powerpc/ftrace: Simplify PPC32's return_to_handler()

return_to_handler() was copied from PPC64. For PPC32 it
just needs to save r3 and r4, and doesn't require any nop
after the bl.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/aab39b77b34fb2c4ed08ed01c547b6ed13643788.1640017960.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/trace/ftrace_32.S b/arch/powerpc/kernel/trace/ftrace_32.S
index 7e2fd72..95ffea2 100644 (file)
--- a/arch/powerpc/kernel/trace/ftrace_32.S
+++ b/arch/powerpc/kernel/trace/ftrace_32.S
@@ -162,22 +162,18 @@ _GLOBAL(ftrace_graph_caller)
 
 _GLOBAL(return_to_handler)
        /* need to save return values */
-       stwu    r1, -32(r1)
-       stw     r3, 20(r1)
-       stw     r4, 16(r1)
-       stw     r31, 12(r1)
-       mr      r31, r1
+       stwu    r1, -16(r1)
+       stw     r3, 8(r1)
+       stw     r4, 12(r1)
 
        bl      ftrace_return_to_handler
-       nop
 
        /* return value has real return address */
        mtlr    r3
 
-       lwz     r3, 20(r1)
-       lwz     r4, 16(r1)
-       lwz     r31,12(r1)
-       lwz     r1, 0(r1)
+       lwz     r3, 8(r1)
+       lwz     r4, 12(r1)
+       addi    r1, r1, 16
 
        /* Jump back to real return address */
        blr