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/soc/litex/Kconfig | 20 ++++++ drivers/soc/litex/Makefile | 3 + drivers/soc/litex/litex_soc_ctrl.c | 127 +++++++++++++++++++++++++++++++++++++ 3 files changed, 150 insertions(+) create mode 100644 drivers/soc/litex/Kconfig create mode 100644 drivers/soc/litex/Makefile create mode 100644 drivers/soc/litex/litex_soc_ctrl.c (limited to 'drivers/soc/litex') diff --git a/drivers/soc/litex/Kconfig b/drivers/soc/litex/Kconfig new file mode 100644 index 000000000..f3f869639 --- /dev/null +++ b/drivers/soc/litex/Kconfig @@ -0,0 +1,20 @@ +# SPDX-License_Identifier: GPL-2.0 + +menu "Enable LiteX SoC Builder specific drivers" + +config LITEX + bool + +config LITEX_SOC_CONTROLLER + tristate "Enable LiteX SoC Controller driver" + depends on OF + depends on HAS_IOMEM + select LITEX + help + This option enables the SoC Controller Driver which verifies + LiteX CSR access and provides common litex_[read|write]* + accessors. + All drivers that use functions from litex.h must depend on + LITEX. + +endmenu diff --git a/drivers/soc/litex/Makefile b/drivers/soc/litex/Makefile new file mode 100644 index 000000000..98ff7325b --- /dev/null +++ b/drivers/soc/litex/Makefile @@ -0,0 +1,3 @@ +# SPDX-License_Identifier: GPL-2.0 + +obj-$(CONFIG_LITEX_SOC_CONTROLLER) += litex_soc_ctrl.o diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c new file mode 100644 index 000000000..104a5f9bf --- /dev/null +++ b/drivers/soc/litex/litex_soc_ctrl.c @@ -0,0 +1,127 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * LiteX SoC Controller Driver + * + * Copyright (C) 2020 Antmicro + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* reset register located at the base address */ +#define RESET_REG_OFF 0x00 +#define RESET_REG_VALUE 0x00000001 + +#define SCRATCH_REG_OFF 0x04 +#define SCRATCH_REG_VALUE 0x12345678 +#define SCRATCH_TEST_VALUE 0xdeadbeef + +/* + * Check LiteX CSR read/write access + * + * This function reads and writes a scratch register in order to verify if CSR + * access works. + * + * In case any problems are detected, the driver should panic. + * + * Access to the LiteX CSR is, by design, done in CPU native endianness. + * The driver should not dynamically configure access functions when + * the endianness mismatch is detected. Such situation indicates problems in + * the soft SoC design and should be solved at the LiteX generator level, + * not in the software. + */ +static int litex_check_csr_access(void __iomem *reg_addr) +{ + unsigned long reg; + + reg = litex_read32(reg_addr + SCRATCH_REG_OFF); + + if (reg != SCRATCH_REG_VALUE) { + panic("Scratch register read error - the system is probably broken! Expected: 0x%x but got: 0x%lx", + SCRATCH_REG_VALUE, reg); + return -EINVAL; + } + + litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_TEST_VALUE); + reg = litex_read32(reg_addr + SCRATCH_REG_OFF); + + if (reg != SCRATCH_TEST_VALUE) { + panic("Scratch register write error - the system is probably broken! Expected: 0x%x but got: 0x%lx", + SCRATCH_TEST_VALUE, reg); + return -EINVAL; + } + + /* restore original value of the SCRATCH register */ + litex_write32(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_VALUE); + + pr_info("LiteX SoC Controller driver initialized"); + + return 0; +} + +struct litex_soc_ctrl_device { + void __iomem *base; +}; + +static int litex_reset_handler(struct sys_off_data *data) +{ + struct litex_soc_ctrl_device *soc_ctrl_dev = data->cb_data; + + litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE); + return NOTIFY_DONE; +} + +static const struct of_device_id litex_soc_ctrl_of_match[] = { + {.compatible = "litex,soc-controller"}, + {}, +}; +MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match); + +static int litex_soc_ctrl_probe(struct platform_device *pdev) +{ + struct litex_soc_ctrl_device *soc_ctrl_dev; + int error; + + soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL); + if (!soc_ctrl_dev) + return -ENOMEM; + + soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(soc_ctrl_dev->base)) + return PTR_ERR(soc_ctrl_dev->base); + + error = litex_check_csr_access(soc_ctrl_dev->base); + if (error) + return error; + + error = devm_register_restart_handler(&pdev->dev, + litex_reset_handler, + soc_ctrl_dev); + if (error) { + dev_warn(&pdev->dev, "cannot register restart handler: %d\n", + error); + } + + return 0; +} + +static struct platform_driver litex_soc_ctrl_driver = { + .driver = { + .name = "litex-soc-controller", + .of_match_table = litex_soc_ctrl_of_match, + }, + .probe = litex_soc_ctrl_probe, +}; + +module_platform_driver(litex_soc_ctrl_driver); +MODULE_DESCRIPTION("LiteX SoC Controller driver"); +MODULE_AUTHOR("Antmicro "); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1