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 */