linux-kernel - RE: [PATCH 2/4] arm64: implement support for static call trampolines

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Message-ID: <9247968df0fa4ab8a617b24195f178b4@AcuMS.aculab.com>
Date:   Mon, 25 Oct 2021 14:38:38 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Ard Biesheuvel' <ardb@...nel.org>
CC:     Frederic Weisbecker <frederic@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        James Morse <james.morse@....com>,
        Quentin Perret <qperret@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: RE: [PATCH 2/4] arm64: implement support for static call trampolines

From: Ard Biesheuvel
> Sent: 25 October 2021 15:32
...
> On arm64, we can only patch NOPs into branch instructions or vice
> versa, or we'd have to run the whole thing under stop_machine() to
> ensure that other cores don't fetch garbage.

Ok, I was thinking it would be safe to patch a single instruction.
Clearly you can't patch more than one without danger of 'garbage'.

	David

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