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 --- drivers/leds/led-test.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 drivers/leds/led-test.c (limited to 'drivers/leds/led-test.c') diff --git a/drivers/leds/led-test.c b/drivers/leds/led-test.c new file mode 100644 index 000000000..ddf9aa967 --- /dev/null +++ b/drivers/leds/led-test.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Google LLC + * + * Author: Lee Jones + */ + +#include +#include +#include +#include + +#define LED_TEST_POST_REG_BRIGHTNESS 10 + +struct led_test_ddata { + struct led_classdev cdev; + struct device *dev; +}; + +static enum led_brightness led_test_brightness_get(struct led_classdev *cdev) +{ + return LED_TEST_POST_REG_BRIGHTNESS; +} + +static void led_test_class_register(struct kunit *test) +{ + struct led_test_ddata *ddata = test->priv; + struct led_classdev *cdev_clash, *cdev = &ddata->cdev; + struct device *dev = ddata->dev; + int ret; + + /* Register a LED class device */ + cdev->name = "led-test"; + cdev->brightness_get = led_test_brightness_get; + cdev->brightness = 0; + + ret = devm_led_classdev_register(dev, cdev); + KUNIT_ASSERT_EQ(test, ret, 0); + + KUNIT_EXPECT_EQ(test, cdev->max_brightness, LED_FULL); + KUNIT_EXPECT_EQ(test, cdev->brightness, LED_TEST_POST_REG_BRIGHTNESS); + KUNIT_EXPECT_STREQ(test, cdev->dev->kobj.name, "led-test"); + + /* Register again with the same name - expect it to pass with the LED renamed */ + cdev_clash = devm_kmemdup(dev, cdev, sizeof(*cdev), GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cdev_clash); + + ret = devm_led_classdev_register(dev, cdev_clash); + KUNIT_ASSERT_EQ(test, ret, 0); + + KUNIT_EXPECT_STREQ(test, cdev_clash->dev->kobj.name, "led-test_1"); + KUNIT_EXPECT_STREQ(test, cdev_clash->name, "led-test"); + + /* Enable name conflict rejection and register with the same name again - expect failure */ + cdev_clash->flags |= LED_REJECT_NAME_CONFLICT; + ret = devm_led_classdev_register(dev, cdev_clash); + KUNIT_EXPECT_EQ(test, ret, -EEXIST); +} + +static void led_test_class_add_lookup_and_get(struct kunit *test) +{ + struct led_test_ddata *ddata = test->priv; + struct led_classdev *cdev = &ddata->cdev, *cdev_get; + struct device *dev = ddata->dev; + struct led_lookup_data lookup; + int ret; + + /* First, register a LED class device */ + cdev->name = "led-test"; + ret = devm_led_classdev_register(dev, cdev); + KUNIT_ASSERT_EQ(test, ret, 0); + + /* Then make the LED available for lookup */ + lookup.provider = cdev->name; + lookup.dev_id = dev_name(dev); + lookup.con_id = "led-test-1"; + led_add_lookup(&lookup); + + /* Finally, attempt to look it up via the API - imagine this was an orthogonal driver */ + cdev_get = devm_led_get(dev, "led-test-1"); + KUNIT_ASSERT_FALSE(test, IS_ERR(cdev_get)); + + KUNIT_EXPECT_STREQ(test, cdev_get->name, cdev->name); + + led_remove_lookup(&lookup); +} + +static struct kunit_case led_test_cases[] = { + KUNIT_CASE(led_test_class_register), + KUNIT_CASE(led_test_class_add_lookup_and_get), + { } +}; + +static int led_test_init(struct kunit *test) +{ + struct led_test_ddata *ddata; + struct device *dev; + + ddata = kunit_kzalloc(test, sizeof(*ddata), GFP_KERNEL); + if (!ddata) + return -ENOMEM; + + test->priv = ddata; + + dev = kunit_device_register(test, "led_test"); + if (IS_ERR(dev)) + return PTR_ERR(dev); + + ddata->dev = get_device(dev); + + return 0; +} + +static void led_test_exit(struct kunit *test) +{ + struct led_test_ddata *ddata = test->priv; + + if (ddata && ddata->dev) + put_device(ddata->dev); +} + +static struct kunit_suite led_test_suite = { + .name = "led", + .init = led_test_init, + .exit = led_test_exit, + .test_cases = led_test_cases, +}; +kunit_test_suite(led_test_suite); + +MODULE_AUTHOR("Lee Jones "); +MODULE_DESCRIPTION("KUnit tests for the LED framework"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1