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/fprobe/fprobe_example.c | 154 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 samples/fprobe/fprobe_example.c (limited to 'samples/fprobe/fprobe_example.c') diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c new file mode 100644 index 000000000..bfe98ce82 --- /dev/null +++ b/samples/fprobe/fprobe_example.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Here's a sample kernel module showing the use of fprobe to dump a + * stack trace and selected registers when kernel_clone() is called. + * + * For more information on theory of operation of kprobes, see + * Documentation/trace/kprobes.rst + * + * You will see the trace data in /var/log/messages and on the console + * whenever kernel_clone() is invoked to create a new process. + */ + +#define pr_fmt(fmt) "%s: " fmt, __func__ + +#include +#include +#include +#include +#include + +#define BACKTRACE_DEPTH 16 +#define MAX_SYMBOL_LEN 4096 +static struct fprobe sample_probe; +static unsigned long nhit; + +static char symbol[MAX_SYMBOL_LEN] = "kernel_clone"; +module_param_string(symbol, symbol, sizeof(symbol), 0644); +MODULE_PARM_DESC(symbol, "Probed symbol(s), given by comma separated symbols or a wildcard pattern."); + +static char nosymbol[MAX_SYMBOL_LEN] = ""; +module_param_string(nosymbol, nosymbol, sizeof(nosymbol), 0644); +MODULE_PARM_DESC(nosymbol, "Not-probed symbols, given by a wildcard pattern."); + +static bool stackdump = true; +module_param(stackdump, bool, 0644); +MODULE_PARM_DESC(stackdump, "Enable stackdump."); + +static bool use_trace = false; +module_param(use_trace, bool, 0644); +MODULE_PARM_DESC(use_trace, "Use trace_printk instead of printk. This is only for debugging."); + +static void show_backtrace(void) +{ + unsigned long stacks[BACKTRACE_DEPTH]; + unsigned int len; + + len = stack_trace_save(stacks, BACKTRACE_DEPTH, 2); + stack_trace_print(stacks, len, 24); +} + +static int sample_entry_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, + struct ftrace_regs *fregs, void *data) +{ + if (use_trace) + /* + * This is just an example, no kernel code should call + * trace_printk() except when actively debugging. + */ + trace_printk("Enter <%pS> ip = 0x%p\n", (void *)ip, (void *)ip); + else + pr_info("Enter <%pS> ip = 0x%p\n", (void *)ip, (void *)ip); + nhit++; + if (stackdump) + show_backtrace(); + return 0; +} + +static void sample_exit_handler(struct fprobe *fp, unsigned long ip, + unsigned long ret_ip, struct ftrace_regs *regs, + void *data) +{ + unsigned long rip = ret_ip; + + if (use_trace) + /* + * This is just an example, no kernel code should call + * trace_printk() except when actively debugging. + */ + trace_printk("Return from <%pS> ip = 0x%p to rip = 0x%p (%pS)\n", + (void *)ip, (void *)ip, (void *)rip, (void *)rip); + else + pr_info("Return from <%pS> ip = 0x%p to rip = 0x%p (%pS)\n", + (void *)ip, (void *)ip, (void *)rip, (void *)rip); + nhit++; + if (stackdump) + show_backtrace(); +} + +static int __init fprobe_init(void) +{ + char *p, *symbuf = NULL; + const char **syms; + int ret, count, i; + + sample_probe.entry_handler = sample_entry_handler; + sample_probe.exit_handler = sample_exit_handler; + + if (strchr(symbol, '*')) { + /* filter based fprobe */ + ret = register_fprobe(&sample_probe, symbol, + nosymbol[0] == '\0' ? NULL : nosymbol); + goto out; + } else if (!strchr(symbol, ',')) { + symbuf = symbol; + ret = register_fprobe_syms(&sample_probe, (const char **)&symbuf, 1); + goto out; + } + + /* Comma separated symbols */ + symbuf = kstrdup(symbol, GFP_KERNEL); + if (!symbuf) + return -ENOMEM; + p = symbuf; + count = 1; + while ((p = strchr(++p, ',')) != NULL) + count++; + + pr_info("%d symbols found\n", count); + + syms = kcalloc(count, sizeof(char *), GFP_KERNEL); + if (!syms) { + kfree(symbuf); + return -ENOMEM; + } + + p = symbuf; + for (i = 0; i < count; i++) + syms[i] = strsep(&p, ","); + + ret = register_fprobe_syms(&sample_probe, syms, count); + kfree(syms); + kfree(symbuf); +out: + if (ret < 0) + pr_err("register_fprobe failed, returned %d\n", ret); + else + pr_info("Planted fprobe at %s\n", symbol); + + return ret; +} + +static void __exit fprobe_exit(void) +{ + unregister_fprobe(&sample_probe); + + pr_info("fprobe at %s unregistered. %ld times hit, %ld times missed\n", + symbol, nhit, sample_probe.nmissed); +} + +module_init(fprobe_init) +module_exit(fprobe_exit) +MODULE_DESCRIPTION("sample kernel module showing the use of fprobe"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1