# git rev-parse -q --verify e620d45065c7b5b8d6ae11217c09c09380103b83^{commit} e620d45065c7b5b8d6ae11217c09c09380103b83 already have revision, skipping fetch # git checkout -q -f -B kisskb e620d45065c7b5b8d6ae11217c09c09380103b83 # git clean -qxdf # < git log -1 # commit e620d45065c7b5b8d6ae11217c09c09380103b83 # Author: Breno Leitao # Date: Wed Jan 16 14:47:44 2019 -0200 # # powerpc/tm: Avoid machine crash on rt_sigreturn() # # There is a kernel crash that happens if rt_sigreturn() is called inside # a transactional block. # # This crash happens if the kernel hits an in-kernel page fault when # accessing userspace memory, usually through copy_ckvsx_to_user(). A # major page fault calls might_sleep() function, which can cause a task # reschedule. A task reschedule (switch_to()) reclaim and recheckpoint # the TM states, but, in the signal return path, the checkpointed memory # was already reclaimed, thus the exception stack has MSR that points to # MSR[TS]=0. # # When the code returns from might_sleep() and a task reschedule # happened, then this task is returned with the memory recheckpointed, # and CPU MSR[TS] = suspended. # # This means that there is a side effect at might_sleep() if it is # called with CPU MSR[TS] = 0 and the task has regs->msr[TS] != 0. # # This side effect can cause a TM bad thing, since at the exception # entrance, the stack saves MSR[TS]=0, and this is what will be used at # RFID, but, the processor has MSR[TS] = Suspended, and this transition # will be invalid and a TM Bad thing will be raised, causing the # following crash: # # Unexpected TM Bad Thing exception at c00000000000e9ec (msr 0x8000000302a03031) tm_scratch=800000010280b033 # cpu 0xc: Vector: 700 (Program Check) at [c00000003ff1fd70] # pc: c00000000000e9ec: fast_exception_return+0x100/0x1bc # lr: c000000000032948: handle_rt_signal64+0xb8/0xaf0 # sp: c0000004263ebc40 # msr: 8000000302a03031 # current = 0xc000000415050300 # paca = 0xc00000003ffc4080 irqmask: 0x03 irq_happened: 0x01 # pid = 25006, comm = sigfuz # Linux version 5.0.0-rc1-00001-g3bd6e94bec12 (breno@debian) (gcc version 8.2.0 (Debian 8.2.0-3)) #899 SMP Mon Jan 7 11:30:07 EST 2019 # WARNING: exception is not recoverable, can't continue # enter ? for help # [c0000004263ebc40] c000000000032948 handle_rt_signal64+0xb8/0xaf0 (unreliable) # [c0000004263ebd30] c000000000022780 do_notify_resume+0x2f0/0x430 # [c0000004263ebe20] c00000000000e844 ret_from_except_lite+0x70/0x74 # --- Exception: c00 (System Call) at 00007fffbaac400c # SP (7fffeca90f40) is in userspace # # The solution for this problem is running the sigreturn code with # regs->msr[TS] disabled, thus, avoiding hitting the side effect above. # This does not seem to be a problem since regs->msr will be replaced by # the ucontext value, so, it is being flushed already. In this case, it # is flushed earlier. # # Signed-off-by: Breno Leitao # Acked-by: Michael Neuling # Signed-off-by: Michael Ellerman # < /opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux-gcc --version # < /opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux-ld --version # < git log --format=%s --max-count=1 e620d45065c7b5b8d6ae11217c09c09380103b83 # < make -s -j 120 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux- defconfig arch/m68k/configs/multi_defconfig:333:warning: symbol value 'm' invalid for NET_DEVLINK arch/m68k/configs/multi_defconfig:534:warning: symbol value 'm' invalid for FS_ENCRYPTION # make -s -j 120 ARCH=m68k O=/kisskb/build/powerpc-next_m68k-defconfig_m68k CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/m68k-linux/bin/m68k-linux- :1478:2: warning: #warning syscall pidfd_send_signal not implemented [-Wcpp] :1481:2: warning: #warning syscall io_uring_setup not implemented [-Wcpp] :1484:2: warning: #warning syscall io_uring_enter not implemented [-Wcpp] :1487:2: warning: #warning syscall io_uring_register not implemented [-Wcpp] /kisskb/src/arch/m68k/mvme147/config.c: In function 'mvme147_hwclk': /kisskb/src/arch/m68k/mvme147/config.c:150:2: warning: #warning check me! [-Wcpp] /kisskb/src/arch/m68k/mvme16x/config.c: In function 'mvme16x_hwclk': /kisskb/src/arch/m68k/mvme16x/config.c:397:2: warning: #warning check me! [-Wcpp] /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:187:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/ipc/shm.c: In function 'ksys_shmdt': /kisskb/src/ipc/shm.c:1712:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c: In function 'proc_reg_open': /kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/proc/inode.c:337:21: note: 'pdeo' was declared here /kisskb/src/lib/mpi/mpicoder.c: In function 'mpi_read_raw_from_sgl': /kisskb/src/lib/mpi/mpicoder.c:336:12: warning: 'buff' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/fs/ocfs2/alloc.c: In function 'ocfs2_trim_mainbm': /kisskb/src/fs/ocfs2/alloc.c:7604:17: warning: 'first_bit' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/acct.c: In function 'acct_pin_kill': /kisskb/src/kernel/acct.c:177:2: warning: value computed is not used [-Wunused-value] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:201:12: warning: '__ei_open' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:230:12: warning: '__ei_close' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:254:13: warning: '__ei_tx_timeout' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:300:20: warning: '__ei_start_xmit' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:509:13: warning: '__ei_poll' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:850:33: warning: '__ei_get_stats' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:950:13: warning: '__ei_set_multicast_list' defined but not used [-Wunused-function] /kisskb/src/drivers/net/ethernet/8390/lib8390.c:988:27: warning: '____alloc_ei_netdev' defined but not used [-Wunused-function] /kisskb/src/fs/ocfs2/file.c: In function 'ocfs2_file_write_iter': /kisskb/src/fs/ocfs2/file.c:2386:3: warning: value computed is not used [-Wunused-value] /kisskb/src/net/core/gen_stats.c: In function '__gnet_stats_copy_basic': /kisskb/src/net/core/gen_stats.c:161:19: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/mm/mprotect.c: In function 'change_pte_range': /kisskb/src/mm/mprotect.c:42:20: warning: unused variable 'mm' [-Wunused-variable] /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/ipv4/ip_output.c: In function '__ip_append_data.isra.40': /kisskb/src/include/linux/skbuff.h:1397:6: warning: 'extra_uref' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/ipv4/ip_output.c:885:14: note: 'extra_uref' was declared here /kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker': /kisskb/src/lib/rhashtable.c:264:2: warning: 'next' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c:229:28: note: 'next' was declared here /kisskb/src/net/core/dev.c: In function 'validate_xmit_skb_list': /kisskb/src/net/core/dev.c:3405:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_del_rxsa': /kisskb/src/drivers/net/macsec.c:1926:2: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:1926:2: warning: 'rx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_del_txsa': /kisskb/src/drivers/net/macsec.c:2003:2: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2003:2: warning: 'tx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c: In function 'macsec_upd_txsa': /kisskb/src/drivers/net/macsec.c:2068:5: warning: 'assoc_num' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2068:24: warning: 'tx_sc' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/macsec.c:2069:21: warning: 'secy' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/filter.c: In function 'bpf_clear_redirect_map': /kisskb/src/net/core/filter.c:3479:4: warning: value computed is not used [-Wunused-value] /kisskb/src/fs/posix_acl.c: In function 'get_acl': /kisskb/src/fs/posix_acl.c:147:3: warning: value computed is not used [-Wunused-value] /kisskb/src/drivers/net/tun.c: In function 'tun_get_user': /kisskb/src/drivers/net/tun.c:1842:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1535:31: warning: 'linear' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/net/tun.c:1755:46: note: 'linear' was declared here /kisskb/src/net/sctp/output.c: In function 'sctp_packet_config': /kisskb/src/include/net/sock.h:1949:19: warning: 'sk' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/sctp/output.c:94:15: note: 'sk' was declared here /kisskb/src/net/ipv6/ip6_output.c: In function '__ip6_append_data.isra.38': /kisskb/src/include/linux/skbuff.h:1397:6: warning: 'extra_uref' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/ipv6/ip6_output.c:1276:14: note: 'extra_uref' was declared here Completed OK # rm -rf /kisskb/build/powerpc-next_m68k-defconfig_m68k # Build took: 0:00:42.266231