[4.14,00/17] V4.14 backport of more 32-bit arm spectre patches

Message ID 20190110175150.5239-1-dave.long@linaro.org
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David Long Jan. 10, 2019, 5:51 p.m.
From: "David A. Long" <dave.long@linaro.org>


V4.14 backport of spectre patches from Russell M. King's spectre branch.

Julien Thierry (10):
  ARM: 8789/1: signal: copy registers using __copy_to_user()
  ARM: 8790/1: signal: always use __copy_to_user to save iwmmxt context
  ARM: 8791/1: vfp: use __copy_to_user() when saving VFP state
  ARM: 8792/1: oabi-compat: copy oabi events using __copy_to_user()
  ARM: 8793/1: signal: replace __put_user_error with __put_user
  ARM: 8794/1: uaccess: Prevent speculative use of the current
    addr_limit
  ARM: 8795/1: spectre-v1.1: use put_user() for __put_user()
  ARM: 8796/1: spectre-v1,v1.1: provide helpers for address sanitization
  ARM: 8797/1: spectre-v1.1: harden __copy_to_user
  ARM: 8810/1: vfp: Fix wrong assignement to ufp_exc

Russell King (7):
  ARM: make lookup_processor_type() non-__init
  ARM: split out processor lookup
  ARM: clean up per-processor check_bugs method call
  ARM: add PROC_VTABLE and PROC_TABLE macros
  ARM: spectre-v2: per-CPU vtables to work around big.Little systems
  ARM: ensure that processor vtables is not lost after boot
  ARM: fix the cockup in the previous patch

 arch/arm/include/asm/assembler.h   | 11 ++++
 arch/arm/include/asm/cputype.h     |  1 +
 arch/arm/include/asm/proc-fns.h    | 61 ++++++++++++++++++-----
 arch/arm/include/asm/thread_info.h |  4 +-
 arch/arm/include/asm/uaccess.h     | 49 +++++++++++++++---
 arch/arm/kernel/bugs.c             |  4 +-
 arch/arm/kernel/head-common.S      |  6 +--
 arch/arm/kernel/setup.c            | 40 +++++++++------
 arch/arm/kernel/signal.c           | 80 ++++++++++++++++--------------
 arch/arm/kernel/smp.c              | 31 ++++++++++++
 arch/arm/kernel/sys_oabi-compat.c  |  8 ++-
 arch/arm/lib/copy_from_user.S      |  6 +--
 arch/arm/lib/copy_to_user.S        |  6 ++-
 arch/arm/lib/uaccess_with_memcpy.c |  3 +-
 arch/arm/mm/proc-macros.S          | 10 ++++
 arch/arm/mm/proc-v7-bugs.c         | 17 +------
 arch/arm/vfp/vfpmodule.c           | 20 +++-----
 17 files changed, 245 insertions(+), 112 deletions(-)

-- 
2.17.1

Comments

Greg Kroah-Hartman Jan. 15, 2019, 3:45 p.m. | #1
On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:
> From: "David A. Long" <dave.long@linaro.org>

> 

> V4.14 backport of spectre patches from Russell M. King's spectre branch.


If I take these, than 4.19 is vulnerable.  So someone upgrading from
4.14 to 4.19 will regress :(

Can you please send me a 4.19 series so I can apply that before this
one?

thanks,

greg k-h
David Long Jan. 15, 2019, 4:07 p.m. | #2
On 1/15/19 10:45 AM, Greg KH wrote:
> On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

>> From: "David A. Long" <dave.long@linaro.org>

>>

>> V4.14 backport of spectre patches from Russell M. King's spectre branch.

> 

> If I take these, than 4.19 is vulnerable.  So someone upgrading from

> 4.14 to 4.19 will regress :(

> 

> Can you please send me a 4.19 series so I can apply that before this

> one?

> 

> thanks,

> 

> greg k-h

> 



OK, didn't think about that being a problem. Working on it. Pretty sure 
there's exactly one patch needed for that.

-dl
Greg Kroah-Hartman Jan. 15, 2019, 4:30 p.m. | #3
On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:
> On 1/15/19 10:45 AM, Greg KH wrote:

> > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > From: "David A. Long" <dave.long@linaro.org>

> > > 

> > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > 

> > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > 4.14 to 4.19 will regress :(

> > 

> > Can you please send me a 4.19 series so I can apply that before this

> > one?

> > 

> > thanks,

> > 

> > greg k-h

> > 

> 

> 

> OK, didn't think about that being a problem. Working on it. Pretty sure

> there's exactly one patch needed for that.


one?  All of these except one showed up in 4.20 and were not backported
to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even
backported to 4.20 either, which means someone messed up and didn't tag
it properly with a cc: stable patch :(

thanks,

greg k-h
David Long Jan. 15, 2019, 4:39 p.m. | #4
On 1/15/19 11:30 AM, Greg KH wrote:
> On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

>> On 1/15/19 10:45 AM, Greg KH wrote:

>>> On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

>>>> From: "David A. Long" <dave.long@linaro.org>

>>>>

>>>> V4.14 backport of spectre patches from Russell M. King's spectre branch.

>>>

>>> If I take these, than 4.19 is vulnerable.  So someone upgrading from

>>> 4.14 to 4.19 will regress :(

>>>

>>> Can you please send me a 4.19 series so I can apply that before this

>>> one?

>>>

>>> thanks,

>>>

>>> greg k-h

>>>

>>

>>

>> OK, didn't think about that being a problem. Working on it. Pretty sure

>> there's exactly one patch needed for that.

> 

> one?  All of these except one showed up in 4.20 and were not backported

> to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> backported to 4.20 either, which means someone messed up and didn't tag

> it properly with a cc: stable patch :(

> 

> thanks,

> 

> greg k-h

> 



OK, I will give it good looking over at any rate.

-dl
Russell King - ARM Linux admin Jan. 15, 2019, 5:06 p.m. | #5
On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:
> On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

> > On 1/15/19 10:45 AM, Greg KH wrote:

> > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > From: "David A. Long" <dave.long@linaro.org>

> > > > 

> > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > 

> > > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > > 4.14 to 4.19 will regress :(

> > > 

> > > Can you please send me a 4.19 series so I can apply that before this

> > > one?

> > > 

> > > thanks,

> > > 

> > > greg k-h

> > > 

> > 

> > 

> > OK, didn't think about that being a problem. Working on it. Pretty sure

> > there's exactly one patch needed for that.

> 

> one?  All of these except one showed up in 4.20 and were not backported

> to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> backported to 4.20 either, which means someone messed up and didn't tag

> it properly with a cc: stable patch :(


Or they didn't think it was important enough to warrant backporting.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
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Greg Kroah-Hartman Jan. 15, 2019, 5:19 p.m. | #6
On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:
> On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

> > On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

> > > On 1/15/19 10:45 AM, Greg KH wrote:

> > > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > > From: "David A. Long" <dave.long@linaro.org>

> > > > > 

> > > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > > 

> > > > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > > > 4.14 to 4.19 will regress :(

> > > > 

> > > > Can you please send me a 4.19 series so I can apply that before this

> > > > one?

> > > > 

> > > > thanks,

> > > > 

> > > > greg k-h

> > > > 

> > > 

> > > 

> > > OK, didn't think about that being a problem. Working on it. Pretty sure

> > > there's exactly one patch needed for that.

> > 

> > one?  All of these except one showed up in 4.20 and were not backported

> > to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> > backported to 4.20 either, which means someone messed up and didn't tag

> > it properly with a cc: stable patch :(

> 

> Or they didn't think it was important enough to warrant backporting.


Fair enough, then I have to ask why it's included in this series at
all...

thanks,

greg k-h
David Long Jan. 16, 2019, 7:27 p.m. | #7
On 1/15/19 12:19 PM, Greg KH wrote:
> On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:

>> On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

>>> On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

>>>> On 1/15/19 10:45 AM, Greg KH wrote:

>>>>> On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

>>>>>> From: "David A. Long" <dave.long@linaro.org>

>>>>>>

>>>>>> V4.14 backport of spectre patches from Russell M. King's spectre branch.

>>>>>

>>>>> If I take these, than 4.19 is vulnerable.  So someone upgrading from

>>>>> 4.14 to 4.19 will regress :(

>>>>>

>>>>> Can you please send me a 4.19 series so I can apply that before this

>>>>> one?

>>>>>

>>>>> thanks,

>>>>>

>>>>> greg k-h

>>>>>

>>>>

>>>>

>>>> OK, didn't think about that being a problem. Working on it. Pretty sure

>>>> there's exactly one patch needed for that.

>>>

>>> one?  All of these except one showed up in 4.20 and were not backported

>>> to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

>>> backported to 4.20 either, which means someone messed up and didn't tag

>>> it properly with a cc: stable patch :(

>>


My bad, I see now I was looking at v4.20 when I made that comment, not 
v4.19.

>> Or they didn't think it was important enough to warrant backporting.

> 

> Fair enough, then I have to ask why it's included in this series at

> all...

> 


I've been backporting all "spectre" branch patches as kept in the 
linux-arm repo, with the assumption they're all important. If the last 
patch is not deemed worthy of going into stable now would be a good time 
to declare it so as I have patch sets for v4.19 and v4.9 stable versions 
about ready to publish.

> thanks,

> 

> greg k-h

> 


Thanks,
-dl
Greg Kroah-Hartman Jan. 16, 2019, 7:33 p.m. | #8
On Wed, Jan 16, 2019 at 02:27:13PM -0500, David Long wrote:
> On 1/15/19 12:19 PM, Greg KH wrote:

> > On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:

> > > On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

> > > > On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

> > > > > On 1/15/19 10:45 AM, Greg KH wrote:

> > > > > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > > > > From: "David A. Long" <dave.long@linaro.org>

> > > > > > > 

> > > > > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > > > > 

> > > > > > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > > > > > 4.14 to 4.19 will regress :(

> > > > > > 

> > > > > > Can you please send me a 4.19 series so I can apply that before this

> > > > > > one?

> > > > > > 

> > > > > > thanks,

> > > > > > 

> > > > > > greg k-h

> > > > > > 

> > > > > 

> > > > > 

> > > > > OK, didn't think about that being a problem. Working on it. Pretty sure

> > > > > there's exactly one patch needed for that.

> > > > 

> > > > one?  All of these except one showed up in 4.20 and were not backported

> > > > to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> > > > backported to 4.20 either, which means someone messed up and didn't tag

> > > > it properly with a cc: stable patch :(

> > > 

> 

> My bad, I see now I was looking at v4.20 when I made that comment, not

> v4.19.

> 

> > > Or they didn't think it was important enough to warrant backporting.

> > 

> > Fair enough, then I have to ask why it's included in this series at

> > all...

> > 

> 

> I've been backporting all "spectre" branch patches as kept in the linux-arm

> repo, with the assumption they're all important. If the last patch is not

> deemed worthy of going into stable now would be a good time to declare it so

> as I have patch sets for v4.19 and v4.9 stable versions about ready to

> publish.


Isn't it up to you to determine what is and is not important to get this
all working properly?  You are testing all of this, right?  :)

thanks,

greg k-h
David Long Jan. 16, 2019, 7:40 p.m. | #9
On 1/16/19 2:33 PM, Greg KH wrote:
> On Wed, Jan 16, 2019 at 02:27:13PM -0500, David Long wrote:

>> On 1/15/19 12:19 PM, Greg KH wrote:

>>> On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:

>>>> On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

>>>>> On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

>>>>>> On 1/15/19 10:45 AM, Greg KH wrote:

>>>>>>> On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

>>>>>>>> From: "David A. Long" <dave.long@linaro.org>

>>>>>>>>

>>>>>>>> V4.14 backport of spectre patches from Russell M. King's spectre branch.

>>>>>>>

>>>>>>> If I take these, than 4.19 is vulnerable.  So someone upgrading from

>>>>>>> 4.14 to 4.19 will regress :(

>>>>>>>

>>>>>>> Can you please send me a 4.19 series so I can apply that before this

>>>>>>> one?

>>>>>>>

>>>>>>> thanks,

>>>>>>>

>>>>>>> greg k-h

>>>>>>>

>>>>>>

>>>>>>

>>>>>> OK, didn't think about that being a problem. Working on it. Pretty sure

>>>>>> there's exactly one patch needed for that.

>>>>>

>>>>> one?  All of these except one showed up in 4.20 and were not backported

>>>>> to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

>>>>> backported to 4.20 either, which means someone messed up and didn't tag

>>>>> it properly with a cc: stable patch :(

>>>>

>>

>> My bad, I see now I was looking at v4.20 when I made that comment, not

>> v4.19.

>>

>>>> Or they didn't think it was important enough to warrant backporting.

>>>

>>> Fair enough, then I have to ask why it's included in this series at

>>> all...

>>>

>>

>> I've been backporting all "spectre" branch patches as kept in the linux-arm

>> repo, with the assumption they're all important. If the last patch is not

>> deemed worthy of going into stable now would be a good time to declare it so

>> as I have patch sets for v4.19 and v4.9 stable versions about ready to

>> publish.

> 

> Isn't it up to you to determine what is and is not important to get this

> all working properly?  You are testing all of this, right?  :)

> 


It is all going through kernelci and a local kvm unit test.

The last patch in this set exists to fix a (apparently) non-critical 
regression in a security patch preceding it.  How worried are we about 
patches to stable introducing regressions? My assumption was that this 
is a bad enough thing to be fixed, but maybe not.

> thanks,

> 

> greg k-h

> 


Thanks,
-dl
Greg Kroah-Hartman Jan. 16, 2019, 7:48 p.m. | #10
On Wed, Jan 16, 2019 at 02:40:10PM -0500, David Long wrote:
> On 1/16/19 2:33 PM, Greg KH wrote:

> > On Wed, Jan 16, 2019 at 02:27:13PM -0500, David Long wrote:

> > > On 1/15/19 12:19 PM, Greg KH wrote:

> > > > On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:

> > > > > On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

> > > > > > On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

> > > > > > > On 1/15/19 10:45 AM, Greg KH wrote:

> > > > > > > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > > > > > > From: "David A. Long" <dave.long@linaro.org>

> > > > > > > > > 

> > > > > > > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > > > > > > 

> > > > > > > > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > > > > > > > 4.14 to 4.19 will regress :(

> > > > > > > > 

> > > > > > > > Can you please send me a 4.19 series so I can apply that before this

> > > > > > > > one?

> > > > > > > > 

> > > > > > > > thanks,

> > > > > > > > 

> > > > > > > > greg k-h

> > > > > > > > 

> > > > > > > 

> > > > > > > 

> > > > > > > OK, didn't think about that being a problem. Working on it. Pretty sure

> > > > > > > there's exactly one patch needed for that.

> > > > > > 

> > > > > > one?  All of these except one showed up in 4.20 and were not backported

> > > > > > to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> > > > > > backported to 4.20 either, which means someone messed up and didn't tag

> > > > > > it properly with a cc: stable patch :(

> > > > > 

> > > 

> > > My bad, I see now I was looking at v4.20 when I made that comment, not

> > > v4.19.

> > > 

> > > > > Or they didn't think it was important enough to warrant backporting.

> > > > 

> > > > Fair enough, then I have to ask why it's included in this series at

> > > > all...

> > > > 

> > > 

> > > I've been backporting all "spectre" branch patches as kept in the linux-arm

> > > repo, with the assumption they're all important. If the last patch is not

> > > deemed worthy of going into stable now would be a good time to declare it so

> > > as I have patch sets for v4.19 and v4.9 stable versions about ready to

> > > publish.

> > 

> > Isn't it up to you to determine what is and is not important to get this

> > all working properly?  You are testing all of this, right?  :)

> > 

> 

> It is all going through kernelci and a local kvm unit test.


That just tests if you didn't break anything, how are you testing that
you really are mitigating the issue that you think you are fixing?  What
spectre-specific tests are you using to validate all of this?

> The last patch in this set exists to fix a (apparently) non-critical

> regression in a security patch preceding it.  How worried are we about

> patches to stable introducing regressions? My assumption was that this is a

> bad enough thing to be fixed, but maybe not.


You tell me, what is the result if that patch is not applied?  Is it a
bug?  Performance issue?  Documentation issue?  Something else?

I understand why it was fixed (cleanups are good to do), but you need to
determine if what the cleanup is doing is actually something that
matters.

thanks,

greg k-h
Russell King - ARM Linux admin Jan. 16, 2019, 7:49 p.m. | #11
On Wed, Jan 16, 2019 at 02:27:13PM -0500, David Long wrote:
> On 1/15/19 12:19 PM, Greg KH wrote:

> > On Tue, Jan 15, 2019 at 05:06:59PM +0000, Russell King - ARM Linux admin wrote:

> > > On Tue, Jan 15, 2019 at 05:30:51PM +0100, Greg KH wrote:

> > > > On Tue, Jan 15, 2019 at 11:07:08AM -0500, David Long wrote:

> > > > > On 1/15/19 10:45 AM, Greg KH wrote:

> > > > > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > > > > From: "David A. Long" <dave.long@linaro.org>

> > > > > > > 

> > > > > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > > > > 

> > > > > > If I take these, than 4.19 is vulnerable.  So someone upgrading from

> > > > > > 4.14 to 4.19 will regress :(

> > > > > > 

> > > > > > Can you please send me a 4.19 series so I can apply that before this

> > > > > > one?

> > > > > > 

> > > > > > thanks,

> > > > > > 

> > > > > > greg k-h

> > > > > > 

> > > > > 

> > > > > 

> > > > > OK, didn't think about that being a problem. Working on it. Pretty sure

> > > > > there's exactly one patch needed for that.

> > > > 

> > > > one?  All of these except one showed up in 4.20 and were not backported

> > > > to 4.19 from what I can tell.  The last one is in 5.0-rc1 and not even

> > > > backported to 4.20 either, which means someone messed up and didn't tag

> > > > it properly with a cc: stable patch :(

> > > 

> 

> My bad, I see now I was looking at v4.20 when I made that comment, not

> v4.19.

> 

> > > Or they didn't think it was important enough to warrant backporting.

> > 

> > Fair enough, then I have to ask why it's included in this series at

> > all...

> > 

> 

> I've been backporting all "spectre" branch patches as kept in the linux-arm

> repo, with the assumption they're all important. If the last patch is not

> deemed worthy of going into stable now would be a good time to declare it so

> as I have patch sets for v4.19 and v4.9 stable versions about ready to

> publish.


Let me be absolutely clear:

The final patch is a minor fix for the previous patch.  I do not
consider it important enough to warrant backporting to 4.19 on an
automated basis - if it was important, I could have sent it to Linus
before 4.19 was released.  That is not to say that there is no reason
not to apply it to 4.19, I just don't deem it important enough to have
a Cc to stable (especially as *none* of the ARM Spectre patches have a
Cc to stable.)

If someone does want to request that the stable team pick it up for
4.19, then that's fine by me.

If we are going to the effort of backporting the rest of the series to
kernels such as 4.14, it is worth picking it up for those with the rest
of the patches as it avoids unintentionally always placing data in the
.rodata section that could otherwise be discarded under certain
configurations.

However, the saving from having it in the init sections is normally
minimal - in terms of the size of the kernel, the per-processor type
data structure is rather small.  We are talking around 256 bytes in
an ARMv7 kernel.

It only makes sense for kernels with big.Little disabled or the Spectre
workarounds disabled (since we need this data in the .rodata section for
big.Little kernels with Spectre workarounds enabled).  All other
configurations, this data can be located in the init sections.

The patch is more a correctness issue with the previous patch in terms
of the placement of the affected data.

I get the feeling that we're making something of a mountain out of a
molehill over this really trivial patch.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
Greg Kroah-Hartman Jan. 18, 2019, 4:07 p.m. | #12
On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:
> From: "David A. Long" <dave.long@linaro.org>

> 

> V4.14 backport of spectre patches from Russell M. King's spectre branch.


Based on some recent private email threads I had about this series, here
is what I would like to see for the next time this is posted:

- Patch series such that someone moving from one tree to a newer one
  does not experience regressions (i.e. a 4.19 version of this series,
  and 4.20 where needed.)

- a statement saying how this was tested.  As part of that statement,
  there better be something like "we tested using our reproducer and it
  shows that there is no longer an issue."  Yes, I know Spectre
  reproducers are hard to come by, but they are out there and I do not
  want to take a patch series that is not at least tested for the thing
  that it is supposed to be solving.

thanks,

greg k-h
David Long Jan. 18, 2019, 8:24 p.m. | #13
On 1/18/19 11:07 AM, Greg KH wrote:
> On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

>> From: "David A. Long" <dave.long@linaro.org>

>>

>> V4.14 backport of spectre patches from Russell M. King's spectre branch.

> 

> Based on some recent private email threads I had about this series, here

> is what I would like to see for the next time this is posted:

> 

> - Patch series such that someone moving from one tree to a newer one

>    does not experience regressions (i.e. a 4.19 version of this series,

>    and 4.20 where needed.)


The v4.19 and v4.9 versions are ready. Not sure I understand why there 
would be a need for a v4.20 version even if it is one patch shy.

> 

> - a statement saying how this was tested.  As part of that statement,

>    there better be something like "we tested using our reproducer and it

>    shows that there is no longer an issue."  Yes, I know Spectre

>    reproducers are hard to come by, but they are out there and I do not

>    want to take a patch series that is not at least tested for the thing

>    that it is supposed to be solving.

> 


I'll see what I can figure out for spectre testing but at best this 
stuff is pretty non-deterministic.

-dl
Greg Kroah-Hartman Jan. 19, 2019, 8:08 a.m. | #14
On Fri, Jan 18, 2019 at 03:24:01PM -0500, David Long wrote:
> On 1/18/19 11:07 AM, Greg KH wrote:

> > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > From: "David A. Long" <dave.long@linaro.org>

> > > 

> > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > 

> > Based on some recent private email threads I had about this series, here

> > is what I would like to see for the next time this is posted:

> > 

> > - Patch series such that someone moving from one tree to a newer one

> >    does not experience regressions (i.e. a 4.19 version of this series,

> >    and 4.20 where needed.)

> 

> The v4.19 and v4.9 versions are ready. Not sure I understand why there would

> be a need for a v4.20 version even if it is one patch shy.


Then backport that one patch :)
Russell King - ARM Linux admin Jan. 19, 2019, 9:56 a.m. | #15
On Sat, Jan 19, 2019 at 09:08:51AM +0100, Greg KH wrote:
> On Fri, Jan 18, 2019 at 03:24:01PM -0500, David Long wrote:

> > On 1/18/19 11:07 AM, Greg KH wrote:

> > > On Thu, Jan 10, 2019 at 12:51:33PM -0500, David Long wrote:

> > > > From: "David A. Long" <dave.long@linaro.org>

> > > > 

> > > > V4.14 backport of spectre patches from Russell M. King's spectre branch.

> > > 

> > > Based on some recent private email threads I had about this series, here

> > > is what I would like to see for the next time this is posted:

> > > 

> > > - Patch series such that someone moving from one tree to a newer one

> > >    does not experience regressions (i.e. a 4.19 version of this series,

> > >    and 4.20 where needed.)

> > 

> > The v4.19 and v4.9 versions are ready. Not sure I understand why there would

> > be a need for a v4.20 version even if it is one patch shy.

> 

> Then backport that one patch :)


You could just pick the patch up - it'll cherry-pick just fine
across onto 4.19, so it should be trivial just like all the others
that get automatically picked out of mainline that don't have a Cc
to stable.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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