[0/3] Add OpenRISC restartable sequences support

Message

Stafford Horne Jan. 10, 2025, 10:22 a.m. UTC

This series adds restartable sequences support to OpenRISC.  This came after
discussions with Michael on the libc-alpha list where he added some preliminary
rseq support [1].

The changes use mostly the riscv port as a template.

The patches were tested with selftests on qemu using my glibc branch containing
rseq patches [2].

Note the RSEQ_SIG instruction I chose is a `l.nop 0x35` which is just a nop,
which is different than most other architectures that use a `break` instruction.
As the signature does not need to actually be a break or trap instruction I
figured the nop is good for this.

[1] https://gcc.gnu.org/pipermail/libc-alpha/2025-January/163504.html
[2] https://github.com/stffrdhrn/or1k-glibc/commits/or1k-rseq/

Michael Jeanson (1):
  openrisc: Add HAVE_REGS_AND_STACK_ACCESS_API support

Stafford Horne (2):
  openrisc: Add support for restartable sequences
  rseq/selftests: Add support for OpenRISC

 arch/openrisc/Kconfig                         |   2 +
 arch/openrisc/include/asm/ptrace.h            |  73 +++-
 arch/openrisc/kernel/entry.S                  |   4 +
 arch/openrisc/kernel/ptrace.c                 |  96 ++++
 arch/openrisc/kernel/signal.c                 |   2 +
 tools/testing/selftests/rseq/param_test.c     |  24 +
 tools/testing/selftests/rseq/rseq-or1k-bits.h | 412 ++++++++++++++++++
 .../selftests/rseq/rseq-or1k-thread-pointer.h |  13 +
 tools/testing/selftests/rseq/rseq-or1k.h      | 181 ++++++++
 .../selftests/rseq/rseq-thread-pointer.h      |   2 +
 tools/testing/selftests/rseq/rseq.h           |   2 +
 11 files changed, 810 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/rseq/rseq-or1k-bits.h
 create mode 100644 tools/testing/selftests/rseq/rseq-or1k-thread-pointer.h
 create mode 100644 tools/testing/selftests/rseq/rseq-or1k.h