From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- lib/kunit/Kconfig | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 lib/kunit/Kconfig (limited to 'lib/kunit/Kconfig') diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig new file mode 100644 index 000000000..94ff8e408 --- /dev/null +++ b/lib/kunit/Kconfig @@ -0,0 +1,145 @@ +# +# KUnit base configuration +# + +menuconfig KUNIT + tristate "KUnit - Enable support for unit tests" + select GLOB + help + Enables support for kernel unit tests (KUnit), a lightweight unit + testing and mocking framework for the Linux kernel. These tests are + able to be run locally on a developer's workstation without a VM or + special hardware when using UML. Can also be used on most other + architectures. For more information, please see + Documentation/dev-tools/kunit/. + +if KUNIT + +config KUNIT_DEBUGFS + bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation" + depends on DEBUG_FS + default y + help + Enable debugfs representation for kunit. Currently this consists + of /sys/kernel/debug/kunit//results files for each + test suite, which allow users to see results of the last test suite + run that occurred. + +config KUNIT_FAULT_TEST + bool "Enable KUnit tests which print BUG stacktraces" + depends on KUNIT_TEST + depends on !UML + default !PANIC_ON_OOPS + help + Enables fault handling tests for the KUnit framework. These tests may + trigger a kernel BUG(), and the associated stack trace, even when they + pass. If this conflicts with your test infrastrcture (or is confusing + or annoying), they can be disabled by setting this to N. + +config KUNIT_TEST + tristate "KUnit test for KUnit" if !KUNIT_ALL_TESTS + default KUNIT_ALL_TESTS + help + Enables the unit tests for the KUnit test framework. These tests test + the KUnit test framework itself; the tests are both written using + KUnit and test KUnit. This option should only be enabled for testing + purposes by developers interested in testing that KUnit works as + expected. + +config KUNIT_EXAMPLE_TEST + tristate "Example test for KUnit" if !KUNIT_ALL_TESTS + default KUNIT_ALL_TESTS + help + Enables an example unit test that illustrates some of the basic + features of KUnit. This test only exists to help new users understand + what KUnit is and how it is used. Please refer to the example test + itself, lib/kunit/example-test.c, for more information. This option + is intended for curious hackers who would like to understand how to + use KUnit for kernel development. + +config KUNIT_ALL_TESTS + tristate "All KUnit tests with satisfied dependencies" + help + Enables all KUnit tests, if they can be enabled. + KUnit tests run during boot and output the results to the debug log + in TAP format (http://testanything.org/). Only useful for kernel devs + running the KUnit test harness, and not intended for inclusion into a + production build. + + For more information on KUnit and unit tests in general please refer + to the KUnit documentation in Documentation/dev-tools/kunit/. + + If unsure, say N. + +config KUNIT_DEFAULT_ENABLED + bool "Default value of kunit.enable" + default y + help + Sets the default value of kunit.enable. If set to N then KUnit + tests will not execute unless kunit.enable=1 is passed to the + kernel command line. + + In most cases this should be left as Y. Only if additional opt-in + behavior is needed should this be set to N. + +config KUNIT_AUTORUN_ENABLED + bool "Default value of kunit.autorun" + default y + help + Sets the default value of kunit.autorun. If set to N then KUnit + tests will not run after initialization unless kunit.autorun=1 is + passed to the kernel command line. The test can still be run manually + via debugfs interface. + + In most cases this should be left as Y. Only if additional opt-in + behavior is needed should this be set to N. + +config KUNIT_DEFAULT_FILTER_GLOB + string "Default value of the filter_glob module parameter" + help + Sets the default value of kunit.filter_glob. If set to a non-empty + string only matching tests are executed. + + If unsure, leave empty so all tests are executed. + +config KUNIT_DEFAULT_FILTER + string "Default value of the filter module parameter" + help + Sets the default value of kunit.filter. If set to a non-empty + string only matching tests are executed. + + If unsure, leave empty so all tests are executed. + +config KUNIT_DEFAULT_FILTER_ACTION + string "Default value of the filter_action module parameter" + help + Sets the default value of kunit.filter_action. If set to a non-empty + string only matching tests are executed. + + If unsure, leave empty so all tests are executed. + +config KUNIT_DEFAULT_TIMEOUT + int "Default value of the timeout module parameter" + default 300 + help + Sets the default timeout, in seconds, for Kunit test cases. This value + is further multiplied by a factor determined by the assigned speed + setting: 1x for `DEFAULT`, 3x for `KUNIT_SPEED_SLOW`, and 12x for + `KUNIT_SPEED_VERY_SLOW`. This allows slower tests on slower machines + sufficient time to complete. + + If unsure, the default timeout of 300 seconds is suitable for most + cases. + +config KUNIT_UML_PCI + bool "KUnit UML PCI Support" + depends on UML + select UML_PCI + help + Enables the PCI subsystem on UML for use by KUnit tests. + Some KUnit tests require the PCI core which is not enabled by + default on UML. + + If unsure, say N. + +endif # KUNIT -- cgit v1.3.1