From: Andy Lutomirski <luto@amacapital.net>
To: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Andrew Lutomirski <luto@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>
Subject: Re: [PATCHv10 1/2] x86/vdso: add mremap hook to vm_special_mapping
Date: Wed, 6 Jul 2016 07:03:48 -0700 [thread overview]
Message-ID: <CALCETrVMk35yej228NTMnP1Y2iHo=U54nTkzbiwO5ba-MQT7NQ@mail.gmail.com> (raw)
In-Reply-To: <20160628113539.13606-2-dsafonov@virtuozzo.com>
On Tue, Jun 28, 2016 at 4:35 AM, Dmitry Safonov <dsafonov@virtuozzo.com> wrote:
> Add possibility for userspace 32-bit applications to move
> vdso mapping. Previously, when userspace app called
> mremap for vdso, in return path it would land on previous
> address of vdso page, resulting in segmentation violation.
> Now it lands fine and returns to userspace with remapped vdso.
> This will also fix context.vdso pointer for 64-bit, which does not
> affect the user of vdso after mremap by now, but this may change.
>
> As suggested by Andy, return EINVAL for mremap that splits vdso image.
>
> Renamed and moved text_mapping structure declaration inside
> map_vdso, as it used only there and now it complement
> vvar_mapping variable.
>
> There is still problem for remapping vdso in glibc applications:
> linker relocates addresses for syscalls on vdso page, so
> you need to relink with the new addresses. Or the next syscall
> through glibc may fail:
> Program received signal SIGSEGV, Segmentation fault.
> #0 0xf7fd9b80 in __kernel_vsyscall ()
> #1 0xf7ec8238 in _exit () from /usr/lib32/libc.so.6
Acked-by: Andy Lutomirski <luto@kernel.org>
next prev parent reply other threads:[~2016-07-06 14:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-28 11:35 [PATCHv10 0/2] mremap vDSO for 32-bit Dmitry Safonov
2016-06-28 11:35 ` [PATCHv10 1/2] x86/vdso: add mremap hook to vm_special_mapping Dmitry Safonov
2016-07-06 14:03 ` Andy Lutomirski [this message]
2016-07-08 13:16 ` [tip:x86/mm] x86/vdso: Add " tip-bot for Dmitry Safonov
2016-06-28 11:35 ` [PATCHv10 2/2] selftest/x86: add mremap vdso test Dmitry Safonov
2016-07-08 12:17 ` Ingo Molnar
2016-07-08 13:16 ` [tip:x86/mm] selftests/x86: Add vDSO mremap() test tip-bot for Dmitry Safonov
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