Nicholas Piggin [off-list ref] writes:

ink

You can just use:

ifdef CONFIG_PPC64

We shouldn't need the true anymore should we?

heck.sh

We run this explicitly via $(CONFIG_SHELL), so having a shebang here is
redundant and also a little confusing. I added "-x" here, to turn on
tracing, but it doesn't take effect, so I think better to just drop the
line. If anyone wants to run it manually they can just pass it to sh.

+# Copyright =C2=A9 2016 IBM Corporation
+
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version
+# 2 of the License, or (at your option) any later version.
+
+# This script checks the head of a vmlinux for linker stubs that
+# break our placement of fixed-location code for 64-bit.
+
+# based on relocs_check.pl
+# Copyright =C2=A9 2009 IBM Corporation
+
+# READ THIS
+#
+# If the build dies here, it's likely code in head_64.S or nearby is
+# referencing labels it can't reach, which results in the linker inserti=

ng

+# stubs without the assembler's knowledge. This can move code around in =

ways

+# that break the fixed location placement stuff (head-64.h). To debug,
+# disassemble the vmlinux and look for branch stubs (long_branch, plt_br=

anch

+# etc) in the fixed section region (0 - 0x8000ish). Check what places are
+# calling those stubs.
+#
+# Linker stubs use the TOC pointer, so even if fixed section code could
+# tolerate them being inserted into head code, they can't be allowed in =

low

+# level entry code (boot, interrupt vectors, etc) until r2 is set up. Th=

is

+# could cause the kernel to die in early boot.

Can you add:

# Turn this on if you want more debug output:
# set -x

+
+if [ $# -lt 2 ]; then
+	echo "$0 [path to nm] [path to vmlinux]" 1>&2
+	exit 1
+fi
+
+# Have Kbuild supply the path to nm so we handle cross compilation.
+nm=3D"$1"
+vmlinux=3D"$2"
+
+nm "$vmlinux" | grep -e " T _stext$" -e " t start_first_256B$" -e " a te=

xt_start$" -e " t start_text$" -m4 > .tmp_symbols.txt

You don't use $nm there.

+
+
+vma=3D$(cat .tmp_symbols.txt | grep " T _stext$" | cut -d' ' -f1)
+
+expected_start_head_addr=3D$vma
+
+start_head_addr=3D$(cat .tmp_symbols.txt | grep " t start_first_256B$" |=

 cut -d' ' -f1)

+
+if [ "$start_head_addr" !=3D "$expected_start_head_addr" ]; then
+	echo "ERROR: head code starts at $start_head_addr, should be 0"
+	echo "ERROR: see comments in arch/powerpc/tools/head_check.sh"

This is blowing up for me with ppc64e_defconfig.

It says:

ERROR: start_text address is c000000000001100, should be c000000000000200


cheers