sparc64: Fill in rest of HAVE_REGS_AND_STACK_ACCESS_API

This lets us enable KPROBE_EVENTS.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/Kconfig

@@ -82,6 +82,7 @@ config SPARC64
 	select HAVE_ARCH_AUDITSYSCALL
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select HAVE_NMI
+	select HAVE_REGS_AND_STACK_ACCESS_API
 
 config ARCH_DEFCONFIG
 	string

arch/sparc/include/asm/ptrace.h

@@ -83,7 +83,8 @@ unsigned long profile_pc(struct pt_regs *);
 
 #define MAX_REG_OFFSET (offsetof(struct pt_regs, magic))
 
-extern int regs_query_register_offset(const char *name);
+int regs_query_register_offset(const char *name);
+unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n);
 
 /**
  * regs_get_register() - get register value from its offset

arch/sparc/kernel/ptrace_64.c

@@ -1162,3 +1162,39 @@ int regs_query_register_offset(const char *name)
 			return roff->offset;
 	return -EINVAL;
 }
+
+/**
+ * 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)
+{
+	unsigned long ksp = kernel_stack_pointer(regs) + STACK_BIAS;
+	return ((addr & ~(THREAD_SIZE - 1))  ==
+		(ksp & ~(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.
+ */
+unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
+{
+	unsigned long ksp = kernel_stack_pointer(regs) + STACK_BIAS;
+	unsigned long *addr = (unsigned long *)ksp;
+	addr += n;
+	if (regs_within_kernel_stack(regs, (unsigned long)addr))
+		return *addr;
+	else
+		return 0;
+}