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/mailbox/mailbox-test.c | 463 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 463 insertions(+) create mode 100644 drivers/mailbox/mailbox-test.c (limited to 'drivers/mailbox/mailbox-test.c') diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c new file mode 100644 index 000000000..7b6ef033e --- /dev/null +++ b/drivers/mailbox/mailbox-test.c @@ -0,0 +1,463 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2015 ST Microelectronics + * + * Author: Lee Jones + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define MBOX_MAX_SIG_LEN 8 +#define MBOX_MAX_MSG_LEN 128 +#define MBOX_BYTES_PER_LINE 16 +#define MBOX_HEXDUMP_LINE_LEN ((MBOX_BYTES_PER_LINE * 4) + 2) +#define MBOX_HEXDUMP_MAX_LEN (MBOX_HEXDUMP_LINE_LEN * \ + (MBOX_MAX_MSG_LEN / MBOX_BYTES_PER_LINE)) + +struct mbox_test_device { + struct device *dev; + void __iomem *tx_mmio; + void __iomem *rx_mmio; + struct mbox_chan *tx_channel; + struct mbox_chan *rx_channel; + char *rx_buffer; + char *signal; + char *message; + spinlock_t lock; + struct mutex mutex; + wait_queue_head_t waitq; + bool data_ready; + struct fasync_struct *async_queue; + struct dentry *root_debugfs_dir; +}; + +static ssize_t mbox_test_signal_write(struct file *filp, + const char __user *userbuf, + size_t count, loff_t *ppos) +{ + struct mbox_test_device *tdev = filp->private_data; + + if (!tdev->tx_channel) { + dev_err(tdev->dev, "Channel cannot do Tx\n"); + return -EINVAL; + } + + if (count > MBOX_MAX_SIG_LEN) { + dev_err(tdev->dev, + "Signal length %zd greater than max allowed %d\n", + count, MBOX_MAX_SIG_LEN); + return -EINVAL; + } + + /* Only allocate memory if we need to */ + if (!tdev->signal) { + tdev->signal = kzalloc(MBOX_MAX_SIG_LEN, GFP_KERNEL); + if (!tdev->signal) + return -ENOMEM; + } + + if (copy_from_user(tdev->signal, userbuf, count)) { + kfree(tdev->signal); + tdev->signal = NULL; + return -EFAULT; + } + + return count; +} + +static const struct file_operations mbox_test_signal_ops = { + .write = mbox_test_signal_write, + .open = simple_open, + .llseek = generic_file_llseek, +}; + +static int mbox_test_message_fasync(int fd, struct file *filp, int on) +{ + struct mbox_test_device *tdev = filp->private_data; + + return fasync_helper(fd, filp, on, &tdev->async_queue); +} + +static ssize_t mbox_test_message_write(struct file *filp, + const char __user *userbuf, + size_t count, loff_t *ppos) +{ + struct mbox_test_device *tdev = filp->private_data; + char *message; + void *data; + int ret; + + if (!tdev->tx_channel) { + dev_err(tdev->dev, "Channel cannot do Tx\n"); + return -EINVAL; + } + + if (count > MBOX_MAX_MSG_LEN) { + dev_err(tdev->dev, + "Message length %zd greater than max allowed %d\n", + count, MBOX_MAX_MSG_LEN); + return -EINVAL; + } + + message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL); + if (!message) + return -ENOMEM; + + mutex_lock(&tdev->mutex); + + tdev->message = message; + ret = copy_from_user(tdev->message, userbuf, count); + if (ret) { + ret = -EFAULT; + goto out; + } + + /* + * A separate signal is only of use if there is + * MMIO to subsequently pass the message through + */ + if (tdev->tx_mmio && tdev->signal) { + print_hex_dump_bytes("Client: Sending: Signal: ", DUMP_PREFIX_ADDRESS, + tdev->signal, MBOX_MAX_SIG_LEN); + + data = tdev->signal; + } else + data = tdev->message; + + print_hex_dump_bytes("Client: Sending: Message: ", DUMP_PREFIX_ADDRESS, + tdev->message, MBOX_MAX_MSG_LEN); + + ret = mbox_send_message(tdev->tx_channel, data); + if (ret < 0) + dev_err(tdev->dev, "Failed to send message via mailbox\n"); + +out: + kfree(tdev->signal); + kfree(tdev->message); + tdev->signal = NULL; + + mutex_unlock(&tdev->mutex); + + return ret < 0 ? ret : count; +} + +static bool mbox_test_message_data_ready(struct mbox_test_device *tdev) +{ + bool data_ready; + unsigned long flags; + + spin_lock_irqsave(&tdev->lock, flags); + data_ready = tdev->data_ready; + spin_unlock_irqrestore(&tdev->lock, flags); + + return data_ready; +} + +static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf, + size_t count, loff_t *ppos) +{ + struct mbox_test_device *tdev = filp->private_data; + unsigned long flags; + char *touser, *ptr; + int l = 0; + int ret; + + DECLARE_WAITQUEUE(wait, current); + + touser = kzalloc(MBOX_HEXDUMP_MAX_LEN + 1, GFP_KERNEL); + if (!touser) + return -ENOMEM; + + if (!tdev->rx_channel) { + ret = snprintf(touser, 20, "\n"); + ret = simple_read_from_buffer(userbuf, count, ppos, + touser, ret); + goto kfree_err; + } + + add_wait_queue(&tdev->waitq, &wait); + + do { + __set_current_state(TASK_INTERRUPTIBLE); + + if (mbox_test_message_data_ready(tdev)) + break; + + if (filp->f_flags & O_NONBLOCK) { + ret = -EAGAIN; + goto waitq_err; + } + + if (signal_pending(current)) { + ret = -ERESTARTSYS; + goto waitq_err; + } + schedule(); + + } while (1); + + spin_lock_irqsave(&tdev->lock, flags); + + ptr = tdev->rx_buffer; + while (l < MBOX_HEXDUMP_MAX_LEN) { + hex_dump_to_buffer(ptr, + MBOX_BYTES_PER_LINE, + MBOX_BYTES_PER_LINE, 1, touser + l, + MBOX_HEXDUMP_LINE_LEN, true); + + ptr += MBOX_BYTES_PER_LINE; + l += MBOX_HEXDUMP_LINE_LEN; + *(touser + (l - 1)) = '\n'; + } + *(touser + l) = '\0'; + + memset(tdev->rx_buffer, 0, MBOX_MAX_MSG_LEN); + tdev->data_ready = false; + + spin_unlock_irqrestore(&tdev->lock, flags); + + ret = simple_read_from_buffer(userbuf, count, ppos, touser, MBOX_HEXDUMP_MAX_LEN); +waitq_err: + __set_current_state(TASK_RUNNING); + remove_wait_queue(&tdev->waitq, &wait); +kfree_err: + kfree(touser); + return ret; +} + +static __poll_t +mbox_test_message_poll(struct file *filp, struct poll_table_struct *wait) +{ + struct mbox_test_device *tdev = filp->private_data; + + poll_wait(filp, &tdev->waitq, wait); + + if (mbox_test_message_data_ready(tdev)) + return EPOLLIN | EPOLLRDNORM; + return 0; +} + +static const struct file_operations mbox_test_message_ops = { + .write = mbox_test_message_write, + .read = mbox_test_message_read, + .fasync = mbox_test_message_fasync, + .poll = mbox_test_message_poll, + .open = simple_open, + .llseek = generic_file_llseek, +}; + +static int mbox_test_add_debugfs(struct platform_device *pdev, + struct mbox_test_device *tdev) +{ + if (!debugfs_initialized()) + return 0; + + tdev->root_debugfs_dir = debugfs_create_dir(dev_name(&pdev->dev), NULL); + if (IS_ERR(tdev->root_debugfs_dir)) { + dev_err(&pdev->dev, "Failed to create Mailbox debugfs\n"); + return -EINVAL; + } + + debugfs_create_file("message", 0600, tdev->root_debugfs_dir, + tdev, &mbox_test_message_ops); + + debugfs_create_file("signal", 0200, tdev->root_debugfs_dir, + tdev, &mbox_test_signal_ops); + + return 0; +} + +static void mbox_test_receive_message(struct mbox_client *client, void *message) +{ + struct mbox_test_device *tdev = dev_get_drvdata(client->dev); + unsigned long flags; + + spin_lock_irqsave(&tdev->lock, flags); + if (tdev->rx_mmio) { + memcpy_fromio(tdev->rx_buffer, tdev->rx_mmio, MBOX_MAX_MSG_LEN); + print_hex_dump_bytes("Client: Received [MMIO]: ", DUMP_PREFIX_ADDRESS, + tdev->rx_buffer, MBOX_MAX_MSG_LEN); + } else if (message) { + print_hex_dump_bytes("Client: Received [API]: ", DUMP_PREFIX_ADDRESS, + message, MBOX_MAX_MSG_LEN); + memcpy(tdev->rx_buffer, message, MBOX_MAX_MSG_LEN); + } + tdev->data_ready = true; + spin_unlock_irqrestore(&tdev->lock, flags); + + wake_up_interruptible(&tdev->waitq); + + kill_fasync(&tdev->async_queue, SIGIO, POLL_IN); +} + +static void mbox_test_prepare_message(struct mbox_client *client, void *message) +{ + struct mbox_test_device *tdev = dev_get_drvdata(client->dev); + + if (tdev->tx_mmio) { + if (tdev->signal) + memcpy_toio(tdev->tx_mmio, tdev->message, MBOX_MAX_MSG_LEN); + else + memcpy_toio(tdev->tx_mmio, message, MBOX_MAX_MSG_LEN); + } +} + +static void mbox_test_message_sent(struct mbox_client *client, + void *message, int r) +{ + if (r) + dev_warn(client->dev, + "Client: Message could not be sent: %d\n", r); + else + dev_info(client->dev, + "Client: Message sent\n"); +} + +static struct mbox_chan * +mbox_test_request_channel(struct platform_device *pdev, const char *name) +{ + struct mbox_client *client; + struct mbox_chan *channel; + + client = devm_kzalloc(&pdev->dev, sizeof(*client), GFP_KERNEL); + if (!client) + return NULL; + + client->dev = &pdev->dev; + client->rx_callback = mbox_test_receive_message; + client->tx_prepare = mbox_test_prepare_message; + client->tx_done = mbox_test_message_sent; + client->tx_block = true; + client->knows_txdone = false; + client->tx_tout = 500; + + channel = mbox_request_channel_byname(client, name); + if (IS_ERR(channel)) { + dev_warn(&pdev->dev, "Failed to request %s channel\n", name); + return NULL; + } + + return channel; +} + +static void __iomem *mbox_test_ioremap(struct platform_device *pdev, unsigned int res_num) +{ + struct resource *res; + void __iomem *mmio; + + res = platform_get_resource(pdev, IORESOURCE_MEM, res_num); + if (!res) + return NULL; + + mmio = devm_ioremap_resource(&pdev->dev, res); + if (PTR_ERR(mmio) == -EBUSY) { + dev_info(&pdev->dev, "trying workaround with plain ioremap\n"); + return devm_ioremap(&pdev->dev, res->start, resource_size(res)); + } + + return IS_ERR(mmio) ? NULL : mmio; +} + +static int mbox_test_probe(struct platform_device *pdev) +{ + struct mbox_test_device *tdev; + int ret; + + tdev = devm_kzalloc(&pdev->dev, sizeof(*tdev), GFP_KERNEL); + if (!tdev) + return -ENOMEM; + + tdev->dev = &pdev->dev; + spin_lock_init(&tdev->lock); + mutex_init(&tdev->mutex); + init_waitqueue_head(&tdev->waitq); + platform_set_drvdata(pdev, tdev); + + /* It's okay for MMIO to be NULL */ + tdev->tx_mmio = mbox_test_ioremap(pdev, 0); + + /* If specified, second reg entry is Rx MMIO */ + tdev->rx_mmio = mbox_test_ioremap(pdev, 1); + if (!tdev->rx_mmio) + tdev->rx_mmio = tdev->tx_mmio; + + tdev->tx_channel = mbox_test_request_channel(pdev, "tx"); + tdev->rx_channel = mbox_test_request_channel(pdev, "rx"); + + if (!tdev->tx_channel && !tdev->rx_channel) + return -EPROBE_DEFER; + + /* If Rx is not specified but has Rx MMIO, then Rx = Tx */ + if (!tdev->rx_channel && (tdev->rx_mmio != tdev->tx_mmio)) + tdev->rx_channel = tdev->tx_channel; + + if (tdev->rx_channel) { + tdev->rx_buffer = devm_kzalloc(&pdev->dev, + MBOX_MAX_MSG_LEN, GFP_KERNEL); + if (!tdev->rx_buffer) { + ret = -ENOMEM; + goto err_free_chans; + } + } + + ret = mbox_test_add_debugfs(pdev, tdev); + if (ret) + goto err_free_chans; + + dev_info(&pdev->dev, "Successfully registered\n"); + + return 0; + +err_free_chans: + if (tdev->tx_channel) + mbox_free_channel(tdev->tx_channel); + if (tdev->rx_channel && tdev->rx_channel != tdev->tx_channel) + mbox_free_channel(tdev->rx_channel); + return ret; +} + +static void mbox_test_remove(struct platform_device *pdev) +{ + struct mbox_test_device *tdev = platform_get_drvdata(pdev); + + debugfs_remove_recursive(tdev->root_debugfs_dir); + + if (tdev->tx_channel) + mbox_free_channel(tdev->tx_channel); + if (tdev->rx_channel && tdev->rx_channel != tdev->tx_channel) + mbox_free_channel(tdev->rx_channel); +} + +static const struct of_device_id mbox_test_match[] = { + { .compatible = "mailbox-test" }, + {}, +}; +MODULE_DEVICE_TABLE(of, mbox_test_match); + +static struct platform_driver mbox_test_driver = { + .driver = { + .name = "mailbox_test", + .of_match_table = mbox_test_match, + }, + .probe = mbox_test_probe, + .remove = mbox_test_remove, +}; +module_platform_driver(mbox_test_driver); + +MODULE_DESCRIPTION("Generic Mailbox Testing Facility"); +MODULE_AUTHOR("Lee Jones