From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sun, 20 Sep 2020 16:15:10 +0100 From: Matthew Wilcox Subject: Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Message-ID: <20200920151510.GS32101@casper.infradead.org> References: <20200918124533.3487701-1-hch@lst.de> <20200918124533.3487701-2-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200918124533.3487701-2-hch@lst.de> List-ID: To: Christoph Hellwig Cc: Alexander Viro , 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 02:45:25PM +0200, Christoph Hellwig wrote: > Add a flag to force processing a syscall as a compat syscall. This is > required so that in_compat_syscall() works for I/O submitted by io_uring > helper threads on behalf of compat syscalls. Al doesn't like this much, but my suggestion is to introduce two new opcodes -- IORING_OP_READV32 and IORING_OP_WRITEV32. The compat code can translate IORING_OP_READV to IORING_OP_READV32 and then the core code can know what that user pointer is pointing to.