Patch "powerpc/boot: Request no dynamic linker for boot wrapper" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/boot: Request no dynamic linker for boot wrapper

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-boot-request-no-dynamic-linker-for-boot-wrapper.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Nicholas Piggin <[email protected]>
Date: Mon, 28 Nov 2016 12:42:26 +1100
Subject: powerpc/boot: Request no dynamic linker for boot wrapper

From: Nicholas Piggin <[email protected]>

commit ff45000fcb56b5b0f1a14a865d3541746d838a0a upstream.

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.

---
 arch/powerpc/boot/wrapper |   24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

@@ -181,6 +181,28 @@ 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

@@ -446,7 +468,7 @@ if [ "$platform" != "miboot" ]; then
         text_start="-Ttext $link_address"
     fi
 #link everything
-    ${CROSS}ld -m $format -T $lds $text_start $pie -o "$ofile" \
+    ${CROSS}ld -m $format -T $lds $text_start $pie $nodl -o "$ofile" \
 	$platformo $tmp $object/wrapper.a
     rm $tmp
 fi

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/powerpc-boot-request-no-dynamic-linker-for-boot-wrapper.patch queue-4.9/perf-annotate-don-t-throw-error-for-zero-length-symbols.patch queue-4.9/powerpc-64e-convert-cmpi-to-cmpwi-in-head_64.s.patch