openpower/linux/0010-powerpc-boot-Request-no-dynamic-linker-for-boot-wrap.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Mon, 28 Nov 2016 12:42:26 +1100
Subject: [PATCH 10/11] powerpc/boot: Request no dynamic linker for boot
 wrapper

The boot wrapper performs its own relocations and does not require
PT_INTERP segment. However currently we don't tell the linker that.

Prior to binutils 2.28 that works OK. But since binutils commit
1a9ccd70f9a7 ("Fix the linker so that it will not silently generate ELF
binaries with invalid program headers. Fix readelf to report such
invalid binaries.") binutils tries to create a program header segment
due to PT_INTERP, and the link fails because there is no space for it:

  ld: arch/powerpc/boot/zImage.pseries: Not enough room for program headers, try linking with -N
  ld: final link failed: Bad value

So tell the linker not to do that, by passing --no-dynamic-linker.

Cc: stable@vger.kernel.org
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Drop dependency on ld-version.sh and massage change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit ff45000fcb56b5b0f1a14a865d3541746d838a0a)
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
---
 arch/powerpc/boot/wrapper | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/boot/wrapper b/arch/powerpc/boot/wrapper
index ceaa75d5a684..8c8394e4e164 100755
--- a/arch/powerpc/boot/wrapper
+++ b/arch/powerpc/boot/wrapper
@@ -161,6 +161,28 @@ case "$elfformat" in
     elf32-powerpc)	format=elf32ppc	;;
 esac
 
+ld_version()
+{
+    # Poached from scripts/ld-version.sh, but we don't want to call that because
+    # this script (wrapper) is distributed separately from the kernel source.
+    # Extract linker version number from stdin and turn into single number.
+    awk '{
+	gsub(".*\\)", "");
+	gsub(".*version ", "");
+	gsub("-.*", "");
+	split($1,a, ".");
+	print a[1]*100000000 + a[2]*1000000 + a[3]*10000;
+	exit
+    }'
+}
+
+# Do not include PT_INTERP segment when linking pie. Non-pie linking
+# just ignores this option.
+LD_VERSION=$(${CROSS}ld --version | ld_version)
+LD_NO_DL_MIN_VERSION=$(echo 2.26 | ld_version)
+if [ "$LD_VERSION" -ge "$LD_NO_DL_MIN_VERSION" ] ; then
+	nodl="--no-dynamic-linker"
+fi
 
 platformo=$object/"$platform".o
 lds=$object/zImage.lds
@@ -412,7 +434,8 @@ if [ "$platform" != "miboot" ]; then
     if [ -n "$link_address" ] ; then
         text_start="-Ttext $link_address"
     fi
-    ${CROSS}ld -m $format -T $lds $text_start $pie -o "$ofile" \
+#link everything
+    ${CROSS}ld -m $format -T $lds $text_start $pie $nodl -o "$ofile" \
 	$platformo $tmp $object/wrapper.a
     rm $tmp
 fi