[PATCH 0/8] x86/module: rework ROX cache to avoid writable copy

[Mike Rapoport]

From: "Mike Rapoport (Microsoft)" <rppt at kernel.org>

Hi,

Following Peter's comments [1] these patches rework handling of ROX caches
for module text allocations. 

Instead of using a writable copy that really complicates alternatives
patching, temporarily remap parts of a large ROX page as RW for the time of
module formation and then restore it's ROX protections when the module is
ready.

To keep the ROX memory mapped with large pages, make set_memory code
capable of restoring large pages (more details are in patch 3).

The patches also available in git
https://git.kernel.org/rppt/h/execmem/x86-rox/v8

[1] https://lore.kernel.org/all/20241209083818.GK8562@noisy.programming.kicks-ass.net

Kirill A. Shutemov (1):
  x86/mm/pat: Restore large pages after fragmentation

Mike Rapoport (Microsoft) (7):
  x86/mm/pat: cpa-test: fix length for CPA_ARRAY test
  x86/mm/pat: drop duplicate variable in cpa_flush()
  execmem: add API for temporal remapping as RW and restoring ROX
    afterwards
  module: introduce MODULE_STATE_GONE
  modules: switch to execmem API for remapping as RW and restoring ROX
  Revert "x86/module: prepare module loading for ROX allocations of
    text"
  module: drop unused module_writable_address()

 arch/um/kernel/um_arch.c                      |  11 +-
 arch/x86/entry/vdso/vma.c                     |   3 +-
 arch/x86/include/asm/alternative.h            |  14 +-
 arch/x86/include/asm/pgtable_types.h          |   2 +
 arch/x86/kernel/alternative.c                 | 181 ++++++---------
 arch/x86/kernel/ftrace.c                      |  30 ++-
 arch/x86/kernel/module.c                      |  45 ++--
 arch/x86/mm/pat/cpa-test.c                    |   2 +-
 arch/x86/mm/pat/set_memory.c                  | 216 +++++++++++++++++-
 include/linux/execmem.h                       |  31 +++
 include/linux/module.h                        |  21 +-
 include/linux/moduleloader.h                  |   4 -
 include/linux/vm_event_item.h                 |   2 +
 kernel/module/kallsyms.c                      |   8 +-
 kernel/module/kdb.c                           |   2 +-
 kernel/module/main.c                          |  86 ++-----
 kernel/module/procfs.c                        |   2 +-
 kernel/module/strict_rwx.c                    |   9 +-
 kernel/tracepoint.c                           |   2 +
 lib/kunit/test.c                              |   2 +
 mm/execmem.c                                  | 118 ++++++++--
 mm/vmstat.c                                   |   2 +
 samples/livepatch/livepatch-callbacks-demo.c  |   1 +
 .../test_modules/test_klp_callbacks_demo.c    |   1 +
 .../test_modules/test_klp_callbacks_demo2.c   |   1 +
 .../livepatch/test_modules/test_klp_state.c   |   1 +
 .../livepatch/test_modules/test_klp_state2.c  |   1 +
 27 files changed, 511 insertions(+), 287 deletions(-)

-- 
2.45.2