# git rev-parse -q --verify 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3^{commit}
51c3c62b58b357e8d35e4cc32f7b4ec907426fe3
already have revision, skipping fetch
# git checkout -q -f -B kisskb 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3
# git clean -qxdf
# < git log -1
# commit 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3
# Author: Michael Neuling <mikey@neuling.org>
# Date:   Fri Sep 14 11:14:11 2018 +1000
# 
#     powerpc: Avoid code patching freed init sections
#     
#     This stops us from doing code patching in init sections after they've
#     been freed.
#     
#     In this chain:
#       kvm_guest_init() ->
#         kvm_use_magic_page() ->
#           fault_in_pages_readable() ->
#              __get_user() ->
#                __get_user_nocheck() ->
#                  barrier_nospec();
#     
#     We have a code patching location at barrier_nospec() and
#     kvm_guest_init() is an init function. This whole chain gets inlined,
#     so when we free the init section (hence kvm_guest_init()), this code
#     goes away and hence should no longer be patched.
#     
#     We seen this as userspace memory corruption when using a memory
#     checker while doing partition migration testing on powervm (this
#     starts the code patching post migration via
#     /sys/kernel/mobility/migration). In theory, it could also happen when
#     using /sys/kernel/debug/powerpc/barrier_nospec.
#     
#     Cc: stable@vger.kernel.org # 4.13+
#     Signed-off-by: Michael Neuling <mikey@neuling.org>
#     Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
#     Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < git log --format=%s --max-count=1 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-fixes_40x_kilauea_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  40x/kilauea_defconfig
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-fixes_40x_kilauea_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
/kisskb/src/arch/powerpc/kernel/head_40x.S: Assembler messages:
/kisskb/src/arch/powerpc/kernel/head_40x.S:883: Warning: invalid register expression
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_40x_kilauea_defconfig_powerpc-gcc5
# Build took: 0:00:36.700847