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/mfd/syscon.c | 362 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 362 insertions(+) create mode 100644 drivers/mfd/syscon.c (limited to 'drivers/mfd/syscon.c') diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c new file mode 100644 index 000000000..21a7fcdd2 --- /dev/null +++ b/drivers/mfd/syscon.c @@ -0,0 +1,362 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * System Control Driver + * + * Copyright (C) 2012 Freescale Semiconductor, Inc. + * Copyright (C) 2012 Linaro Ltd. + * + * Author: Dong Aisheng + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static DEFINE_MUTEX(syscon_list_lock); +static LIST_HEAD(syscon_list); + +struct syscon { + struct device_node *np; + struct regmap *regmap; + struct reset_control *reset; + struct list_head list; +}; + +static const struct regmap_config syscon_regmap_config = { + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, +}; + +static struct syscon *of_syscon_register(struct device_node *np, bool check_res) +{ + struct clk *clk; + struct regmap *regmap; + void __iomem *base; + u32 reg_io_width; + int ret; + struct regmap_config syscon_config = syscon_regmap_config; + struct resource res; + struct reset_control *reset; + resource_size_t res_size; + + WARN_ON(!mutex_is_locked(&syscon_list_lock)); + + struct syscon *syscon __free(kfree) = kzalloc_obj(*syscon); + if (!syscon) + return ERR_PTR(-ENOMEM); + + if (of_address_to_resource(np, 0, &res)) + return ERR_PTR(-ENOMEM); + + base = of_iomap(np, 0); + if (!base) + return ERR_PTR(-ENOMEM); + + /* Parse the device's DT node for an endianness specification */ + if (of_property_read_bool(np, "big-endian")) + syscon_config.val_format_endian = REGMAP_ENDIAN_BIG; + else if (of_property_read_bool(np, "little-endian")) + syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE; + else if (of_property_read_bool(np, "native-endian")) + syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE; + + /* + * search for reg-io-width property in DT. If it is not provided, + * default to 4 bytes. regmap_init_mmio will return an error if values + * are invalid so there is no need to check them here. + */ + ret = of_property_read_u32(np, "reg-io-width", ®_io_width); + if (ret) + reg_io_width = 4; + + ret = of_hwspin_lock_get_id(np, 0); + if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) { + syscon_config.use_hwlock = true; + syscon_config.hwlock_id = ret; + syscon_config.hwlock_mode = HWLOCK_IRQSTATE; + } else if (ret < 0) { + switch (ret) { + case -ENOENT: + /* Ignore missing hwlock, it's optional. */ + break; + default: + pr_err("Failed to retrieve valid hwlock: %d\n", ret); + fallthrough; + case -EPROBE_DEFER: + goto err_regmap; + } + } + + res_size = resource_size(&res); + if (res_size < reg_io_width) { + ret = -EFAULT; + goto err_regmap; + } + + syscon_config.name = kasprintf(GFP_KERNEL, "%pOFn@%pa", np, &res.start); + if (!syscon_config.name) { + ret = -ENOMEM; + goto err_regmap; + } + syscon_config.reg_stride = reg_io_width; + syscon_config.val_bits = reg_io_width * 8; + syscon_config.max_register = res_size - reg_io_width; + if (!syscon_config.max_register) + syscon_config.max_register_is_0 = true; + + regmap = regmap_init_mmio(NULL, base, &syscon_config); + kfree(syscon_config.name); + if (IS_ERR(regmap)) { + pr_err("regmap init failed\n"); + ret = PTR_ERR(regmap); + goto err_regmap; + } + + if (check_res) { + clk = of_clk_get(np, 0); + if (IS_ERR(clk)) { + ret = PTR_ERR(clk); + /* clock is optional */ + if (ret != -ENOENT) + goto err_clk; + } else { + ret = regmap_mmio_attach_clk(regmap, clk); + if (ret) + goto err_attach_clk; + } + + reset = of_reset_control_get_optional_exclusive(np, NULL); + if (IS_ERR(reset)) { + ret = PTR_ERR(reset); + goto err_attach_clk; + } + + ret = reset_control_deassert(reset); + if (ret) + goto err_reset; + } + + syscon->regmap = regmap; + syscon->np = np; + + list_add_tail(&syscon->list, &syscon_list); + + return_ptr(syscon); + +err_reset: + reset_control_put(reset); +err_attach_clk: + if (!IS_ERR(clk)) + clk_put(clk); +err_clk: + regmap_exit(regmap); +err_regmap: + iounmap(base); + return ERR_PTR(ret); +} + +static struct regmap *device_node_get_regmap(struct device_node *np, + bool create_regmap, + bool check_res) +{ + struct syscon *entry, *syscon = NULL; + + mutex_lock(&syscon_list_lock); + + list_for_each_entry(entry, &syscon_list, list) + if (entry->np == np) { + syscon = entry; + break; + } + + if (!syscon) { + if (create_regmap) + syscon = of_syscon_register(np, check_res); + else + syscon = ERR_PTR(-EPROBE_DEFER); + } + mutex_unlock(&syscon_list_lock); + + if (IS_ERR(syscon)) + return ERR_CAST(syscon); + + return syscon->regmap; +} + +/** + * of_syscon_register_regmap() - Register regmap for specified device node + * @np: Device tree node + * @regmap: Pointer to regmap object + * + * Register an externally created regmap object with syscon for the specified + * device tree node. This regmap will then be returned to client drivers using + * the syscon_regmap_lookup_by_phandle() API. + * + * Return: 0 on success, negative error code on failure. + */ +int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap) +{ + struct syscon *entry, *syscon = NULL; + int ret; + + if (!np || !regmap) + return -EINVAL; + + syscon = kzalloc_obj(*syscon); + if (!syscon) + return -ENOMEM; + + /* check if syscon entry already exists */ + mutex_lock(&syscon_list_lock); + + list_for_each_entry(entry, &syscon_list, list) + if (entry->np == np) { + ret = -EEXIST; + goto err_unlock; + } + + syscon->regmap = regmap; + syscon->np = np; + + /* register the regmap in syscon list */ + list_add_tail(&syscon->list, &syscon_list); + mutex_unlock(&syscon_list_lock); + + return 0; + +err_unlock: + mutex_unlock(&syscon_list_lock); + kfree(syscon); + return ret; +} +EXPORT_SYMBOL_GPL(of_syscon_register_regmap); + +/** + * device_node_to_regmap() - Get or create a regmap for specified device node + * @np: Device tree node + * + * Get a regmap for the specified device node. If there's not an existing + * regmap, then one is instantiated. This function should not be used if the + * device node has a custom regmap driver or has resources (clocks, resets) to + * be managed. Use syscon_node_to_regmap() instead for those cases. + * + * Return: regmap ptr on success, negative error code on failure. + */ +struct regmap *device_node_to_regmap(struct device_node *np) +{ + return device_node_get_regmap(np, true, false); +} +EXPORT_SYMBOL_GPL(device_node_to_regmap); + +/** + * syscon_node_to_regmap() - Get or create a regmap for specified syscon device node + * @np: Device tree node + * + * Get a regmap for the specified device node. If there's not an existing + * regmap, then one is instantiated if the node is a generic "syscon". This + * function is safe to use for a syscon registered with + * of_syscon_register_regmap(). + * + * Return: regmap ptr on success, negative error code on failure. + */ +struct regmap *syscon_node_to_regmap(struct device_node *np) +{ + return device_node_get_regmap(np, of_device_is_compatible(np, "syscon"), true); +} +EXPORT_SYMBOL_GPL(syscon_node_to_regmap); + +struct regmap *syscon_regmap_lookup_by_compatible(const char *s) +{ + struct device_node *syscon_np; + struct regmap *regmap; + + syscon_np = of_find_compatible_node(NULL, NULL, s); + if (!syscon_np) + return ERR_PTR(-ENODEV); + + regmap = syscon_node_to_regmap(syscon_np); + of_node_put(syscon_np); + + return regmap; +} +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible); + +struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np, + const char *property) +{ + struct device_node *syscon_np; + struct regmap *regmap; + + if (property) + syscon_np = of_parse_phandle(np, property, 0); + else + syscon_np = np; + + if (!syscon_np) + return ERR_PTR(-ENODEV); + + regmap = syscon_node_to_regmap(syscon_np); + + if (property) + of_node_put(syscon_np); + + return regmap; +} +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle); + +struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np, + const char *property, + int arg_count, + unsigned int *out_args) +{ + struct device_node *syscon_np; + struct of_phandle_args args; + struct regmap *regmap; + unsigned int index; + int rc; + + rc = of_parse_phandle_with_fixed_args(np, property, arg_count, + 0, &args); + if (rc) + return ERR_PTR(rc); + + syscon_np = args.np; + if (!syscon_np) + return ERR_PTR(-ENODEV); + + regmap = syscon_node_to_regmap(syscon_np); + for (index = 0; index < arg_count; index++) + out_args[index] = args.args[index]; + of_node_put(syscon_np); + + return regmap; +} +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_args); + +/* + * It behaves the same as syscon_regmap_lookup_by_phandle() except where + * there is no regmap phandle. In this case, instead of returning -ENODEV, + * the function returns NULL. + */ +struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np, + const char *property) +{ + struct regmap *regmap; + + regmap = syscon_regmap_lookup_by_phandle(np, property); + if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV) + return NULL; + + return regmap; +} +EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_optional); -- cgit v1.3.1