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>

diff --git a/arch/sparc/lib/mcount.S b/arch/sparc/lib/mcount.S
index 73ed0f3..153c80e 100644 (file)
--- 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