# git rev-parse -q --verify c64316502008064c158fa40cc250665e461b0f2a^{commit}
c64316502008064c158fa40cc250665e461b0f2a
already have revision, skipping fetch
# git checkout -q -f -B kisskb c64316502008064c158fa40cc250665e461b0f2a
# git clean -qxdf
# < git log -1
# commit c64316502008064c158fa40cc250665e461b0f2a
# Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
# Date:   Sat Feb 16 14:51:26 2019 +0100
# 
#     crypto: sha512/arm - fix crash bug in Thumb2 build
#     
#     The SHA512 code we adopted from the OpenSSL project uses a rather
#     peculiar way to take the address of the round constant table: it
#     takes the address of the sha256_block_data_order() routine, and
#     substracts a constant known quantity to arrive at the base of the
#     table, which is emitted by the same assembler code right before
#     the routine's entry point.
#     
#     However, recent versions of binutils have helpfully changed the
#     behavior of references emitted via an ADR instruction when running
#     in Thumb2 mode: it now takes the Thumb execution mode bit into
#     account, which is bit 0 af the address. This means the produced
#     table address also has bit 0 set, and so we end up with an address
#     value pointing 1 byte past the start of the table, which results
#     in crashes such as
#     
#       Unable to handle kernel paging request at virtual address bf825000
#       pgd = 42f44b11
#       [bf825000] *pgd=80000040206003, *pmd=5f1bd003, *pte=00000000
#       Internal error: Oops: 207 [#1] PREEMPT SMP THUMB2
#       Modules linked in: sha256_arm(+) sha1_arm_ce sha1_arm ...
#       CPU: 7 PID: 396 Comm: cryptomgr_test Not tainted 5.0.0-rc6+ #144
#       Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
#       PC is at sha256_block_data_order+0xaaa/0xb30 [sha256_arm]
#       LR is at __this_module+0x17fd/0xffffe800 [sha256_arm]
#       pc : [<bf820bca>]    lr : [<bf824ffd>]    psr: 800b0033
#       sp : ebc8bbe8  ip : faaabe1c  fp : 2fdd3433
#       r10: 4c5f1692  r9 : e43037df  r8 : b04b0a5a
#       r7 : c369d722  r6 : 39c3693e  r5 : 7a013189  r4 : 1580d26b
#       r3 : 8762a9b0  r2 : eea9c2cd  r1 : 3e9ab536  r0 : 1dea4ae7
#       Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA Thumb  Segment user
#       Control: 70c5383d  Table: 6b8467c0  DAC: dbadc0de
#       Process cryptomgr_test (pid: 396, stack limit = 0x69e1fe23)
#       Stack: (0xebc8bbe8 to 0xebc8c000)
#       ...
#       unwind: Unknown symbol address bf820bca
#       unwind: Index not found bf820bca
#       Code: 441a ea80 40f9 440a (f85e) 3b04
#       ---[ end trace e560cce92700ef8a ]---
#     
#     Given that this affects older kernels as well, in case they are built
#     with a recent toolchain, apply a minimal backportable fix, which is
#     to emit another non-code label at the start of the routine, and
#     reference that instead. (This is similar to the current upstream state
#     of this file in OpenSSL)
#     
#     Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
#     Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
# < /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 c64316502008064c158fa40cc250665e461b0f2a
# < make -s -j 10 ARCH=powerpc O=/kisskb/build/crypto_powernv_defconfig_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# make -s -j 10 ARCH=powerpc O=/kisskb/build/crypto_powernv_defconfig_ppc64le-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
WARNING: modpost: Found 2 section mismatch(es).
To see full details build your kernel with:
'make CONFIG_DEBUG_SECTION_MISMATCH=y'
Completed OK
# rm -rf /kisskb/build/crypto_powernv_defconfig_ppc64le-gcc5
# Build took: 0:03:10.654731