# git rev-parse -q --verify 81b654c273914704a4bdf580f28d67aaba1094e4^{commit} 81b654c273914704a4bdf580f28d67aaba1094e4 already have revision, skipping fetch # git checkout -q -f -B kisskb 81b654c273914704a4bdf580f28d67aaba1094e4 # git clean -qxdf # < git log -1 # commit 81b654c273914704a4bdf580f28d67aaba1094e4 # Author: Michael Ellerman # Date: Thu Apr 12 22:24:45 2018 +1000 # # powerpc/64s: Fix CPU_FTRS_ALWAYS vs DT CPU features # # The cpu_has_feature() mechanism has an optimisation where at build # time we construct a mask of the CPU feature bits that will always be # true for the given .config, based on the platform/bitness/etc. that we # are building for. # # That is incompatible with DT CPU features, where the set of CPU # features is dependent on feature flags that are given to us by # firmware. # # The result is that some feature bits can not be *disabled* by DT CPU # features. Or more accurately, they can be disabled but they will still # appear in the ALWAYS mask, meaning cpu_has_feature() will always # return true for them. # # In the past this hasn't really been a problem because on Book3S # 64 (where we support DT CPU features), the set of ALWAYS bits has been # very small. That was because we always built for POWER4 and later, # meaning the set of common bits was small. # # The only bit that could be cleared by DT CPU features that was also in # the ALWAYS mask was CPU_FTR_NODSISRALIGN, and that was only used in # the alignment handler to create a fake DSISR. That code was itself # deleted in 31bfdb036f12 ("powerpc: Use instruction emulation # infrastructure to handle alignment faults") (Sep 2017). # # However the set of ALWAYS features changed with the recent commit # db5ae1c155af ("powerpc/64s: Refine feature sets for little endian # builds") which restricted the set of feature flags when building # little endian to Power7 or later. That caused the ALWAYS mask to # become much larger for little endian builds. # # The result is that the following feature bits can currently not # be *disabled* by DT CPU features: # # CPU_FTR_REAL_LE, CPU_FTR_MMCRA, CPU_FTR_CTRL, CPU_FTR_SMT, # CPU_FTR_PURR, CPU_FTR_SPURR, CPU_FTR_DSCR, CPU_FTR_PKEY, # CPU_FTR_VMX_COPY, CPU_FTR_CFAR, CPU_FTR_HAS_PPR. # # To fix it we need to mask the set of ALWAYS features with the base set # of DT CPU features, ie. the features that are always enabled by DT CPU # features. That way there are no bits in the ALWAYS mask that are not # also always set by DT CPU features. # # Fixes: db5ae1c155af ("powerpc/64s: Refine feature sets for little endian builds") # Reviewed-by: Nicholas Piggin # Signed-off-by: Michael Ellerman # < /opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux-gcc --version # < git log --format=%s --max-count=1 81b654c273914704a4bdf580f28d67aaba1094e4 # < make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mipsel CROSS_COMPILE=/opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux- defconfig # make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mipsel CROSS_COMPILE=/opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux- arch/mips/boot/dts/img/boston.dtb: Warning (pci_bridge): /pci@10000000: missing bus-range for PCI bridge arch/mips/boot/dts/img/boston.dtb: Warning (pci_bridge): /pci@12000000: missing bus-range for PCI bridge arch/mips/boot/dts/img/boston.dtb: Warning (pci_bridge): /pci@14000000: missing bus-range for PCI bridge arch/mips/boot/dts/img/boston.dtb: Warning (pci_device_bus_num): Failed prerequisite 'pci_bridge' /kisskb/src/kernel/bpf/syscall.c:1229:12: warning: 'bpf_prog_attach_check_attach_type' defined but not used [-Wunused-function] static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog, ^ FIT description: Linux 4.16.0-g81b654c Created: Sat Apr 14 00:08:56 2018 Image 0 (kernel@0) Description: Linux 4.16.0-g81b654c Created: Sat Apr 14 00:08:56 2018 Type: Kernel Image Compression: gzip compressed Data Size: 4417629 Bytes = 4314.09 kB = 4.21 MB Architecture: MIPS OS: Linux Load Address: 0x80100000 Entry Point: 0x80880600 Hash algo: sha1 Hash value: ab397d9f6b32b7b33e13e6e00ae0c5ccdb622902 Image 1 (fdt@boston) Description: img,boston Device Tree Created: Sat Apr 14 00:08:56 2018 Type: Flat Device Tree Compression: uncompressed Data Size: 3602 Bytes = 3.52 kB = 0.00 MB Architecture: MIPS Hash algo: sha1 Hash value: dabc84017c5ea1c23fdb5a4b25d185bdf81faa6a Image 2 (fdt@ni169445) Description: NI 169445 device tree Created: Sat Apr 14 00:08:56 2018 Type: Flat Device Tree Compression: uncompressed Data Size: 1871 Bytes = 1.83 kB = 0.00 MB Architecture: MIPS Hash algo: sha1 Hash value: 51b89b31605ee62038c8468c429af091dfc75ec7 Default Configuration: 'conf@default' Configuration 0 (conf@default) Description: Generic Linux kernel Kernel: kernel@0 Configuration 1 (conf@boston) Description: Boston Linux kernel Kernel: kernel@0 FDT: fdt@boston Configuration 2 (conf@ni169445) Description: NI 169445 Linux Kernel Kernel: kernel@0 FDT: fdt@ni169445 Completed OK # rm -rf /kisskb/build/powerpc-fixes_mips-defconfig_mipsel # Build took: 0:04:12.280177