2 files changed, 9 insertions, 43 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7ecc0d1855c3..6f7eb7e00c79 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1162,39 +1162,17 @@ machine_check_in_rtas:
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-        stwu    r1,-48(r1)
-        stw     r3, 12(r1)
-        stw     r4, 16(r1)
-        stw     r5, 20(r1)
-        stw     r6, 24(r1)
-        mflr    r3
-        stw     r7, 28(r1)
-        mfcr    r5
-        stw     r8, 32(r1)
-        stw     r9, 36(r1)
-        stw     r10,40(r1)
-        stw     r3, 44(r1)
-        stw     r5, 8(r1)
-        subi    r3, r3, MCOUNT_INSN_SIZE
-        .globl mcount_call
-mcount_call:
-        bl      ftrace_stub
-        nop
-        lwz     r6, 8(r1)
-        lwz     r0, 44(r1)
-        lwz     r3, 12(r1)
+        /*
+         * It is required that _mcount on PPC32 must preserve the
+         * link register. But we have r0 to play with. We use r0
+         * to push the return address back to the caller of mcount
+         * into the ctr register, restore the link register and
+         * then jump back using the ctr register.
+         */
+        mflr    r0
         mtctr   r0
-        lwz     r4, 16(r1)
-        mtcr    r6
-        lwz     r5, 20(r1)
-        lwz     r6, 24(r1)
-        lwz     r0, 52(r1)
-        lwz     r7, 28(r1)
-        lwz     r8, 32(r1)
+        lwz     r0, 4(r1)
         mtlr    r0
-        lwz     r9, 36(r1)
-        lwz     r10,40(r1)
-        addi    r1, r1, 48
         bctr
 
 _GLOBAL(ftrace_caller)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e6d52845854f..b00982e0d1ee 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -888,18 +888,6 @@ _GLOBAL(enter_prom)
 #ifdef CONFIG_DYNAMIC_FTRACE
 _GLOBAL(mcount)
 _GLOBAL(_mcount)
-        /* Taken from output of objdump from lib64/glibc */
-        mflr    r3
-        stdu    r1, -112(r1)
-        std     r3, 128(r1)
-        subi    r3, r3, MCOUNT_INSN_SIZE
-        .globl mcount_call
-mcount_call:
-        bl      ftrace_stub
-        nop
-        ld      r0, 128(r1)
-        mtlr    r0
-        addi    r1, r1, 112
         blr
 
 _GLOBAL(ftrace_caller)