From: Christoph Hellwig <hch@lst.de>
To: Jann Horn <jannh@google.com>
Cc: Rich Felker <dalias@libc.org>,
linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Linux-sh list <linux-sh@vger.kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>, Linux-MM <linux-mm@kvack.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Mark Salter <msalter@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Aurelien Jacquiot <jacquiot.aurelien@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"Eric W . Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH v2 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU
Date: Tue, 05 May 2020 12:15:57 +0000 [thread overview]
Message-ID: <20200505121557.GA24052@lst.de> (raw)
In-Reply-To: <CAG48ez3F70-UXwdHmO4CnR0bAForn-SBtstW5WAYjcrLFwS_9A@mail.gmail.com>
On Tue, May 05, 2020 at 01:42:12PM +0200, Jann Horn wrote:
> On Tue, May 5, 2020 at 12:48 PM Christoph Hellwig <hch@lst.de> wrote:
> > On Wed, Apr 29, 2020 at 11:49:50PM +0200, Jann Horn wrote:
> > > dump_emit() is for kernel pointers, and VMAs describe userspace memory.
> > > Let's be tidy here and avoid accessing userspace pointers under KERNEL_DS,
> > > even if it probably doesn't matter much on !MMU systems - especially given
> > > that it looks like we can just use the same get_dump_page() as on MMU if
> > > we move it out of the CONFIG_MMU block.
> >
> > Looks sensible. Did you get a chance to test this with a nommu setup?
>
> Nope. Do you happen to have a recommendation for a convenient
> environment I can use with QEMU, or something like that? I'm guessing
> that just running a standard armel Debian userspace with a !mmu ARM
> kernel wouldn't work so well?
Nommu generally needs special userspace either using uclibc-ng or musl.
When I did the RISC-V nommu work I used buildroot for my root file
systems. We haven't gotten elffdpic to work on RISC-V yet, so I can't
use that setup for testing, but it should support ARM as well.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jann Horn <jannh@google.com>
Cc: Christoph Hellwig <hch@lst.de>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
kernel list <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Oleg Nesterov <oleg@redhat.com>,
Russell King <linux@armlinux.org.uk>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Mark Salter <msalter@redhat.com>,
Aurelien Jacquiot <jacquiot.aurelien@gmail.com>,
linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
Linux-sh list <linux-sh@vger.kernel.org>
Subject: Re: [PATCH v2 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU
Date: Tue, 5 May 2020 14:15:57 +0200 [thread overview]
Message-ID: <20200505121557.GA24052@lst.de> (raw)
In-Reply-To: <CAG48ez3F70-UXwdHmO4CnR0bAForn-SBtstW5WAYjcrLFwS_9A@mail.gmail.com>
On Tue, May 05, 2020 at 01:42:12PM +0200, Jann Horn wrote:
> On Tue, May 5, 2020 at 12:48 PM Christoph Hellwig <hch@lst.de> wrote:
> > On Wed, Apr 29, 2020 at 11:49:50PM +0200, Jann Horn wrote:
> > > dump_emit() is for kernel pointers, and VMAs describe userspace memory.
> > > Let's be tidy here and avoid accessing userspace pointers under KERNEL_DS,
> > > even if it probably doesn't matter much on !MMU systems - especially given
> > > that it looks like we can just use the same get_dump_page() as on MMU if
> > > we move it out of the CONFIG_MMU block.
> >
> > Looks sensible. Did you get a chance to test this with a nommu setup?
>
> Nope. Do you happen to have a recommendation for a convenient
> environment I can use with QEMU, or something like that? I'm guessing
> that just running a standard armel Debian userspace with a !mmu ARM
> kernel wouldn't work so well?
Nommu generally needs special userspace either using uclibc-ng or musl.
When I did the RISC-V nommu work I used buildroot for my root file
systems. We haven't gotten elffdpic to work on RISC-V yet, so I can't
use that setup for testing, but it should support ARM as well.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jann Horn <jannh@google.com>
Cc: Rich Felker <dalias@libc.org>,
linux-c6x-dev@linux-c6x.org,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Linux-sh list <linux-sh@vger.kernel.org>,
kernel list <linux-kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>, Linux-MM <linux-mm@kvack.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Mark Salter <msalter@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Aurelien Jacquiot <jacquiot.aurelien@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
"Eric W . Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH v2 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU
Date: Tue, 5 May 2020 14:15:57 +0200 [thread overview]
Message-ID: <20200505121557.GA24052@lst.de> (raw)
In-Reply-To: <CAG48ez3F70-UXwdHmO4CnR0bAForn-SBtstW5WAYjcrLFwS_9A@mail.gmail.com>
On Tue, May 05, 2020 at 01:42:12PM +0200, Jann Horn wrote:
> On Tue, May 5, 2020 at 12:48 PM Christoph Hellwig <hch@lst.de> wrote:
> > On Wed, Apr 29, 2020 at 11:49:50PM +0200, Jann Horn wrote:
> > > dump_emit() is for kernel pointers, and VMAs describe userspace memory.
> > > Let's be tidy here and avoid accessing userspace pointers under KERNEL_DS,
> > > even if it probably doesn't matter much on !MMU systems - especially given
> > > that it looks like we can just use the same get_dump_page() as on MMU if
> > > we move it out of the CONFIG_MMU block.
> >
> > Looks sensible. Did you get a chance to test this with a nommu setup?
>
> Nope. Do you happen to have a recommendation for a convenient
> environment I can use with QEMU, or something like that? I'm guessing
> that just running a standard armel Debian userspace with a !mmu ARM
> kernel wouldn't work so well?
Nommu generally needs special userspace either using uclibc-ng or musl.
When I did the RISC-V nommu work I used buildroot for my root file
systems. We haven't gotten elffdpic to work on RISC-V yet, so I can't
use that setup for testing, but it should support ARM as well.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-05-05 12:15 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 21:49 [PATCH v2 0/5] Fix ELF / FDPIC ELF core dumping, and use mmap_sem properly in there Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` [PATCH v2 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-05-05 10:48 ` Christoph Hellwig
2020-05-05 10:48 ` Christoph Hellwig
2020-05-05 10:48 ` Christoph Hellwig
2020-05-05 11:42 ` Jann Horn
2020-05-05 11:42 ` Jann Horn
2020-05-05 11:42 ` Jann Horn
2020-05-05 11:42 ` Jann Horn
2020-05-05 12:15 ` Christoph Hellwig [this message]
2020-05-05 12:15 ` Christoph Hellwig
2020-05-05 12:15 ` Christoph Hellwig
2020-08-11 3:05 ` Jann Horn
2020-08-11 3:05 ` Jann Horn
2020-08-11 3:05 ` Jann Horn
2020-08-11 3:05 ` Jann Horn
2020-04-29 21:49 ` [PATCH v2 2/5] coredump: Let dump_emit() bail out on short writes Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` [PATCH v2 3/5] coredump: Refactor page range dumping into common helper Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-05-05 10:50 ` Christoph Hellwig
2020-05-05 10:50 ` Christoph Hellwig
2020-05-05 10:50 ` Christoph Hellwig
2020-05-05 11:44 ` Jann Horn
2020-05-05 11:44 ` Jann Horn
2020-05-05 11:44 ` Jann Horn
2020-05-05 11:44 ` Jann Horn
2020-04-29 21:49 ` [PATCH v2 4/5] binfmt_elf, binfmt_elf_fdpic: Use a VMA list snapshot Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-05-05 11:03 ` Christoph Hellwig
2020-05-05 11:03 ` Christoph Hellwig
2020-05-05 11:03 ` Christoph Hellwig
2020-05-05 12:11 ` Jann Horn
2020-05-05 12:11 ` Jann Horn
2020-05-05 12:11 ` Jann Horn
2020-05-05 12:11 ` Jann Horn
2020-04-29 21:49 ` [PATCH v2 5/5] mm/gup: Take mmap_sem in get_dump_page() Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:49 ` Jann Horn
2020-04-29 21:56 ` [PATCH v2 0/5] Fix ELF / FDPIC ELF core dumping, and use mmap_sem properly in there Russell King - ARM Linux admin
2020-04-29 21:56 ` Russell King - ARM Linux admin
2020-04-29 21:56 ` Russell King - ARM Linux admin
2020-04-29 23:03 ` Linus Torvalds
2020-04-29 23:03 ` Linus Torvalds
2020-04-29 23:03 ` Linus Torvalds
2020-04-29 23:03 ` Linus Torvalds
2020-04-30 1:27 ` Nicolas Pitre
2020-04-30 1:27 ` Nicolas Pitre
2020-04-30 1:27 ` Nicolas Pitre
2020-04-30 1:27 ` Nicolas Pitre
2020-04-30 14:10 ` Greg Ungerer
2020-04-30 14:10 ` Greg Ungerer
2020-04-30 14:10 ` Greg Ungerer
2020-04-30 14:51 ` Rich Felker
2020-04-30 14:51 ` Rich Felker
2020-04-30 14:51 ` Rich Felker
2020-04-30 21:13 ` Rob Landley
2020-04-30 21:13 ` Rob Landley
2020-04-30 21:13 ` Rob Landley
2020-05-01 6:00 ` Greg Ungerer
2020-05-01 6:00 ` Greg Ungerer
2020-05-01 6:00 ` Greg Ungerer
2020-05-01 19:09 ` Rob Landley
2020-05-01 19:09 ` Rob Landley
2020-05-01 19:09 ` Rob Landley
2020-04-30 16:54 ` Linus Torvalds
2020-04-30 16:54 ` Linus Torvalds
2020-04-30 16:54 ` Linus Torvalds
2020-04-30 16:54 ` Linus Torvalds
2020-04-30 19:07 ` Eric W. Biederman
2020-04-30 19:07 ` Eric W. Biederman
2020-04-30 19:07 ` Eric W. Biederman
2020-04-30 19:07 ` Eric W. Biederman
2020-05-01 5:44 ` Greg Ungerer
2020-05-01 5:44 ` Greg Ungerer
2020-05-01 5:44 ` Greg Ungerer
2020-05-01 11:13 ` Eric W. Biederman
2020-05-01 11:13 ` Eric W. Biederman
2020-05-01 11:13 ` Eric W. Biederman
2020-05-01 11:13 ` Eric W. Biederman
2020-05-01 7:14 ` Greg Ungerer
2020-05-01 7:14 ` Greg Ungerer
2020-05-01 7:14 ` Greg Ungerer
2020-04-30 1:59 ` Nicolas Pitre
2020-04-30 1:59 ` Nicolas Pitre
2020-04-30 1:59 ` Nicolas Pitre
2020-04-30 1:59 ` Nicolas Pitre
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