[RFC PATCH 0/5] RSEQ selftests uplift for glibc-2.35 compatibility

[Mathieu Desnoyers]

glibc-2.35 will be released on 2022-02-01. It introduces a user-space ABI
based on the thread pointer to access a reserved area of the TCB.

The rseq selftests originally expected the rseq thread data to sit in a
__rseq_abi TLS variable.

Considering that the rseq ABI only allows a single rseq registration per
thread, both cannot actively coexist in a process.

Adapt the selftests librseq implementation to become compatible with
glibc-2.35. Keep a fallback implementation based on TLS available when
an older glibc is detected.

Feedback is welcome,

Thanks,

Mathieu

Mathieu Desnoyers (5):
  selftests/rseq: Remove useless assignment to cpu variable
  selftests/rseq: Remove volatile from __rseq_abi
  selftests/rseq: Introduce rseq_get_abi() helper
  selftests/rseq: Introduce thread pointer getters
  selftests/rseq: Uplift rseq selftests for compatibility with
    glibc-2.35

 tools/testing/selftests/rseq/Makefile         |   2 +-
 tools/testing/selftests/rseq/param_test.c     |   4 +-
 tools/testing/selftests/rseq/rseq-arm.h       |  32 ++--
 tools/testing/selftests/rseq/rseq-arm64.h     |  32 ++--
 .../rseq/rseq-generic-thread-pointer.h        |  25 +++
 tools/testing/selftests/rseq/rseq-mips.h      |  32 ++--
 .../selftests/rseq/rseq-ppc-thread-pointer.h  |  30 ++++
 tools/testing/selftests/rseq/rseq-ppc.h       |  32 ++--
 tools/testing/selftests/rseq/rseq-s390.h      |  24 +--
 .../selftests/rseq/rseq-thread-pointer.h      |  19 +++
 .../selftests/rseq/rseq-x86-thread-pointer.h  |  40 +++++
 tools/testing/selftests/rseq/rseq-x86.h       |  30 ++--
 tools/testing/selftests/rseq/rseq.c           | 161 +++++++++---------
 tools/testing/selftests/rseq/rseq.h           |  24 ++-
 14 files changed, 302 insertions(+), 185 deletions(-)
 create mode 100644 tools/testing/selftests/rseq/rseq-generic-thread-pointer.h
 create mode 100644 tools/testing/selftests/rseq/rseq-ppc-thread-pointer.h
 create mode 100644 tools/testing/selftests/rseq/rseq-thread-pointer.h
 create mode 100644 tools/testing/selftests/rseq/rseq-x86-thread-pointer.h

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2.17.1