAME(num)	\
+	{.name = __stringify(tr##num), .offset = offsetof(struct pt_regs, tregs[num])}
+
 #else
 /*
  * GCC defines register number like this:
@@ -66,6 +75,9 @@ struct pt_regs {
 	long tra;
 };
 
+#define MAX_REG_OFFSET		offsetof(struct pt_regs, tra)
+#define regs_return_value(regs)	((regs)->regs[0])
+
 /*
  * This struct defines the way the DSP registers are stored on the
  * kernel stack during a system call or other kernel entry.
@@ -113,16 +125,87 @@ struct pt_dspregs {
 #include <asm/system.h>
 
 #define user_mode(regs)			(((regs)->sr & 0x40000000)==0)
+#define user_stack_pointer(regs)	((unsigned long)(regs)->regs[15])
+#define kernel_stack_pointer(regs)	((unsigned long)(regs)->regs[15])
 #define instruction_pointer(regs)	((unsigned long)(regs)->pc)
 
 extern void show_regs(struct pt_regs *);
 
+#define arch_has_single_step()	(1)
+
 /*
- * These are defined as per linux/ptrace.h.
+ * kprobe-based event tracer support
  */
-struct task_struct;
+#include <linux/stddef.h>
+#include <linux/thread_info.h>
 
-#define arch_has_single_step()	(1)
+struct pt_regs_offset {
+	const char *name;
+	int offset;
+};
+
+#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
+#define REGS_OFFSET_NAME(num)	\
+	{.name = __stringify(r##num), .offset = offsetof(struct pt_regs, regs[num])}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+
+/* Query offset/name of register from its name/offset */
+extern int regs_query_register_offset(const char *name);
+extern const char *regs_query_register_name(unsigned int offset);
+
+extern const struct pt_regs_offset regoffset_table[];
+
+/**
+ * regs_get_register() - get register value from its offset
+ * @regs:	pt_regs from which register value is gotten.
+ * @offset:	offset number of the register.
+ *
+ * regs_get_register returns the value of a register. The @offset is the
+ * offset of the register in struct pt_regs address which specified by @regs.
+ * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
+ */
+static inline unsigned long regs_get_register(struct pt_regs *regs,
+					      unsigned int offset)
+{
+	if (unlikely(offset > MAX_REG_OFFSET))
+		return 0;
+	return *(unsigned long *)((unsigned long)regs + offset);
+}
+
+/**
+ * regs_within_kernel_stack() - check the address in the stack
+ * @regs:	pt_regs which contains kernel stack pointer.
+ * @addr:	address which is checked.
+ *
+ * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
+ * If @addr is within the kernel stack, it returns true. If not, returns false.
+ */
+static inline int regs_within_kernel_stack(struct pt_regs *regs,
+					   unsigned long addr)
+{
+	return ((addr & ~(THREAD_SIZE - 1))  ==
+		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
+}
+
+/**
+ * regs_get_kernel_stack_nth() - get Nth entry of the stack
+ * @regs:	pt_regs which contains kernel stack pointer.
+ * @n:		stack entry number.
+ *
+ * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
+ * is specified by @regs. If the @n th entry is NOT in the kernel stack,
+ * this returns 0.
+ */
+static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
+						      unsigned int n)
+{
+	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
+	addr += n;
+	if (regs_within_kernel_stack(regs, (unsigned long)addr))
+		return *addr;
+	else
+		return 0;
+}
 
 struct perf_event;
 struct perf_sample_data;