3 files changed, 39 insertions, 1 deletions

diff --git a/arch/sparc64/kernel/entry.S b/arch/sparc64/kernel/entry.S
index 6be4d2d2904e..49eca4b1cf25 100644
--- a/arch/sparc64/kernel/entry.S
+++ b/arch/sparc64/kernel/entry.S
@@ -1705,6 +1705,36 @@ __flushw_user:
 2:	retl
 	 nop
 
+	/* Flush %fp and %i7 to the stack for all register
+	 * windows active inside of the cpu.  This allows
+	 * show_stack_trace() to avoid using an expensive
+	 * 'flushw'.
+	 */
+	.globl		stack_trace_flush
+	.type		stack_trace_flush,#function
+stack_trace_flush:
+	rdpr		%pstate, %o0
+	wrpr		%o0, PSTATE_IE, %pstate
+
+	rdpr		%cwp, %g1
+	rdpr		%canrestore, %g2
+	sub		%g1, 1, %g3
+
+1:	brz,pn		%g2, 2f
+	 sub		%g2, 1, %g2
+	wrpr		%g3, %cwp
+	stx		%fp, [%sp + STACK_BIAS + RW_V9_I6]
+	stx		%i7, [%sp + STACK_BIAS + RW_V9_I7]
+	ba,pt		%xcc, 1b
+	 sub		%g3, 1, %g3
+
+2:	wrpr		%g1, %cwp
+	wrpr		%o0, %pstate
+
+	retl
+	 nop
+	.size		stack_trace_flush,.-stack_trace_flush
+
 #ifdef CONFIG_SMP
 	.globl		hard_smp_processor_id
 hard_smp_processor_id:
diff --git a/arch/sparc64/kernel/stacktrace.c b/arch/sparc64/kernel/stacktrace.c
index 47f92a59be18..84d39e873e88 100644
--- a/arch/sparc64/kernel/stacktrace.c
+++ b/arch/sparc64/kernel/stacktrace.c
@@ -2,13 +2,15 @@
 #include <linux/stacktrace.h>
 #include <linux/thread_info.h>
 #include <asm/ptrace.h>
+#include <asm/stacktrace.h>
 
 void save_stack_trace(struct stack_trace *trace)
 {
 	unsigned long ksp, fp, thread_base;
 	struct thread_info *tp = task_thread_info(current);
 
-	flushw_all();
+	stack_trace_flush();
+
 	__asm__ __volatile__(
 		"mov	%%fp, %0"
 		: "=r" (ksp)
diff --git a/include/asm-sparc64/stacktrace.h b/include/asm-sparc64/stacktrace.h
new file mode 100644
index 000000000000..6cee39adf6d6
--- /dev/null
+++ b/include/asm-sparc64/stacktrace.h
@@ -0,0 +1,6 @@
+#ifndef _SPARC64_STACKTRACE_H
+#define _SPARC64_STACKTRACE_H
+
+extern void stack_trace_flush(void);
+
+#endif /* _SPARC64_STACKTRACE_H */