linux-kernel - [PATCH 1/1] arch/powerpc: Don't assume start_text & head

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Date:   Wed, 13 Mar 2019 14:38:51 +1100
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     "Alastair D'Silva" <alastair@...ilva.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] arch/powerpc: Don't assume start_text & head_end align

From: Alastair D'Silva <alastair@...ilva.org>

When building LTO kernels, the start_text symbol is not guaranteed to mark
the end of the head section.

Instead, look explicitly for __head_end.

Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
 arch/powerpc/tools/head_check.sh | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/tools/head_check.sh b/arch/powerpc/tools/head_check.sh
index ad9e57209aa4..1b0f634038c3 100644
--- a/arch/powerpc/tools/head_check.sh
+++ b/arch/powerpc/tools/head_check.sh
@@ -44,7 +44,7 @@ nm="$1"
 vmlinux="$2"
 
 # gcc-4.6-era toolchain make _stext an A (absolute) symbol rather than T
-$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " t start_text$" -m4 > .tmp_symbols.txt
+$nm "$vmlinux" | grep -e " [TA] _stext$" -e " t start_first_256B$" -e " a text_start$" -e " T __head_end$" -m4 > .tmp_symbols.txt
 
 
 vma=$(cat .tmp_symbols.txt | grep -e " [TA] _stext$" | cut -d' ' -f1)
@@ -63,12 +63,12 @@ fi
 
 top_vma=$(echo $vma | cut -d'0' -f1)
 
-expected_start_text_addr=$(cat .tmp_symbols.txt | grep " a text_start$" | cut -d' ' -f1 | sed "s/^0/$top_vma/")
+expected_head_end_addr=$(cat .tmp_symbols.txt | grep " a text_start$" | cut -d' ' -f1 | sed "s/^0/$top_vma/")
 
-start_text_addr=$(cat .tmp_symbols.txt | grep " t start_text$" | cut -d' ' -f1)
+head_end_addr=$(cat .tmp_symbols.txt | grep " T __head_end$" | cut -d' ' -f1)
 
-if [ "$start_text_addr" != "$expected_start_text_addr" ]; then
-	echo "ERROR: start_text address is $start_text_addr, should be $expected_start_text_addr"
+if [ "$head_end_addr" != "$expected_head_end_addr" ]; then
+	echo "ERROR: __head_end address is $head_end_addr, should be $expected_head_end_addr"
 	echo "ERROR: try to enable LD_HEAD_STUB_CATCH config option"
 	echo "ERROR: see comments in arch/powerpc/tools/head_check.sh"
 
-- 
2.20.1