Re: [PATCH 3/3] x86-64: Rework vsyscall emulation and add vsyscall= parameter

From: Andrew Lutomirski
Date: Wed Aug 10 2011 - 17:19:07 EST

On Wed, Aug 10, 2011 at 5:14 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> Andrew Lutomirski <luto@xxxxxxx> wrote:
>>On Wed, Aug 10, 2011 at 1:21 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>>> On 08/10/2011 10:15 AM, Andy Lutomirski wrote:
>>>> There are three choices:
>>>> vsyscall=native: Vsyscalls are native code that issues the
>>>> corresponding syscalls.
>>>> vsyscall=emulate (default): Vsyscalls are emulated by instruction
>>>> fault traps, tested in the bad_area path.  The actual contents of
>>>> the vsyscall page is the same as the vsyscall=native case except
>>>> that it's marked NX.  This way programs that make assumptions about
>>>> what the code in the page does will not be confused when they read
>>>> that code.
>>>> vsyscall=none: Trying to execute a vsyscall will segfault.
>>>> Signed-off-by: Andy Lutomirski <luto@xxxxxxx>
>>> Hi Andy,
>>> This patch doesn't apply.  What is your baseline for this patch?
>>My baseline was a commit that probably only lives in my tree, but the
>>patches should apply cleanly on top of
>>c149a665ac488e0dac22a42287f45ad1bda06ff1, which is the current
> Please rebase your patch on the current -linus since it appears to have changed since x86/vdso was merged.

Can you double-check? I think it's the other way around: x86/vdso has
fixes that should be pushed to Linus.

$ git log tip/x86/vdso ^origin/master --oneline
c149a66 x86-64: Add vsyscall:emulate_vsyscall trace event
318f5a2 x86-64: Add user_64bit_mode paravirt op
5d5791a x86-64, xen: Enable the vvar mapping
f670bb7 x86-64: Work around gold bug 13023
9c40818 x86-64: Move the "user" vsyscall segment out of the data segment.
1bdfac1 x86-64: Pad vDSO to a page boundary
17b0436 Merge commit 'v3.0' into x86/vdso

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