# git rev-parse -q --verify 2974d421aac1374d3269fe4f1fba2068aa33134d^{commit}
2974d421aac1374d3269fe4f1fba2068aa33134d
already have revision, skipping fetch
# git checkout -q -f -B kisskb 2974d421aac1374d3269fe4f1fba2068aa33134d
# git clean -qxdf
# < git log -1
# commit 2974d421aac1374d3269fe4f1fba2068aa33134d
# Author: Christophe Leroy <christophe.leroy@csgroup.eu>
# Date:   Fri Sep 17 15:57:31 2021 +0200
# 
#     powerpc/32: Don't use a struct based type for pte_t
#     
#     Long time ago we had a config item called STRICT_MM_TYPECHECKS
#     to build the kernel with pte_t defined as a structure in order
#     to perform additional build checks or build it with pte_t
#     defined as a simple type in order to get simpler generated code.
#     
#     Commit 670eea924198 ("powerpc/mm: Always use STRICT_MM_TYPECHECKS")
#     made the struct based definition the only one, considering that the
#     generated code was similar in both cases.
#     
#     That's right on ppc64 because the ABI is such that the content of a
#     struct having a single simple type element is passed as register,
#     but on ppc32 such a structure is passed via the stack like any
#     structure.
#     
#     Simple test function:
#     
#             pte_t test(pte_t pte)
#             {
#                     return pte;
#             }
#     
#     Before this patch we get
#     
#             c00108ec <test>:
#             c00108ec:       81 24 00 00     lwz     r9,0(r4)
#             c00108f0:       91 23 00 00     stw     r9,0(r3)
#             c00108f4:       4e 80 00 20     blr
#     
#     So, for PPC32, restore the simple type behaviour we got before
#     commit 670eea924198, but instead of adding a config option to
#     activate type check, do it when __CHECKER__ is set so that type
#     checking is performed by 'sparse' and provides feedback like:
#     
#             arch/powerpc/mm/pgtable.c:466:16: warning: incorrect type in return expression (different base types)
#             arch/powerpc/mm/pgtable.c:466:16:    expected unsigned long
#             arch/powerpc/mm/pgtable.c:466:16:    got struct pte_t [usertype] x
#     
#     With this patch we now get
#     
#             c0010890 <test>:
#             c0010890:       4e 80 00 20     blr
#     
#     Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
#     [mpe: Define STRICT_MM_TYPECHECKS rather than repeating the condition]
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/c904599f33aaf6bb7ee2836a9ff8368509e0d78d.1631887042.git.christophe.leroy@csgroup.eu
# < /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 2974d421aac1374d3269fe4f1fba2068aa33134d
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_adder875_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  adder875_defconfig
# < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_adder875_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_adder875_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_adder875_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-next_adder875_defconfig_powerpc-gcc5
# Build took: 0:00:49.166092