sparc64: Give a stack frame to the ftrace call sites.

It's the only way we'll be able to implement the function
graph tracer properly.

A positive is that we no longer have to worry about the
linker over-optimizing the tail call, since we don't
use a tail call any more.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 15 deletions

diff --git a/arch/sparc/lib/mcount.S b/arch/sparc/lib/mcount.S
index 73ed0f3aaa0c..153c80e62cf1 100644
--- a/arch/sparc/lib/mcount.S
+++ b/arch/sparc/lib/mcount.S
@@ -33,9 +33,13 @@ mcount:
         or              %g2, %lo(ftrace_stub), %g2
         cmp             %g1, %g2
         be,pn           %icc, 1f
-         mov            %i7, %o1
-        jmpl            %g1, %g0
-         mov            %o7, %o0
+         mov            %i7, %g2
+        save            %sp, -128, %sp
+        mov             %g2, %o1
+        jmpl            %g1, %o7
+         mov            %i7, %o0
+        ret
+         restore
         /* not reached */
 1:
 #endif
@@ -57,21 +61,18 @@ ftrace_stub:
         .type           ftrace_caller,#function
 ftrace_caller:
         sethi           %hi(function_trace_stop), %g1
-        mov             %i7, %o1
-        lduw            [%g1 + %lo(function_trace_stop)], %g2
-        brnz,pn         %g2, ftrace_stub
-         mov            %o7, %o0
+        mov             %i7, %g2
+        lduw            [%g1 + %lo(function_trace_stop)], %g3
+        brnz,pn         %g3, ftrace_stub
+         nop
+        save            %sp, -128, %sp
+        mov             %g2, %o1
         .globl          ftrace_call
 ftrace_call:
-        /* If the final kernel link ever turns on relaxation, we'll need
-         * to do something about this tail call.  Otherwise the linker
-         * will rewrite the call into a branch and nop out the move
-         * instruction.
-         */
         call            ftrace_stub
-         mov            %o0, %o7
-        retl
-         nop
+         mov            %i7, %o0
+        ret
+         restore
         .size           ftrace_call,.-ftrace_call
         .size           ftrace_caller,.-ftrace_caller
 #endif