uml: implement get_wchan

Implement get_wchan - the algorithm is similar to x86.  It starts with the
stack pointer of the process in question and looks above that for addresses
that are kernel text.  The second one which isn't in the scheduler is the one
that's returned.  The first one is ignored because that will be UML's own
context switching routine.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/asm-um/processor-generic.h b/include/asm-um/processor-generic.h
index 78c0599cc80c..057a76d41569 100644
--- a/include/asm-um/processor-generic.h
+++ b/include/asm-um/processor-generic.h
@@ -128,6 +128,6 @@ extern struct cpuinfo_um cpu_data[];
 
 
 #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
-#define get_wchan(p) (0)
+extern unsigned long get_wchan(struct task_struct *p);
 
 #endif