[PATCH v2 0/2] uaccess: Add unsafe accessors for arm64

[Julien Thierry <julien.thierry@arm.com>]

Hi,

First version of this series[1] was briefly in linux-next but had to be
reverted due to a bug where schedule would end up being called while
user_access was active[2].

After clarifications[3], rescheduling while in a user_access region is not
allowed.

* Patch 1 clarifies this restriction in the API and attempts to check
  against violations of the restriction.
* Patch 2 implements the unsafe accessors for arm64

Changes since v1:
- Add a way to detect code calling schedule within a user_access region
- Make sure put_user/get_user arguments are evaluated before disabling PAN

[1] https://www.spinics.net/lists/arm-kernel/msg674925.html
[2] https://patchwork.kernel.org/patch/10634783/
[3] https://lkml.org/lkml/2018/11/28/50

Cheers,

Julien

-->

Julien Thierry (2):
  uaccess: Check no rescheduling function is called in unsafe region
  arm64: uaccess: Implement unsafe accessors

 arch/arm64/include/asm/sysreg.h  |  2 +
 arch/arm64/include/asm/uaccess.h | 89 +++++++++++++++++++++++++++++++---------
 include/linux/kernel.h           |  6 ++-
 include/linux/uaccess.h          | 11 +++++
 kernel/sched/core.c              | 19 +++++++++
 5 files changed, 105 insertions(+), 22 deletions(-)

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1.9.1