# 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/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < git log --format=%s --max-count=1 81b654c273914704a4bdf580f28d67aaba1094e4 # < make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-fixes_mvme5100_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- mvme5100_defconfig # make -s -j 80 ARCH=powerpc O=/kisskb/build/powerpc-fixes_mvme5100_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/ipc/shm.c: In function 'ksys_shmdt': /kisskb/src/ipc/shm.c:1607:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:182:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker': /kisskb/src/lib/rhashtable.c:269:2: warning: 'next' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c:234:28: note: 'next' was declared here /kisskb/src/drivers/net/tun.c: In function 'tun_get_user': /kisskb/src/drivers/net/tun.c:1820:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1530:31: warning: 'linear' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1730:46: note: 'linear' was declared here /kisskb/src/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': /kisskb/src/drivers/tty/serial/8250/8250_core.c:246:2: warning: 'i' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/tty/serial/8250/8250_core.c:231:19: note: 'i' was declared here /kisskb/src/kernel/time/tick-sched.c: In function 'tick_nohz_idle_exit': /kisskb/src/kernel/time/tick-sched.c:637:17: warning: 'now' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/time/tick-sched.c:1044:10: note: 'now' was declared here /kisskb/src/net/core/gen_stats.c: In function '__gnet_stats_copy_basic': /kisskb/src/net/core/gen_stats.c:149:19: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/flow_dissector.c: In function '__skb_flow_dissect': /kisskb/src/net/core/flow_dissector.c:789:7: warning: 'vlan' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:157:15: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/dev.c: In function 'validate_xmit_skb_list': /kisskb/src/net/core/dev.c:3176:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized] INFO: Uncompressed kernel (size 0x409f5c) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) Completed OK # rm -rf /kisskb/build/powerpc-fixes_mvme5100_defconfig_powerpc # Build took: 0:00:40.572913