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From: Arnd Bergmann <arnd@arndb.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>, David Howells <dhowells@redhat.com>,
	David Laight <David.Laight@aculab.com>,
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	"open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
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	Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
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	io-uring@vger.kernel.org, linux-arch <linux-arch@vger.kernel.org>,
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	LSM List <linux-security-module@vger.kernel.org>
Subject: Re: [PATCH 5/9] fs: remove various compat readv/writev helpers
Date: Wed, 23 Sep 2020 18:45:51 +0000	[thread overview]
Message-ID: <CAK8P3a3nkLUOkR+jwz2_2LcYTUTqdVf8JOtZqKWbtEDotNhFZA@mail.gmail.com> (raw)
In-Reply-To: <20200923163831.GO3421308@ZenIV.linux.org.uk>

On Wed, Sep 23, 2020 at 6:38 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> I wonder if we should do something like
>
> SYSCALL_DECLARE3(readv, unsigned long, fd, const struct iovec __user *, vec,
>                  unsigned long, vlen);
> in syscalls.h instead, and not under that ifdef.
>
> Let it expand to declaration of sys_...() in generic case and, on x86, into
> __do_sys_...() and __ia32_sys_...()/__x64_sys_...(), with types matching
> what SYSCALL_DEFINE ends up using.
>
> Similar macro would cover compat_sys_...() declarations.  That would
> restore mismatch checking for x86 and friends.  AFAICS, the cost wouldn't
> be terribly high - cpp would have more to chew through in syscalls.h,
> but it shouldn't be all that costly.  Famous last words, of course...
>
> Does anybody see fundamental problems with that?

I've had some ideas along those lines in the past and I think it should work.

As a variation of this, the SYSCALL_DEFINEx() macros could go away
entirely, leaving only the macro instantiations from the header to
require that syntax. It would require first changing the remaining
architectures to build the syscall table from C code instead of
assembler though.

Regardless of that, another advantage of having the SYSCALL_DECLAREx()
would be the ability to include that header file from elsewhere with a different
macro definition to create a machine-readable version of the interface when
combined with the syscall.tbl files. This could be used to create a user
space stub for calling into the low-level syscall regardless of the
libc interfaces,
or for synchronizing the interfaces with strace, qemu-user, or anything that
needs to deal with the low-level interface.

      Arnd

  parent reply	other threads:[~2020-09-23 18:45 UTC|newest]

Thread overview: 184+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-18 12:45 let import_iovec deal with compat_iovecs as well Christoph Hellwig
2020-09-18 12:45 ` [PATCH 1/9] kernel: add a PF_FORCE_COMPAT flag Christoph Hellwig
2020-09-18 13:40   ` Al Viro
2020-09-18 13:44     ` Christoph Hellwig
2020-09-18 13:58       ` Al Viro
2020-09-18 15:16         ` Christoph Hellwig
2020-09-19 16:21           ` Andy Lutomirski
2020-09-19 21:16             ` Arnd Bergmann
2020-09-19 21:52               ` Finn Thain
2020-09-19 22:22               ` Andy Lutomirski
2020-09-21 16:10                 ` Pavel Begunkov
2020-09-21 16:13                   ` Pavel Begunkov
2020-09-21 23:51                     ` Andy Lutomirski
2020-09-22  0:22                       ` Pavel Begunkov
2020-09-22  0:58                         ` Andy Lutomirski
2020-09-22  6:30                           ` Pavel Begunkov
2020-09-22  7:23                             ` Arnd Bergmann
2020-09-22  7:57                               ` Pavel Begunkov
2020-09-22  9:01                                 ` Arnd Bergmann
2020-09-22 16:20                                   ` Andy Lutomirski
2020-09-23  8:01                                   ` Pavel Begunkov
2020-09-23 13:22                                     ` Al Viro
2020-09-19 22:09           ` Al Viro
2020-09-19 22:23             ` Andy Lutomirski
2020-09-19 22:41               ` Al Viro
2020-09-19 22:53                 ` Andy Lutomirski
2020-09-19 23:24                   ` Al Viro
2020-09-20  0:14                     ` Andy Lutomirski
2020-09-20  2:57                       ` Al Viro
2020-09-20 16:59                         ` Andy Lutomirski
2020-09-20 18:12                           ` Al Viro
2020-09-20 13:55             ` Arnd Bergmann
2020-09-20 15:02               ` Al Viro
2020-09-19 14:53         ` David Laight
2020-09-18 13:59       ` Arnd Bergmann
2020-09-20 15:15   ` Matthew Wilcox
2020-09-20 15:55     ` William Kucharski
2020-09-21 16:20       ` Pavel Begunkov
2020-09-20 16:00     ` Arnd Bergmann
2020-09-20 18:07     ` Al Viro
2020-09-20 18:41       ` Al Viro
2020-09-20 19:01       ` Matthew Wilcox
2020-09-20 19:10         ` Al Viro
2020-09-20 19:22           ` Matthew Wilcox
2020-09-20 19:28             ` Andy Lutomirski
2020-09-20 20:49               ` Arnd Bergmann
2020-09-20 21:13                 ` David Laight
2020-09-21 16:31                   ` Pavel Begunkov
2020-09-20 21:42             ` Al Viro
2020-09-21 16:26             ` Pavel Begunkov
2020-09-20 19:14       ` Andy Lutomirski
2020-09-21  4:28         ` Christoph Hellwig
2020-09-18 12:45 ` [PATCH 2/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-18 13:37   ` Johannes Thumshirn
2020-09-18 12:45 ` [PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector Christoph Hellwig
2020-09-18 12:56   ` Matthew Wilcox
2020-09-18 13:39   ` Johannes Thumshirn
2020-09-18 12:45 ` [PATCH 4/9] fs: handle the compat case in import_iovec Christoph Hellwig
2020-09-18 12:45 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-18 12:45 ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-18 12:45 ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-18 12:45 ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-18 13:48   ` Arnd Bergmann
2020-09-18 12:45 ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-19 14:24 ` let import_iovec deal with compat_iovecs as well David Laight
2020-09-21  4:41   ` 'Christoph Hellwig'
2020-09-21 11:11     ` David Laight
2020-09-21 14:34 ` let import_iovec deal with compat_iovecs as well v2 Christoph Hellwig
2020-09-21 14:34   ` [PATCH 01/11] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-21 14:34   ` [PATCH 02/11] mm: call import_iovec() instead of rw_copy_check_uvector() in process_vm_rw() Christoph Hellwig
2020-09-21 14:48     ` Matthew Wilcox
2020-09-21 15:02     ` Al Viro
2020-09-21 15:21       ` David Laight
2020-09-21 15:29         ` Al Viro
2020-09-21 15:44           ` David Laight
2020-09-21 16:27             ` Al Viro
2020-09-21 16:12           ` Christoph Hellwig
2020-09-21 14:34   ` [PATCH 03/11] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c and mark it static Christoph Hellwig
2020-09-21 14:34   ` [PATCH 04/11] iov_iter: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:05     ` David Laight
2020-09-21 15:11       ` Al Viro
2020-09-21 15:26         ` David Laight
2020-09-21 15:07     ` Al Viro
2020-09-21 14:34   ` [PATCH 05/11] iov_iter: merge the compat case into rw_copy_check_uvector Christoph Hellwig
2020-09-21 15:14     ` Al Viro
2021-01-08 11:49     ` David Laight
2020-09-21 14:34   ` [PATCH 06/11] iov_iter: handle the compat case in import_iovec Christoph Hellwig
2020-09-21 15:20     ` Al Viro
2020-09-21 14:34   ` [PATCH 07/11] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-21 14:34   ` [PATCH 08/11] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-21 14:34   ` [PATCH 09/11] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-21 14:34   ` [PATCH 10/11] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-21 14:34   ` [PATCH 11/11] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-23  6:05 ` let import_iovec deal with compat_iovecs as well v3 Christoph Hellwig
2020-09-23  6:05   ` [PATCH 1/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-23  6:05   ` [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Christoph Hellwig
2020-09-23  6:05   ` [PATCH 3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec Christoph Hellwig
2020-09-23 14:16     ` Al Viro
2020-09-23 14:38       ` David Laight
2020-09-23 14:49         ` Al Viro
2020-09-23 14:40       ` Al Viro
2020-09-23  6:05   ` [PATCH 4/9] iov_iter: transparently handle compat iovecs in import_iovec Christoph Hellwig
2020-09-23  6:05   ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-23 14:25     ` Al Viro
2020-09-23 14:32       ` Christoph Hellwig
2020-09-23 14:59         ` Al Viro
2020-09-23 16:38           ` Al Viro
2020-09-23 17:05             ` Al Viro
2020-09-23 17:46               ` Christoph Hellwig
2020-09-23 17:08             ` Brian Gerst
2020-09-23 18:45             ` Arnd Bergmann [this message]
2020-09-23 19:47               ` Al Viro
2020-09-23 19:52                 ` Arnd Bergmann
2020-09-23 21:30               ` David Laight
2020-09-23  6:05   ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-23  6:05   ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-23  6:05   ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-23  6:05   ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-25  4:51 ` let import_iovec deal with compat_iovecs as well v4 Christoph Hellwig
2020-09-25  4:51   ` [PATCH 1/9] compat.h: fix a spelling error in <linux/compat.h> Christoph Hellwig
2020-09-25  4:51   ` [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c Christoph Hellwig
2020-10-21 16:13     ` Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Greg KH
2020-10-21 20:59       ` David Laight
2020-10-21 23:39       ` Al Viro
2020-10-22  8:26         ` Greg KH
2020-10-22  8:35           ` David Hildenbrand
2020-10-22  8:40             ` David Laight
2020-10-22  8:48               ` David Hildenbrand
2020-10-22  9:01                 ` Greg KH
2020-10-22  9:06                   ` David Laight
2020-10-22  9:19                   ` David Hildenbrand
2020-10-22  9:25                     ` David Hildenbrand
2020-10-22  9:32                       ` David Laight
2020-10-22  9:36                         ` David Hildenbrand
2020-10-22 10:48                           ` Greg KH
2020-10-22 12:18                             ` Greg KH
2020-10-22 12:42                               ` David Hildenbrand
2020-10-22 12:57                                 ` Greg KH
2020-10-22 13:50                                   ` Greg KH
     [not found]                                     ` <CAK8P3a1B7OVdyzW0-97JwzZiwp0D0fnSfyete16QTvPp_1m07A@mail.gmail.com>
2020-10-22 14:40                                       ` Greg KH
2020-10-22 16:15                                         ` David Laight
2020-10-23 12:46                                     ` David Laight
2020-10-23 13:09                                       ` David Hildenbrand
2020-10-23 14:33                                         ` David Hildenbrand
2020-10-23 14:39                                           ` David Laight
2020-10-23 14:47                                             ` 'Greg KH'
2020-10-23 16:33                                               ` David Hildenbrand
2020-11-02  9:06                                               ` David Laight
2020-11-02 13:52                                                 ` 'Greg KH'
2020-11-02 18:23                                                   ` David Laight
2020-10-23 17:58                                         ` Al Viro
2020-10-23 18:27                                           ` Segher Boessenkool
2020-10-23 21:28                                             ` David Laight
2020-10-24 17:29                                               ` Segher Boessenkool
2020-10-24 21:12                                                 ` David Laight
     [not found]                                       ` <CAK8P3a1n+b8hOMhNQSDzgic03dyXbmpccfTJ3C1bGKvzsgMXbg@mail.gmail.com>
2020-10-23 13:28                                         ` David Laight
2020-10-22 13:23                           ` Christoph Hellwig
2020-10-22 16:35                             ` David Laight
2020-10-22 16:40                               ` Matthew Wilcox
2020-10-22 16:50                                 ` David Laight
2020-10-22 17:00                                 ` Nick Desaulniers
2020-10-22 20:59                                   ` Eric Biggers
2020-10-22 21:28                                     ` Al Viro
2020-10-22 18:19                                 ` Al Viro
2020-10-22 17:54                               ` Nick Desaulniers
     [not found]                                 ` <CAK8P3a3LjG+ZvmQrkb9zpgov8xBkQQWrkHBPgjfYSqBKGrwT4w@mail.gmail.com>
2020-10-22 19:04                                   ` Nick Desaulniers
2020-10-22 19:24                                     ` Al Viro
2020-10-22 19:27                                       ` Al Viro
2020-10-22 20:06                                       ` Al Viro
2020-10-22 20:09                                         ` Al Viro
2020-10-22 20:11                                       ` Nick Desaulniers
2020-10-22 22:07                                       ` David Laight
2020-10-23 13:12                                       ` David Hildenbrand
2020-10-22 22:04                                     ` David Laight
2020-10-22  9:28                     ` David Laight
2020-10-22  9:02                 ` David Laight
2020-09-25  4:51   ` [PATCH 3/9] iov_iter: refactor rw_copy_check_uvector and import_iovec Christoph Hellwig
2020-09-25  4:51   ` [PATCH 4/9] iov_iter: transparently handle compat iovecs in import_iovec Christoph Hellwig
2020-09-25  4:51   ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-25  4:51   ` [PATCH 6/9] fs: remove the compat readv/writev syscalls Christoph Hellwig
2020-09-25  4:51   ` [PATCH 7/9] fs: remove compat_sys_vmsplice Christoph Hellwig
2020-09-25  4:51   ` [PATCH 8/9] mm: remove compat_process_vm_{readv,writev} Christoph Hellwig
2020-09-25  4:51   ` [PATCH 9/9] security/keys: remove compat_keyctl_instantiate_key_iov Christoph Hellwig
2020-09-25 15:23   ` let import_iovec deal with compat_iovecs as well v4 Al Viro

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