linux-kernel - [PATCH v4 0/2] riscv: Add remaining module relocations and tests

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Message-Id: <20231017-module_relocations-v4-0-937f5ef316f0@rivosinc.com>
Date:   Tue, 17 Oct 2023 22:34:15 -0700
From:   Charlie Jenkins <charlie@...osinc.com>
To:     linux-riscv@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Eric Biederman <ebiederm@...ssion.com>,
        Kees Cook <keescook@...omium.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Charlie Jenkins <charlie@...osinc.com>
Subject: [PATCH v4 0/2] riscv: Add remaining module relocations and tests

A handful of module relocations were missing, this patch includes the
remaining ones. I also wrote some test cases to ensure that module
loading works properly. Some relocations cannot be supported in the
kernel, these include the ones that rely on thread local storage and
dynamic linking.

ULEB128 handling is a bit special because SET and SUB relocations must
happen together, and SET must happen before SUB. A psABI proposal [1]
mandates that the first SET_ULEB128 that appears before a SUB_ULEB128
is the associated SET_ULEB128.

This can be tested by enabling KUNIT, RUNTIME_KERNEL_TESTING_MENU, and
RISCV_MODULE_LINKING_KUNIT.

[1] https://github.com/riscv-non-isa/riscv-elf-psabi-doc/pull/403

Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
---
Changes in v4:
- Complete removal of R_RISCV_RVC_LUI
- Fix bug in R_RISCV_SUB6 linking
- Only build ULEB128 tests if supported by toolchain
- Link to v3: https://lore.kernel.org/r/20231016-module_relocations-v3-0-a667fd6071e9@rivosinc.com

Changes in v3:
- Add prototypes to test_module_linking_main as recommended by intel
  zero day bot
- Improve efficiency of ULEB128 pair matching
- Link to v2: https://lore.kernel.org/r/20231006-module_relocations-v2-0-47566453fedc@rivosinc.com

Changes in v2:
- Added ULEB128 relocations
- Link to v1: https://lore.kernel.org/r/20230913-module_relocations-v1-0-bb3d8467e793@rivosinc.com

---
Charlie Jenkins (2):
      riscv: Add remaining module relocations
      riscv: Add tests for riscv module loading

 arch/riscv/Kconfig.debug                           |   1 +
 arch/riscv/include/uapi/asm/elf.h                  |   5 +-
 arch/riscv/kernel/Makefile                         |   1 +
 arch/riscv/kernel/module.c                         | 207 ++++++++++++++++++---
 arch/riscv/kernel/tests/Kconfig.debug              |  35 ++++
 arch/riscv/kernel/tests/Makefile                   |   1 +
 arch/riscv/kernel/tests/module_test/Makefile       |  15 ++
 .../tests/module_test/test_module_linking_main.c   |  85 +++++++++
 arch/riscv/kernel/tests/module_test/test_set16.S   |  23 +++
 arch/riscv/kernel/tests/module_test/test_set32.S   |  20 ++
 arch/riscv/kernel/tests/module_test/test_set6.S    |  23 +++
 arch/riscv/kernel/tests/module_test/test_set8.S    |  23 +++
 arch/riscv/kernel/tests/module_test/test_sub16.S   |  22 +++
 arch/riscv/kernel/tests/module_test/test_sub32.S   |  22 +++
 arch/riscv/kernel/tests/module_test/test_sub6.S    |  22 +++
 arch/riscv/kernel/tests/module_test/test_sub64.S   |  27 +++
 arch/riscv/kernel/tests/module_test/test_sub8.S    |  22 +++
 arch/riscv/kernel/tests/module_test/test_uleb128.S |  20 ++
 18 files changed, 548 insertions(+), 26 deletions(-)
---
base-commit: 4d320c2d9a2b22f53523a1b012cda17a50220965
change-id: 20230908-module_relocations-f63ced651bd7
-- 
- Charlie