kernel.git/arch/s390/kernel, branch linux-5.0.y

s390/kexec_file: Fix detection of text segment in ELF loader

2019-05-31T13:44:57Z

[ Upstream commit 729829d775c9a5217abc784b2f16087d79c4eec8 ] To register data for the next kernel (command line, oldmem_base, etc.) the current kernel needs to find the ELF segment that contains head.S. This is currently done by checking ifor 'phdr->p_paddr == 0'. This works fine for the current kernel build but in theory the first few pages could be skipped. Make the detection more robust by checking if the entry point lies within the segment. Signed-off-by: Philipp Rudo Signed-off-by: Martin Schwidefsky Signed-off-by: Sasha Levin

s390/speculation: Support 'mitigations=' cmdline option

2019-05-14T17:17:13Z

commit 0336e04a6520bdaefdb0769d2a70084fa52e81ed upstream Configure s390 runtime CPU speculation bug mitigations in accordance with the 'mitigations=' cmdline option. This affects Spectre v1 and Spectre v2. The default behavior is unchanged. Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Tested-by: Jiri Kosina (on x86) Reviewed-by: Jiri Kosina Cc: Borislav Petkov Cc: "H . Peter Anvin" Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Jiri Kosina Cc: Waiman Long Cc: Andrea Arcangeli Cc: Jon Masters Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: linux-s390@vger.kernel.org Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org Cc: Greg Kroah-Hartman Cc: Tyler Hicks Cc: Linus Torvalds Cc: Randy Dunlap Cc: Steven Price Cc: Phil Auld Link: https://lkml.kernel.org/r/e4a161805458a5ec88812aac0307ae3908a030fc.1555085500.git.jpoimboe@redhat.com Signed-off-by: Greg Kroah-Hartman

perf/aux: Make perf_event accessible to setup_aux()

2019-04-05T20:34:42Z

[ Upstream commit 840018668ce2d96783356204ff282d6c9b0e5f66 ] When pmu::setup_aux() is called the coresight PMU needs to know which sink to use for the session by looking up the information in the event's attr::config2 field. As such simply replace the cpu information by the complete perf_event structure and change all affected customers. Signed-off-by: Mathieu Poirier Reviewed-by: Suzuki Poulouse Acked-by: Peter Zijlstra Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexei Starovoitov Cc: Greg Kroah-Hartman Cc: H. Peter Anvin Cc: Heiko Carstens Cc: Jiri Olsa Cc: Mark Rutland Cc: Martin Schwidefsky Cc: Namhyung Kim Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arm-kernel@lists.infradead.org Cc: linux-s390@vger.kernel.org Link: http://lkml.kernel.org/r/20190131184714.20388-2-mathieu.poirier@linaro.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin

s390/setup: fix boot crash for machine without EDAT-1

2019-03-23T19:11:41Z

commit 86a86804e4f18fc3880541b3d5a07f4df0fe29cb upstream. The fix to make WARN work in the early boot code created a problem on older machines without EDAT-1. The setup_lowcore_dat_on function uses the pointer from lowcore_ptr[0] to set the DAT bit in the new PSWs. That does not work if the kernel page table is set up with 4K pages as the prefix address maps to absolute zero. To make this work the PSWs need to be changed with via address 0 in form of the S390_lowcore definition. Reported-by: Guenter Roeck Tested-by: Cornelia Huck Fixes: 94f85ed3e2f8 ("s390/setup: fix early warning messages") Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/setup: fix early warning messages

2019-03-23T19:11:20Z

commit 8727638426b0aea59d7f904ad8ddf483f9234f88 upstream. The setup_lowcore() function creates a new prefix page for the boot CPU. The PSW mask for the system_call, external interrupt, i/o interrupt and the program check handler have the DAT bit set in this new prefix page. At the time setup_lowcore is called the system still runs without virtual address translation, the paging_init() function creates the kernel page table and loads the CR13 with the kernel ASCE. Any code between setup_lowcore() and the end of paging_init() that has a BUG or WARN statement will create a program check that can not be handled correctly as there is no kernel page table yet. To allow early WARN statements initially setup the lowcore with DAT off and set the DAT bit only after paging_init() has completed. Cc: stable@vger.kernel.org Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman

s390/suspend: fix stack setup in swsusp_arch_suspend

2019-01-28T14:43:17Z

The patch that added support for the virtually mapped kernel stacks changed swsusp_arch_suspend to switch to the nodat-stack as the vmap stack is not available while going in and out of suspend. Unfortunately the switch to the nodat-stack is incorrect which breaks suspend to disk. Cc: stable@vger.kernel.org # v4.20 Fixes: ce3dc447493f ("s390: add support for virtually mapped kernel stacks") Signed-off-by: Martin Schwidefsky

s390/smp: Fix calling smp_call_ipl_cpu() from ipl CPU

2019-01-11T16:12:03Z

When calling smp_call_ipl_cpu() from the IPL CPU, we will try to read from pcpu_devices->lowcore. However, due to prefixing, that will result in reading from absolute address 0 on that CPU. We have to go via the actual lowcore instead. This means that right now, we will read lc->nodat_stack == 0 and therfore work on a very wrong stack. This BUG essentially broke rebooting under QEMU TCG (which will report a low address protection exception). And checking under KVM, it is also broken under KVM. With 1 VCPU it can be easily triggered. :/# echo 1 > /proc/sys/kernel/sysrq :/# echo b > /proc/sysrq-trigger [ 28.476745] sysrq: SysRq : Resetting [ 28.476793] Kernel stack overflow. [ 28.476817] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 [ 28.476820] Hardware name: IBM 2964 NE1 716 (KVM/Linux) [ 28.476826] Krnl PSW : 0400c00180000000 0000000000115c0c (pcpu_delegate+0x12c/0x140) [ 28.476861] R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 [ 28.476863] Krnl GPRS: ffffffffffffffff 0000000000000000 000000000010dff8 0000000000000000 [ 28.476864] 0000000000000000 0000000000000000 0000000000ab7090 000003e0006efbf0 [ 28.476864] 000000000010dff8 0000000000000000 0000000000000000 0000000000000000 [ 28.476865] 000000007fffc000 0000000000730408 000003e0006efc58 0000000000000000 [ 28.476887] Krnl Code: 0000000000115bfe: 4170f000 la %r7,0(%r15) [ 28.476887] 0000000000115c02: 41f0a000 la %r15,0(%r10) [ 28.476887] #0000000000115c06: e370f0980024 stg %r7,152(%r15) [ 28.476887] >0000000000115c0c: c0e5fffff86e brasl %r14,114ce8 [ 28.476887] 0000000000115c12: 41f07000 la %r15,0(%r7) [ 28.476887] 0000000000115c16: a7f4ffa8 brc 15,115b66 [ 28.476887] 0000000000115c1a: 0707 bcr 0,%r7 [ 28.476887] 0000000000115c1c: 0707 bcr 0,%r7 [ 28.476901] Call Trace: [ 28.476902] Last Breaking-Event-Address: [ 28.476920] [<0000000000a01c4a>] arch_call_rest_init+0x22/0x80 [ 28.476927] Kernel panic - not syncing: Corrupt kernel stack, can't continue. [ 28.476930] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13 [ 28.476932] Hardware name: IBM 2964 NE1 716 (KVM/Linux) [ 28.476932] Call Trace: Fixes: 2f859d0dad81 ("s390/smp: reduce size of struct pcpu") Cc: stable@vger.kernel.org # 4.0+ Reported-by: Cornelia Huck Signed-off-by: David Hildenbrand Signed-off-by: Martin Schwidefsky

s390/vdso: correct vdso mapping for compat tasks

2019-01-11T16:12:02Z

While "s390/vdso: avoid 64-bit vdso mapping for compat tasks" fixed 64-bit vdso mapping for compat tasks under gdb it introduced another problem. "compat_mm" flag is not inherited during fork and when 31-bit process forks a child (but does not perform exec) it ends up with 64-bit vdso. To address that, init_new_context (which is called during fork and exec) now initialize compat_mm based on thread TIF_31BIT flag. Later compat_mm is adjusted in arch_setup_additional_pages, which is called during exec. Fixes: d1befa65823e ("s390/vdso: avoid 64-bit vdso mapping for compat tasks") Reported-by: Stefan Liebler Reviewed-by: Heiko Carstens Cc: # v4.20+ Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky

s390/smp: fix CPU hotplug deadlock with CPU rescan

2019-01-11T16:12:02Z

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

s390/early: improve machine detection

2019-01-11T16:12:02Z

Right now the early machine detection code check stsi 3.2.2 for "KVM" and set MACHINE_IS_VM if this is different. As the console detection uses diagnose 8 if MACHINE_IS_VM returns true this will crash Linux early for any non z/VM system that sets a different value than KVM. So instead of assuming z/VM, do not set any of MACHINE_IS_LPAR, MACHINE_IS_VM, or MACHINE_IS_KVM. CC: stable@vger.kernel.org Reviewed-by: Heiko Carstens Signed-off-by: Christian Borntraeger Signed-off-by: Martin Schwidefsky