[Crash-utility] arm64: Support overflow stack panic

[Hong YANG3 杨红]

Hi Lianbo

Please help to review the new patch v7 with only one change for removing the redundant code.

Patch is patch, what's  the better way attach it into an email? Copy & paste would not applicable for a large patch file.

I have no vmcore file, but there is a kernel module which would help to trigger an overflow stack panic for testing, please download the module form link [1] and compile it as a module to load it into your test box, please read the README.txt and the source code for more details.

[1] https://github.com/yangh/crash/tree/pso-kernel-module/kernel-modules/panic-stack-overflow

Best regards
Hong
________________________________
From: Hong YANG3 杨红 <hong.yang3 at nio.com>
Sent: Monday, November 29, 2021 11:40
To: lijiang <lijiang at redhat.com>; Discussion list for crash utility usage, maintenance and development <crash-utility at redhat.com>
Subject: Re: arm64: Support overflow stack panic

Hi Lianbo

I'm using outlook to send mail to this list, I'll try to find a better way to send out patch and mails more friendly for all reader, .

I'll send out a demo kernel module which can trigger an overflow panic for testing, and also the patch will be updated as your comment in previous mail.

Thanks for your quickly reply.

Best regards
Hong
________________________________
From: lijiang <lijiang at redhat.com>
Sent: Monday, November 29, 2021 10:58
To: Hong YANG3 杨红 <hong.yang3 at nio.com>; Discussion list for crash utility usage, maintenance and development <crash-utility at redhat.com>
Subject: Re: arm64: Support overflow stack panic

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Hi, Hong

Thank you for the patch.  I added the comments below, other changes look good to me.

@@ -1978,7 +2028,10 @@ arm64_in_exception_text(ulong ptr)
                if ((ptr >= ms->__exception_text_start) &&
                    (ptr < ms->__exception_text_end))
                        return TRUE;
-       } else if ((name = closest_symbol(ptr))) {  /* Linux 5.5 and later */
+       }
+
+       name = closest_symbol(ptr);
+       if (name != NULL) { /* Linux 5.5 and later */

The above changes are irrelevant to your patch itself. But anyway this looks more readable to me.

                for (func = &arm64_exception_functions[0]; *func; func++) {
                        if (STREQ(name, *func))
                                return TRUE;
@@ -2255,12 +2308,14 @@ arm64_unwind_frame(struct bt_info *bt, struct arm64_stackframe *frame)
        if (!(machdep->flags & IRQ_STACKS))
                return TRUE;

-       if (!(machdep->flags & IRQ_STACKS))
+       if (!(machdep->flags & OVERFLOW_STACKS))
                return TRUE;

Originally, it had two same(repeated) statements, one of which must be redundant.  This time, can it be changed to a statement as below?

if (!(machdep->flags & (IRQ_STACKS | OVERFLOW_STACKS)))
        return TRUE;

BTW:  this patch was sent as an attachment, which is inconvenient for other reviewers to add comments.

In addition, I  have a request: can you share the vmcore with me if it doesn't have confidential data? I'm collecting the specific vmcore
for the test, at least I haven't reproduced it.

Thanks.
Lianbo
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