Blackfin: add new cacheflush syscall

Flushing caches sometimes requires anomaly workarounds which require
supervisor-only insns.  Normally we don't need to flush caches from
userspace so this isn't a problem, but when gcc generates trampolines
on the stack, we do.

So add a new syscall for gcc to use modeled after the mips version.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/include/asm/ptrace.h b/arch/blackfin/include/asm/ptrace.h
index aaa1c6c..832d7c0 100644
--- a/arch/blackfin/include/asm/ptrace.h
+++ b/arch/blackfin/include/asm/ptrace.h
@@ -113,6 +113,9 @@
 /* common code demands this function */
 #define ptrace_disable(child) user_disable_single_step(child)
 
+extern int is_user_addr_valid(struct task_struct *child,
+			      unsigned long start, unsigned long len);
+
 /*
  * Get the address of the live pt_regs for the specified task.
  * These are saved onto the top kernel stack when the process