# git rev-parse -q --verify c7dee506ec3450717e84518ab3a6a3f2ce755cf6^{commit}
c7dee506ec3450717e84518ab3a6a3f2ce755cf6
already have revision, skipping fetch
# git checkout -q -f -B kisskb c7dee506ec3450717e84518ab3a6a3f2ce755cf6
# git clean -qxdf
# < git log -1
# commit c7dee506ec3450717e84518ab3a6a3f2ce755cf6
# Author: Michael Ellerman <mpe@ellerman.id.au>
# Date:   Tue Aug 31 23:41:15 2021 +1000
# 
#     powerpc/ptdump: Fix generic ptdump for 64-bit
#     
#     Since the conversion to generic ptdump we see crashes on 64-bit:
#     
#       BUG: Unable to handle kernel data access on read at 0xc0eeff7f00000000
#       Faulting instruction address: 0xc00000000045e5fc
#       Oops: Kernel access of bad area, sig: 11 [#1]
#       ...
#       NIP __walk_page_range+0x2bc/0xce0
#       LR  __walk_page_range+0x240/0xce0
#       Call Trace:
#         __walk_page_range+0x240/0xce0 (unreliable)
#         walk_page_range_novma+0x74/0xb0
#         ptdump_walk_pgd+0x98/0x170
#         ptdump_check_wx+0x88/0xd0
#         mark_rodata_ro+0x48/0x80
#         kernel_init+0x74/0x1a0
#         ret_from_kernel_thread+0x5c/0x64
#     
#     What's happening is that have walked off the end of the kernel page
#     tables, and started dereferencing junk values.
#     
#     That happens because we initialised the ptdump_range to span all the way
#     up to 0xffffffffffffffff:
#     
#     static struct ptdump_range ptdump_range[] __ro_after_init = {
#             {TASK_SIZE_MAX, ~0UL},
#     
#     But the kernel page tables don't span that far. So on 64-bit set the end
#     of the range to be the address immediately past the end of the kernel
#     page tables, to limit the page table walk to valid addresses.
#     
#     Fixes: e084728393a5 ("powerpc/ptdump: Convert powerpc to GENERIC_PTDUMP")
#     Reported-by: Nathan Chancellor <nathan@kernel.org>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 c7dee506ec3450717e84518ab3a6a3f2ce755cf6
# < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc44x_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  ppc44x_defconfig
# < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc44x_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc44x_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_ppc44x_defconfig_powerpc-gcc9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-9.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
Completed OK
# rm -rf /kisskb/build/powerpc-next_ppc44x_defconfig_powerpc-gcc9
# Build took: 0:00:47.001262