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Date:   Wed, 29 Aug 2018 00:00:36 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Todd Kjos <tkjos@android.com>
Cc:     tkjos@google.com, gregkh@linuxfoundation.org, arve@android.com,
        devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org,
        maco@google.com, christian.brauner@canonical.com,
        ben@decadent.org.uk,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH] binder: use standard functions to allocate fds
Message-ID: <20180829070036.GA13718@infradead.org>
References: <20180828160005.90796-1-tkjos@google.com>
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>  config ANDROID_BINDER_IPC
>  	bool "Android Binder IPC Driver"
> -	depends on MMU
> +	depends on MMU && !CPU_CACHE_VIVT

Thats is a purely arm specific symbol which should not be
used in common code.  Nevermind that there generally should
be no good reason for it.

> +	fixup->offset = (uintptr_t)fdp - (uintptr_t)t->buffer->data;

This looks completely broken.  Why would you care at what exact
place the fd is placed?  Oh, because you share an array with fds
with userspace, which is a hell of a bad idea, and then maninpulate
that buffer mapped to userspace from kernel threads.

I think we just need to rm -rf drivers/android/binder*.c and be done
with it, as this piece of crap should never have been merged to start
with.