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/acpi/ec_sys.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 drivers/acpi/ec_sys.c (limited to 'drivers/acpi/ec_sys.c') diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c new file mode 100644 index 000000000..c074a0fae --- /dev/null +++ b/drivers/acpi/ec_sys.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ec_sys.c + * + * Copyright (C) 2010 SUSE Products GmbH/Novell + * Author: + * Thomas Renninger + */ + +#include +#include +#include +#include +#include +#include "internal.h" + +MODULE_AUTHOR("Thomas Renninger "); +MODULE_DESCRIPTION("ACPI EC sysfs access driver"); +MODULE_LICENSE("GPL"); + +static bool write_support; +module_param_hw(write_support, bool, other, 0644); +MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may " + "be needed."); + +#define EC_SPACE_SIZE 256 + +static struct dentry *acpi_ec_debugfs_dir; + +static ssize_t acpi_ec_read_io(struct file *f, char __user *buf, + size_t count, loff_t *off) +{ + /* Use this if support reading/writing multiple ECs exists in ec.c: + * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private; + */ + unsigned int size = EC_SPACE_SIZE; + loff_t init_off = *off; + int err = 0; + + if (*off >= size) + return 0; + if (*off + count >= size) { + size -= *off; + count = size; + } else + size = count; + + while (size) { + u8 byte_read; + err = ec_read(*off, &byte_read); + if (err) + return err; + if (put_user(byte_read, buf + *off - init_off)) { + if (*off - init_off) + return *off - init_off; /* partial read */ + return -EFAULT; + } + *off += 1; + size--; + } + return count; +} + +static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf, + size_t count, loff_t *off) +{ + /* Use this if support reading/writing multiple ECs exists in ec.c: + * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private; + */ + + unsigned int size = count; + loff_t init_off = *off; + int err = 0; + + if (!write_support) + return -EINVAL; + + if (*off >= EC_SPACE_SIZE) + return 0; + if (*off + count >= EC_SPACE_SIZE) { + size = EC_SPACE_SIZE - *off; + count = size; + } + + while (size) { + u8 byte_write; + if (get_user(byte_write, buf + *off - init_off)) { + if (*off - init_off) + return *off - init_off; /* partial write */ + return -EFAULT; + } + err = ec_write(*off, byte_write); + if (err) + return err; + + *off += 1; + size--; + } + return count; +} + +static const struct file_operations acpi_ec_io_ops = { + .owner = THIS_MODULE, + .open = simple_open, + .read = acpi_ec_read_io, + .write = acpi_ec_write_io, + .llseek = default_llseek, +}; + +static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count) +{ + struct dentry *dev_dir; + char name[64]; + umode_t mode = 0400; + + if (ec_device_count == 0) + acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL); + + sprintf(name, "ec%u", ec_device_count); + dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir); + + debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe); + debugfs_create_bool("use_global_lock", 0444, dev_dir, + &first_ec->global_lock); + + if (write_support) + mode = 0600; + debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops); +} + +static int __init acpi_ec_sys_init(void) +{ + if (first_ec) + acpi_ec_add_debugfs(first_ec, 0); + return 0; +} + +static void __exit acpi_ec_sys_exit(void) +{ + debugfs_remove_recursive(acpi_ec_debugfs_dir); +} + +module_init(acpi_ec_sys_init); +module_exit(acpi_ec_sys_exit); -- cgit v1.3.1