From: Brian Gerst <brgerst@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Al Viro <viro@zeniv.linux.org.uk>,
Luis Chamberlain <mcgrof@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"open list:BROADCOM NVRAM DRIVER" <linux-mips@vger.kernel.org>,
Parisc List <linux-parisc@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
linux-s390 <linux-s390@vger.kernel.org>,
sparclinux <sparclinux@vger.kernel.org>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/6] exec: simplify the compat syscall handling
Date: Mon, 15 Jun 2020 10:48:26 -0400 [thread overview]
Message-ID: <CAMzpN2heSzZzg16ws3yQkd7YZwmPPx_4RFCpb9JYfFWJ9gfPhA@mail.gmail.com> (raw)
In-Reply-To: <20200615141239.GA12951@lst.de>
On Mon, Jun 15, 2020 at 10:13 AM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Jun 15, 2020 at 03:31:35PM +0200, Arnd Bergmann wrote:
> > > #ifdef CONFIG_COMPAT
> > > - if (unlikely(argv.is_compat)) {
> > > + if (in_compat_syscall()) {
> > > + const compat_uptr_t __user *compat_argv =
> > > + compat_ptr((unsigned long)argv);
> > > compat_uptr_t compat;
> > >
> > > - if (get_user(compat, argv.ptr.compat + nr))
> > > + if (get_user(compat, compat_argv + nr))
> > > return ERR_PTR(-EFAULT);
> > >
> > > return compat_ptr(compat);
> > > }
> > > #endif
> >
> > I would expect that the "#ifdef CONFIG_COMPAT" can be removed
> > now, since compat_ptr() and in_compat_syscall() are now defined
> > unconditionally. I have not tried that though.
>
> True, I'll give it a spin.
>
> > > +/*
> > > + * x32 syscalls are listed in the same table as x86_64 ones, so we need to
> > > + * define compat syscalls that are exactly the same as the native version for
> > > + * the syscall table machinery to work. Sigh..
> > > + */
> > > +#ifdef CONFIG_X86_X32
> > > COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
> > > - const compat_uptr_t __user *, argv,
> > > - const compat_uptr_t __user *, envp)
> > > + const char __user *const __user *, argv,
> > > + const char __user *const __user *, envp)
> > > {
> > > - return do_compat_execve(AT_FDCWD, getname(filename), argv, envp, 0);
> > > + return do_execveat(AT_FDCWD, getname(filename), argv, envp, 0, NULL);
> > > }
> >
> > Maybe move it to arch/x86/kernel/process_64.c or arch/x86/entry/syscall_x32.c
> > to keep it out of the common code if this is needed.
>
> I'd rather keep it in common code as that allows all the low-level
> exec stuff to be marked static, and avoid us growing new pointless
> compat variants through copy and paste.
> smart compiler to d
>
> > I don't really understand
> > the comment, why can't this just use this?
>
> That errors out with:
>
> ld: arch/x86/entry/syscall_x32.o:(.rodata+0x1040): undefined reference to
> `__x32_sys_execve'
> ld: arch/x86/entry/syscall_x32.o:(.rodata+0x1108): undefined reference to
> `__x32_sys_execveat'
> make: *** [Makefile:1139: vmlinux] Error 1
I think I have a fix for this, by modifying the syscall wrappers to
add an alias for the __x32 variant to the native __x64_sys_foo().
I'll get back to you with a patch.
--
Brian Gerst
next prev parent reply other threads:[~2020-06-15 14:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 13:00 properly support exec and wait with kernel pointers Christoph Hellwig
2020-06-15 13:00 ` [PATCH 1/6] exec: cleanup the execve wrappers Christoph Hellwig
2020-06-15 13:00 ` [PATCH 2/6] exec: simplify the compat syscall handling Christoph Hellwig
2020-06-15 13:31 ` Arnd Bergmann
2020-06-15 14:12 ` Christoph Hellwig
2020-06-15 14:40 ` Arnd Bergmann
2020-06-15 14:43 ` Christoph Hellwig
2020-06-15 14:46 ` Arnd Bergmann
2020-06-15 15:09 ` Christoph Hellwig
2020-06-15 15:33 ` Brian Gerst
2020-06-15 16:41 ` Christoph Hellwig
2020-06-15 14:48 ` Brian Gerst [this message]
2020-06-15 18:47 ` Arnd Bergmann
2020-06-15 19:45 ` Brian Gerst
2020-06-15 13:00 ` [PATCH 3/6] exec: cleanup the count() function Christoph Hellwig
2020-06-15 13:00 ` [PATCH 4/6] exec: split prepare_arg_pages Christoph Hellwig
2020-06-15 13:00 ` [PATCH 5/6] exec: add a kernel_execveat helper Christoph Hellwig
2020-06-15 13:00 ` [PATCH 6/6] kernel: add a kernel_wait helper Christoph Hellwig
2020-06-15 13:42 ` properly support exec and wait with kernel pointers Arnd Bergmann
2020-06-18 14:46 properly support exec and wait with kernel pointers v2 Christoph Hellwig
2020-06-18 14:46 ` [PATCH 2/6] exec: simplify the compat syscall handling Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAMzpN2heSzZzg16ws3yQkd7YZwmPPx_4RFCpb9JYfFWJ9gfPhA@mail.gmail.com \
--to=brgerst@gmail.com \
--cc=arnd@arndb.de \
--cc=hch@lst.de \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mcgrof@kernel.org \
--cc=sparclinux@vger.kernel.org \
--cc=viro@zeniv.linux.org.uk \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).