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Date:   Fri, 18 Sep 2020 15:44:06 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Christoph Hellwig <hch@lst.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>, Arnd Bergmann <arnd@arndb.de>,
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Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
Message-ID: <20200918134406.GA17064@lst.de>
References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200918134012.GY3421308@ZenIV.linux.org.uk>
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On Fri, Sep 18, 2020 at 02:40:12PM +0100, Al Viro wrote:
> >  	/* Vector 0x110 is LINUX_32BIT_SYSCALL_TRAP */
> > -	return pt_regs_trap_type(current_pt_regs()) == 0x110;
> > +	return pt_regs_trap_type(current_pt_regs()) == 0x110 ||
> > +		(current->flags & PF_FORCE_COMPAT);
> 
> Can't say I like that approach ;-/  Reasoning about the behaviour is much
> harder when it's controlled like that - witness set_fs() shite...

I don't particularly like it either.  But do you have a better idea
how to deal with io_uring vs compat tasks?