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/power/reset/syscon-reboot.c | 160 ++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 drivers/power/reset/syscon-reboot.c (limited to 'drivers/power/reset/syscon-reboot.c') diff --git a/drivers/power/reset/syscon-reboot.c b/drivers/power/reset/syscon-reboot.c new file mode 100644 index 000000000..2e2cf5f62 --- /dev/null +++ b/drivers/power/reset/syscon-reboot.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Generic Syscon Reboot Driver + * + * Copyright (c) 2013, Applied Micro Circuits Corporation + * Author: Feng Kan + */ +#include +#include +#include +#include +#include +#include +#include +#include + +struct reboot_mode_bits { + u32 offset; + u32 mask; + u32 value; + bool valid; +}; + +struct reboot_data { + struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1]; + struct reboot_mode_bits catchall; +}; + +struct syscon_reboot_context { + struct regmap *map; + + const struct reboot_data *rd; /* from of match data, if any */ + struct reboot_mode_bits catchall; /* from DT */ + + struct notifier_block restart_handler; +}; + +static int syscon_restart_handle(struct notifier_block *this, + unsigned long mode, void *cmd) +{ + struct syscon_reboot_context *ctx = + container_of(this, struct syscon_reboot_context, + restart_handler); + const struct reboot_mode_bits *mode_bits; + + if (ctx->rd) { + if (mode < ARRAY_SIZE(ctx->rd->mode_bits) && + ctx->rd->mode_bits[mode].valid) + mode_bits = &ctx->rd->mode_bits[mode]; + else + mode_bits = &ctx->rd->catchall; + } else { + mode_bits = &ctx->catchall; + } + + /* Issue the reboot */ + regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask, + mode_bits->value); + + mdelay(1000); + + pr_emerg("Unable to restart system\n"); + return NOTIFY_DONE; +} + +static int syscon_reboot_probe(struct platform_device *pdev) +{ + struct syscon_reboot_context *ctx; + struct device *dev = &pdev->dev; + int priority; + int err; + + ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + + ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap"); + if (IS_ERR(ctx->map)) { + ctx->map = syscon_node_to_regmap(dev->parent->of_node); + if (IS_ERR(ctx->map)) + return PTR_ERR(ctx->map); + } + + if (of_property_read_s32(pdev->dev.of_node, "priority", &priority)) + priority = 192; + + ctx->rd = of_device_get_match_data(dev); + if (!ctx->rd) { + int mask_err, value_err; + + if (of_property_read_u32(pdev->dev.of_node, "offset", + &ctx->catchall.offset) && + of_property_read_u32(pdev->dev.of_node, "reg", + &ctx->catchall.offset)) + return -EINVAL; + + value_err = of_property_read_u32(pdev->dev.of_node, "value", + &ctx->catchall.value); + mask_err = of_property_read_u32(pdev->dev.of_node, "mask", + &ctx->catchall.mask); + if (value_err && mask_err) { + dev_err(dev, "unable to read 'value' and 'mask'"); + return -EINVAL; + } + + if (value_err) { + /* support old binding */ + ctx->catchall.value = ctx->catchall.mask; + ctx->catchall.mask = 0xFFFFFFFF; + } else if (mask_err) { + /* support value without mask */ + ctx->catchall.mask = 0xFFFFFFFF; + } + } + + ctx->restart_handler.notifier_call = syscon_restart_handle; + ctx->restart_handler.priority = priority; + err = register_restart_handler(&ctx->restart_handler); + if (err) + dev_err(dev, "can't register restart notifier (err=%d)\n", err); + + return err; +} + +static const struct reboot_data gs101_reboot_data = { + .mode_bits = { + [REBOOT_WARM] = { + .offset = 0x3a00, /* SYSTEM_CONFIGURATION */ + .mask = 0x00000002, /* SWRESET_SYSTEM */ + .value = 0x00000002, + .valid = true, + }, + [REBOOT_SOFT] = { + .offset = 0x3a00, /* SYSTEM_CONFIGURATION */ + .mask = 0x00000002, /* SWRESET_SYSTEM */ + .value = 0x00000002, + .valid = true, + }, + }, + .catchall = { + .offset = 0x3e9c, /* PAD_CTRL_PWR_HOLD */ + .mask = 0x00000100, + .value = 0x00000000, + }, +}; + +static const struct of_device_id syscon_reboot_of_match[] = { + { .compatible = "google,gs101-reboot", .data = &gs101_reboot_data }, + { .compatible = "syscon-reboot" }, + {} +}; + +static struct platform_driver syscon_reboot_driver = { + .probe = syscon_reboot_probe, + .driver = { + .name = "syscon-reboot", + .of_match_table = syscon_reboot_of_match, + }, +}; +builtin_platform_driver(syscon_reboot_driver); -- cgit v1.3.1