From: Rich Felker <dalias@libc.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: musl@lists.openwall.com, Christian Brauner <brauner@kernel.org>
Subject: Re: [musl] Re: add loongarch64 port
Date: Sat, 9 Apr 2022 09:30:45 -0400 [thread overview]
Message-ID: <20220409133044.GL7074@brightrain.aerifal.cx> (raw)
In-Reply-To: <20220409131939.GK7074@brightrain.aerifal.cx>
On Sat, Apr 09, 2022 at 09:19:39AM -0400, Rich Felker wrote:
> On Sat, Apr 09, 2022 at 01:06:13PM +0200, Arnd Bergmann wrote:
> > On Sat, Apr 9, 2022 at 5:55 AM 王洪亮 <wanghongliang@loongson.cn> wrote:
> > > 在 2022/4/8 下午2:46, Arnd Bergmann 写道:
> > > > On Fri, Apr 8, 2022 at 4:21 AM 王洪亮 <wanghongliang@loongson.cn> wrote:
> > > >
> > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fa729c4df5589
> > > >
> > > > What happens in the clone() syscall in the kernel is that the size
> > > > gets added to the initial pointer on normal architectures (parisc and ia64
> > > > being the exceptions). If you already have the stack pointer, I think you can
> > > > just pass size=0 as we do internally in the kernel.
> > > >
> > > > If there was a port of musl to one of the architectures that does it
> > > > differently,
> > > > then changing callers such as
> > > >
> > > > pid = __clone(child, stack+sizeof stack,
> > > > CLONE_VM|CLONE_VFORK|SIGCHLD, &args);
> > > >
> > > > would be required, and the separate size argument in clone3() could
> > > > help keep that hidden from musl.
> > > >
> > > > Arnd
> > >
> > >
> > > In LoongArch,the stack is grows down.
> > >
> > > As previous suggested,I implement __NR_clone3 syscall within __clone()
> > > in loongarch port,based on __clone() interface unchanged and the
> > > architecture-independent code of call __clone() unchanged.
> > >
> > > In __NR_clone3 syscall,I need pass the lowest address of memory area to
> > > clone_args.stack,and pass stack_size to clone_args.stack_size(stack_size
> > > must not be 0)
> > > if (kargs->stack_size == 0)
> > > return false;
> > >
> > > current,the __clone()'s input parameters have no "stack_size",so I can't
> > > pass valid(must be size!=0) stack_size to clone3.
> > >
> > > your meaning is pass stack_size=0 when the input parameter "stack" of
> > > __clone()
> > > is already stack point? but pass stack_size=0 is illegal.
> >
> > Ah, you are right, that doesn't work at the moment. You dropped Christian
> > from the Cc list, adding him back because he probably has an idea
> > for how to address that.
> >
> > It looks like it could be fixed for the internal callers of __clone() by
> > adding a __clone3() call that takes the size argument, and falls back
> > to calling __clone() on architectures that have that. I don't see how
> > one would do it for the generic clone() library function call though.
>
> size=4k and passing stack-4k? O_o
>
> This seems like a ridiculous kernel regression to require a size when
> none may be available...
Actually, if there aren't yet archs lacking SYS_clone, this API
regression may be a good argument not to drop SYS_clone on new archs
yet until there's a way for new archs to get the same behavior
(unspecified stack size).
Rich
next prev parent reply other threads:[~2022-04-09 13:31 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 6:20 王洪亮
2022-03-31 8:14 ` Arnd Bergmann
2022-04-01 7:40 ` 王洪亮
2022-04-01 7:48 ` Arnd Bergmann
2022-04-02 6:19 ` 王洪亮
2022-04-02 7:21 ` Rich Felker
2022-04-02 9:53 ` 王洪亮
2022-04-27 1:58 ` 王洪亮
2022-04-27 2:13 ` Rich Felker
2022-03-31 18:47 ` Rich Felker
2022-04-02 7:59 ` 王洪亮
2022-04-06 2:08 ` 王洪亮
2022-04-06 16:00 ` Markus Wichmann
2022-04-08 2:21 ` 王洪亮
2022-04-08 6:46 ` Arnd Bergmann
2022-04-09 3:54 ` 王洪亮
2022-04-09 11:06 ` Arnd Bergmann
2022-04-09 13:19 ` Rich Felker
2022-04-09 13:30 ` Rich Felker [this message]
2022-04-10 10:30 ` Arnd Bergmann
2022-04-10 15:26 ` Rich Felker
2022-04-11 8:03 ` Arnd Bergmann
2022-04-11 12:11 ` Rich Felker
2022-04-11 13:01 ` Arnd Bergmann
2022-04-12 1:11 ` 王洪亮
2022-04-13 1:16 ` 王洪亮
2022-04-13 7:26 ` Christian Brauner
2022-04-13 8:26 ` Arnd Bergmann
2022-04-13 9:04 ` Christian Brauner
2022-04-13 13:25 ` Arnd Bergmann
2022-04-13 14:09 ` Rich Felker
2022-04-14 9:36 ` Christian Brauner
2022-04-20 9:09 ` 王洪亮
2022-04-20 13:33 ` Christian Brauner
2022-04-20 13:54 ` Rich Felker
2022-04-21 6:54 ` 王洪亮
2022-04-14 9:36 ` Christian Brauner
2022-04-13 7:19 ` Christian Brauner
2022-04-13 14:06 ` Rich Felker
2022-04-11 3:40 ` 王洪亮
-- strict thread matches above, loose matches on Subject: below --
2022-03-22 3:52 [musl] " 王洪亮
2022-03-29 8:12 ` [musl] " 王洪亮
2022-03-29 8:26 ` Arnd Bergmann
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=20220409133044.GL7074@brightrain.aerifal.cx \
--to=dalias@libc.org \
--cc=arnd@kernel.org \
--cc=brauner@kernel.org \
--cc=musl@lists.openwall.com \
/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.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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).