# git rev-parse -q --verify cb42033f5d172b5779b6c8301c65693ff6a0a778^{commit}
cb42033f5d172b5779b6c8301c65693ff6a0a778
already have revision, skipping fetch
# git checkout -q -f -B kisskb cb42033f5d172b5779b6c8301c65693ff6a0a778
# git clean -qxdf
# < git log -1
# commit cb42033f5d172b5779b6c8301c65693ff6a0a778
# Author: Christophe Leroy <christophe.leroy@c-s.fr>
# Date:   Mon Mar 11 08:30:38 2019 +0000
# 
#     powerpc/32s: Implement Kernel Userspace Access Protection
#     
#     This patch implements Kernel Userspace Access Protection for
#     book3s/32.
#     
#     Due to limitations of the processor page protection capabilities,
#     the protection is only against writing. read protection cannot be
#     achieved using page protection.
#     
#     The previous patch modifies the page protection so that RW user
#     pages are RW for Key 0 and RO for Key 1, and it sets Key 0 for
#     both user and kernel.
#     
#     This patch changes userspace segment registers are set to Ku 0
#     and Ks 1. When kernel needs to write to RW pages, the associated
#     segment register is then changed to Ks 0 in order to allow write
#     access to the kernel.
#     
#     In order to avoid having the read all segment registers when
#     locking/unlocking the access, some data is kept in the thread_struct
#     and saved on stack on exceptions. The field identifies both the
#     first unlocked segment and the first segment following the last
#     unlocked one. When no segment is unlocked, it contains value 0.
#     
#     As the hash_page() function is not able to easily determine if a
#     protfault is due to a bad kernel access to userspace, protfaults
#     need to be handled by handle_page_fault when KUAP is set.
#     
#     Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
#     [mpe: Drop allow_read/write_to/from_user() as they're now in kup.h,
#           and adapt allow_user_access() to do nothing when to == NULL]
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-gcc --version
# < /opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-ld --version
# < git log --format=%s --max-count=1 cb42033f5d172b5779b6c8301c65693ff6a0a778
# < make -s -j 120 ARCH=openrisc O=/kisskb/build/mpe_or1ksim_defconfig_or32 CROSS_COMPILE=/opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-  or1ksim_defconfig
# make -s -j 120 ARCH=openrisc O=/kisskb/build/mpe_or1ksim_defconfig_or32 CROSS_COMPILE=/opt/cross/kisskb/or1k-linux-5.4.0-20170218/or1k-linux/bin/or1k-linux-  
/kisskb/src/mm/mprotect.c: In function 'change_pte_range':
/kisskb/src/mm/mprotect.c:42:20: warning: unused variable 'mm' [-Wunused-variable]
  struct mm_struct *mm = vma->vm_mm;
                    ^
Completed OK
# rm -rf /kisskb/build/mpe_or1ksim_defconfig_or32
# Build took: 0:00:14.887461