user/sven/linux.git/kernel/panic.c, branch v5.16

Merge branch 'rework/printk_safe-removal' into for-linus

2021-08-30T14:36:10Z

printk: remove safe buffers

2021-07-26T13:09:34Z

With @logbuf_lock removed, the high level printk functions for storing messages are lockless. Messages can be stored from any context, so there is no need for the NMI and safe buffers anymore. Remove the NMI and safe buffers. Although the safe buffers are removed, the NMI and safe context tracking is still in place. In these contexts, store the message immediately but still use irq_work to defer the console printing. Since printk recursion tracking is in place, safe context tracking for most of printk is not needed. Remove it. Only safe context tracking relating to the console and console_owner locks is left in place. This is because the console and console_owner locks are needed for the actual printing. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210715193359.25946-4-john.ogness@linutronix.de

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

panic: don't dump stack twice on warn

2020-11-14T19:26:04Z

Before commit 3f388f28639f ("panic: dump registers on panic_on_warn"), __warn() was calling show_regs() when regs was not NULL, and show_stack() otherwise. After that commit, show_stack() is called regardless of whether show_regs() has been called or not, leading to duplicated Call Trace: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/nohash/8xx.c:186 mmu_mark_initmem_nx+0x24/0x94 CPU: 0 PID: 1 Comm: swapper Not tainted 5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty #4092 NIP: c00128b4 LR: c0010228 CTR: 00000000 REGS: c9023e40 TRAP: 0700 Not tainted (5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty) MSR: 00029032 CR: 24000424 XER: 00000000 GPR00: c0010228 c9023ef8 c2100000 0074c000 ffffffff 00000000 c2151000 c07b3880 GPR08: ff000900 0074c000 c8000000 c33b53a8 24000822 00000000 c0003a20 00000000 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00800000 NIP [c00128b4] mmu_mark_initmem_nx+0x24/0x94 LR [c0010228] free_initmem+0x20/0x58 Call Trace: free_initmem+0x20/0x58 kernel_init+0x1c/0x114 ret_from_kernel_thread+0x14/0x1c Instruction dump: 7d291850 7d234b78 4e800020 9421ffe0 7c0802a6 bfc10018 3fe0c060 3bff0000 3fff4080 3bffffff 90010024 57ff0010 <0fe00000> 392001cd 7c3e0b78 953e0008 CPU: 0 PID: 1 Comm: swapper Not tainted 5.10.0-rc2-s3k-dev-01375-gf46ec0d3ecbd-dirty #4092 Call Trace: __warn+0x8c/0xd8 (unreliable) report_bug+0x11c/0x154 program_check_exception+0x1dc/0x6e0 ret_from_except_full+0x0/0x4 --- interrupt: 700 at mmu_mark_initmem_nx+0x24/0x94 LR = free_initmem+0x20/0x58 free_initmem+0x20/0x58 kernel_init+0x1c/0x114 ret_from_kernel_thread+0x14/0x1c ---[ end trace 31702cd2a9570752 ]--- Only call show_stack() when regs is NULL. Fixes: 3f388f28639f ("panic: dump registers on panic_on_warn") Signed-off-by: Christophe Leroy Signed-off-by: Andrew Morton Cc: Alexey Kardashevskiy Cc: Kefeng Wang Link: https://lkml.kernel.org/r/e8c055458b080707f1bc1a98ff8bea79d0cec445.1604748361.git.christophe.leroy@csgroup.eu Signed-off-by: Linus Torvalds

panic: dump registers on panic_on_warn

2020-10-16T18:11:22Z

Currently we print stack and registers for ordinary warnings but we do not for panic_on_warn which looks as oversight - panic() will reboot the machine but won't print registers. This moves printing of registers and modules earlier. This does not move the stack dumping as panic() dumps it. Signed-off-by: Alexey Kardashevskiy Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Cc: Douglas Anderson Cc: Ingo Molnar Cc: Kees Cook Cc: Rafael Aquini Cc: Thomas Gleixner Cc: Will Deacon Cc: Nicholas Piggin Link: https://lkml.kernel.org/r/20200804095054.68724-1-aik@ozlabs.ru Signed-off-by: Linus Torvalds

panic: make print_oops_end_marker() static

2020-08-12T17:58:02Z

Since print_oops_end_marker() is not used externally, also remove it in kernel.h at the same time. Signed-off-by: Yue Hu Signed-off-by: Andrew Morton Cc: Kees Cook Link: http://lkml.kernel.org/r/20200724011516.12756-1-zbestahu@gmail.com Signed-off-by: Linus Torvalds

kernel/panic.c: make oops_may_print() return bool

2020-08-12T17:58:01Z

The return value of oops_may_print() is true or false, so change its type to reflect that. Signed-off-by: Tiezhu Yang Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Cc: Xuefeng Li Link: http://lkml.kernel.org/r/1591103358-32087-1-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Linus Torvalds

bug: Annotate WARN/BUG/stackfail as noinstr safe

2020-06-11T13:14:36Z

Warnings, bugs and stack protection fails from noinstr sections, e.g. low level and early entry code, are likely to be fatal. Mark them as "safe" to be invoked from noinstr protected code to avoid annotating all usage sites. Getting the information out is important. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134100.376598577@linutronix.de

panic: add sysctl to dump all CPUs backtraces on oops event

2020-06-08T18:05:56Z

Usually when the kernel reaches an oops condition, it's a point of no return; in case not enough debug information is available in the kernel splat, one of the last resorts would be to collect a kernel crash dump and analyze it. The problem with this approach is that in order to collect the dump, a panic is required (to kexec-load the crash kernel). When in an environment of multiple virtual machines, users may prefer to try living with the oops, at least until being able to properly shutdown their VMs / finish their important tasks. This patch implements a way to collect a bit more debug details when an oops event is reached, by printing all the CPUs backtraces through the usage of NMIs (on architectures that support that). The sysctl added (and documented) here was called "oops_all_cpu_backtrace", and when set will (as the name suggests) dump all CPUs backtraces. Far from ideal, this may be the last option though for users that for some reason cannot panic on oops. Most of times oopses are clear enough to indicate the kernel portion that must be investigated, but in virtual environments it's possible to observe hypervisor/KVM issues that could lead to oopses shown in other guests CPUs (like virtual APIC crashes). This patch hence aims to help debug such complex issues without resorting to kdump. Signed-off-by: Guilherme G. Piccoli Signed-off-by: Andrew Morton Reviewed-by: Kees Cook Cc: Luis Chamberlain Cc: Iurii Zaikin Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Randy Dunlap Cc: Matthew Wilcox Link: http://lkml.kernel.org/r/20200327224116.21030-1-gpiccoli@canonical.com Signed-off-by: Linus Torvalds

kernel: add panic_on_taint

2020-06-08T18:05:56Z

Analogously to the introduction of panic_on_warn, this patch introduces a kernel option named panic_on_taint in order to provide a simple and generic way to stop execution and catch a coredump when the kernel gets tainted by any given flag. This is useful for debugging sessions as it avoids having to rebuild the kernel to explicitly add calls to panic() into the code sites that introduce the taint flags of interest. For instance, if one is interested in proceeding with a post-mortem analysis at the point a given code path is hitting a bad page (i.e. unaccount_page_cache_page(), or slab_bug()), a coredump can be collected by rebooting the kernel with 'panic_on_taint=0x20' amended to the command line. Another, perhaps less frequent, use for this option would be as a means for assuring a security policy case where only a subset of taints, or no single taint (in paranoid mode), is allowed for the running system. The optional switch 'nousertaint' is handy in this particular scenario, as it will avoid userspace induced crashes by writes to sysctl interface /proc/sys/kernel/tainted causing false positive hits for such policies. [akpm@linux-foundation.org: tweak kernel-parameters.txt wording] Suggested-by: Qian Cai Signed-off-by: Rafael Aquini Signed-off-by: Andrew Morton Reviewed-by: Luis Chamberlain Cc: Dave Young Cc: Baoquan He Cc: Jonathan Corbet Cc: Kees Cook Cc: Randy Dunlap Cc: "Theodore Ts'o" Cc: Adrian Bunk Cc: Greg Kroah-Hartman Cc: Laura Abbott Cc: Jeff Mahoney Cc: Jiri Kosina Cc: Takashi Iwai Link: http://lkml.kernel.org/r/20200515175502.146720-1-aquini@redhat.com Signed-off-by: Linus Torvalds