[SRU][Trusty][PULL] Update to upstream's implementation of Spectre v1 mitigation (LP: #1774181)

[Stefan Bader]

On 28.06.2018 16:40, Juerg Haefliger wrote:
> BugLink: https://bugs.launchpad.net/bugs/1774181
> 
> Xenial/Trusty/Precise are currently lacking full support of upstream's Spectre
> v1 mitigation. Add the missing patches and merge them with Ubuntu's current
> implementation.
> 
> == SRU Justification ==
> Ubuntu's Spectre v1 mitigation is based on the original embargoed patchset
> which introduced a barrier macro to prevent speculation beyond array boundaries
> for user controlled indices. What eventually landed in upstream is slightly
> different and uses a barrier macro in combination with a masking solution (plus
> syscall table and user pointer sanitation). During the updates to newer stable
> upstream versions, all those patches were skipped. After reviewing them, we
> want to bring them back and merge them with the current implementation which
> brings us back in sync with upstream stable.

I went through the set and ended more or less with the same comments as Khaled:
- some patches look like picked from 4.4.y without mentioning that
- personally I like to start a new section with the backported/cherry picked
  line, this makes it a bit more obvious where the new block starts. Not really
  important but some patches do it that way and some not. So either one style
  or the other would be good.
- I would squash moving that WARN_ON_ONCE and removing it into one patch with
  the commit message of the removal
- Renaming osb() and fixing the last uses really should be one patch for bi-
  section.

-Stefan
> 
> == Fix ==
> Add all the missing Spectre v1 patches from upstream stable 4.4.118 to 4.4.131.
> Where appropriate, replace Ubuntu's additional barriers with the masking macro.
> 
> == Regression Potential ==
> Low. The patches have been in upstream for quite a while now and we keep the
> speculation barriers that are currently in Ubuntu but not in upstream.
> 
> == Test Case ==
> TBD.
> 
> Compile-tested all supported architectures.
> 
> Signed-off-by: Juerg Haefliger <juergh at canonical.com>
> ---
> 
> The following changes since commit ae41eb7e6e1f4431c8a6d98578588d15b7240bf8:
> 
>   fscache: Fix hanging wait on page discarded by writeback (2018-06-18 17:44:37 +0200)
> 
> are available in the Git repository at:
> 
>   git://git.launchpad.net/~juergh/+git/trusty-linux lp1774181
> 
> for you to fetch changes up to 182dabb3ee807633a0a11e8bbac93a64d111fdd3:
> 
>   UBUNTU: SAUCE: filter: Use barrier_nospec() instead of osb() (2018-06-28 16:08:50 +0200)
> 
> ----------------------------------------------------------------
> Ben Hutchings (1):
>       x86/syscall: Sanitize syscall table de-references under speculation
> 
> Dan Williams (9):
>       array_index_nospec: Sanitize speculative array de-references
>       x86: Implement array_index_mask_nospec
>       x86: Introduce barrier_nospec
>       x86/get_user: Use pointer masking to limit speculation
>       vfs, fdtable: Prevent bounds-check bypass via speculative execution
>       nl80211: Sanitize array index in parse_txq_params
>       x86/spectre: Report get_user mitigation for spectre_v1
>       x86/kvm: Update spectre-v1 mitigation
>       nospec: Kill array_index_nospec_mask_check()
> 
> Juerg Haefliger (3):
>       UBUNTU: SAUCE: Replace osb() calls with array_index_nospec()
>       UBUNTU: SAUCE: Rename osb() to barrier_nospec()
>       UBUNTU: SAUCE: filter: Use barrier_nospec() instead of osb()
> 
> Mark Rutland (1):
>       Documentation: Document array_index_nospec
> 
> Rasmus Villemoes (1):
>       nospec: Allow index argument to have const-qualified type
> 
> Will Deacon (1):
>       nospec: Move array_index_nospec() parameter checking into separate macro
> 
>  Documentation/speculation.txt            | 90 ++++++++++++++++++++++++++++++++
>  arch/arm/include/asm/barrier.h           |  3 --
>  arch/arm64/include/asm/barrier.h         |  3 --
>  arch/powerpc/include/asm/barrier.h       |  3 +-
>  arch/s390/include/asm/barrier.h          | 13 +++--
>  arch/x86/ia32/ia32entry.S                | 36 ++++++++-----
>  arch/x86/include/asm/barrier.h           | 32 ++++++++++--
>  arch/x86/kernel/cpu/bugs.c               | 10 +---
>  arch/x86/kernel/entry_32.S               |  4 ++
>  arch/x86/kernel/entry_64.S               | 16 +++---
>  arch/x86/kvm/vmx.c                       | 15 ++++--
>  arch/x86/lib/getuser.S                   | 10 ++++
>  drivers/media/usb/uvc/uvc_v4l2.c         |  5 +-
>  drivers/net/wireless/ath/carl9170/main.c |  3 +-
>  drivers/scsi/qla2xxx/qla_mr.c            |  5 +-
>  fs/udf/misc.c                            | 13 ++---
>  include/asm-generic/barrier.h            | 11 ----
>  include/linux/fdtable.h                  |  3 +-
>  include/linux/nospec.h                   | 53 +++++++++++++++++++
>  kernel/user_namespace.c                  |  3 +-
>  net/core/filter.c                        |  5 +-
>  net/wireless/nl80211.c                   |  9 ++--
>  22 files changed, 268 insertions(+), 77 deletions(-)
>  create mode 100644 Documentation/speculation.txt
> 


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