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/vx855.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 drivers/mfd/vx855.c (limited to 'drivers/mfd/vx855.c') diff --git a/drivers/mfd/vx855.c b/drivers/mfd/vx855.c new file mode 100644 index 000000000..985f81c17 --- /dev/null +++ b/drivers/mfd/vx855.c @@ -0,0 +1,123 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Linux multi-function-device driver (MFD) for the integrated peripherals + * of the VIA VX855 chipset + * + * Copyright (C) 2009 VIA Technologies, Inc. + * Copyright (C) 2010 One Laptop per Child + * Author: Harald Welte + * All rights reserved. + */ + +#include +#include +#include +#include +#include +#include + +/* offset into pci config space indicating the 16bit register containing + * the power management IO space base */ +#define VX855_CFG_PMIO_OFFSET 0x88 + +/* ACPI I/O Space registers */ +#define VX855_PMIO_ACPI 0x00 +#define VX855_PMIO_ACPI_LEN 0x0b + +/* Processor Power Management */ +#define VX855_PMIO_PPM 0x10 +#define VX855_PMIO_PPM_LEN 0x08 + +/* General Purpose Power Management */ +#define VX855_PMIO_GPPM 0x20 +#define VX855_PMIO_R_GPI 0x48 +#define VX855_PMIO_R_GPO 0x4c +#define VX855_PMIO_GPPM_LEN 0x33 + +#define VSPIC_MMIO_SIZE 0x1000 + +static struct resource vx855_gpio_resources[] = { + { + .flags = IORESOURCE_IO, + }, + { + .flags = IORESOURCE_IO, + }, +}; + +static const struct mfd_cell vx855_cells[] = { + { + .name = "vx855_gpio", + .num_resources = ARRAY_SIZE(vx855_gpio_resources), + .resources = vx855_gpio_resources, + + /* we must ignore resource conflicts, for reasons outlined in + * the vx855_gpio driver */ + .ignore_resource_conflicts = true, + }, +}; + +static int vx855_probe(struct pci_dev *pdev, + const struct pci_device_id *id) +{ + int ret; + u16 gpio_io_offset; + + ret = pci_enable_device(pdev); + if (ret) + return -ENODEV; + + pci_read_config_word(pdev, VX855_CFG_PMIO_OFFSET, &gpio_io_offset); + if (!gpio_io_offset) { + dev_warn(&pdev->dev, + "BIOS did not assign PMIO base offset?!?\n"); + ret = -ENODEV; + goto out; + } + + /* mask out the lowest seven bits, as they are always zero, but + * hardware returns them as 0x01 */ + gpio_io_offset &= 0xff80; + + /* As the region identified here includes many non-GPIO things, we + * only work with the specific registers that concern us. */ + vx855_gpio_resources[0].start = gpio_io_offset + VX855_PMIO_R_GPI; + vx855_gpio_resources[0].end = vx855_gpio_resources[0].start + 3; + vx855_gpio_resources[1].start = gpio_io_offset + VX855_PMIO_R_GPO; + vx855_gpio_resources[1].end = vx855_gpio_resources[1].start + 3; + + ret = mfd_add_devices(&pdev->dev, -1, vx855_cells, ARRAY_SIZE(vx855_cells), + NULL, 0, NULL); + + /* we always return -ENODEV here in order to enable other + * drivers like old, not-yet-platform_device ported i2c-viapro */ + return -ENODEV; +out: + pci_disable_device(pdev); + return ret; +} + +static void vx855_remove(struct pci_dev *pdev) +{ + mfd_remove_devices(&pdev->dev); + pci_disable_device(pdev); +} + +static const struct pci_device_id vx855_pci_tbl[] = { + { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX855) }, + { 0, } +}; +MODULE_DEVICE_TABLE(pci, vx855_pci_tbl); + +static struct pci_driver vx855_pci_driver = { + .name = "vx855", + .id_table = vx855_pci_tbl, + .probe = vx855_probe, + .remove = vx855_remove, +}; + +module_pci_driver(vx855_pci_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Harald Welte "); +MODULE_DESCRIPTION("Driver for the VIA VX855 chipset"); -- cgit v1.3.1