From: Josh Poimboeuf <jpoimboe@redhat.com>
To: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
Cc: Mark Brown <broonie@kernel.org>,
mark.rutland@arm.com, ardb@kernel.org, jthierry@redhat.com,
catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org,
pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v4 1/2] arm64: Introduce stack trace reliability checks in the unwinder
Date: Fri, 21 May 2021 15:08:06 -0500 [thread overview]
Message-ID: <20210521200806.nk3m7aldelmi3l2r@treble> (raw)
In-Reply-To: <bf3a5289-8199-b665-0327-ed8240dd7827@linux.microsoft.com>
On Fri, May 21, 2021 at 02:41:56PM -0500, Madhavan T. Venkataraman wrote:
> > Or is frame->reliable supposed to be checked after all? Looking at the
> > code again, I'm not sure.
> >
> > Either way it would be good to document the interface more clearly in a
> > comment above the function.
> >
>
> So, arch_stack_walk_reliable() would do this:
>
> start_backtrace(frame);
>
> while (...) {
> if (!frame->reliable)
> return error;
>
> consume_entry(...);
>
> ret = unwind_frame(...);
>
> if (ret)
> break;
> }
>
> if (ret == -ENOENT)
> return success;
> return error;
>
>
> Something like that.
I see. So basically there are six possible combinations of return
states:
1) No error frame->reliable
2) No error !frame->reliable
3) -ENOENT frame->reliable
5) -ENOENT !frame->reliable (doesn't happen in practice)
4) Other error frame->reliable (doesn't happen in practice)
6) Other error !frame->reliable
On x86 we have fewer combinations:
1) No error state->error
2) No error !state->error
3) Error state->error
4) Error !state->error (doesn't happen in practice)
I think the x86 interface seems more robust, because it's more narrow
and has fewer edge cases. Also it doesn't have to distinguish between
error enums, which can get hairy if a downstream callee happens to
return -ENOENT for a different reason.
--
Josh
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next prev parent reply other threads:[~2021-05-21 20:10 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <68eeda61b3e9579d65698a884b26c8632025e503>
2021-05-16 4:00 ` [RFC PATCH v4 0/2] arm64: Stack trace reliability checks in the unwinder madvenka
2021-05-16 4:00 ` [RFC PATCH v4 1/2] arm64: Introduce stack " madvenka
2021-05-21 16:11 ` Mark Brown
2021-05-21 17:23 ` Madhavan T. Venkataraman
2021-05-21 17:42 ` Mark Brown
2021-05-21 17:47 ` Madhavan T. Venkataraman
2021-05-21 17:53 ` Mark Brown
2021-05-21 18:48 ` Josh Poimboeuf
2021-05-21 18:59 ` Madhavan T. Venkataraman
2021-05-21 19:11 ` Josh Poimboeuf
2021-05-21 19:16 ` Josh Poimboeuf
2021-05-21 19:41 ` Madhavan T. Venkataraman
2021-05-21 20:08 ` Josh Poimboeuf [this message]
2021-05-25 21:44 ` Madhavan T. Venkataraman
2021-05-16 4:00 ` [RFC PATCH v4 2/2] arm64: Create a list of SYM_CODE functions, blacklist them " madvenka
2021-05-19 2:06 ` nobuta.keiya
2021-05-19 3:38 ` Madhavan T. Venkataraman
2021-05-19 19:27 ` Mark Brown
2021-05-20 2:00 ` Madhavan T. Venkataraman
2021-05-21 17:18 ` [RFC PATCH v4 0/2] arm64: Stack trace reliability checks " Mark Brown
2021-05-21 17:32 ` Madhavan T. Venkataraman
2021-05-21 17:47 ` Mark Brown
2021-05-21 17:48 ` Madhavan T. Venkataraman
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