Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751277AbbBLRH1 (ORCPT ); Thu, 12 Feb 2015 12:07:27 -0500 Received: from foss-mx-na.arm.com ([217.140.108.86]:43452 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043AbbBLRH0 (ORCPT ); Thu, 12 Feb 2015 12:07:26 -0500 Date: Thu, 12 Feb 2015 17:07:15 +0000 From: Catalin Marinas To: Szabolcs Nagy Cc: musl@lists.openwall.com, Rich Felker , Andrew Pinski , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "pinskia@gmail.com" , "libc-alpha@sourceware.org" , Marcus Shawcroft Subject: Re: [musl] Re: [PATCHv3 00/24] ILP32 support in ARM64 Message-ID: <20150212170715.GB25491@e104818-lin.cambridge.arm.com> References: <20141002155217.GH32147@e104818-lin.cambridge.arm.com> <20150210181302.GA23886@brightrain.aerifal.cx> <20150211173919.GF9058@e104818-lin.cambridge.arm.com> <20150211190537.GK32724@port70.net> <20150212081234.GL32724@port70.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150212081234.GL32724@port70.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2364 Lines: 59 On Thu, Feb 12, 2015 at 09:12:34AM +0100, Szabolcs Nagy wrote: > * Szabolcs Nagy [2015-02-11 20:05:37 +0100]: > > (i think this is also a problem if userspace code uses syscall(2) directly, > > libc cannot possibly know where to signextend and the kernel side does not > > do the fixup right now) > > nobody picked up this issue, is this resolved? > > ie. if userspace calls syscall(SYS_foo,...) directly with 32bit > longs does it always work out correctly on the kernel side? I think the only way to solve this is to have syscall wrappers in the kernel rather than glibc. > the sign extension is a problem for signed long arguments, > i only found these in the kernel: > > fs/buffer.c:SYSCALL_DEFINE2(bdflush, int, func, long, data) This is part of the deprecated syscalls, it is not used on new user ABIs. > fs/open.c:SYSCALL_DEFINE2(truncate, const char __user *, path, long, length) The kernel uses a long (64-bit) here and the user ABI defines this as an off_t. With x32, this should be a long long (__kernel_long_t), so not a problem. > fs/aio.c:SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, > fs/aio.c- struct iocb __user * __user *, iocbpp) > > fs/aio.c:SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, > fs/aio.c- long, min_nr, > fs/aio.c- long, nr, These would need some int->long conversion for nr, min_nr (it may be done in x32 glibc already but as you said it would not work via syscall() directly). > kernel/ptrace.c:SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, > kernel/ptrace.c- unsigned long, data) The pid in user space would be pid_t which is 32-bit. The kernel seems to use it as pid_t afterwards, so looks safe. For addr and data, I guess it needs wrappers to zero the top part. > ipc/syscall.c:SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second, > ipc/syscall.c- unsigned long, third, void __user *, ptr, long, fifth) ipc(2) shows the first, second, third as ints. I guess some kernel wrapper is needed here as well. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/