From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Fri, 18 Sep 2020 13:44:06 +0000 Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-Id: <20200918134406.GA17064@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> <20200918134012.GY3421308@ZenIV.linux.org.uk> In-Reply-To: <20200918134012.GY3421308@ZenIV.linux.org.uk> To: Al Viro Cc: Christoph Hellwig , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org 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?