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/usb/serial/empeg.c | 122 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100644 drivers/usb/serial/empeg.c (limited to 'drivers/usb/serial/empeg.c') diff --git a/drivers/usb/serial/empeg.c b/drivers/usb/serial/empeg.c new file mode 100644 index 000000000..4937575ca --- /dev/null +++ b/drivers/usb/serial/empeg.c @@ -0,0 +1,122 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * USB Empeg empeg-car player driver + * + * Copyright (C) 2000, 2001 + * Gary Brubaker (xavyer@ix.netcom.com) + * + * Copyright (C) 1999 - 2001 + * Greg Kroah-Hartman (greg@kroah.com) + * + * See Documentation/usb/usb-serial.rst for more information on using this + * driver + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#define DRIVER_AUTHOR "Greg Kroah-Hartman , Gary Brubaker " +#define DRIVER_DESC "USB Empeg Mark I/II Driver" + +#define EMPEG_VENDOR_ID 0x084f +#define EMPEG_PRODUCT_ID 0x0001 + +/* function prototypes for an empeg-car player */ +static int empeg_startup(struct usb_serial *serial); +static void empeg_init_termios(struct tty_struct *tty); + +static const struct usb_device_id id_table[] = { + { USB_DEVICE(EMPEG_VENDOR_ID, EMPEG_PRODUCT_ID) }, + { } /* Terminating entry */ +}; + +MODULE_DEVICE_TABLE(usb, id_table); + +static struct usb_serial_driver empeg_device = { + .driver = { + .name = "empeg", + }, + .id_table = id_table, + .num_ports = 1, + .bulk_out_size = 256, + .throttle = usb_serial_generic_throttle, + .unthrottle = usb_serial_generic_unthrottle, + .attach = empeg_startup, + .init_termios = empeg_init_termios, +}; + +static struct usb_serial_driver * const serial_drivers[] = { + &empeg_device, NULL +}; + +static int empeg_startup(struct usb_serial *serial) +{ + int r; + + if (serial->dev->actconfig->desc.bConfigurationValue != 1) { + dev_err(&serial->dev->dev, "active config #%d != 1 ??\n", + serial->dev->actconfig->desc.bConfigurationValue); + return -ENODEV; + } + + r = usb_reset_configuration(serial->dev); + + /* continue on with initialization */ + return r; +} + +static void empeg_init_termios(struct tty_struct *tty) +{ + struct ktermios *termios = &tty->termios; + + /* + * The empeg-car player wants these particular tty settings. + * You could, for example, change the baud rate, however the + * player only supports 115200 (currently), so there is really + * no point in support for changes to the tty settings. + * (at least for now) + * + * The default requirements for this device are: + */ + termios->c_iflag + &= ~(IGNBRK /* disable ignore break */ + | BRKINT /* disable break causes interrupt */ + | PARMRK /* disable mark parity errors */ + | ISTRIP /* disable clear high bit of input characters */ + | INLCR /* disable translate NL to CR */ + | IGNCR /* disable ignore CR */ + | ICRNL /* disable translate CR to NL */ + | IXON); /* disable enable XON/XOFF flow control */ + + termios->c_oflag + &= ~OPOST; /* disable postprocess output characters */ + + termios->c_lflag + &= ~(ECHO /* disable echo input characters */ + | ECHONL /* disable echo new line */ + | ICANON /* disable erase, kill, werase, and rprnt special characters */ + | ISIG /* disable interrupt, quit, and suspend special characters */ + | IEXTEN); /* disable non-POSIX special characters */ + + termios->c_cflag + &= ~(CSIZE /* no size */ + | PARENB /* disable parity bit */ + | CBAUD); /* clear current baud rate */ + + termios->c_cflag + |= CS8; /* character size 8 bits */ + + tty_encode_baud_rate(tty, 115200, 115200); +} + +module_usb_serial_driver(serial_drivers, id_table); + +MODULE_AUTHOR(DRIVER_AUTHOR); +MODULE_DESCRIPTION(DRIVER_DESC); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1