lwn.git/arch/arc/kernel/stacktrace.c, branch docs-5.13

ARC: stack unwinding: reorganize how initial register state setup

2020-11-18T04:12:01+00:00

This is a non-functional change, if anything a better fall-back handling. Signed-off-by: Vineet Gupta

ARC: stack unwinding: don't assume non-current task is sleeping

2020-11-18T04:12:01+00:00

To start stack unwinding (SP, PC and BLINK) are needed. When the explicit execution context (pt_regs etc) is not available, unwinder assumes the task is sleeping (in __switch_to()) and fetches SP and BLINK from kernel mode stack. But this assumption is not true, specially in a SMP system, when top runs on 1 core, there may be active running processes on all cores. So when unwinding non courrent tasks, ensure they are NOT running. And while at it, handle the self unwinding case explicitly. This came out of investigation of a customer reported hang with rcutorture+top Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/31 Signed-off-by: Vineet Gupta

ARC: stack unwinding: avoid indefinite looping

2020-11-02T19:45:08+00:00

Currently stack unwinder is a while(1) loop which relies on the dwarf unwinder to signal termination, which in turn relies on dwarf info to do so. This in theory could cause an infinite loop if the dwarf info was somehow messed up or the register contents were etc. This fix thus detects the excessive looping and breaks the loop. | Mem: 26184K used, 1009136K free, 0K shrd, 0K buff, 14416K cached | CPU: 0.0% usr 72.8% sys 0.0% nic 27.1% idle 0.0% io 0.0% irq 0.0% sirq | Load average: 4.33 2.60 1.11 2/74 139 | PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND | 133 2 root SWN 0 0.0 3 22.9 [rcu_torture_rea] | 132 2 root SWN 0 0.0 0 22.0 [rcu_torture_rea] | 131 2 root SWN 0 0.0 3 21.5 [rcu_torture_rea] | 126 2 root RW 0 0.0 2 5.4 [rcu_torture_wri] | 129 2 root SWN 0 0.0 0 0.2 [rcu_torture_fak] | 137 2 root SW 0 0.0 0 0.2 [rcu_torture_cbf] | 127 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 138 115 root R 1464 0.1 2 0.1 top | 130 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 128 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 115 1 root S 1472 0.1 1 0.0 -/bin/sh | 104 1 root S 1464 0.1 0 0.0 inetd | 1 0 root S 1456 0.1 2 0.0 init | 78 1 root S 1456 0.1 0 0.0 syslogd -O /var/log/messages | 134 2 root SW 0 0.0 2 0.0 [rcu_torture_sta] | 10 2 root IW 0 0.0 1 0.0 [rcu_preempt] | 88 2 root IW 0 0.0 1 0.0 [kworker/1:1-eve] | 66 2 root IW 0 0.0 2 0.0 [kworker/2:2-eve] | 39 2 root IW 0 0.0 2 0.0 [kworker/2:1-eve] | unwinder looping too long, aborting ! Cc: Signed-off-by: Vineet Gupta

kernel: rename show_stack_loglvl() => show_stack()

2020-06-09T16:39:13+00:00

Now the last users of show_stack() got converted to use an explicit log level, show_stack_loglvl() can drop it's redundant suffix and become once again well known show_stack(). Signed-off-by: Dmitry Safonov Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com Signed-off-by: Linus Torvalds

arc: add show_stack_loglvl()

2020-06-09T16:39:10+00:00

Currently, the log-level of show_stack() depends on a platform realization. It creates situations where the headers are printed with lower log level or higher than the stacktrace (depending on a platform or user). Furthermore, it forces the logic decision from user to an architecture side. In result, some users as sysrq/kdb/etc are doing tricks with temporary rising console_loglevel while printing their messages. And in result it not only may print unwanted messages from other CPUs, but also omit printing at all in the unlucky case where the printk() was deferred. Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems an easier approach than introducing more printk buffers. Also, it will consolidate printings with headers. Introduce show_stack_loglvl(), that eventually will substitute show_stack(). As a good side-effect header "Stack Trace:" is now printed with the same log level as the rest of backtrace. [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u Signed-off-by: Dmitry Safonov Signed-off-by: Andrew Morton Cc: Vineet Gupta Link: http://lkml.kernel.org/r/20200418201944.482088-4-dima@arista.com Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

arc: do not use __print_symbol()

2017-12-20T20:41:43+00:00

__print_symbol() uses extra stack space to sprintf() symbol information and then to feed that buffer to printk() char buffer[KSYM_SYMBOL_LEN]; sprint_symbol(buffer, address); printk(fmt, buffer); Replace __print_symbol() with a direct printk("%pS") call. Signed-off-by: Sergey Senozhatsky Signed-off-by: Vineet Gupta

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34+00:00

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

arc: unwind: warn only once if DW2_UNWIND is disabled

2016-06-28T05:41:44+00:00

If CONFIG_ARC_DW2_UNWIND is disabled every time arc_unwind_core() gets called following message gets printed in debug console: ----------------->8--------------- CONFIG_ARC_DW2_UNWIND needs to be enabled ----------------->8--------------- That message makes sense if user indeed wants to see a backtrace or get nice function call-graphs in perf but what if user disabled unwinder for the purpose? Why pollute his debug console? So instead we'll warn user about possibly missing feature once and let him decide if that was what he or she really wanted. Signed-off-by: Alexey Brodkin Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta

ARC: Fix misspellings in comments.

2016-03-11T09:29:53+00:00

Signed-off-by: Adam Buchbinder Signed-off-by: Vineet Gupta