scripts/gdb: add a timer list command

Implement a command to print the timer list, much like how
/proc/timer_list is implemented. This can be used to look at the
pending timers on a crashed system.

[[e-mail]: v2]
Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>
Cc: Douglas Anderson <[e-mail]>
Cc: Nikolay Borisov <[e-mail]>
Cc: Kieran Bingham <[e-mail]>
Cc: Jan Kiszka <[e-mail]>
Cc: Jackie Liu <[e-mail]>
Cc: Jason Wessel <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

scripts/gdb/linux/constants.py.in

···
  */
 
 #include <linux/fs.h>
+#include <linux/hrtimer.h>
 #include <linux/mount.h>
 #include <linux/of_fdt.h>
+#include <linux/threads.h>
 
 /* We need to stringify expanded macros so that they can be parsed */
 
···
 LX_VALUE(SB_NOATIME)
 LX_VALUE(SB_NODIRATIME)
 
+/* linux/htimer.h */
+LX_GDBPARSED(hrtimer_resolution)
+
 /* linux/mount.h */
 LX_VALUE(MNT_NOSUID)
 LX_VALUE(MNT_NODEV)
···
 LX_VALUE(MNT_NODIRATIME)
 LX_VALUE(MNT_RELATIME)
 
+/* linux/threads.h */
+LX_VALUE(NR_CPUS)
+
 /* linux/of_fdt.h> */
 LX_VALUE(OF_DT_HEADER)
 
 /* Kernel Configs */
+LX_CONFIG(CONFIG_GENERIC_CLOCKEVENTS)
+LX_CONFIG(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
+LX_CONFIG(CONFIG_HIGH_RES_TIMERS)
+LX_CONFIG(CONFIG_NR_CPUS)
 LX_CONFIG(CONFIG_OF)
+LX_CONFIG(CONFIG_TICK_ONESHOT)

scripts/gdb/linux/timerlist.py

···
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright 2019 Google LLC.
+
+import binascii
+import gdb
+
+from linux import constants
+from linux import cpus
+from linux import rbtree
+from linux import utils
+
+timerqueue_node_type = utils.CachedType("struct timerqueue_node").get_type()
+hrtimer_type = utils.CachedType("struct hrtimer").get_type()
+
+
+def ktime_get():
+    """Returns the current time, but not very accurately
+
+    We can't read the hardware timer itself to add any nanoseconds
+    that need to be added since we last stored the time in the
+    timekeeper. But this is probably good enough for debug purposes."""
+    tk_core = gdb.parse_and_eval("&tk_core")
+
+    return tk_core['timekeeper']['tkr_mono']['base']
+
+
+def print_timer(rb_node, idx):
+    timerqueue = utils.container_of(rb_node, timerqueue_node_type.pointer(),
+                                    "node")
+    timer = utils.container_of(timerqueue, hrtimer_type.pointer(), "node")
+
+    function = str(timer['function']).split(" ")[1].strip("<>")
+    softexpires = timer['_softexpires']
+    expires = timer['node']['expires']
+    now = ktime_get()
+
+    text = " #{}: <{}>, {}, ".format(idx, timer, function)
+    text += "S:{:02x}\n".format(int(timer['state']))
+    text += " # expires at {}-{} nsecs [in {} to {} nsecs]\n".format(
+            softexpires, expires, softexpires - now, expires - now)
+    return text
+
+
+def print_active_timers(base):
+    curr = base['active']['next']['node']
+    curr = curr.address.cast(rbtree.rb_node_type.get_type().pointer())
+    idx = 0
+    while curr:
+        yield print_timer(curr, idx)
+        curr = rbtree.rb_next(curr)
+        idx += 1
+
+
+def print_base(base):
+    text = " .base:       {}\n".format(base.address)
+    text += " .index:      {}\n".format(base['index'])
+
+    text += " .resolution: {} nsecs\n".format(constants.LX_hrtimer_resolution)
+
+    text += " .get_time:   {}\n".format(base['get_time'])
+    if constants.LX_CONFIG_HIGH_RES_TIMERS:
+        text += "  .offset:     {} nsecs\n".format(base['offset'])
+    text += "active timers:\n"
+    text += "".join([x for x in print_active_timers(base)])
+    return text
+
+
+def print_cpu(hrtimer_bases, cpu, max_clock_bases):
+    cpu_base = cpus.per_cpu(hrtimer_bases, cpu)
+    jiffies = gdb.parse_and_eval("jiffies_64")
+    tick_sched_ptr = gdb.parse_and_eval("&tick_cpu_sched")
+    ts = cpus.per_cpu(tick_sched_ptr, cpu)
+
+    text = "cpu: {}\n".format(cpu)
+    for i in xrange(max_clock_bases):
+        text += " clock {}:\n".format(i)
+        text += print_base(cpu_base['clock_base'][i])
+
+        if constants.LX_CONFIG_HIGH_RES_TIMERS:
+            fmts = [("  .{}   : {} nsecs", 'expires_next'),
+                    ("  .{}    : {}", 'hres_active'),
+                    ("  .{}      : {}", 'nr_events'),
+                    ("  .{}     : {}", 'nr_retries'),
+                    ("  .{}       : {}", 'nr_hangs'),
+                    ("  .{}  : {}", 'max_hang_time')]
+            text += "\n".join([s.format(f, cpu_base[f]) for s, f in fmts])
+            text += "\n"
+
+        if constants.LX_CONFIG_TICK_ONESHOT:
+            fmts = [("  .{}      : {}", 'nohz_mode'),
+                    ("  .{}      : {} nsecs", 'last_tick'),
+                    ("  .{}   : {}", 'tick_stopped'),
+                    ("  .{}   : {}", 'idle_jiffies'),
+                    ("  .{}     : {}", 'idle_calls'),
+                    ("  .{}    : {}", 'idle_sleeps'),
+                    ("  .{} : {} nsecs", 'idle_entrytime'),
+                    ("  .{}  : {} nsecs", 'idle_waketime'),
+                    ("  .{}  : {} nsecs", 'idle_exittime'),
+                    ("  .{} : {} nsecs", 'idle_sleeptime'),
+                    ("  .{}: {} nsecs", 'iowait_sleeptime'),
+                    ("  .{}   : {}", 'last_jiffies'),
+                    ("  .{}     : {}", 'next_timer'),
+                    ("  .{}   : {} nsecs", 'idle_expires')]
+            text += "\n".join([s.format(f, ts[f]) for s, f in fmts])
+            text += "\njiffies: {}\n".format(jiffies)
+
+        text += "\n"
+
+    return text
+
+
+def print_tickdevice(td, cpu):
+    dev = td['evtdev']
+    text = "Tick Device: mode:     {}\n".format(td['mode'])
+    if cpu < 0:
+            text += "Broadcast device\n"
+    else:
+            text += "Per CPU device: {}\n".format(cpu)
+
+    text += "Clock Event Device: "
+    if dev == 0:
+            text += "<NULL>\n"
+            return text
+
+    text += "{}\n".format(dev['name'])
+    text += " max_delta_ns:   {}\n".format(dev['max_delta_ns'])
+    text += " min_delta_ns:   {}\n".format(dev['min_delta_ns'])
+    text += " mult:           {}\n".format(dev['mult'])
+    text += " shift:          {}\n".format(dev['shift'])
+    text += " mode:           {}\n".format(dev['state_use_accessors'])
+    text += " next_event:     {} nsecs\n".format(dev['next_event'])
+
+    text += " set_next_event: {}\n".format(dev['set_next_event'])
+
+    members = [('set_state_shutdown', " shutdown: {}\n"),
+               ('set_state_periodic', " periodic: {}\n"),
+               ('set_state_oneshot', " oneshot:  {}\n"),
+               ('set_state_oneshot_stopped', " oneshot stopped: {}\n"),
+               ('tick_resume', " resume:   {}\n")]
+    for member, fmt in members:
+        if dev[member]:
+            text += fmt.format(dev[member])
+
+    text += " event_handler:  {}\n".format(dev['event_handler'])
+    text += " retries:        {}\n".format(dev['retries'])
+
+    return text
+
+
+def pr_cpumask(mask):
+    nr_cpu_ids = 1
+    if constants.LX_NR_CPUS > 1:
+        nr_cpu_ids = gdb.parse_and_eval("nr_cpu_ids")
+
+    inf = gdb.inferiors()[0]
+    bits = mask['bits']
+    num_bytes = (nr_cpu_ids + 7) / 8
+    buf = utils.read_memoryview(inf, bits, num_bytes).tobytes()
+    buf = binascii.b2a_hex(buf)
+
+    chunks = []
+    i = num_bytes
+    while i > 0:
+        i -= 1
+        start = i * 2
+        end = start + 2
+        chunks.append(buf[start:end])
+        if i != 0 and i % 4 == 0:
+            chunks.append(',')
+
+    extra = nr_cpu_ids % 8
+    if 0 < extra <= 4:
+        chunks[0] = chunks[0][0]  # Cut off the first 0
+
+    return "".join(chunks)
+
+
+class LxTimerList(gdb.Command):
+    """Print /proc/timer_list"""
+
+    def __init__(self):
+        super(LxTimerList, self).__init__("lx-timerlist", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        hrtimer_bases = gdb.parse_and_eval("&hrtimer_bases")
+        max_clock_bases = gdb.parse_and_eval("HRTIMER_MAX_CLOCK_BASES")
+
+        text = "Timer List Version: gdb scripts\n"
+        text += "HRTIMER_MAX_CLOCK_BASES: {}\n".format(max_clock_bases)
+        text += "now at {} nsecs\n".format(ktime_get())
+
+        for cpu in cpus.each_online_cpu():
+            text += print_cpu(hrtimer_bases, cpu, max_clock_bases)
+
+        if constants.LX_CONFIG_GENERIC_CLOCKEVENTS:
+            if constants.LX_CONFIG_GENERIC_CLOCKEVENTS_BROADCAST:
+                bc_dev = gdb.parse_and_eval("&tick_broadcast_device")
+                text += print_tickdevice(bc_dev, -1)
+                text += "\n"
+                mask = gdb.parse_and_eval("tick_broadcast_mask")
+                mask = pr_cpumask(mask)
+                text += "tick_broadcast_mask: {}\n".format(mask)
+                if constants.LX_CONFIG_TICK_ONESHOT:
+                    mask = gdb.parse_and_eval("tick_broadcast_oneshot_mask")
+                    mask = pr_cpumask(mask)
+                    text += "tick_broadcast_oneshot_mask: {}\n".format(mask)
+                text += "\n"
+
+            tick_cpu_devices = gdb.parse_and_eval("&tick_cpu_device")
+            for cpu in cpus.each_online_cpu():
+                tick_dev = cpus.per_cpu(tick_cpu_devices, cpu)
+                text += print_tickdevice(tick_dev, cpu)
+                text += "\n"
+
+        gdb.write(text)
+
+
+LxTimerList()

scripts/gdb/vmlinux-gdb.py

···
     import linux.rbtree
     import linux.proc
     import linux.constants
+    import linux.timerlist