commit 641bd53a615b35d7a2e9a3de764e7c4953948679
author Anton Blanchard <anton@samba.org> Tue May 22 17:58:41 2012 +0000
committer Benjamin Herrenschmidt <benh@kernel.crashing.org> Tue Jul 03 14:14:40 2012 +1000
tree 3d7b21aa7864e4fe86f80ddbfabfadb5c619b6cf
parent 16aaaff68440dd95de98adb075303355814be6e0

powerpc: Enable jump label support

When looking through some instruction traces I noticed our tracepoint
checks were inline. It turns out we don't have CONFIG_JUMP_LABEL
enabled.

By enabling CONFIG_JUMP_LABEL we replace a load/compare/branch with
a nop at every tracepoint call. For example in do_IRQ:

CONFIG_JUMP_LABEL disabled:
        stdx 3,11,9
        lwz 0,8(29)
        cmpwi 7,0,0
        bne- 7,.L124
        bl .irq_enter

CONFIG_JUMP_LABEL enabled:
        stdx 3,11,9
        nop
        bl .irq_enter

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/configs/ppc64_defconfig

diff --git a/arch/powerpc/configs/ppc64_defconfig b/arch/powerpc/configs/ppc64_defconfig
index c1442a3..273e2bd 100644
--- a/arch/powerpc/configs/ppc64_defconfig
+++ b/arch/powerpc/configs/ppc64_defconfig
@@ -16,6 +16,7 @@
 CONFIG_PROFILING=y
 CONFIG_OPROFILE=y
 CONFIG_KPROBES=y
+CONFIG_JUMP_LABEL=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
 CONFIG_MODVERSIONS=y