linux-kernel - Re: [PATCH 1/3] powerpc/uaccess: Switch __put_user_size_allowed() to __put_user_asm

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Message-Id: <160034201413.3339803.2260455102175755865.b4-ty@ellerman.id.au>
Date:   Thu, 17 Sep 2020 21:27:17 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] powerpc/uaccess: Switch __put_user_size_allowed() to __put_user_asm_goto()

On Fri, 4 Sep 2020 11:01:30 +0000 (UTC), Christophe Leroy wrote:
> __put_user_asm_goto() provides more flexibility to GCC and avoids using
> a local variable to tell if the write succeeded or not.
> GCC can then avoid implementing a cmp in the fast path.
> 
> See the difference for a small function like the PPC64 version of
> save_general_regs() in arch/powerpc/kernel/signal_32.c:
> 
> [...]

Applied to powerpc/next.

[1/3] powerpc/uaccess: Switch __put_user_size_allowed() to __put_user_asm_goto()
      https://git.kernel.org/powerpc/c/ee0a49a6870ea75e25b4d4984c1bb6b3b7c65f2b
[2/3] powerpc/uaccess: Switch __patch_instruction() to __put_user_asm_goto()
      https://git.kernel.org/powerpc/c/e64ac41ab0c510b3f85199a585eb886cad92fb19
[3/3] powerpc/uaccess: Remove __put_user_asm() and __put_user_asm2()
      https://git.kernel.org/powerpc/c/7fdf966bed155b214f4f1f9b67825a40b2e9b998

cheers