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Merge pull request #34 from daniel-k/pr/gdb_task_backtrace

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gdb-scripts: backtrace and context switching for tasks
This commit is contained in:
Stefan Lankes 2016-08-30 22:00:33 +02:00 • committed by GitHub
commit 2c8a1a3a45
2 changed files with 211 additions and 3 deletions
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50
hermit/usr/gdb/README.md
View file

@ -57,3 +57,53 @@ Note that these are not signal handlers registered by newlib
4 | 0x989660 <signal_dispatcher>
5 | 0x989660 <signal_dispatcher>
```
Show backtrace of suspended (or any) task:
```
(gdb) hermit-ps
ID | STATE | CPU | PRIO | STACK | INSTRUCTION POINTER
--------------------------------------------------------------------
0 | IDL | 0 | 0 | 0x88d000 | 0x80a756 <reschedule+41>
1 | IDL | 1 | 0 | 0x88f000 | 0x80a756 <reschedule+41>
2 | IDL | 2 | 0 | 0x891000 | 0x80a756 <reschedule+41>
3 | IDL | 3 | 0 | 0x893000 | 0x80a756 <reschedule+41>
4 | BLK | 0 | 8 | 0xde000 | 0x80a756 <reschedule+41>
5 | BLK | 0 | 16 | 0xf8000 | 0x80a756 <reschedule+41>
6 | RUN | 1 | 8 | 0x115000 | 0x990070 <thread_func+64>
7 | RUN | 2 | 8 | 0x12b000 | 0x990070 <thread_func+64>
8 | RUN | 3 | 8 | 0x141000 | 0x990070 <thread_func+64>
9 | RUN | 0 | 8 | 0x157000 | 0x990070 <thread_func+64>
(gdb) hermit-bt 4
#0 0x000000000081701c in rollback ()
#1 0x000000000080a756 in reschedule () at kernel/tasks.c:909
#2 0x0000000000813f7b in timer_wait (ticks=50) at arch/x86/kernel/timer.c:139
#3 0x000000000080b9f7 in sys_msleep (ms=500) at kernel/syscall.c:357
#4 0x000000000098fd5e in main ()
```
Switch current context to any task to investigate call stack. Remember to
restore the context if you want to continue execution.
```
(gdb) info threads
Id Target Id Frame
* 1 Thread 1 (CPU#0 [running]) 0x0000000000990070 in thread_func ()
2 Thread 2 (CPU#1 [running]) 0x0000000000990070 in thread_func ()
3 Thread 3 (CPU#2 [running]) 0x0000000000990070 in thread_func ()
4 Thread 4 (CPU#3 [running]) 0x0000000000990070 in thread_func ()
(gdb) hermit-switch-context 4
(gdb) info threads
Id Target Id Frame
* 1 Thread 1 (CPU#0 [running]) 0x000000000081701c in rollback ()
2 Thread 2 (CPU#1 [running]) 0x0000000000990070 in thread_func ()
3 Thread 3 (CPU#2 [running]) 0x0000000000990070 in thread_func ()
4 Thread 4 (CPU#3 [running]) 0x0000000000990070 in thread_func ()
(gdb) bt
#0 0x000000000081701c in rollback ()
#1 0x000000000080a756 in reschedule () at kernel/tasks.c:909
#2 0x0000000000813f7b in timer_wait (ticks=50) at arch/x86/kernel/timer.c:139
#3 0x000000000080b9f7 in sys_msleep (ms=500) at kernel/syscall.c:357
#4 0x000000000098fd5e in main ()
(gdb) hermit-restore-context
```

164
hermit/usr/gdb/hermit/tasks.py
View file

@ -136,9 +136,6 @@ class HermitLsSighandler(gdb.Command):
gdb.write(header)
gdb.write((len(header) - 1) * '-' + '\n')
inferior = gdb.selected_inferior()
currentInferiorThread = gdb.selected_thread()
for task in task_lists():
gdb.write(rowfmt.format(
@ -147,3 +144,164 @@ class HermitLsSighandler(gdb.Command):
))
HermitLsSighandler()
def stripSymbol(value):
s = "%s" % value
return s.split(' ')[0]
class HermitTaskState:
def __init__(self, address = None):
import re
self.info_reg_regex = re.compile("(?P<register>[\w]+)\s+(?P<value>0x[0-9a-f]+).*")
if address:
self.address = address
self.registers = {
'gs': self.address + 0,
'fs': self.address + 1,
'r15': self.address + 2,
'r14': self.address + 3,
'r13': self.address + 4,
'r12': self.address + 5,
'r11': self.address + 6,
'r10': self.address + 7,
'r9': self.address + 8,
'r8': self.address + 9,
'rdi': self.address + 10,
'rsi': self.address + 11,
'rbp': self.address + 12,
'rsp': self.address + 13,
'rbx': self.address + 14,
'rdx': self.address + 15,
'rcx': self.address + 16,
'rax': self.address + 17,
# int_no
# error
'rip': self.address + 20,
'cs': self.address + 21,
'eflags': self.address + 22,
# userrsp
'ss': self.address + 24,
}
# make nice strings out of register values
for register, valptr in self.registers.items():
self.registers[register] = stripSymbol(valptr.dereference())
else:
self.address = False
self.info_registers = gdb.execute('info registers', to_string=True)
self.registers = {}
for line in self.info_registers.split('\n'):
match = self.info_reg_regex.match(line)
if match:
self.registers[match.group('register')] = match.group('value')
def switch(self):
for register, value in self.registers.items():
try:
gdb.execute("set $%s = %s" % (register, value))
except:
print("Cannot restore %s=%s, skipping ..." % (register, value))
class HermitTaskBacktrace(gdb.Command):
"""Show backtrace for HermitCore task.
Usage: hermit-bt ID"""
def __init__(self):
super(HermitTaskBacktrace, self).__init__("hermit-bt", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
argv = gdb.string_to_argv(arg)
if len(argv) != 1:
raise gdb.GdbError("hermit-bt takes one argument")
task = get_task_by_pid(int(argv[0]))
if task['status'] == 2:
gdb.execute('bt')
return
current_state = HermitTaskState()
task_state = HermitTaskState(task['last_stack_pointer'])
try:
task_state.switch()
gdb.execute('bt')
finally:
current_state.switch()
HermitTaskBacktrace()
original_state = {}
def saveCurrentState(state):
curr_thread = gdb.selected_thread()
for thread in gdb.selected_inferior().threads():
if not thread.num in state:
thread.switch()
state[thread.num] = HermitTaskState()
curr_thread.switch()
def restoreCurrentState(state):
curr_thread = gdb.selected_thread()
for thread in gdb.selected_inferior().threads():
if thread.num in state:
thread.switch()
state[thread.num].switch()
curr_thread.switch()
state = {}
class HermitSwitchContext(gdb.Command):
"""Switch current context to given HermitCore task
Usage: hermit-switch-context ID"""
def __init__(self):
super(HermitSwitchContext, self).__init__("hermit-switch-context", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
global original_state
argv = gdb.string_to_argv(arg)
if len(argv) != 1:
raise gdb.GdbError("hermit-switch-context takes one argument")
# save original state to go back to it later
saveCurrentState(original_state)
task = get_task_by_pid(int(argv[0]))
# switch current inferior thread to where task has run last
for thread in gdb.selected_inferior().threads():
if (thread.num - 1) == task['last_core']:
thread.switch()
break
# apply it's state
task_state = HermitTaskState(task['last_stack_pointer'])
task_state.switch()
HermitSwitchContext()
class HermitRestoreContext(gdb.Command):
"""Restore context to state before it was switched
Usage: hermit-restore-context"""
def __init__(self):
super(HermitRestoreContext, self).__init__("hermit-restore-context", gdb.COMMAND_DATA)
def invoke(self, arg, from_tty):
global original_state
restoreCurrentState(original_state)
HermitRestoreContext()