Hello, This is the 5th version of the series for the boot-time tracing. Previous version is here. https://lkml.kernel.org/r/157528159833.22451.14878731055438721716.stgit@devnote2 In this version, I removed RFC tag from the series. Changes from the v4 are here, updating bootconfig things. - [1/22] Fix help comment and indent of Kconfig. Restrict available characters in values(*) Drop backslash escape from quoted value(**) - [3/22] Fix Makefile to compile tool correctly Remove unused pattern from Makefile - [4/22] Show test target bootconfig Add printable value testcases Add bad array testcase - [9/22] Fix TOC list Add notes about available characters. Fix to use correct quotes (``) for .rst. (*) this is for preventing admin from shoot himself. (**) this rule is from legacy command line. Boot-time tracing features are not modified. I know Tom is working on exporting synthetic event (and dynamic events) APIs for module. If that APIs are merged first, I will update my series on top of that. This series can be applied on v5.5-rc3 or directly available at; https://github.com/mhiramat/linux.git ftrace-boottrace-v5 Extra Boot Config ================= Extra boot config allows admin to pass a tree-structured key-value list when booting up the kernel. This expands the kernel command line in an efficient way. Each key is described as a dot-jointed-words. And user can write the key-words in tree stlye. (In this version, the tailing ';' becomes optional. See Documentation/admin-guide/bootconfig.rst) For example, feature.option.foo = 1 feature.option.bar = 2 can be also written in feature.option { foo = 1 bar = 2 } or more compact, feature.option{foo=1;bar=2} (Note that in both style, the same words are merged automatically and make a single tree) All values are treated as a string, or array of strings, e.g. feature.options = "foo", "bar" User can see the loaded key-value list via /proc/bootconfig. The size is limited upto 32KB and 1024 key-words and values in total. Boot with a Boot Config ======================= This version doesn't require to modify boot loaders anymore. The boot config is loaded with initrd, and there is new "bootconfig" command under tools/bootconfig. To add (append) a bootconfig file to an initrd, you can use the bootconfig command like: # tools/bootconfig/bootconfig -a your-config /boot/initrd.img-X.Y.Z This verifies the configuration file too. Boot-time Tracing ================= Boot-time tracing supports following boot configs. Please read Documentation/trace/boottime-trace.rst for details. - kernel.dump_on_oops [= MODE] - kernel.traceoff_on_warning - kernel.tp_printk - kernel.fgraph_filters = FILTER[, FILTER2...] - kernel.fgraph_notraces = FILTER[, FILTER2...] - kernel.fgraph_max_depth = MAX_DEPTH - ftrace.[instance.INSTANCE.]options = OPT1[,OPT2...] - ftrace.[instance.INSTANCE.]trace_clock = CLOCK - ftrace.[instance.INSTANCE.]buffer_size = SIZE - ftrace.[instance.INSTANCE.]alloc_snapshot - ftrace.[instance.INSTANCE.]cpumask = CPUMASK - ftrace.[instance.INSTANCE.]events = EVENT[, EVENT2...] - ftrace.[instance.INSTANCE.]tracer = TRACER - ftrace.[instance.INSTANCE.]ftrace.filters - ftrace.[instance.INSTANCE.]ftrace.notraces - ftrace.[instance.INSTANCE.]event.GROUP.EVENT.filter = FILTER - ftrace.[instance.INSTANCE.]event.GROUP.EVENT.actions = ACTION[, ACTION2...] - ftrace.[instance.INSTANCE.]event.GROUP.EVENT.enable - ftrace.[instance.INSTANCE.]event.kprobes.EVENT.probes = PROBE[, PROBE2...] - ftrace.[instance.INSTANCE.]event.synthetic.EVENT.fields = FIELD[, FIELD2...] Kernel and Init Command Line ============================ Boot config also supports kernel and init command line parameters except for early kernel parameters. In boot config, all key-values start with "kernel." are automatically merged into user passed boot command line, and key-values which start with "init." are also passed to init. These options are visible on /proc/cmdline. For example, kernel { audit = on audit_backlog_limit = 256 } init.systemd.unified_cgroup_hierarchy = 1 Usage ===== With this series, we can setup new kprobe and synthetic events, more complicated event filters and trigger actions including histogram via supplemental kernel cmdline. We can add filter and actions for each event, define kprobe events, and synthetic events with histogram like below. ftrace.event { task.task_newtask { filter = "pid < 128" enable } kprobes.vfs_read { probes = "vfs_read $arg1 $arg2" filter = "common_pid < 200" enable } synthetic.initcall_latency { fields = "unsigned long func", "u64 lat" actions = "hist:keys=func.sym,lat:vals=lat:sort=lat" } initcall.initcall_start { actions = "hist:keys=func:ts0=common_timestamp.usecs" } initcall.initcall_finish { actions = "hist:keys=func:lat=common_timestamp.usecs-$ts0:onmatch(initcall.initcall_start).initcall_latency(func,$lat)" } } Also, this supports "instance" node, which allows us to run several tracers for different purpose at once. For example, one tracer is for tracing functions start with "user_", and others tracing "kernel_", you can write boot config as: ftrace.instance { foo { tracer = "function" ftrace-filters = "user_*" } bar { tracer = "function" ftrace-filters = "function_*" } } The instance node also accepts event nodes so that each instance can customize its event tracing. This boot-time trace also supports ftrace kernel parameters. For example, following kernel parameters trace_options=sym-addr trace_event=initcall:* tp_printk trace_buf_size=1M ftrace=function ftrace_filter="vfs*" it can be written in boot config like below. ftrace { options = sym-addr; events = "initcall:*"; tp-printk; buffer-size = 1MB; ftrace-filters = "vfs*"; } However, since the initialization timing is different, if you need to trace very early boot, please use normal kernel parameters. Some Notes ========== - To align the legacy command line rule, I made the quotes (double quotes or single quotes) not able to be escaped. Also, this rejects non-printable chars (except for space). Actually legacy cmdline accepts any of them, but it might confuse users if they put a control code by mistake. Imagine that they put a "\b" on it... - Since it is not easy to write boot-time tracing without any bug in bootconfig, a user-helper command will be needed. That command will generate a boot config file from current ftrace settings, or try to apply given boot config setting to the ftrace. - It is also possible to embed boot config file into the kernel image for the environment which doesn't use initrd. But in that case, user can not update the boot config. - As you can see, the EVENT.actions value is a bit ugly since histogram interface settings are bit complicated. Maybe we can introduce more abstractive syntax for that. e.g. ftrace.event.synthetic.initcall_latency { fields = "unsigned long func", "u64 lat" hist { from { event = initcall.initcall_start key = func assigns = "ts0=common_timestamp.usecs" } to { event = initcall.initcall_finish key = func assigns = "lat=common_timestamp.usecs-$ts0" onmatch = func, $lat } keys = func.sym, lat vals = lat sort = lat } } Any suggestions, thoughts? Thank you, --- Masami Hiramatsu (22): bootconfig: Add Extra Boot Config support bootconfig: Load boot config from the tail of initrd tools: bootconfig: Add bootconfig command tools: bootconfig: Add bootconfig test script proc: bootconfig: Add /proc/bootconfig to show boot config list init/main.c: Alloc initcall_command_line in do_initcall() and free it bootconfig: init: Allow admin to use bootconfig for kernel command line bootconfig: init: Allow admin to use bootconfig for init command line Documentation: bootconfig: Add a doc for extended boot config tracing: Apply soft-disabled and filter to tracepoints printk tracing: kprobes: Output kprobe event to printk buffer tracing: kprobes: Register to dynevent earlier stage tracing: Accept different type for synthetic event fields tracing: Add NULL trace-array check in print_synth_event() tracing/boot: Add boot-time tracing tracing/boot: Add per-event settings tracing/boot Add kprobe event support tracing/boot: Add synthetic event support tracing/boot: Add instance node support tracing/boot: Add cpu_mask option support tracing/boot: Add function tracer filter options Documentation: tracing: Add boot-time tracing document tools/bootconfig/.gitignore | 1 tools/bootconfig/Makefile | 23 ++ tools/bootconfig/include/linux/bootconfig.h | 7 tools/bootconfig/include/linux/bug.h | 12 + tools/bootconfig/include/linux/ctype.h | 7 tools/bootconfig/include/linux/errno.h | 7 tools/bootconfig/include/linux/kernel.h | 18 + tools/bootconfig/include/linux/printk.h | 13 + tools/bootconfig/include/linux/string.h | 32 ++ tools/bootconfig/main.c | 337 +++++++++++++++++++++++ tools/bootconfig/samples/bad-array.bconf | 2 tools/bootconfig/samples/bad-dotword.bconf | 4 tools/bootconfig/samples/bad-empty.bconf | 1 tools/bootconfig/samples/bad-keyerror.bconf | 2 tools/bootconfig/samples/bad-longkey.bconf | 1 tools/bootconfig/samples/bad-manywords.bconf | 1 tools/bootconfig/samples/bad-no-keyword.bconf | 2 tools/bootconfig/samples/bad-nonprintable.bconf | 2 tools/bootconfig/samples/bad-spaceword.bconf | 2 tools/bootconfig/samples/bad-tree.bconf | 5 tools/bootconfig/samples/bad-value.bconf | 3 tools/bootconfig/samples/escaped.bconf | 3 tools/bootconfig/samples/good-printables.bconf | 2 tools/bootconfig/samples/good-simple.bconf | 11 + tools/bootconfig/samples/good-single.bconf | 4 tools/bootconfig/samples/good-tree.bconf | 12 + tools/bootconfig/test-bootconfig.sh | 80 +++++ 27 files changed, 594 insertions(+) create mode 100644 tools/bootconfig/.gitignore create mode 100644 tools/bootconfig/Makefile create mode 100644 tools/bootconfig/include/linux/bootconfig.h create mode 100644 tools/bootconfig/include/linux/bug.h create mode 100644 tools/bootconfig/include/linux/ctype.h create mode 100644 tools/bootconfig/include/linux/errno.h create mode 100644 tools/bootconfig/include/linux/kernel.h create mode 100644 tools/bootconfig/include/linux/printk.h create mode 100644 tools/bootconfig/include/linux/string.h create mode 100644 tools/bootconfig/main.c create mode 100644 tools/bootconfig/samples/bad-array.bconf create mode 100644 tools/bootconfig/samples/bad-dotword.bconf create mode 100644 tools/bootconfig/samples/bad-empty.bconf create mode 100644 tools/bootconfig/samples/bad-keyerror.bconf create mode 100644 tools/bootconfig/samples/bad-longkey.bconf create mode 100644 tools/bootconfig/samples/bad-manywords.bconf create mode 100644 tools/bootconfig/samples/bad-no-keyword.bconf create mode 100644 tools/bootconfig/samples/bad-nonprintable.bconf create mode 100644 tools/bootconfig/samples/bad-spaceword.bconf create mode 100644 tools/bootconfig/samples/bad-tree.bconf create mode 100644 tools/bootconfig/samples/bad-value.bconf create mode 100644 tools/bootconfig/samples/escaped.bconf create mode 100644 tools/bootconfig/samples/good-printables.bconf create mode 100644 tools/bootconfig/samples/good-simple.bconf create mode 100644 tools/bootconfig/samples/good-single.bconf create mode 100644 tools/bootconfig/samples/good-tree.bconf create mode 100755 tools/bootconfig/test-bootconfig.sh -- Masami Hiramatsu (Linaro) <mhiramat@xxxxxxxxxx>
