1 files changed, 33 insertions, 13 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index f884b85030b7..c06f0481163b 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -34,6 +34,7 @@
 #include <asm/processor.h>
 #include <asm/system.h>
 #include <asm/thread_notify.h>
+#include <asm/stacktrace.h>
 #include <asm/mach/time.h>
 
 static const char *processor_modes[] = {
@@ -434,6 +435,23 @@ asm(	".section .text\n"
 "	.size	kernel_thread_helper, . - kernel_thread_helper\n"
 "	.previous");
 
+#ifdef CONFIG_ARM_UNWIND
+extern void kernel_thread_exit(long code);
+asm(	".section .text\n"
+"	.align\n"
+"	.type	kernel_thread_exit, #function\n"
+"kernel_thread_exit:\n"
+"	.fnstart\n"
+"	.cantunwind\n"
+"	bl	do_exit\n"
+"	nop\n"
+"	.fnend\n"
+"	.size	kernel_thread_exit, . - kernel_thread_exit\n"
+"	.previous");
+#else
+#define kernel_thread_exit	do_exit
+#endif
+
 /*
  * Create a kernel thread.
  */
@@ -445,9 +463,13 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 
 	regs.ARM_r1 = (unsigned long)arg;
 	regs.ARM_r2 = (unsigned long)fn;
-	regs.ARM_r3 = (unsigned long)do_exit;
+	regs.ARM_r3 = (unsigned long)kernel_thread_exit;
 	regs.ARM_pc = (unsigned long)kernel_thread_helper;
-	regs.ARM_cpsr = SVC_MODE;
+	regs.ARM_cpsr = SVC_MODE | PSR_ENDSTATE | PSR_ISETSTATE;
+#ifdef CONFIG_CPU_V7M
+	/* Return to Handler mode */
+	regs.ARM_EXC_lr = 0xfffffff1L;
+#endif
 
 	return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
@@ -455,23 +477,21 @@ EXPORT_SYMBOL(kernel_thread);
 
 unsigned long get_wchan(struct task_struct *p)
 {
-	unsigned long fp, lr;
-	unsigned long stack_start, stack_end;
+	struct stackframe frame;
 	int count = 0;
 	if (!p || p == current || p->state == TASK_RUNNING)
 		return 0;
 
-	stack_start = (unsigned long)end_of_stack(p);
-	stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
-
-	fp = thread_saved_fp(p);
+	frame.fp = thread_saved_fp(p);
+	frame.sp = thread_saved_sp(p);
+	frame.lr = 0;			/* recovered from the stack */
+	frame.pc = thread_saved_pc(p);
 	do {
-		if (fp < stack_start || fp > stack_end)
+		int ret = unwind_frame(&frame);
+		if (ret < 0)
 			return 0;
-		lr = ((unsigned long *)fp)[-1];
-		if (!in_sched_functions(lr))
-			return lr;
-		fp = *(unsigned long *) (fp - 12);
+		if (!in_sched_functions(frame.pc))
+			return frame.pc;
 	} while (count ++ < 16);
 	return 0;
 }