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From: Vegard Nossum <vegard.nossum@gmail.com>
Date: Sat, 17 Sep 2016 11:11:44 +0200
Message-ID: <CAOMGZ=Fcwsx0C4HmjbPCLbc67JvA-cpO-0bU3HxqYabROJOLwA@mail.gmail.com>
Subject: Re: [PATCH] scripts: add script for translating stack dump function offsets
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Stephane Eranian <eranian@google.com>,
        Vince Weaver <vincent.weaver@maine.edu>,
        LKML <linux-kernel@vger.kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Ingo Molnar <mingo@kernel.org>, Kees Cook <keescook@chromium.org>
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On 16 September 2016 at 21:17, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> On Fri, Sep 16, 2016 at 11:12:10AM -0700, Linus Torvalds wrote:
>> Side note: I find addr2line almost completely useless in many cases
>> not because of address space randomization, but because of how complex
>> the inlining often is. I just had something where I decided to use
>> addr2line and it just pointed me to the __read_once_size_nocheck()
>> line in <linux/compiler.h>. That was not very useful.
>>
>> I ended up actually looking at the instructions *around* it, to find
>> where that one instruction had been inlined from.
>>
>> So I'm wondering if this kind of helper script could be extended to
>> have that "look around it" thing to help.
>
> I think that issue is solved by addr2line's '--inline' option, which the
> script uses:

Another small gotcha is that stack trace addresses are _return
addresses_, not callsites. So you'll sometimes want to pass 'addr - 1'
instead of just addr, as the next address (the return address) may
belong to a completely unrelated deeply inlined function.


Vegard