/* * 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, _do_fork is instrumented * * For more information on theory of operation of kretprobes, see * Documentation/kprobes.txt * * 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 #include static char func_name[NAME_MAX] = "_do_fork"; module_param_string(func, func_name, NAME_MAX, S_IRUGO); 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_hanlder 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; } /* * 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; } 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 -1; } 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_LICENSE("GPL"); lass='label'>context:space:mode:
authorMarkus Mayer <mmayer@broadcom.com>2016-12-19 12:10:28 -0800
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-01-27 11:43:49 +0100
commit3c223c19aea85d3dda1416c187915f4a30b04b1f (patch)
tree2d2021f8161db3e9ed38b9a966a225b66dff8e58 /tools
parent9b02c54bc951fca884ba5719f42a27e8240965bf (diff)
cpufreq: brcmstb-avs-cpufreq: properly retrieve P-state upon suspend
The AVS GET_PMAP command does return a P-state along with the P-map information. However, that P-state is the initial P-state when the P-map was first downloaded to AVS. It is *not* the current P-state. Therefore, we explicitly retrieve the P-state using the GET_PSTATE command. Signed-off-by: Markus Mayer <mmayer@broadcom.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'tools')