linux-kernel - Re: [PATCH v4 3/9] x86/entry: Convert ret_from

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Message-ID: <20210318003839.ag3hetynstt6n2l4@treble>
Date:   Wed, 17 Mar 2021 19:38:39 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     x86@...nel.org, LKML <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH v4 3/9] x86/entry: Convert ret_from_fork to C

On Wed, Mar 17, 2021 at 11:12:42AM -0700, Andy Lutomirski wrote:
> ret_from_fork is written in asm, slightly differently, for x86_32 and
> x86_64.  Convert it to C.
> 
> This is a straight conversion without any particular cleverness.  As a
> further cleanup, the code that sets up the ret_from_fork argument registers
> could be adjusted to put the arguments in the correct registers.
> 
> This will cause the ORC unwinder to find pt_regs even for kernel threads on
> x86_64.  This seems harmless.
> 
> The 32-bit comment above the now-deleted schedule_tail_wrapper was
> obsolete: the encode_frame_pointer mechanism (see copy_thread()) solves the
> same problem more cleanly.
> 
> Cc: Josh Poimboeuf <jpoimboe@...hat.com>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>

Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>

-- 
Josh