kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

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 <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 465 insertions, 0 deletions

diff --git a/drivers/clk/clk-gate_test.c b/drivers/clk/clk-gate_test.c
new file mode 100644
index 000000000..e276cd974
--- /dev/null
+++ b/drivers/clk/clk-gate_test.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kunit tests for clk gate
+ */
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/platform_device.h>
+
+#include <kunit/test.h>
+
+static void clk_gate_register_test_dev(struct kunit *test)
+{
+	struct clk_hw *ret;
+	struct platform_device *pdev;
+
+	pdev = platform_device_register_simple("test_gate_device", -1, NULL, 0);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	ret = clk_hw_register_gate(&pdev->dev, "test_gate", NULL, 0, NULL,
+				   0, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ret);
+	KUNIT_EXPECT_STREQ(test, "test_gate", clk_hw_get_name(ret));
+	KUNIT_EXPECT_EQ(test, 0UL, clk_hw_get_flags(ret));
+
+	clk_hw_unregister_gate(ret);
+	platform_device_put(pdev);
+}
+
+static void clk_gate_register_test_parent_names(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *ret;
+
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    1000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	ret = clk_hw_register_gate(NULL, "test_gate", "test_parent", 0, NULL,
+				   0, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ret);
+	KUNIT_EXPECT_PTR_EQ(test, parent, clk_hw_get_parent(ret));
+
+	clk_hw_unregister_gate(ret);
+	clk_hw_unregister_fixed_rate(parent);
+}
+
+static void clk_gate_register_test_parent_data(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *ret;
+	struct clk_parent_data pdata = { };
+
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    1000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+	pdata.hw = parent;
+
+	ret = clk_hw_register_gate_parent_data(NULL, "test_gate", &pdata, 0,
+					       NULL, 0, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ret);
+	KUNIT_EXPECT_PTR_EQ(test, parent, clk_hw_get_parent(ret));
+
+	clk_hw_unregister_gate(ret);
+	clk_hw_unregister_fixed_rate(parent);
+}
+
+static void clk_gate_register_test_parent_data_legacy(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *ret;
+	struct clk_parent_data pdata = { };
+
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    1000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+	pdata.name = "test_parent";
+
+	ret = clk_hw_register_gate_parent_data(NULL, "test_gate", &pdata, 0,
+					       NULL, 0, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ret);
+	KUNIT_EXPECT_PTR_EQ(test, parent, clk_hw_get_parent(ret));
+
+	clk_hw_unregister_gate(ret);
+	clk_hw_unregister_fixed_rate(parent);
+}
+
+static void clk_gate_register_test_parent_hw(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *ret;
+
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    1000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	ret = clk_hw_register_gate_parent_hw(NULL, "test_gate", parent, 0, NULL,
+					     0, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ret);
+	KUNIT_EXPECT_PTR_EQ(test, parent, clk_hw_get_parent(ret));
+
+	clk_hw_unregister_gate(ret);
+	clk_hw_unregister_fixed_rate(parent);
+}
+
+static void clk_gate_register_test_hiword_invalid(struct kunit *test)
+{
+	struct clk_hw *ret;
+
+	ret = clk_hw_register_gate(NULL, "test_gate", NULL, 0, NULL,
+				   20, CLK_GATE_HIWORD_MASK, NULL);
+
+	KUNIT_EXPECT_TRUE(test, IS_ERR(ret));
+}
+
+static struct kunit_case clk_gate_register_test_cases[] = {
+	KUNIT_CASE(clk_gate_register_test_dev),
+	KUNIT_CASE(clk_gate_register_test_parent_names),
+	KUNIT_CASE(clk_gate_register_test_parent_data),
+	KUNIT_CASE(clk_gate_register_test_parent_data_legacy),
+	KUNIT_CASE(clk_gate_register_test_parent_hw),
+	KUNIT_CASE(clk_gate_register_test_hiword_invalid),
+	{}
+};
+
+static struct kunit_suite clk_gate_register_test_suite = {
+	.name = "clk-gate-register-test",
+	.test_cases = clk_gate_register_test_cases,
+};
+
+struct clk_gate_test_context {
+	void __iomem *fake_mem;
+	struct clk_hw *hw;
+	struct clk_hw *parent;
+	__le32 fake_reg; /* Keep at end, KASAN can detect out of bounds */
+};
+
+static struct clk_gate_test_context *clk_gate_test_alloc_ctx(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx;
+
+	test->priv = ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+	ctx->fake_mem = (void __force __iomem *)&ctx->fake_reg;
+
+	return ctx;
+}
+
+static void clk_gate_test_parent_rate(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	unsigned long prate = clk_hw_get_rate(parent);
+	unsigned long rate = clk_hw_get_rate(hw);
+
+	KUNIT_EXPECT_EQ(test, prate, rate);
+}
+
+static void clk_gate_test_enable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = BIT(5);
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+
+	KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(parent));
+}
+
+static void clk_gate_test_disable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = BIT(5);
+	u32 disable_val = 0;
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+	KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+
+	clk_disable_unprepare(clk);
+	KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(parent));
+}
+
+static struct kunit_case clk_gate_test_cases[] = {
+	KUNIT_CASE(clk_gate_test_parent_rate),
+	KUNIT_CASE(clk_gate_test_enable),
+	KUNIT_CASE(clk_gate_test_disable),
+	{}
+};
+
+static int clk_gate_test_init(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    2000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	hw = clk_hw_register_gate_parent_hw(NULL, "test_gate", parent, 0,
+					    ctx->fake_mem, 5, 0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+
+	ctx->hw = hw;
+	ctx->parent = parent;
+
+	return 0;
+}
+
+static void clk_gate_test_exit(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+
+	clk_hw_unregister_gate(ctx->hw);
+	clk_hw_unregister_fixed_rate(ctx->parent);
+}
+
+static struct kunit_suite clk_gate_test_suite = {
+	.name = "clk-gate-test",
+	.init = clk_gate_test_init,
+	.exit = clk_gate_test_exit,
+	.test_cases = clk_gate_test_cases,
+};
+
+static void clk_gate_test_invert_enable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = 0;
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+
+	KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(parent));
+}
+
+static void clk_gate_test_invert_disable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = 0;
+	u32 disable_val = BIT(15);
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+	KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+
+	clk_disable_unprepare(clk);
+	KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(parent));
+}
+
+static struct kunit_case clk_gate_test_invert_cases[] = {
+	KUNIT_CASE(clk_gate_test_invert_enable),
+	KUNIT_CASE(clk_gate_test_invert_disable),
+	{}
+};
+
+static int clk_gate_test_invert_init(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    2000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	ctx->fake_reg = cpu_to_le32(BIT(15)); /* Default to off */
+	hw = clk_hw_register_gate_parent_hw(NULL, "test_gate", parent, 0,
+					    ctx->fake_mem, 15,
+					    CLK_GATE_SET_TO_DISABLE, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+
+	ctx->hw = hw;
+	ctx->parent = parent;
+
+	return 0;
+}
+
+static struct kunit_suite clk_gate_test_invert_suite = {
+	.name = "clk-gate-invert-test",
+	.init = clk_gate_test_invert_init,
+	.exit = clk_gate_test_exit,
+	.test_cases = clk_gate_test_invert_cases,
+};
+
+static void clk_gate_test_hiword_enable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = BIT(9) | BIT(9 + 16);
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+
+	KUNIT_EXPECT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_TRUE(test, clk_hw_is_prepared(parent));
+}
+
+static void clk_gate_test_hiword_disable(struct kunit *test)
+{
+	struct clk_gate_test_context *ctx = test->priv;
+	struct clk_hw *parent = ctx->parent;
+	struct clk_hw *hw = ctx->hw;
+	struct clk *clk = hw->clk;
+	u32 enable_val = BIT(9) | BIT(9 + 16);
+	u32 disable_val = BIT(9 + 16);
+
+	KUNIT_ASSERT_EQ(test, clk_prepare_enable(clk), 0);
+	KUNIT_ASSERT_EQ(test, enable_val, le32_to_cpu(ctx->fake_reg));
+
+	clk_disable_unprepare(clk);
+	KUNIT_EXPECT_EQ(test, disable_val, le32_to_cpu(ctx->fake_reg));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(hw));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_enabled(parent));
+	KUNIT_EXPECT_FALSE(test, clk_hw_is_prepared(parent));
+}
+
+static struct kunit_case clk_gate_test_hiword_cases[] = {
+	KUNIT_CASE(clk_gate_test_hiword_enable),
+	KUNIT_CASE(clk_gate_test_hiword_disable),
+	{}
+};
+
+static int clk_gate_test_hiword_init(struct kunit *test)
+{
+	struct clk_hw *parent;
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	parent = clk_hw_register_fixed_rate(NULL, "test_parent", NULL, 0,
+					    2000000);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, parent);
+
+	hw = clk_hw_register_gate_parent_hw(NULL, "test_gate", parent, 0,
+					    ctx->fake_mem, 9,
+					    CLK_GATE_HIWORD_MASK, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+
+	ctx->hw = hw;
+	ctx->parent = parent;
+
+	return 0;
+}
+
+static struct kunit_suite clk_gate_test_hiword_suite = {
+	.name = "clk-gate-hiword-test",
+	.init = clk_gate_test_hiword_init,
+	.exit = clk_gate_test_exit,
+	.test_cases = clk_gate_test_hiword_cases,
+};
+
+static void clk_gate_test_is_enabled(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	ctx->fake_reg = cpu_to_le32(BIT(7));
+	hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 7,
+				  0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+	KUNIT_ASSERT_TRUE(test, clk_hw_is_enabled(hw));
+
+	clk_hw_unregister_gate(hw);
+}
+
+static void clk_gate_test_is_disabled(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	ctx->fake_reg = cpu_to_le32(BIT(4));
+	hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 7,
+				  0, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+	KUNIT_ASSERT_FALSE(test, clk_hw_is_enabled(hw));
+
+	clk_hw_unregister_gate(hw);
+}
+
+static void clk_gate_test_is_enabled_inverted(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	ctx->fake_reg = cpu_to_le32(BIT(31));
+	hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 2,
+				  CLK_GATE_SET_TO_DISABLE, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+	KUNIT_ASSERT_TRUE(test, clk_hw_is_enabled(hw));
+
+	clk_hw_unregister_gate(hw);
+}
+
+static void clk_gate_test_is_disabled_inverted(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_gate_test_context *ctx;
+
+	ctx = clk_gate_test_alloc_ctx(test);
+	ctx->fake_reg = cpu_to_le32(BIT(29));
+	hw = clk_hw_register_gate(NULL, "test_gate", NULL, 0, ctx->fake_mem, 29,
+				  CLK_GATE_SET_TO_DISABLE, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+	KUNIT_ASSERT_FALSE(test, clk_hw_is_enabled(hw));
+
+	clk_hw_unregister_gate(hw);
+}
+
+static struct kunit_case clk_gate_test_enabled_cases[] = {
+	KUNIT_CASE(clk_gate_test_is_enabled),
+	KUNIT_CASE(clk_gate_test_is_disabled),
+	KUNIT_CASE(clk_gate_test_is_enabled_inverted),
+	KUNIT_CASE(clk_gate_test_is_disabled_inverted),
+	{}
+};
+
+static struct kunit_suite clk_gate_test_enabled_suite = {
+	.name = "clk-gate-is_enabled-test",
+	.test_cases = clk_gate_test_enabled_cases,
+};
+
+kunit_test_suites(
+	&clk_gate_register_test_suite,
+	&clk_gate_test_suite,
+	&clk_gate_test_invert_suite,
+	&clk_gate_test_hiword_suite,
+	&clk_gate_test_enabled_suite
+);
+MODULE_DESCRIPTION("Kunit tests for clk gate");
+MODULE_LICENSE("GPL v2");