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. This patch also overhauls the implementation of ADD/SUB/SET/ULEB128 relocations to handle overflow. "Overflow" is different for ULEB128 since it is a variable-length encoding that the compiler can be expected to generate enough space for. Instead of overflowing, ULEB128 will expand into the next 8-bit segment of the location. A psABI proposal [1] was merged that mandates that SET_ULEB128 and SUB_ULEB128 are paired, however the discussion following the merging of the pull request revealed that while the pull request was valid, it would be better for linkers to properly handle this overflow. This patch proactively implements this methodology for future compatibility. 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@xxxxxxxxxxxx> --- Changes in v9: - Use uintptr_t where applicable (Emil) - Split up insn_rmw changes into correct patch (Emil) - Make reloc_handlers const and simplify struct (Emil) - Link to v8: https://lore.kernel.org/r/20231031-module_relocations-v8-0-09b5b720c1fe@xxxxxxxxxxxx Changes in v8: - Fix up riscv_insn_rmw to work with big-endian systems (Andreas/Emil) - Improve readability of bitops throughout module.c (Emil) - Consolidate all relocation handler functions into a single struct so array doesn't need to be duplicated 3 times - Use .space assember op instead of .rept - Fix up name of uleb128 testcase - Define prototypes of some new functions to conform to -Wmissing-prototypes - Remove unused variable "first" - Link to v7: https://lore.kernel.org/r/20231031-module_relocations-v7-0-6f4719b64bf7@xxxxxxxxxxxx Changes in v7: - Overhaul ADD/SUB/SET/ULEB128 relocations - Fix ULEB128 so it produces correct values when more than 1 byte is needed - Link to v6: https://lore.kernel.org/r/20231019-module_relocations-v6-0-94726e644321@xxxxxxxxxxxx Changes in v6: - Use (void *) instead of (u32 *) for handler type - Constrain ULEB128 to be consecutive relocations - Link to v5: https://lore.kernel.org/r/20231018-module_relocations-v5-0-dfee32d4dfc3@xxxxxxxxxxxx Changes in v5: - Brought in patch by Emil and fixed it up to force little endian - Fixed up issues with apply_r_riscv_32_pcrel_rela and apply_r_riscv_plt32_rela (Samuel) - Added u8 cast in apply_r_riscv_sub6_rela (Andreas) - Link to v4: https://lore.kernel.org/r/20231017-module_relocations-v4-0-937f5ef316f0@xxxxxxxxxxxx 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@xxxxxxxxxxxx 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@xxxxxxxxxxxx Changes in v2: - Added ULEB128 relocations - Link to v1: https://lore.kernel.org/r/20230913-module_relocations-v1-0-bb3d8467e793@xxxxxxxxxxxx --- Charlie Jenkins (2): riscv: Add remaining module relocations riscv: Add tests for riscv module loading Emil Renner Berthing (1): riscv: Avoid unaligned access when relocating modules arch/riscv/Kconfig.debug | 1 + arch/riscv/include/uapi/asm/elf.h | 5 +- arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/module.c | 603 +++++++++++++++++---- 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 | 88 +++ 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 | 20 + arch/riscv/kernel/tests/module_test/test_sub32.S | 20 + arch/riscv/kernel/tests/module_test/test_sub6.S | 20 + arch/riscv/kernel/tests/module_test/test_sub64.S | 25 + arch/riscv/kernel/tests/module_test/test_sub8.S | 20 + arch/riscv/kernel/tests/module_test/test_uleb128.S | 31 ++ 18 files changed, 869 insertions(+), 105 deletions(-) --- base-commit: 3bcce01fcbcd868b8cf3a5632fde283e122d7213 change-id: 20230908-module_relocations-f63ced651bd7 -- - Charlie
