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, 468 insertions, 0 deletions

diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
new file mode 100644
index 000000000..eec369d21
--- /dev/null
+++ b/drivers/clk/qcom/common.c
@@ -0,0 +1,468 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+#include <linux/interconnect-clk.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset-controller.h>
+#include <linux/of.h>
+
+#include "common.h"
+#include "clk-alpha-pll.h"
+#include "clk-branch.h"
+#include "clk-rcg.h"
+#include "clk-regmap.h"
+#include "reset.h"
+#include "gdsc.h"
+
+struct qcom_cc {
+	struct qcom_reset_controller reset;
+	struct clk_regmap **rclks;
+	size_t num_rclks;
+	struct dev_pm_domain_list *pd_list;
+};
+
+const
+struct freq_tbl *qcom_find_freq(const struct freq_tbl *f, unsigned long rate)
+{
+	if (!f)
+		return NULL;
+
+	if (!f->freq)
+		return f;
+
+	for (; f->freq; f++)
+		if (rate <= f->freq)
+			return f;
+
+	/* Default to our fastest rate */
+	return f - 1;
+}
+EXPORT_SYMBOL_GPL(qcom_find_freq);
+
+const struct freq_multi_tbl *qcom_find_freq_multi(const struct freq_multi_tbl *f,
+						  unsigned long rate)
+{
+	if (!f)
+		return NULL;
+
+	if (!f->freq)
+		return f;
+
+	for (; f->freq; f++)
+		if (rate <= f->freq)
+			return f;
+
+	/* Default to our fastest rate */
+	return f - 1;
+}
+EXPORT_SYMBOL_GPL(qcom_find_freq_multi);
+
+const struct freq_tbl *qcom_find_freq_floor(const struct freq_tbl *f,
+					    unsigned long rate)
+{
+	const struct freq_tbl *best = NULL;
+
+	for ( ; f->freq; f++) {
+		if (rate >= f->freq)
+			best = f;
+		else
+			break;
+	}
+
+	return best;
+}
+EXPORT_SYMBOL_GPL(qcom_find_freq_floor);
+
+int qcom_find_src_index(struct clk_hw *hw, const struct parent_map *map, u8 src)
+{
+	int i, num_parents = clk_hw_get_num_parents(hw);
+
+	for (i = 0; i < num_parents; i++)
+		if (src == map[i].src)
+			return i;
+
+	return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(qcom_find_src_index);
+
+int qcom_find_cfg_index(struct clk_hw *hw, const struct parent_map *map, u8 cfg)
+{
+	int i, num_parents = clk_hw_get_num_parents(hw);
+
+	for (i = 0; i < num_parents; i++)
+		if (cfg == map[i].cfg)
+			return i;
+
+	return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(qcom_find_cfg_index);
+
+struct regmap *
+qcom_cc_map(struct platform_device *pdev, const struct qcom_cc_desc *desc)
+{
+	void __iomem *base;
+	struct device *dev = &pdev->dev;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return ERR_CAST(base);
+
+	return devm_regmap_init_mmio(dev, base, desc->config);
+}
+EXPORT_SYMBOL_GPL(qcom_cc_map);
+
+void
+qcom_pll_set_fsm_mode(struct regmap *map, u32 reg, u8 bias_count, u8 lock_count)
+{
+	u32 val;
+	u32 mask;
+
+	/* De-assert reset to FSM */
+	regmap_update_bits(map, reg, PLL_VOTE_FSM_RESET, 0);
+
+	/* Program bias count and lock count */
+	val = bias_count << PLL_BIAS_COUNT_SHIFT |
+		lock_count << PLL_LOCK_COUNT_SHIFT;
+	mask = PLL_BIAS_COUNT_MASK << PLL_BIAS_COUNT_SHIFT;
+	mask |= PLL_LOCK_COUNT_MASK << PLL_LOCK_COUNT_SHIFT;
+	regmap_update_bits(map, reg, mask, val);
+
+	/* Enable PLL FSM voting */
+	regmap_update_bits(map, reg, PLL_VOTE_FSM_ENA, PLL_VOTE_FSM_ENA);
+}
+EXPORT_SYMBOL_GPL(qcom_pll_set_fsm_mode);
+
+static void qcom_cc_gdsc_unregister(void *data)
+{
+	gdsc_unregister(data);
+}
+
+/*
+ * Backwards compatibility with old DTs. Register a pass-through factor 1/1
+ * clock to translate 'path' clk into 'name' clk and register the 'path'
+ * clk as a fixed rate clock if it isn't present.
+ */
+static int _qcom_cc_register_board_clk(struct device *dev, const char *path,
+				       const char *name, unsigned long rate,
+				       bool add_factor)
+{
+	struct device_node *node = NULL;
+	struct device_node *clocks_node;
+	struct clk_fixed_factor *factor;
+	struct clk_fixed_rate *fixed;
+	struct clk_init_data init_data = { };
+	int ret;
+
+	clocks_node = of_find_node_by_path("/clocks");
+	if (clocks_node) {
+		node = of_get_child_by_name(clocks_node, path);
+		of_node_put(clocks_node);
+	}
+
+	if (!node) {
+		fixed = devm_kzalloc(dev, sizeof(*fixed), GFP_KERNEL);
+		if (!fixed)
+			return -EINVAL;
+
+		fixed->fixed_rate = rate;
+		fixed->hw.init = &init_data;
+
+		init_data.name = path;
+		init_data.ops = &clk_fixed_rate_ops;
+
+		ret = devm_clk_hw_register(dev, &fixed->hw);
+		if (ret)
+			return ret;
+	}
+	of_node_put(node);
+
+	if (add_factor) {
+		factor = devm_kzalloc(dev, sizeof(*factor), GFP_KERNEL);
+		if (!factor)
+			return -EINVAL;
+
+		factor->mult = factor->div = 1;
+		factor->hw.init = &init_data;
+
+		init_data.name = name;
+		init_data.parent_names = &path;
+		init_data.num_parents = 1;
+		init_data.flags = 0;
+		init_data.ops = &clk_fixed_factor_ops;
+
+		ret = devm_clk_hw_register(dev, &factor->hw);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int qcom_cc_register_board_clk(struct device *dev, const char *path,
+			       const char *name, unsigned long rate)
+{
+	bool add_factor = true;
+
+	/*
+	 * TODO: The RPM clock driver currently does not support the xo clock.
+	 * When xo is added to the RPM clock driver, we should change this
+	 * function to skip registration of xo factor clocks.
+	 */
+
+	return _qcom_cc_register_board_clk(dev, path, name, rate, add_factor);
+}
+EXPORT_SYMBOL_GPL(qcom_cc_register_board_clk);
+
+int qcom_cc_register_sleep_clk(struct device *dev)
+{
+	return _qcom_cc_register_board_clk(dev, "sleep_clk", "sleep_clk_src",
+					   32768, true);
+}
+EXPORT_SYMBOL_GPL(qcom_cc_register_sleep_clk);
+
+/* Drop 'protected-clocks' from the list of clocks to register */
+static void qcom_cc_drop_protected(struct device *dev, struct qcom_cc *cc)
+{
+	struct device_node *np = dev->of_node;
+	u32 i;
+
+	of_property_for_each_u32(np, "protected-clocks", i) {
+		if (i >= cc->num_rclks)
+			continue;
+
+		cc->rclks[i] = NULL;
+	}
+}
+
+static struct clk_hw *qcom_cc_clk_hw_get(struct of_phandle_args *clkspec,
+					 void *data)
+{
+	struct qcom_cc *cc = data;
+	unsigned int idx = clkspec->args[0];
+
+	if (idx >= cc->num_rclks) {
+		pr_err("%s: invalid index %u\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return cc->rclks[idx] ? &cc->rclks[idx]->hw : NULL;
+}
+
+static int qcom_cc_icc_register(struct device *dev,
+				const struct qcom_cc_desc *desc)
+{
+	struct icc_clk_data *icd;
+	struct clk_hw *hws;
+	int i;
+
+	if (!IS_ENABLED(CONFIG_INTERCONNECT_CLK))
+		return 0;
+
+	if (!desc->icc_hws)
+		return 0;
+
+	icd = devm_kcalloc(dev, desc->num_icc_hws, sizeof(*icd), GFP_KERNEL);
+	if (!icd)
+		return -ENOMEM;
+
+	for (i = 0; i < desc->num_icc_hws; i++) {
+		icd[i].master_id = desc->icc_hws[i].master_id;
+		icd[i].slave_id = desc->icc_hws[i].slave_id;
+		hws = &desc->clks[desc->icc_hws[i].clk_id]->hw;
+		icd[i].clk = devm_clk_hw_get_clk(dev, hws, "icc");
+		if (IS_ERR(icd[i].clk))
+			return dev_err_probe(dev, PTR_ERR(icd[i].clk),
+					     "(%d) clock entry is null\n", i);
+		icd[i].name = clk_hw_get_name(hws);
+	}
+
+	return devm_icc_clk_register(dev, desc->icc_first_node_id,
+						     desc->num_icc_hws, icd);
+}
+
+static int qcom_cc_clk_pll_configure(const struct qcom_cc_driver_data *data,
+				     struct regmap *regmap)
+{
+	const struct clk_init_data *init;
+	struct clk_alpha_pll *pll;
+	int i;
+
+	for (i = 0; i < data->num_alpha_plls; i++) {
+		pll = data->alpha_plls[i];
+		init = pll->clkr.hw.init;
+
+		if (!pll->config || !pll->regs) {
+			pr_err("%s: missing pll config or regs\n", init->name);
+			return -EINVAL;
+		}
+
+		qcom_clk_alpha_pll_configure(pll, regmap);
+	}
+
+	return 0;
+}
+
+static void qcom_cc_clk_regs_configure(struct device *dev, const struct qcom_cc_driver_data *data,
+				       struct regmap *regmap)
+{
+	int i;
+
+	for (i = 0; i < data->num_clk_cbcrs; i++)
+		qcom_branch_set_clk_en(regmap, data->clk_cbcrs[i]);
+
+	if (data->clk_regs_configure)
+		data->clk_regs_configure(dev, regmap);
+}
+
+int qcom_cc_really_probe(struct device *dev,
+			 const struct qcom_cc_desc *desc, struct regmap *regmap)
+{
+	int i, ret;
+	struct qcom_reset_controller *reset;
+	struct qcom_cc *cc;
+	struct gdsc_desc *scd;
+	size_t num_clks = desc->num_clks;
+	struct clk_regmap **rclks = desc->clks;
+	size_t num_clk_hws = desc->num_clk_hws;
+	struct clk_hw **clk_hws = desc->clk_hws;
+
+	cc = devm_kzalloc(dev, sizeof(*cc), GFP_KERNEL);
+	if (!cc)
+		return -ENOMEM;
+
+	ret = devm_pm_domain_attach_list(dev, NULL, &cc->pd_list);
+	if (ret < 0 && ret != -EEXIST)
+		return ret;
+
+	if (desc->use_rpm) {
+		ret = devm_pm_runtime_enable(dev);
+		if (ret)
+			return ret;
+
+		ret = pm_runtime_resume_and_get(dev);
+		if (ret)
+			return ret;
+	}
+
+	if (desc->driver_data) {
+		ret = qcom_cc_clk_pll_configure(desc->driver_data, regmap);
+		if (ret)
+			goto put_rpm;
+
+		qcom_cc_clk_regs_configure(dev, desc->driver_data, regmap);
+	}
+
+	reset = &cc->reset;
+	reset->rcdev.of_node = dev->of_node;
+	reset->rcdev.ops = &qcom_reset_ops;
+	reset->rcdev.owner = dev->driver->owner;
+	reset->rcdev.nr_resets = desc->num_resets;
+	reset->regmap = regmap;
+	reset->reset_map = desc->resets;
+
+	ret = devm_reset_controller_register(dev, &reset->rcdev);
+	if (ret)
+		goto put_rpm;
+
+	if (desc->gdscs && desc->num_gdscs) {
+		scd = devm_kzalloc(dev, sizeof(*scd), GFP_KERNEL);
+		if (!scd) {
+			ret = -ENOMEM;
+			goto put_rpm;
+		}
+		scd->dev = dev;
+		scd->scs = desc->gdscs;
+		scd->num = desc->num_gdscs;
+		scd->pd_list = cc->pd_list;
+		ret = gdsc_register(scd, &reset->rcdev, regmap);
+		if (ret)
+			goto put_rpm;
+		ret = devm_add_action_or_reset(dev, qcom_cc_gdsc_unregister,
+					       scd);
+		if (ret)
+			goto put_rpm;
+	}
+
+	if (desc->driver_data &&
+	    desc->driver_data->dfs_rcgs &&
+	    desc->driver_data->num_dfs_rcgs) {
+		ret = qcom_cc_register_rcg_dfs(regmap,
+					       desc->driver_data->dfs_rcgs,
+					       desc->driver_data->num_dfs_rcgs);
+		if (ret)
+			goto put_rpm;
+	}
+
+	cc->rclks = rclks;
+	cc->num_rclks = num_clks;
+
+	qcom_cc_drop_protected(dev, cc);
+
+	for (i = 0; i < num_clk_hws; i++) {
+		ret = devm_clk_hw_register(dev, clk_hws[i]);
+		if (ret)
+			goto put_rpm;
+	}
+
+	for (i = 0; i < num_clks; i++) {
+		if (!rclks[i])
+			continue;
+
+		ret = devm_clk_register_regmap(dev, rclks[i]);
+		if (ret)
+			goto put_rpm;
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, qcom_cc_clk_hw_get, cc);
+	if (ret)
+		goto put_rpm;
+
+	ret = qcom_cc_icc_register(dev, desc);
+
+put_rpm:
+	if (desc->use_rpm)
+		pm_runtime_put(dev);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_cc_really_probe);
+
+int qcom_cc_probe(struct platform_device *pdev, const struct qcom_cc_desc *desc)
+{
+	struct regmap *regmap;
+
+	regmap = qcom_cc_map(pdev, desc);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return qcom_cc_really_probe(&pdev->dev, desc, regmap);
+}
+EXPORT_SYMBOL_GPL(qcom_cc_probe);
+
+int qcom_cc_probe_by_index(struct platform_device *pdev, int index,
+			   const struct qcom_cc_desc *desc)
+{
+	struct regmap *regmap;
+	void __iomem *base;
+
+	base = devm_platform_ioremap_resource(pdev, index);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(&pdev->dev, base, desc->config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return qcom_cc_really_probe(&pdev->dev, desc, regmap);
+}
+EXPORT_SYMBOL_GPL(qcom_cc_probe_by_index);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("QTI Common Clock module");