# git rev-parse -q --verify b49f9d9b0e428909796b4a7e7f1049f489859e0f^{commit}
b49f9d9b0e428909796b4a7e7f1049f489859e0f
already have revision, skipping fetch
# git checkout -q -f -B kisskb b49f9d9b0e428909796b4a7e7f1049f489859e0f
# git clean -qxdf
# < git log -1
# commit b49f9d9b0e428909796b4a7e7f1049f489859e0f
# Author: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
# Date:   Wed May 19 16:17:17 2021 +0530
# 
#     powerpc/kprobes: Fix validation of prefixed instructions across page boundary
#     
#     When checking if the probed instruction is the suffix of a prefixed
#     instruction, we access the instruction at the previous word. If the
#     probed instruction is the very first word of a module, we can end up
#     trying to access an invalid page.
#     
#     Fix this by skipping the check for all instructions at the beginning of
#     a page. Prefixed instructions cannot cross a 64-byte boundary and as
#     such, we don't expect to encounter a suffix as the very first word in a
#     page for kernel text. Even if there are prefixed instructions crossing
#     a page boundary (from a module, for instance), the instruction will be
#     illegal, so preventing probing on the suffix of such prefix instructions
#     isn't worthwhile.
#     
#     Fixes: b4657f7650ba ("powerpc/kprobes: Don't allow breakpoints on suffixes")
#     Cc: stable@vger.kernel.org # v5.8+
#     Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
#     Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/0df9a032a05576a2fa8e97d1b769af2ff0eafbd6.1621416666.git.naveen.n.rao@linux.vnet.ibm.com
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 b49f9d9b0e428909796b4a7e7f1049f489859e0f
# < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  pseries_defconfig
# < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_pseries_defconfig_powerpc-gcc5
# Build took: 0:03:58.457955