kpatch/0017-kpatch-build-add-compile-flag-fno-reorder-functions.patch

From 2573039f44d58727421c235dca385589f9246d83 Mon Sep 17 00:00:00 2001
From: Zhipeng Xie <xiezhipeng1@huawei.com>
Date: Thu, 12 Mar 2020 06:56:21 -0400
Subject: [PATCH 17/38] kpatch-build: add compile flag -fno-reorder-functions

Sometimes function foo with static variables can be put in
.text.foo section in original binary and be put in
.text.unlikely.foo section in patched binary. This will result
in "reference to static local variable xxx in foo was removed"
problem because the .text.foo section can not be correlated
to .text.unlikely.foo section by create-diff-object.

gcc just put the function in .text.unlikely.xxx section,the
symbol name doesn't change which is different with other
optimization such as ".constprop/.isra/.part". So disable the
optimization with -fno-reorder-functions just make sure the
function is placed in .text.xxx section, kernel can still find
the symbol name to patch or relocate.

Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
---
 kpatch-build/kpatch-build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build
index 67e56e1..0431e0b 100755
--- a/kpatch-build/kpatch-build
+++ b/kpatch-build/kpatch-build
@@ -1194,7 +1194,7 @@ if [[ "$ARCH" = "s390x" ]]; then
 	ARCH_KCFLAGS="-mno-pic-data-is-text-relative -fno-section-anchors"
 fi
 
-export KCFLAGS="-I$DATADIR/patch -ffunction-sections -fdata-sections \
+export KCFLAGS="-I$DATADIR/patch -ffunction-sections -fdata-sections -fno-reorder-functions \
 		$ARCH_KCFLAGS $DEBUG_KCFLAGS"
 
 echo "Reading special section data"
-- 
2.33.0