linux-kernel - [PATCH v3 0/9] riscv: vector: misc ptrace fixes for debug use-cases

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Message-ID: <20251025210655.43099-1-geomatsi@gmail.com>
Date: Sun, 26 Oct 2025 00:06:33 +0300
From: Sergey Matyukevich <geomatsi@...il.com>
To: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Cc: Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Oleg Nesterov <oleg@...hat.com>,
	Shuah Khan <shuah@...nel.org>,
	Thomas Huth <thuth@...hat.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Andy Chiu <andybnac@...il.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Joel Granados <joel.granados@...nel.org>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Yong-Xuan Wang <yongxuan.wang@...ive.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Sergey Matyukevich <geomatsi@...il.com>
Subject: [PATCH v3 0/9] riscv: vector: misc ptrace fixes for debug use-cases

This patch series suggests fixes for several corner cases in the RISC-V
vector ptrace implementation:

- init vector context with proper vlenb, to avoid reading zero vlenb
  by an early attached debugger

- follow gdbserver expectations and return ENODATA instead of EINVAL
  if vector extension is supported but not yet activated for the
  traced process

- validate input vector csr registers in ptrace, to maintain an accurate
  view of the tracee's vector context across multiple halt/resume
  debug cycles

For detailed description see the appropriate commit messages. A new test
suite v_ptrace is added into the tools/testing/selftests/riscv/vector
to verify some of the vector ptrace functionality and corner cases.

Previous versions:
- v2: https://lore.kernel.org/linux-riscv/20250821173957.563472-1-geomatsi@gmail.com/T/#u
- v1: https://lore.kernel.org/linux-riscv/20251007115840.2320557-1-geomatsi@gmail.com/T/#u

Changes in v3:
Address the review comments by Andy Chiu and rework the approach:
- drop forced vector context save entirely
- perform strict validation of vector csr regs in ptrace

Changes in v2:
- add thread_info flag to allow to force vector context save
- force vector context save after vector ptrace to ensure valid vector
  context in the next ptrace operations
- force vector context save on the first context switch after vector
  context init to get proper vlenb

---

Ilya Mamay (1):
  riscv: ptrace: return ENODATA for inactive vector extension

Sergey Matyukevich (8):
  selftests: riscv: test ptrace vector interface
  selftests: riscv: verify initial vector state with ptrace
  riscv: vector: init vector context with proper vlenb
  riscv: csr: define vector registers elements
  riscv: ptrace: validate input vector csr registers
  selftests: riscv: verify ptrace rejects invalid vector csr inputs
  selftests: riscv: verify ptrace accepts valid vector csr values
  selftests: riscv: verify syscalls discard vector context

 arch/riscv/include/asm/csr.h                  |  11 +
 arch/riscv/kernel/ptrace.c                    |  72 +-
 arch/riscv/kernel/vector.c                    |  12 +-
 .../testing/selftests/riscv/vector/.gitignore |   1 +
 tools/testing/selftests/riscv/vector/Makefile |   5 +-
 .../testing/selftests/riscv/vector/v_ptrace.c | 737 ++++++++++++++++++
 6 files changed, 830 insertions(+), 8 deletions(-)
 create mode 100644 tools/testing/selftests/riscv/vector/v_ptrace.c


base-commit: 72761a7e31225971d0b29d9195e0ffa986b77867
-- 
2.51.0