diff options
Diffstat (limited to 'samples')
| -rw-r--r-- | samples/Kconfig | 7 | ||||
| -rw-r--r-- | samples/Makefile | 2 | ||||
| -rw-r--r-- | samples/livepatch/Makefile | 1 | ||||
| -rw-r--r-- | samples/livepatch/livepatch-sample.c | 91 | ||||
| -rw-r--r-- | samples/seccomp/bpf-fancy.c | 4 | ||||
| -rw-r--r-- | samples/seccomp/bpf-helper.c | 6 | ||||
| -rw-r--r-- | samples/trace_events/trace-events-sample.c | 80 | ||||
| -rw-r--r-- | samples/trace_events/trace-events-sample.h | 328 |
8 files changed, 503 insertions, 16 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index 6181c2cc9ca0..224ebb46bed5 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -63,4 +63,11 @@ config SAMPLE_RPMSG_CLIENT to communicate with an AMP-configured remote processor over the rpmsg bus. +config SAMPLE_LIVEPATCH + tristate "Build live patching sample -- loadable modules only" + depends on LIVEPATCH && m + help + Builds a sample live patch that replaces the procfs handler + for /proc/cmdline to print "this has been live patched". + endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile index 1a60c62e2045..f00257bcc5a7 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -1,4 +1,4 @@ # Makefile for Linux samples code -obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ \ +obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \ hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ diff --git a/samples/livepatch/Makefile b/samples/livepatch/Makefile new file mode 100644 index 000000000000..10319d7ea0b1 --- /dev/null +++ b/samples/livepatch/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SAMPLE_LIVEPATCH) += livepatch-sample.o diff --git a/samples/livepatch/livepatch-sample.c b/samples/livepatch/livepatch-sample.c new file mode 100644 index 000000000000..fb8c8614e728 --- /dev/null +++ b/samples/livepatch/livepatch-sample.c @@ -0,0 +1,91 @@ +/* + * livepatch-sample.c - Kernel Live Patching Sample Module + * + * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/livepatch.h> + +/* + * This (dumb) live patch overrides the function that prints the + * kernel boot cmdline when /proc/cmdline is read. + * + * Example: + * + * $ cat /proc/cmdline + * <your cmdline> + * + * $ insmod livepatch-sample.ko + * $ cat /proc/cmdline + * this has been live patched + * + * $ echo 0 > /sys/kernel/livepatch/livepatch_sample/enabled + * $ cat /proc/cmdline + * <your cmdline> + */ + +#include <linux/seq_file.h> +static int livepatch_cmdline_proc_show(struct seq_file *m, void *v) +{ + seq_printf(m, "%s\n", "this has been live patched"); + return 0; +} + +static struct klp_func funcs[] = { + { + .old_name = "cmdline_proc_show", + .new_func = livepatch_cmdline_proc_show, + }, { } +}; + +static struct klp_object objs[] = { + { + /* name being NULL means vmlinux */ + .funcs = funcs, + }, { } +}; + +static struct klp_patch patch = { + .mod = THIS_MODULE, + .objs = objs, +}; + +static int livepatch_init(void) +{ + int ret; + + ret = klp_register_patch(&patch); + if (ret) + return ret; + ret = klp_enable_patch(&patch); + if (ret) { + WARN_ON(klp_unregister_patch(&patch)); + return ret; + } + return 0; +} + +static void livepatch_exit(void) +{ + WARN_ON(klp_disable_patch(&patch)); + WARN_ON(klp_unregister_patch(&patch)); +} + +module_init(livepatch_init); +module_exit(livepatch_exit); +MODULE_LICENSE("GPL"); diff --git a/samples/seccomp/bpf-fancy.c b/samples/seccomp/bpf-fancy.c index 8eb483aaec46..e8b24f443709 100644 --- a/samples/seccomp/bpf-fancy.c +++ b/samples/seccomp/bpf-fancy.c @@ -25,7 +25,9 @@ int main(int argc, char **argv) { - struct bpf_labels l; + struct bpf_labels l = { + .count = 0, + }; static const char msg1[] = "Please type something: "; static const char msg2[] = "You typed: "; char buf[256]; diff --git a/samples/seccomp/bpf-helper.c b/samples/seccomp/bpf-helper.c index 579cfe331886..05cb4d5ff9f5 100644 --- a/samples/seccomp/bpf-helper.c +++ b/samples/seccomp/bpf-helper.c @@ -10,6 +10,7 @@ */ #include <stdio.h> +#include <stdlib.h> #include <string.h> #include "bpf-helper.h" @@ -63,6 +64,11 @@ __u32 seccomp_bpf_label(struct bpf_labels *labels, const char *label) { struct __bpf_label *begin = labels->labels, *end; int id; + + if (labels->count == BPF_LABELS_MAX) { + fprintf(stderr, "Too many labels\n"); + exit(1); + } if (labels->count == 0) { begin->label = label; begin->location = 0xffffffff; diff --git a/samples/trace_events/trace-events-sample.c b/samples/trace_events/trace-events-sample.c index aabc4e970911..880a7d1d27d2 100644 --- a/samples/trace_events/trace-events-sample.c +++ b/samples/trace_events/trace-events-sample.c @@ -10,12 +10,38 @@ #define CREATE_TRACE_POINTS #include "trace-events-sample.h" +static const char *random_strings[] = { + "Mother Goose", + "Snoopy", + "Gandalf", + "Frodo", + "One ring to rule them all" +}; static void simple_thread_func(int cnt) { + int array[6]; + int len = cnt % 5; + int i; + set_current_state(TASK_INTERRUPTIBLE); schedule_timeout(HZ); - trace_foo_bar("hello", cnt); + + for (i = 0; i < len; i++) + array[i] = i + 1; + array[i] = 0; + + /* Silly tracepoints */ + trace_foo_bar("hello", cnt, array, random_strings[len], + tsk_cpus_allowed(current)); + + trace_foo_with_template_simple("HELLO", cnt); + + trace_foo_bar_with_cond("Some times print", cnt); + + trace_foo_with_template_cond("prints other times", cnt); + + trace_foo_with_template_print("I have to be different", cnt); } static int simple_thread(void *arg) @@ -29,6 +55,53 @@ static int simple_thread(void *arg) } static struct task_struct *simple_tsk; +static struct task_struct *simple_tsk_fn; + +static void simple_thread_func_fn(int cnt) +{ + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ); + + /* More silly tracepoints */ + trace_foo_bar_with_fn("Look at me", cnt); + trace_foo_with_template_fn("Look at me too", cnt); +} + +static int simple_thread_fn(void *arg) +{ + int cnt = 0; + + while (!kthread_should_stop()) + simple_thread_func_fn(cnt++); + + return 0; +} + +static DEFINE_MUTEX(thread_mutex); + +void foo_bar_reg(void) +{ + pr_info("Starting thread for foo_bar_fn\n"); + /* + * We shouldn't be able to start a trace when the module is + * unloading (there's other locks to prevent that). But + * for consistency sake, we still take the thread_mutex. + */ + mutex_lock(&thread_mutex); + simple_tsk_fn = kthread_run(simple_thread_fn, NULL, "event-sample-fn"); + mutex_unlock(&thread_mutex); +} + +void foo_bar_unreg(void) +{ + pr_info("Killing thread for foo_bar_fn\n"); + /* protect against module unloading */ + mutex_lock(&thread_mutex); + if (simple_tsk_fn) + kthread_stop(simple_tsk_fn); + simple_tsk_fn = NULL; + mutex_unlock(&thread_mutex); +} static int __init trace_event_init(void) { @@ -42,6 +115,11 @@ static int __init trace_event_init(void) static void __exit trace_event_exit(void) { kthread_stop(simple_tsk); + mutex_lock(&thread_mutex); + if (simple_tsk_fn) + kthread_stop(simple_tsk_fn); + simple_tsk_fn = NULL; + mutex_unlock(&thread_mutex); } module_init(trace_event_init); diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h index 476429281389..a2c8b02b6359 100644 --- a/samples/trace_events/trace-events-sample.h +++ b/samples/trace_events/trace-events-sample.h @@ -1,6 +1,6 @@ /* * If TRACE_SYSTEM is defined, that will be the directory created - * in the ftrace directory under /sys/kernel/debug/tracing/events/<system> + * in the ftrace directory under /sys/kernel/tracing/events/<system> * * The define_trace.h below will also look for a file name of * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here. @@ -54,45 +54,347 @@ * Here it is simply "foo, bar". * * struct: This defines the way the data will be stored in the ring buffer. - * There are currently two types of elements. __field and __array. - * a __field is broken up into (type, name). Where type can be any - * primitive type (integer, long or pointer). __field_struct() can - * be any static complex data value (struct, union, but not an array). - * For an array. there are three fields. (type, name, size). The - * type of elements in the array, the name of the field and the size - * of the array. + * The items declared here become part of a special structure + * called "__entry", which can be used in the fast_assign part of the + * TRACE_EVENT macro. + * + * Here are the currently defined types you can use: + * + * __field : Is broken up into type and name. Where type can be any + * primitive type (integer, long or pointer). + * + * __field(int, foo) + * + * __entry->foo = 5; + * + * __field_struct : This can be any static complex data type (struct, union + * but not an array). Be careful using complex types, as each + * event is limited in size, and copying large amounts of data + * into the ring buffer can slow things down. + * + * __field_struct(struct bar, foo) + * + * __entry->bar.x = y; + + * __array: There are three fields (type, name, size). The type is the + * type of elements in teh array, the name is the name of the array. + * size is the number of items in the array (not the total size). + * + * __array( char, foo, 10) is the same as saying: char foo[10]; + * + * Assigning arrays can be done like any array: + * + * __entry->foo[0] = 'a'; + * + * memcpy(__entry->foo, bar, 10); + * + * __dynamic_array: This is similar to array, but can vary is size from + * instance to instance of the tracepoint being called. + * Like __array, this too has three elements (type, name, size); + * type is the type of the element, name is the name of the array. + * The size is different than __array. It is not a static number, + * but the algorithm to figure out the length of the array for the + * specific instance of tracepoint. Again, size is the numebr of + * items in the array, not the total length in bytes. + * + * __dynamic_array( int, foo, bar) is similar to: int foo[bar]; + * + * Note, unlike arrays, you must use the __get_dynamic_array() macro + * to access the array. + * + * memcpy(__get_dynamic_array(foo), bar, 10); + * + * Notice, that "__entry" is not needed here. + * + * __string: This is a special kind of __dynamic_array. It expects to + * have a nul terminated character array passed to it (it allows + * for NULL too, which would be converted into "(null)"). __string + * takes two paramenter (name, src), where name is the name of + * the string saved, and src is the string to copy into the + * ring buffer. + * + * __string(foo, bar) is similar to: strcpy(foo, bar) + * + * To assign a string, use the helper macro __assign_str(). + * + * __assign_str(foo, bar); + * + * In most cases, the __assign_str() macro will take the same + * parameters as the __string() macro had to declare the string. + * + * __bitmask: This is another kind of __dynamic_array, but it expects + * an array of longs, and the number of bits to parse. It takes + * two parameters (name, nr_bits), where name is the name of the + * bitmask to save, and the nr_bits is the number of bits to record. + * + * __bitmask(target_cpu, nr_cpumask_bits) + * + * To assign a bitmask, use the __assign_bitmask() helper macro. + * + * __assign_bitmask(target_cpus, cpumask_bits(bar), nr_cpumask_bits); * - * __array( char, foo, 10) is the same as saying char foo[10]. * * fast_assign: This is a C like function that is used to store the items - * into the ring buffer. + * into the ring buffer. A special variable called "__entry" will be the + * structure that points into the ring buffer and has the same fields as + * described by the struct part of TRACE_EVENT above. * * printk: This is a way to print out the data in pretty print. This is * useful if the system crashes and you are logging via a serial line, * the data can be printed to the console using this "printk" method. + * This is also used to print out the data from the trace files. + * Again, the __entry macro is used to access the data from the ring buffer. + * + * Note, __dynamic_array, __string, and __bitmask require special helpers + * to access the data. + * + * For __dynamic_array(int, foo, bar) use __get_dynamic_array(foo) + * Use __get_dynamic_array_len(foo) to get the length of the array + * saved. + * + * For __string(foo, bar) use __get_str(foo) + * + * For __bitmask(target_cpus, nr_cpumask_bits) use __get_bitmask(target_cpus) + * * * Note, that for both the assign and the printk, __entry is the handler * to the data structure in the ring buffer, and is defined by the * TP_STRUCT__entry. */ + +/* + * It is OK to have helper functions in the file, but they need to be protected + * from being defined more than once. Remember, this file gets included more + * than once. + */ +#ifndef __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS +#define __TRACE_EVENT_SAMPLE_HELPER_FUNCTIONS +static inline int __length_of(const int *list) +{ + int i; + + if (!list) + return 0; + + for (i = 0; list[i]; i++) + ; + return i; +} +#endif + TRACE_EVENT(foo_bar, - TP_PROTO(char *foo, int bar), + TP_PROTO(const char *foo, int bar, const int *lst, + const char *string, const struct cpumask *mask), - TP_ARGS(foo, bar), + TP_ARGS(foo, bar, lst, string, mask), TP_STRUCT__entry( __array( char, foo, 10 ) __field( int, bar ) + __dynamic_array(int, list, __length_of(lst)) + __string( str, string ) + __bitmask( cpus, num_possible_cpus() ) ), TP_fast_assign( strlcpy(__entry->foo, foo, 10); __entry->bar = bar; + memcpy(__get_dynamic_array(list), lst, + __length_of(lst) * sizeof(int)); + __assign_str(str, string); + __assign_bitmask(cpus, cpumask_bits(mask), num_possible_cpus()); + ), + + TP_printk("foo %s %d %s %s (%s)", __entry->foo, __entry->bar, + __print_array(__get_dynamic_array(list), + __get_dynamic_array_len(list), + sizeof(int)), + __get_str(str), __get_bitmask(cpus)) +); + +/* + * There may be a case where a tracepoint should only be called if + * some condition is set. Otherwise the tracepoint should not be called. + * But to do something like: + * + * if (cond) + * trace_foo(); + * + * Would cause a little overhead when tracing is not enabled, and that + * overhead, even if small, is not something we want. As tracepoints + * use static branch (aka jump_labels), where no branch is taken to + * skip the tracepoint when not enabled, and a jmp is placed to jump + * to the tracepoint code when it is enabled, having a if statement + * nullifies that optimization. It would be nice to place that + * condition within the static branch. This is where TRACE_EVENT_CONDITION + * comes in. + * + * TRACE_EVENT_CONDITION() is just like TRACE_EVENT, except it adds another + * parameter just after args. Where TRACE_EVENT has: + * + * TRACE_EVENT(name, proto, args, struct, assign, printk) + * + * the CONDITION version has: + * + * TRACE_EVENT_CONDITION(name, proto, args, cond, struct, assign, printk) + * + * Everything is the same as TRACE_EVENT except for the new cond. Think + * of the cond variable as: + * + * if (cond) + * trace_foo_bar_with_cond(); + * + * Except that the logic for the if branch is placed after the static branch. + * That is, the if statement that processes the condition will not be + * executed unless that traecpoint is enabled. Otherwise it still remains + * a nop. + */ +TRACE_EVENT_CONDITION(foo_bar_with_cond, + + TP_PROTO(const char *foo, int bar), + + TP_ARGS(foo, bar), + + TP_CONDITION(!(bar % 10)), + + TP_STRUCT__entry( + __string( foo, foo ) + __field( int, bar ) + ), + + TP_fast_assign( + __assign_str(foo, foo); + __entry->bar = bar; + ), + + TP_printk("foo %s %d", __get_str(foo), __entry->bar) +); + +void foo_bar_reg(void); +void foo_bar_unreg(void); + +/* + * Now in the case that some function needs to be called when the + * tracepoint is enabled and/or when it is disabled, the + * TRACE_EVENT_FN() serves this purpose. This is just like TRACE_EVENT() + * but adds two more parameters at the end: + * + * TRACE_EVENT_FN( name, proto, args, struct, assign, printk, reg, unreg) + * + * reg and unreg are functions with the prototype of: + * + * void reg(void) + * + * The reg function gets called before the tracepoint is enabled, and + * the unreg function gets called after the tracepoint is disabled. + * + * Note, reg and unreg are allowed to be NULL. If you only need to + * call a function before enabling, or after disabling, just set one + * function and pass in NULL for the other parameter. + */ +TRACE_EVENT_FN(foo_bar_with_fn, + + TP_PROTO(const char *foo, int bar), + + TP_ARGS(foo, bar), + + TP_STRUCT__entry( + __string( foo, foo ) + __field( int, bar ) + ), + + TP_fast_assign( + __assign_str(foo, foo); + __entry->bar = bar; + ), + + TP_printk("foo %s %d", __get_str(foo), __entry->bar), + + foo_bar_reg, foo_bar_unreg +); + +/* + * Each TRACE_EVENT macro creates several helper functions to produce + * the code to add the tracepoint, create the files in the trace + * directory, hook it to perf, assign the values and to print out + * the raw data from the ring buffer. To prevent too much bloat, + * if there are more than one tracepoint that uses the same format + * for the proto, args, struct, assign and printk, and only the name + * is different, it is highly recommended to use the DECLARE_EVENT_CLASS + * + * DECLARE_EVENT_CLASS() macro creates most of the functions for the + * tracepoint. Then DEFINE_EVENT() is use to hook a tracepoint to those + * functions. This DEFINE_EVENT() is an instance of the class and can + * be enabled and disabled separately from other events (either TRACE_EVENT + * or other DEFINE_EVENT()s). + * + * Note, TRACE_EVENT() itself is simply defined as: + * + * #define TRACE_EVENT(name, proto, args, tstruct, assign, printk) \ + * DEFINE_EVENT_CLASS(name, proto, args, tstruct, assign, printk); \ + * DEFINE_EVENT(name, name, proto, args) + * + * The DEFINE_EVENT() also can be declared with conditions and reg functions: + * + * DEFINE_EVENT_CONDITION(template, name, proto, args, cond); + * DEFINE_EVENT_FN(template, name, proto, args, reg, unreg); + */ +DECLARE_EVENT_CLASS(foo_template, + + TP_PROTO(const char *foo, int bar), + + TP_ARGS(foo, bar), + + TP_STRUCT__entry( + __string( foo, foo ) + __field( int, bar ) + ), + + TP_fast_assign( + __assign_str(foo, foo); + __entry->bar = bar; ), - TP_printk("foo %s %d", __entry->foo, __entry->bar) + TP_printk("foo %s %d", __get_str(foo), __entry->bar) ); + +/* + * Here's a better way for the previous samples (except, the first + * exmaple had more fields and could not be used here). + */ +DEFINE_EVENT(foo_template, foo_with_template_simple, + TP_PROTO(const char *foo, int bar), + TP_ARGS(foo, bar)); + +DEFINE_EVENT_CONDITION(foo_template, foo_with_template_cond, + TP_PROTO(const char *foo, int bar), + TP_ARGS(foo, bar), + TP_CONDITION(!(bar % 8))); + + +DEFINE_EVENT_FN(foo_template, foo_with_template_fn, + TP_PROTO(const char *foo, int bar), + TP_ARGS(foo, bar), + foo_bar_reg, foo_bar_unreg); + +/* + * Anytime two events share basically the same values and have + * the same output, use the DECLARE_EVENT_CLASS() and DEFINE_EVENT() + * when ever possible. + */ + +/* + * If the event is similar to the DECLARE_EVENT_CLASS, but you need + * to have a different output, then use DEFINE_EVENT_PRINT() which + * lets you override the TP_printk() of the class. + */ + +DEFINE_EVENT_PRINT(foo_template, foo_with_template_print, + TP_PROTO(const char *foo, int bar), + TP_ARGS(foo, bar), + TP_printk("bar %s %d", __get_str(foo), __entry->bar)); + #endif /***** NOTICE! The #if protection ends here. *****/ |