Re: [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag
From: Matthew Wilcox <willy@infradead.org>
Date: 2020-09-20 15:15:32
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io-uring, keyrings, linux-arch, linux-arm-kernel, linux-block, linux-fsdevel, linux-mips, linux-mm, linux-s390, linux-scsi, linuxppc-dev, lkml, netdev, sparclinux
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.