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Date:   Mon, 21 Nov 2022 04:22:54 +0100
From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     linux-kernel@vger.kernel.org, patches@lists.linux.dev,
        linux-crypto@vger.kernel.org, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
        Carlos O'Donell <carlos@redhat.com>
Subject: Re: [PATCH v5 2/3] random: introduce generic vDSO getrandom()
 implementation
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On Sun, Nov 20, 2022 at 02:43:31AM +0100, Jason A. Donenfeld wrote:
> On Sun, Nov 20, 2022 at 01:53:53AM +0100, Jason A. Donenfeld wrote:
> > shouldn't fork or something, but that seems disappointing. Or more state
> > could be allocated in the zeroing region, to hold a chacha state, so
> > another 64 bytes, which would be sort of unfortunate. Or something else?
> > I'd be interested to hear your impression of this quandary.
> 
> Another 128 bytes, actually. And the current chacha in there isn't
> cleaning up its stack as one might hope. So maybe the cleanest solution
> would be to just bite the bullet and allocate another 128 bytes per
> state and make a mini chacha that operates over that? (And I guess hope
> it doesn't need to spill and such...)

I've got it implemented without using any stack now. Wasn't so bad. So
all of the additional concerns I added will be addressed in v+1.

Jason