kernel/drivers/s390/char/sclp_con.c, branch linux-6.9.y

s390/consoles: improve panic notifiers reliability

2022-05-06T18:45:13Z

Currently many console drivers for s390 rely on panic/reboot notifiers to invoke callbacks on these events. The panic() function disables local IRQs, secondary CPUs and preemption, so callbacks invoked on panic are effectively running in atomic context. Happens that most of these console callbacks from s390 doesn't take the proper care with regards to atomic context, like taking spinlocks that might be taken in other function/CPU and hence will cause a lockup situation. The goal for this patch is to improve the notifiers reliability, acting on 4 console drivers, as detailed below: (1) con3215: changed a regular spinlock to the trylock alternative. (2) con3270: also changed a regular spinlock to its trylock counterpart, but here we also have another problem: raw3270_activate_view() takes a different spinlock. So, we worked a helper to validate if this other lock is safe to acquire, and if so, raw3270_activate_view() should be safe. Notice though that there is a functional change here: it's now possible to continue the notifier code [reaching con3270_wait_write() and con3270_rebuild_update()] without executing raw3270_activate_view(). (3) sclp: a global lock is used heavily in the functions called from the notifier, so we added a check here - if the lock is taken already, we just bail-out, preventing the lockup. (4) sclp_vt220: same as (3), a lock validation was added to prevent the potential lockup problem. Besides (1)-(4), we also removed useless void functions, adding the code called from the notifier inside its own body, and changed the priority of such notifiers to execute late, since they are "heavyweight" for the panic environment, so we aim to reduce risks here. Changed return values to NOTIFY_DONE as well, the standard one. Signed-off-by: Guilherme G. Piccoli Link: https://lore.kernel.org/r/20220427224924.592546-14-gpiccoli@igalia.com Signed-off-by: Heiko Carstens

s390: cleanup timer API use

2022-03-27T20:18:39Z

cleanup the s390's use of the timer API - del_timer() contains timer_pending() condition - mod_timer(timer, expires) is equivalent to: del_timer(timer); timer->expires = expires; add_timer(timer); If the timer is inactive it will be activated, using add_timer() on condition !timer_pending(&private->timer) is redundant. Just cleanup, no logic change. Signed-off-by: Yu Liao Link: https://lore.kernel.org/r/20220322030057.1243196-1-liaoyu15@huawei.com Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

Merge tag 's390-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2021-07-04T19:17:38Z

Pull s390 updates from Vasily Gorbik: - Rework inline asm to get rid of error prone "register asm" constructs, which are problematic especially when code instrumentation is enabled. In particular introduce and use register pair union to allocate even/odd register pairs. Unfortunately this breaks compatibility with older clang compilers and minimum clang version for s390 has been raised to 13. https://lore.kernel.org/linux-next/CAK7LNARuSmPCEy-ak0erPrPTgZdGVypBROFhtw+=3spoGoYsyw@mail.gmail.com/ - Fix gcc 11 warnings, which triggered various minor reworks all over the code. - Add zstd kernel image compression support. - Rework boot CPU lowcore handling. - De-duplicate and move kernel memory layout setup logic earlier. - Few fixes in preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for mem functions. - Remove broken and unused power management support leftovers in s390 drivers. - Disable stack-protector for decompressor and purgatory to fix buildroot build. - Fix vt220 sclp console name to match the char device name. - Enable HAVE_IOREMAP_PROT and add zpci_set_irq()/zpci_clear_irq() in zPCI code. - Remove some implausible WARN_ON_ONCEs and remove arch specific counter transaction call backs in favour of default transaction handling in perf code. - Extend/add new uevents for online/config/mode state changes of AP card / queue device in zcrypt. - Minor entry and ccwgroup code improvements. - Other small various fixes and improvements all over the code. * tag 's390-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (91 commits) s390/dasd: use register pair instead of register asm s390/qdio: get rid of register asm s390/ioasm: use symbolic names for asm operands s390/ioasm: get rid of register asm s390/cmf: get rid of register asm s390/lib,string: get rid of register asm s390/lib,uaccess: get rid of register asm s390/string: get rid of register asm s390/cmpxchg: use register pair instead of register asm s390/mm,pages-states: get rid of register asm s390/lib,xor: get rid of register asm s390/timex: get rid of register asm s390/hypfs: use register pair instead of register asm s390/zcrypt: Switch to flexible array member s390/speculation: Use statically initialized const for instructions virtio/s390: get rid of open-coded kvm hypercall s390/pci: add zpci_set_irq()/zpci_clear_irq() scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390 s390/ipl: use register pair instead of register asm s390/mem_detect: fix tprot() program check new psw handling ...

kernel.h: split out panic and oops helpers

2021-07-01T18:06:04Z

kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out panic and oops helpers. There are several purposes of doing this: - dropping dependency in bug.h - dropping a loop by moving out panic_notifier.h - unload kernel.h from something which has its own domain At the same time convert users tree-wide to use new headers, although for the time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [akpm@linux-foundation.org: thread_info.h needs limits.h] [andriy.shevchenko@linux.intel.com: ia64 fix] Link: https://lkml.kernel.org/r/20210520130557.55277-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20210511074137.33666-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Reviewed-by: Bjorn Andersson Co-developed-by: Andrew Morton Acked-by: Mike Rapoport Acked-by: Corey Minyard Acked-by: Christian Brauner Acked-by: Arnd Bergmann Acked-by: Kees Cook Acked-by: Wei Liu Acked-by: Rasmus Villemoes Signed-off-by: Andrew Morton Acked-by: Sebastian Reichel Acked-by: Luis Chamberlain Acked-by: Stephen Boyd Acked-by: Thomas Bogendoerfer Acked-by: Helge Deller # parisc Signed-off-by: Linus Torvalds

s390/sclp: Remove console power management support

2021-06-18T14:41:20Z

Power management support was removed for s390 with commit 394216275c7d ("s390: remove broken hibernate / power management support"). Remove leftover sclp console-related power management code. Acked-by: Heiko Carstens Signed-off-by: Peter Oberparleiter Signed-off-by: Vasily Gorbik

s390/sclp: use LIST_HEAD for Initialization

2021-04-07T13:24:57Z

For static initialization of list_head variable, use LIST_HEAD instead of INIT_LIST_HEAD function. Suggested-by: Julian Wiedmann Signed-off-by: Vineeth Vijayan Signed-off-by: Heiko Carstens

s390: use DEFINE_SPINLOCK for initialization

2021-04-07T13:24:56Z

For static initialization of spinlock_t variable, use DEFINE_SPINLOCK instead of explicitly calling spin_lock_init(). Signed-off-by: Vineeth Vijayan Signed-off-by: Heiko Carstens

s390/sclp: increase sclp console line length

2021-03-22T10:36:03Z

Kernel and console/TTY messages written to the SCLP line mode console are wrapped at 80 characters per line by the associated SCLP driver. This makes long lines of output difficult to read, and requires editing of wrapped lines copied from the output device. Neither the firmware interface used to access the SCLP console, nor the HMC "Operating System Messages" web interface that displays these messages require such a length limit. Also other operating systems such as z/VM do not impose similar limits on messages they emit to the same console device. This patch therefore increases the limit to 320 characters per line to make SCLP line mode console output more readable. As a result 99% of lines written during a typical boot will not be wrapped, compared to about 50% wrapped lines at 80 characters per line. Another positive side-effect of this change is that the HMC console interface is able to keep more messages in its history buffer due to fewer line-breaks being generated. In a worst case scenario this means that a 4k console buffer is emitted with the last ~400 bytes empty (320 text + 78 headers). This is more than offset by the fact that each line that is not truncated saves 78 header bytes in the buffer. As a result the actual number of emitted buffers should be about the same as with the 80 character limit. This patch also removes the differentiation between line lengths of SCLP line mode output on z/VM and non-z/VM systems. While the z/VM hypervisor adds a prefix in front of each line ('xx: ' where xx is the number of the CPU issuing the message), adjusting Linux line lengths did not significantly increase readability of console output, and makes even less of a difference with longer lines. Signed-off-by: Peter Oberparleiter Tested-by: Niklas Schnelle Acked-by: Heiko Carstens Signed-off-by: Heiko Carstens

s390/sclp: Convert timers to use timer_setup()

2017-11-14T10:01:39Z

In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Instead of creating an external static data variable, just define a separate callback which encodes the "force restart" desire. Cc: Peter Oberparleiter Cc: Greg Kroah-Hartman Signed-off-by: Kees Cook [heiko.carstens@de.ibm.com: get rid of compile warning] Signed-off-by: Martin Schwidefsky Signed-off-by: Heiko Carstens

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2017-11-13T19:47:01Z

Pull s390 updates from Heiko Carstens: "Since Martin is on vacation you get the s390 pull request for the v4.15 merge window this time from me. Besides a lot of cleanups and bug fixes these are the most important changes: - a new regset for runtime instrumentation registers - hardware accelerated AES-GCM support for the aes_s390 module - support for the new CEX6S crypto cards - support for FORTIFY_SOURCE - addition of missing z13 and new z14 instructions to the in-kernel disassembler - generate opcode tables for the in-kernel disassembler out of a simple text file instead of having to manually maintain those tables - fast memset16, memset32 and memset64 implementations - removal of named saved segment support - hardware counter support for z14 - queued spinlocks and queued rwlocks implementations for s390 - use the stack_depth tracking feature for s390 BPF JIT - a new s390_sthyi system call which emulates the sthyi (store hypervisor information) instruction - removal of the old KVM virtio transport - an s390 specific CPU alternatives implementation which is used in the new spinlock code" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (88 commits) MAINTAINERS: add virtio-ccw.h to virtio/s390 section s390/noexec: execute kexec datamover without DAT s390: fix transactional execution control register handling s390/bpf: take advantage of stack_depth tracking s390: simplify transactional execution elf hwcap handling s390/zcrypt: Rework struct ap_qact_ap_info. s390/virtio: remove unused header file kvm_virtio.h s390: avoid undefined behaviour s390/disassembler: generate opcode tables from text file s390/disassembler: remove insn_to_mnemonic() s390/dasd: avoid calling do_gettimeofday() s390: vfio-ccw: Do not attempt to free no-op, test and tic cda. s390: remove named saved segment support s390/archrandom: Reconsider s390 arch random implementation s390/pci: do not require AIS facility s390/qdio: sanitize put_indicator s390/qdio: use atomic_cmpxchg s390/nmi: avoid using long-displacement facility s390: pass endianness info to sparse s390/decompressor: remove informational messages ...