This patch series introduces Kernel Stack Watch (KSW), a lightweight
debugging tool for detecting kernel stack corruption in real-time.
The motivation comes from cases where corruption happens silently in
one function but only manifests later as a crash in another,
with no direct call trace connection. Such problems are often very
difficult to debug with existing tools.

KSW works by combining hardware breakpoints with kprobes/kretprobes.
It can watch a stack canary or a selected local variable, and detect
the moment the corruption actually occurs. This allows developers to
pinpoint the real source, rather than only observing the final crash.

Key features include:
- Lightweight design with minimal impact on bug reproducibility
- Real-time detection of stack corruption
- Simple configuration through `/proc/kstackwatch`
- Support for recursive functions with configurable nesting depth

To validate the approach, I have also prepared test modules and scripts
that simulate corruption scenarios.

I am sharing this work to seek feedback on the idea and the design.
Any comments or suggestions for improvement are very welcome.

The series is structured as follows:

Jinchao Wang (13):
  mm: Add kstackwatch build infrastructure
  x86/HWBP: Add arch_reinstall_hw_breakpoint() for atomic updates
  mm/kstackwatch: Add module core and configuration interface
  mm/kstackwatch: Add HWBP pre-allocation infrastructure
  mm/kstackwatch: Add atomic HWBP arm/disarm operations
  mm/kstackwatch: Add stack address resolution functions
  mm/kstackwatch: Add kprobe and stack watch control
  mm/kstackwatch: Wire up watch and stack subsystems in module core
  mm/kstackwatch: Add architecture support validation
  mm/kstackwatch: Handle nested function calls
  mm/kstackwatch: Ignore corruption in kretprobe trampolines
  mm/kstackwatch: Add debug and test functions
  mm/kstackwatch: Add a test module and script

 arch/x86/include/asm/hw_breakpoint.h  |   1 +
 arch/x86/kernel/hw_breakpoint.c       |  50 ++++++
 mm/Kconfig.debug                      |  23 +++
 mm/Makefile                           |   1 +
 mm/kstackwatch/Makefile               |  11 ++
 mm/kstackwatch/kernel.c               | 248 ++++++++++++++++++++++++++
 mm/kstackwatch/kstackwatch.h          |  56 ++++++
 mm/kstackwatch/kstackwatch_test.c     | 237 ++++++++++++++++++++++++
 mm/kstackwatch/stack.c                | 222 +++++++++++++++++++++++
 mm/kstackwatch/watch.c                | 240 +++++++++++++++++++++++++
 tools/kstackwatch/kstackwatch_test.sh | 122 +++++++++++++
 11 files changed, 1211 insertions(+)
 create mode 100644 mm/kstackwatch/Makefile
 create mode 100644 mm/kstackwatch/kernel.c
 create mode 100644 mm/kstackwatch/kstackwatch.h
 create mode 100644 mm/kstackwatch/kstackwatch_test.c
 create mode 100644 mm/kstackwatch/stack.c
 create mode 100644 mm/kstackwatch/watch.c
 create mode 100644 tools/kstackwatch/kstackwatch_test.sh

-- 
2.43.0