[PATCH v2 0/3] Make the scheduler stack end check selectable at boot

[Chris Down]

At Meta, some of our host types enable CONFIG_SCHED_STACK_END_CHECK, but
we don't want it generally on because of the extra work on every context
switch.

Right now this is only configurable by setting the Kconfig option at
build time. Let's make it so we can also select it at boot with
sched_stack_end_check=, so that those hosts can share one kernel image.

(Patch 1 is a cleanup I happened upon while working on this, it can
also be taken independently.)

v2:

- Check scs_is_enabled() inside task_scs_end_corrupted() rather than in
  schedule_debug() (Peter)
- Return 1 when sched_stack_end_check= can't be parsed (Randy)
- Say in the changelog why the other task_stack_end_corrupted() callers
  are left alone (Peter)
- Rebase onto tip/sched/core

v1: https://lore.kernel.org/r/cover.1793082868.git.chris@chrisdown.name

Chris Down (3):
  scs: Skip the shadow stack end check when SCS is disabled
  sched/core: Add sched_stack_end_check= boot parameter
  lkdtm/bugs: Add CORRUPT_STACK_END to test the scheduler stack end
    check

 .../admin-guide/kernel-parameters.txt         |  8 +++++
 drivers/misc/lkdtm/bugs.c                     | 21 ++++++++++++
 include/linux/scs.h                           | 19 ++++++-----
 kernel/sched/core.c                           | 33 +++++++++++++++----
 tools/testing/selftests/lkdtm/tests.txt       |  1 +
 5 files changed, 68 insertions(+), 14 deletions(-)


base-commit: d7e670601af6c564ccf6d3b2ddf70ee4f41a6d1c
-- 
2.56.1