linux-kernel - Re: [PATCH 1/1] arm64: Add initial set of stack unwinder self tests

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Message-ID: <20220630065532.i3alwmaenkooiwxw@suse>
Date:   Thu, 30 Jun 2022 09:55:32 +0300
From:   "Ivan T. Ivanov" <iivanov@...e.de>
To:     Mark Brown <broonie@...nel.org>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Madhavan T . Venkataraman" <madvenka@...ux.microsoft.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] arm64: Add initial set of stack unwinder self tests

Hi,

On 06-29 16:59, Mark Brown wrote:
> 
> On Fri, Jun 24, 2022 at 05:10:00PM +0300, Ivan T. Ivanov wrote:
> > Add kunit tests for obvious cases where stack unwind could be needed.
> > Like these:
> > 
> >  * Unwind a separate task
> >  * Unwind starting from caller
> >  * Unwind from irq context
> >  * Unwind from kprobe handler called via ftrace
> >  * Unwind from ftrace handler
> >  * Unwind through kretprobed function
> >  * Unwind from kretprobe handler
> > 
> > Tests are completely based on code used in s390 unwinder tests.
> > Cases which where not relevant to aarch64 where removed and
> > some places where adjusted to address aarch64 specifics.
> 
> I think this would be a bit easier to digest if it were a series which
> builds things up with the test cases in individual patches, or at least
> things like ftrace and kprobes split out a bit more, rather than every
> single test all at once.  I've got a few *very* superficial comments
> below, I think the code is fine but there's several moving pieces to
> check.

Ok. I will split and resend.

> 
> > +/*
> > + * Calls test_arch_stack_walk() which is handy wrapper of aarch64 unwind
> > + * functionality, and verifies that the result contains unwindme_func2
> > + *followed by unwindme_func1.
> 
> Missing space.

Sure.

> 
> > +	ret = register_ftrace_function(fops);
> > +	if (!ret) {
> > +		ret = test_unwind_ftraced_func(u);
> > +		unregister_ftrace_function(fops);
> > +	} else {
> > +		kunit_err(current_test,
> > +			  "failed to register ftrace handler (%d)\n", ret);
> > +	}
> 
> Shouldn't we return an error here?

Error will be returned once we remove test_unwind_ftraced_func
address from ftrace filters.

Regards,
Ivan