linux-kernel - Re: [PATCH] selftests: vDSO: Also test counter in vdso_test

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Message-ID: <ZtUT9t_wr96S2mJe@zx2c4.com>
Date: Mon, 2 Sep 2024 03:25:10 +0200
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH] selftests: vDSO: Also test counter in vdso_test_chacha

On Sun, Sep 01, 2024 at 08:08:13PM +0200, Jason A. Donenfeld wrote:
> > +	reference_chacha20_blocks(output1, key, counter1, BLOCKS);
> > +	__arch_chacha20_blocks_nostack(output2, key, counter2, BLOCKS);
> > +	if (memcmp(output1, output2, sizeof(output1)) ||
> > +	    memcmp(counter2, counter2, sizeof(counter1)))
> > +		return KSFT_FAIL;
> > +
> > +	reference_chacha20_blocks(output1, key, counter1, BLOCKS);
> > +	__arch_chacha20_blocks_nostack(output2, key, counter2, BLOCKS);
> > +	if (memcmp(output1, output2, sizeof(output1)) ||
> > +	    memcmp(counter2, counter2, sizeof(counter1)))
> > +		return KSFT_FAIL;
> > +
> 
> Why repeat these two stanzas? 

Ah, from your commit message:

"The first test verifies that the function properly writes back the
upper word, the second test verifies that the function properly reads
back the upper word."