From: Brian Gerst <[email protected]>
To: Al Viro <[email protected]>
Cc: Christoph Hellwig <[email protected]>,
Andrew Morton <[email protected]>,
Jens Axboe <[email protected]>, Arnd Bergmann <[email protected]>,
David Howells <[email protected]>,
David Laight <[email protected]>,
Linux ARM <[email protected]>,
Linux Kernel Mailing List <[email protected]>,
"open list:BROADCOM NVRAM DRIVER" <[email protected]>,
Parisc List <[email protected]>,
linuxppc-dev <[email protected]>,
linux-s390 <[email protected]>,
sparclinux <[email protected]>,
[email protected], [email protected],
Linux FS-devel Mailing List <[email protected]>,
[email protected], [email protected],
linux-arch <[email protected]>,
Linux-MM <[email protected]>,
[email protected], [email protected],
[email protected]
Subject: Re: [PATCH 5/9] fs: remove various compat readv/writev helpers
Date: Wed, 23 Sep 2020 13:08:49 -0400 [thread overview]
Message-ID: <CAMzpN2idk7bc7+37sj5UFD_PUOXCxn+RS8xmviq6Yc_LU4jyCw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
On Wed, Sep 23, 2020 at 12:39 PM Al Viro <[email protected]> wrote:
>
> On Wed, Sep 23, 2020 at 03:59:01PM +0100, Al Viro wrote:
>
> > > That's a very good question. But it does not just compile but actually
> > > works. Probably because all the syscall wrappers mean that we don't
> > > actually generate the normal names. I just tried this:
> > >
> > > --- a/include/linux/syscalls.h
> > > +++ b/include/linux/syscalls.h
> > > @@ -468,7 +468,7 @@ asmlinkage long sys_lseek(unsigned int fd, off_t offset,
> > > asmlinkage long sys_read(unsigned int fd, char __user *buf, size_t count);
> > > asmlinkage long sys_write(unsigned int fd, const char __user *buf,
> > > size_t count);
> > > -asmlinkage long sys_readv(unsigned long fd,
> > > +asmlinkage long sys_readv(void *fd,
> > >
> > > for fun, and the compiler doesn't care either..
> >
> > Try to build it for sparc or ppc...
>
> FWIW, declarations in syscalls.h used to serve 4 purposes:
> 1) syscall table initializers needed symbols declared
> 2) direct calls needed the same
> 3) catching mismatches between the declarations and definitions
> 4) centralized list of all syscalls
>
> (2) has been (thankfully) reduced for some time; in any case, ksys_... is
> used for the remaining ones.
>
> (1) and (3) are served by syscalls.h in architectures other than x86, arm64
> and s390. On those 3 (1) is done otherwise (near the syscall table initializer)
> and (3) is not done at all.
>
> 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 think this would be a good idea. I have been working on a patchset
to clean up the conditional syscall handling (sys_ni.c), and conflicts
with the prototypes in syscalls.h have been getting in the way.
Having the prototypes use SYSCALL_DECLAREx(...) would solve that
issue.
--
Brian Gerst
next prev parent reply other threads:[~2020-09-23 17:09 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2020-09-23 18:45 ` Arnd Bergmann
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
-- strict thread matches above, loose matches on Subject: below --
2020-09-25 4:51 let import_iovec deal with compat_iovecs as well v4 Christoph Hellwig
2020-09-25 4:51 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
2020-09-18 12:45 let import_iovec deal with compat_iovecs as well Christoph Hellwig
2020-09-18 12:45 ` [PATCH 5/9] fs: remove various compat readv/writev helpers Christoph Hellwig
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