From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- samples/kprobes/kretprobe_example.c | 108 ++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 samples/kprobes/kretprobe_example.c (limited to 'samples/kprobes/kretprobe_example.c') diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c new file mode 100644 index 000000000..65d6dcafd --- /dev/null +++ b/samples/kprobes/kretprobe_example.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kretprobe_example.c + * + * Here's a sample kernel module showing the use of return probes to + * report the return value and total time taken for probed function + * to run. + * + * usage: insmod kretprobe_example.ko func= + * + * If no func_name is specified, kernel_clone is instrumented + * + * For more information on theory of operation of kretprobes, see + * Documentation/trace/kprobes.rst + * + * Build and insert the kernel module as done in the kprobe example. + * You will see the trace data in /var/log/messages and on the console + * whenever the probed function returns. (Some messages may be suppressed + * if syslogd is configured to eliminate duplicate messages.) + */ + +#include +#include +#include +#include +#include + +static char func_name[KSYM_NAME_LEN] = "kernel_clone"; +module_param_string(func, func_name, KSYM_NAME_LEN, 0644); +MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the" + " function's execution time"); + +/* per-instance private data */ +struct my_data { + ktime_t entry_stamp; +}; + +/* Here we use the entry_handler to timestamp function entry */ +static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs) +{ + struct my_data *data; + + if (!current->mm) + return 1; /* Skip kernel threads */ + + data = (struct my_data *)ri->data; + data->entry_stamp = ktime_get(); + return 0; +} +NOKPROBE_SYMBOL(entry_handler); + +/* + * Return-probe handler: Log the return value and duration. Duration may turn + * out to be zero consistently, depending upon the granularity of time + * accounting on the platform. + */ +static int ret_handler(struct kretprobe_instance *ri, struct pt_regs *regs) +{ + unsigned long retval = regs_return_value(regs); + struct my_data *data = (struct my_data *)ri->data; + s64 delta; + ktime_t now; + + now = ktime_get(); + delta = ktime_to_ns(ktime_sub(now, data->entry_stamp)); + pr_info("%s returned %lu and took %lld ns to execute\n", + func_name, retval, (long long)delta); + return 0; +} +NOKPROBE_SYMBOL(ret_handler); + +static struct kretprobe my_kretprobe = { + .handler = ret_handler, + .entry_handler = entry_handler, + .data_size = sizeof(struct my_data), + /* Probe up to 20 instances concurrently. */ + .maxactive = 20, +}; + +static int __init kretprobe_init(void) +{ + int ret; + + my_kretprobe.kp.symbol_name = func_name; + ret = register_kretprobe(&my_kretprobe); + if (ret < 0) { + pr_err("register_kretprobe failed, returned %d\n", ret); + return ret; + } + pr_info("Planted return probe at %s: %p\n", + my_kretprobe.kp.symbol_name, my_kretprobe.kp.addr); + return 0; +} + +static void __exit kretprobe_exit(void) +{ + unregister_kretprobe(&my_kretprobe); + pr_info("kretprobe at %p unregistered\n", my_kretprobe.kp.addr); + + /* nmissed > 0 suggests that maxactive was set too low. */ + pr_info("Missed probing %d instances of %s\n", + my_kretprobe.nmissed, my_kretprobe.kp.symbol_name); +} + +module_init(kretprobe_init) +module_exit(kretprobe_exit) +MODULE_DESCRIPTION("sample kernel module showing the use of return probes"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1