kernel.git/arch/s390/kernel, branch linux-3.18.y

s390/smp: fix CPU hotplug deadlock with CPU rescan

2019-02-06T16:34:51Z

commit b7cb707c373094ce4008d4a6ac9b6b366ec52da5 upstream. smp_rescan_cpus() is called without the device_hotplug_lock, which can lead to a dedlock when a new CPU is found and immediately set online by a udev rule. This was observed on an older kernel version, where the cpu_hotplug_begin() loop was still present, and it resulted in hanging chcpu and systemd-udev processes. This specific deadlock will not show on current kernels. However, there may be other possible deadlocks, and since smp_rescan_cpus() can still trigger a CPU hotplug operation, the device_hotplug_lock should be held. For reference, this was the deadlock with the old cpu_hotplug_begin() loop: chcpu (rescan) systemd-udevd echo 1 > /sys/../rescan -> smp_rescan_cpus() -> (*) get_online_cpus() (increases refcount) -> smp_add_present_cpu() (new CPU found) -> register_cpu() -> device_add() -> udev "add" event triggered -----------> udev rule sets CPU online -> echo 1 > /sys/.../online -> lock_device_hotplug_sysfs() (this is missing in rescan path) -> device_online() -> (**) device_lock(new CPU dev) -> cpu_up() -> cpu_hotplug_begin() (loops until refcount == 0) -> deadlock with (*) -> bus_probe_device() -> device_attach() -> device_lock(new CPU dev) -> deadlock with (**) Fix this by taking the device_hotplug_lock in the CPU rescan path. Cc: Signed-off-by: Gerald Schaefer Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/cpum_cf: Reject request for sampling in event initialization

2018-12-17T09:07:09Z

[ Upstream commit 613a41b0d16e617f46776a93b975a1eeea96417c ] On s390 command perf top fails [root@s35lp76 perf] # ./perf top -F100000 --stdio Error: cycles: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' [root@s35lp76 perf] # Using event -e rb0000 works as designed. Event rb0000 is the event number of the sampling facility for basic sampling. During system start up the following PMUs are installed in the kernel's PMU list (from head to tail): cpum_cf --> s390 PMU counter facility device driver cpum_sf --> s390 PMU sampling facility device driver uprobe kprobe tracepoint task_clock cpu_clock Perf top executes following functions and calls perf_event_open(2) system call with different parameters many times: cmd_top --> __cmd_top --> perf_evlist__add_default --> __perf_evlist__add_default --> perf_evlist__new_cycles (creates event type:0 (HW) config 0 (CPU_CYCLES) --> perf_event_attr__set_max_precise_ip Uses perf_event_open(2) to detect correct precise_ip level. Fails 3 times on s390 which is ok. Then functions cmd_top --> __cmd_top --> perf_top__start_counters -->perf_evlist__config --> perf_can_comm_exec --> perf_probe_api This functions test support for the following events: "cycles:u", "instructions:u", "cpu-clock:u" using --> perf_do_probe_api --> perf_event_open_cloexec Test the close on exec flag support with perf_event_open(2). perf_do_probe_api returns true if the event is supported. The function returns true because event cpu-clock is supported by the PMU cpu_clock. This is achieved by many calls to perf_event_open(2). Function perf_top__start_counters now calls perf_evsel__open() for every event, which is the default event cpu_cycles (config:0) and type HARDWARE (type:0) which a predfined frequence of 4000. Given the above order of the PMU list, the PMU cpum_cf gets called first and returns 0, which indicates support for this sampling. The event is fully allocated in the function perf_event_open (file kernel/event/core.c near line 10521 and the following check fails: event = perf_event_alloc(&attr, cpu, task, group_leader, NULL, NULL, NULL, cgroup_fd); if (IS_ERR(event)) { err = PTR_ERR(event); goto err_cred; } if (is_sampling_event(event)) { if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) { err = -EOPNOTSUPP; goto err_alloc; } } The check for the interrupt capabilities fails and the system call perf_event_open() returns -EOPNOTSUPP (-95). Add a check to return -ENODEV when sampling is requested in PMU cpum_cf. This allows common kernel code in the perf_event_open() system call to test the next PMU in above list. Fixes: 97b1198fece0 (" "s390, perf: Use common PMU interrupt disabled code") Signed-off-by: Thomas Richter Reviewed-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin

s390/vdso: add missing FORCE to build targets

2018-11-27T15:05:36Z

[ Upstream commit b44b136a3773d8a9c7853f8df716bd1483613cbb ] According to Documentation/kbuild/makefiles.txt all build targets using if_changed should use FORCE as well. Add missing FORCE to make sure vdso targets are rebuild properly when not just immediate prerequisites have changed but also when build command differs. Reviewed-by: Philipp Rudo Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin

s390/ftrace/jprobes: Fix conflict between jprobes and function graph tracing

2018-11-10T15:39:13Z

[ Upstream commit e64a5470dcd2900ab8f8f83638c00098b10e6300 ] This fixes the same issue Steven already fixed for x86 in following commit: 237d28db036e ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing It fixes the crash, that happens when function graph tracing and jprobes are used simultaneously. Please refer to above commit for details. Signed-off-by: Jiri Olsa Signed-off-by: Martin Schwidefsky Acked-by: Steven Rostedt Signed-off-by: Sasha Levin

s390/ipl: ensure loadparm valid flag is set

2018-04-24T07:29:24Z

commit 15deb080a6087b73089139569558965750e69d67 upstream. When loadparm is set in reipl parm block, the kernel should also set DIAG308_FLAGS_LP_VALID flag. This fixes loadparm ignoring during z/VM fcp -> ccw reipl and kvm direct boot -> ccw reipl. Cc: Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: move _text symbol to address higher than zero

2018-04-13T17:52:10Z

[ Upstream commit d04a4c76f71dd5335f8e499b59617382d84e2b8d ] The perf tool assumes that kernel symbols are never present at address zero. In fact it assumes if functions that map symbols to addresses return zero, that the symbol was not found. Given that s390's _text symbol historically is located at address zero this yields at least a couple of false errors and warnings in one of perf's test cases about not present symbols ("perf test 1"). To fix this simply move the _text symbol to address 0x200, just behind the initial psw and channel program located at the beginning of the kernel image. This is now hard coded within the linker script. I tried a nicer solution which moves the initial psw and channel program into an own section. However that would move the symbols within the "real" head.text section to different addresses, since the ".org" statements within head.S are relative to the head.text section. If there is a new section in front, everything else will be moved. Alternatively I could have adjusted all ".org" statements. But this current solution seems to be the easiest one, since nobody really cares where the _text symbol is actually located. Reported-by: Zvonko Kosic Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390: fix handling of -1 in set{,fs}[gu]id16 syscalls

2018-02-25T10:01:15Z

commit 6dd0d2d22aa363fec075cb2577ba273ac8462e94 upstream. For some reason, the implementation of some 16-bit ID system calls (namely, setuid16/setgid16 and setfsuid16/setfsgid16) used type cast instead of low2highgid/low2highuid macros for converting [GU]IDs, which led to incorrect handling of value of -1 (which ought to be considered invalid). Discovered by strace test suite. Cc: stable@vger.kernel.org Signed-off-by: Eugene Syromiatnikov Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/disassembler: increase show_code buffer size

2017-11-30T08:35:47Z

commit b192571d1ae375e0bbe0aa3ccfa1a3c3704454b9 upstream. Current buffer size of 64 is too small. objdump shows that there are instructions which would require up to 75 bytes buffer (with current formating). 128 bytes "ought to be enough for anybody". Also replaces 8 spaces with a single tab to reduce the memory footprint. Fixes the following KASAN finding: BUG: KASAN: stack-out-of-bounds in number+0x3fe/0x538 Write of size 1 at addr 000000005a4a75a0 by task bash/1282 CPU: 1 PID: 1282 Comm: bash Not tainted 4.14.0+ #215 Hardware name: IBM 2964 N96 702 (z/VM 6.4.0) Call Trace: ([<000000000011eeb6>] show_stack+0x56/0x88) [<0000000000e1ce1a>] dump_stack+0x15a/0x1b0 [<00000000004e2994>] print_address_description+0xf4/0x288 [<00000000004e2cf2>] kasan_report+0x13a/0x230 [<0000000000e38ae6>] number+0x3fe/0x538 [<0000000000e3dfe4>] vsnprintf+0x194/0x948 [<0000000000e3ea42>] sprintf+0xa2/0xb8 [<00000000001198dc>] print_insn+0x374/0x500 [<0000000000119346>] show_code+0x4ee/0x538 [<000000000011f234>] show_registers+0x34c/0x388 [<000000000011f2ae>] show_regs+0x3e/0xa8 [<000000000011f502>] die+0x1ea/0x2e8 [<0000000000138f0e>] do_no_context+0x106/0x168 [<0000000000139a1a>] do_protection_exception+0x4da/0x7d0 [<0000000000e55914>] pgm_check_handler+0x16c/0x1c0 [<000000000090639e>] sysrq_handle_crash+0x46/0x58 ([<0000000000000007>] 0x7) [<00000000009073fa>] __handle_sysrq+0x102/0x218 [<0000000000907c06>] write_sysrq_trigger+0xd6/0x100 [<000000000061d67a>] proc_reg_write+0xb2/0x128 [<0000000000520be6>] __vfs_write+0xee/0x368 [<0000000000521222>] vfs_write+0x21a/0x278 [<000000000052156a>] SyS_write+0xda/0x178 [<0000000000e555cc>] system_call+0xc4/0x270 The buggy address belongs to the page: page:000003d1016929c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() raw: 0000000000000000 0000000000000000 0000000000000000 ffffffff00000000 raw: 0000000000000100 0000000000000200 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: 000000005a4a7480: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 000000005a4a7500: 00 00 00 00 00 00 00 00 f2 f2 f2 f2 00 00 00 00 >000000005a4a7580: 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00 ^ 000000005a4a7600: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f8 f8 000000005a4a7680: f2 f2 f2 f2 f2 f2 f8 f8 f2 f2 f3 f3 f3 f3 00 00 ================================================================== Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: use correct input data address for setup_randomness

2017-04-18T05:55:53Z

commit 4920e3cf77347d7d7373552d4839e8d832321313 upstream. The current implementation of setup_randomness uses the stack address and therefore the pointer to the SYSIB 3.2.2 block as input data address. Furthermore the length of the input data is the number of virtual-machine description blocks which is typically one. This means that typically a single zero byte is fed to add_device_randomness. Fix both of these and use the address of the first virtual machine description block as input data address and also use the correct length. Fixes: bcfcbb6bae64 ("s390: add system information as device randomness") Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390: make setup_randomness work

2017-04-18T05:55:53Z

commit da8fd820f389a0e29080b14c61bf5cf1d8ef5ca1 upstream. Commit bcfcbb6bae64 ("s390: add system information as device randomness") intended to add some virtual machine specific information to the randomness pool. Unfortunately it uses the page allocator before it is ready to use. In result the page allocator always returns NULL and the setup_randomness function never adds anything to the randomness pool. To fix this use memblock_alloc and memblock_free instead. Fixes: bcfcbb6bae64 ("s390: add system information as device randomness") Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman