[RFC PATCH 0/4] Enable Clang's Source-based Code Coverage and MC/DC for x86-64

[Sasha Levin]

This series adds support for Clang's Source-based Code Coverage to the
Linux kernel, enabling more accurate coverage measurement at the source
level compared to gcov. This is particularly valuable for safety-critical
use cases (automotive, medical, aerospace) where MC/DC coverage is required
for certification.

Changes since previous patchset [1]:
- Rebased on v6.18-rc1
- Adapted to lib/crypto reorganization (curve25519 exclusion moved to
  lib/crypto/Makefile)
- Minor correctness fixes throughout the codebase

The implementation has been tested with a kernel build using Clang 18+ and
boots successfully in a KVM environment with instrumentation enabled.

[1] https://lore.kernel.org/all/20240905043245.1389509-1-wentaoz5@illinois.edu/

Wentao Zhang (4):
  llvm-cov: add Clang's Source-based Code Coverage support
  llvm-cov: add Clang's MC/DC support
  x86: disable llvm-cov instrumentation
  x86: enable llvm-cov support

 Makefile                          |   9 ++
 arch/Kconfig                      |   1 +
 arch/x86/Kconfig                  |   2 +
 arch/x86/crypto/Makefile          |   1 +
 arch/x86/kernel/vmlinux.lds.S     |   2 +
 include/asm-generic/vmlinux.lds.h |  36 +++++
 kernel/Makefile                   |   1 +
 kernel/llvm-cov/Kconfig           | 121 ++++++++++++++
 kernel/llvm-cov/Makefile          |   8 +
 kernel/llvm-cov/fs.c              | 253 ++++++++++++++++++++++++++++++
 kernel/llvm-cov/llvm-cov.h        | 157 ++++++++++++++++++
 lib/crypto/Makefile               |   3 +-
 scripts/Makefile.lib              |  23 +++
 scripts/mod/modpost.c             |   2 +
 14 files changed, 618 insertions(+), 1 deletion(-)
 create mode 100644 kernel/llvm-cov/Kconfig
 create mode 100644 kernel/llvm-cov/Makefile
 create mode 100644 kernel/llvm-cov/fs.c
 create mode 100644 kernel/llvm-cov/llvm-cov.h

-- 
2.51.0