Re: [Crash-utility] arm64: Support overflow stack panic

Hi Kazu Thanks for your time to review the patches and all the detailed comments, the 3rd patch attached with all the refinement.

By the way, do I need to squash all the 3 patches as one before them get accepted?

Thanks Hong ________________________________ From: HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab(a)nec.com&gt; Sent: Friday, November 19, 2021 16:21 To: Hong Yang3 杨红 <hong.yang3(a)nio.com&gt; Cc: Discussion list for crash utility usage, maintenance and development <crash-utility(a)redhat.com&gt; Subject: RE: arm64: Support overflow stack panic 注意：此封邮件来自于公司外部，请注意信息安全！ Attention: This email comes from outside of the company, please pay attention to the information security! Hi Hong, Thanks for the refinement. > + if (symbol_exists("overflow_stack") && > + (sp = per_cpu_symbol_search("overflow_stack")) && > + get_symbol_type("overflow_stack", NULL, req)) { > + if (CRASHDEBUG(1)) { > + fprintf(fp, "overflow_stack: \n"); > + fprintf(fp, " type: %x, %s\n", > + (int)req->typecode, > + (req->typecode == TYPE_CODE_PTR) ? > + "TYPE_CODE_PTR" : "other"); Given that overflow_stack is array, TYPE_CODE_ARRAY would be better. > @@ -2673,6 +2724,12 @@ arm64_back_trace_cmd(struct bt_info *bt) > bt->hp->eip : GET_STACK_ULONG(bt->hp->esp); > stackframe.sp = bt->hp->esp + 8; > bt->flags &= ~BT_REGS_NOT_FOUND; > + } else if (arm64_on_overflow_stack(bt->tc->processor, bt->frameptr)) { > + arm64_set_overflow_stack(bt); > + bt->flags |= BT_OVERFLOW_STACK; I would prefer to place this into the else block below > + stackframe.sp = bt->stkptr; > + stackframe.pc = bt->instptr; > + stackframe.fp = bt->frameptr; then we can remove these three lines. > } else { > if (arm64_on_irq_stack(bt->tc->processor, bt->frameptr)) { > arm64_set_irq_stack(bt); > +static int > +arm64_in_alternate_stack(int cpu, ulong stkptr) > +{ > + struct machine_specific *ms = machdep->machspec; > + > + return arm64_in_alternate_stackv(cpu, stkptr, > + ms->irq_stacks, ms->irq_stack_size); > +} Given that in_alternate_stack() should check if it's in non-process stacks, I think we should check also for overflow_stacks here. So how about making these function like this? arm64_in_alternate_stack arm64_on_irq_stack arm64_on_overflow_stack arm64_on_irq_stack arm64_in_alternate_stackv(irq_stacks) arm64_on_overflow_stack arm64_in_alternate_stackv(overflow_stacks) Thanks, Kazu -----Original Message----- > Hi Kazu > > Here are the latest patches for supporting to run bt command against a core dump with kernel stack overflow > exception for arm64. > > Please help to review and advise if any further change needed. > > Tested bt command with options: > > bt > bt -a > bt -c 3 > > By the way, 'mach' command also updated to show overflow stacks info as same as IRQ stacks. > > Thanks > Hong > ________________________________ > > From: HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab(a)nec.com&gt; > Sent: Wednesday, November 17, 2021 15:23 > To: Hong Yang3 杨红 <hong.yang3(a)nio.com&gt; > Cc: Discussion list for crash utility usage, maintenance and development <crash-utility(a)redhat.com&gt; > Subject: RE: arm64: Support overflow stack panic > > 注意：此封邮件来自于公司外部，请注意信息安全！ > Attention: This email comes from outside of the company, please pay attention to the information security! > > Hi Hong, > > Thank you for the patch and sending it to this list. > > -----Original Message----- > > Hi Crash > > > > I'll keep refining the patch before it get approved: > > OK, so we will wait for the refined patch. > > Thanks, > Kazu > > > > > > > 1. Fix the error in arm64_overflow_stack_init() which saved the overflow stack address into > > ms->irqstacks[], which would cause bt command crash on other cpus. The normal IRQ stacks should be used > > for bt command for other cpus. > > 2. In addition to unwind on the overflow stack, try to go through the IRQ stack to find more useful > > information > > > > Kernel stack overflow case would be rarely but I'd like to sharp the crash to cover this kind of issue. > > > > Best regards > > Hong > > ________________________________ > > > > From: Hong Yang3 杨红 > > Sent: Tuesday, November 16, 2021 9:55 > > To: crash-utility(a)redhat.com <crash-utility(a)redhat.com&gt; > > Subject: arm64: Support overflow stack panic > > > > Hi All > > > > When I was trying to open a core of an overflow stack panic result, the bt command caused a segment fault, > > after a while I figured out the overflow stack is not supported by crash utility. > > > > This patch is trying to initialize the overflow stack information on startup stage, and the bt command > works > > as expected to dump the correct call trace in the overflow stack, currently it only apply to arm64 target. > > > > I'm not sure if any other sub command also need to be fixed for full support for the overflow stack, please > > advise and I'll try to improve the patch. > > > > Thanks > > Hong YANG