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/cpufreq/bmips-cpufreq.c | 186 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 186 insertions(+) create mode 100644 drivers/cpufreq/bmips-cpufreq.c (limited to 'drivers/cpufreq/bmips-cpufreq.c') diff --git a/drivers/cpufreq/bmips-cpufreq.c b/drivers/cpufreq/bmips-cpufreq.c new file mode 100644 index 000000000..a8e35bc75 --- /dev/null +++ b/drivers/cpufreq/bmips-cpufreq.c @@ -0,0 +1,186 @@ +/* + * CPU frequency scaling for Broadcom BMIPS SoCs + * + * Copyright (c) 2017 Broadcom + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation version 2. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include +#include +#include + +/* for mips_hpt_frequency */ +#include + +#define BMIPS_CPUFREQ_PREFIX "bmips" +#define BMIPS_CPUFREQ_NAME BMIPS_CPUFREQ_PREFIX "-cpufreq" + +#define TRANSITION_LATENCY (25 * 1000) /* 25 us */ + +#define BMIPS5_CLK_DIV_SET_SHIFT 0x7 +#define BMIPS5_CLK_DIV_SHIFT 0x4 +#define BMIPS5_CLK_DIV_MASK 0xf + +enum bmips_type { + BMIPS5000, + BMIPS5200, +}; + +struct cpufreq_compat { + const char *compatible; + unsigned int bmips_type; + unsigned int clk_mult; + unsigned int max_freqs; +}; + +#define BMIPS(c, t, m, f) { \ + .compatible = c, \ + .bmips_type = (t), \ + .clk_mult = (m), \ + .max_freqs = (f), \ +} + +static struct cpufreq_compat bmips_cpufreq_compat[] = { + BMIPS("brcm,bmips5000", BMIPS5000, 8, 4), + BMIPS("brcm,bmips5200", BMIPS5200, 8, 4), + { } +}; + +static struct cpufreq_compat *priv; + +static int htp_freq_to_cpu_freq(unsigned int clk_mult) +{ + return mips_hpt_frequency * clk_mult / 1000; +} + +static struct cpufreq_frequency_table * +bmips_cpufreq_get_freq_table(const struct cpufreq_policy *policy) +{ + struct cpufreq_frequency_table *table; + unsigned long cpu_freq; + int i; + + cpu_freq = htp_freq_to_cpu_freq(priv->clk_mult); + + table = kmalloc_objs(*table, priv->max_freqs + 1); + if (!table) + return ERR_PTR(-ENOMEM); + + for (i = 0; i < priv->max_freqs; i++) { + table[i].frequency = cpu_freq / (1 << i); + table[i].driver_data = i; + } + table[i].frequency = CPUFREQ_TABLE_END; + + return table; +} + +static unsigned int bmips_cpufreq_get(unsigned int cpu) +{ + unsigned int div; + uint32_t mode; + + switch (priv->bmips_type) { + case BMIPS5200: + case BMIPS5000: + mode = read_c0_brcm_mode(); + div = ((mode >> BMIPS5_CLK_DIV_SHIFT) & BMIPS5_CLK_DIV_MASK); + break; + default: + div = 0; + } + + return htp_freq_to_cpu_freq(priv->clk_mult) / (1 << div); +} + +static int bmips_cpufreq_target_index(struct cpufreq_policy *policy, + unsigned int index) +{ + unsigned int div = policy->freq_table[index].driver_data; + + switch (priv->bmips_type) { + case BMIPS5200: + case BMIPS5000: + change_c0_brcm_mode(BMIPS5_CLK_DIV_MASK << BMIPS5_CLK_DIV_SHIFT, + (1 << BMIPS5_CLK_DIV_SET_SHIFT) | + (div << BMIPS5_CLK_DIV_SHIFT)); + break; + default: + return -ENOTSUPP; + } + + return 0; +} + +static void bmips_cpufreq_exit(struct cpufreq_policy *policy) +{ + kfree(policy->freq_table); +} + +static int bmips_cpufreq_init(struct cpufreq_policy *policy) +{ + struct cpufreq_frequency_table *freq_table; + + freq_table = bmips_cpufreq_get_freq_table(policy); + if (IS_ERR(freq_table)) { + pr_err("%s: couldn't determine frequency table (%ld).\n", + BMIPS_CPUFREQ_NAME, PTR_ERR(freq_table)); + return PTR_ERR(freq_table); + } + + cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY); + pr_info("%s: registered\n", BMIPS_CPUFREQ_NAME); + + return 0; +} + +static struct cpufreq_driver bmips_cpufreq_driver = { + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = bmips_cpufreq_target_index, + .get = bmips_cpufreq_get, + .init = bmips_cpufreq_init, + .exit = bmips_cpufreq_exit, + .name = BMIPS_CPUFREQ_PREFIX, +}; + +static int __init bmips_cpufreq_driver_init(void) +{ + struct cpufreq_compat *cc; + struct device_node *np; + + for (cc = bmips_cpufreq_compat; cc->compatible; cc++) { + np = of_find_compatible_node(NULL, "cpu", cc->compatible); + if (np) { + of_node_put(np); + priv = cc; + break; + } + } + + /* We hit the guard element of the array. No compatible CPU found. */ + if (!cc->compatible) + return -ENODEV; + + return cpufreq_register_driver(&bmips_cpufreq_driver); +} +module_init(bmips_cpufreq_driver_init); + +static void __exit bmips_cpufreq_driver_exit(void) +{ + cpufreq_unregister_driver(&bmips_cpufreq_driver); +} +module_exit(bmips_cpufreq_driver_exit); + +MODULE_AUTHOR("Markus Mayer "); +MODULE_DESCRIPTION("CPUfreq driver for Broadcom BMIPS SoCs"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1