libhermit/usr/gdb

GDB-scripts for HermitCore awareness

The scripts located in this folder can be used when debugging HermitCore applications to gain more insight into kernel internals.

To use the scripts you have to load them from inside GDB:

(gdb) source ../gdb/hermit-gdb.py

Examples

Show state of all tasks:

(gdb) hermit-ps 
 ID | STATE | CPU | PRIO |      STACK | INSTRUCTION POINTER
--------------------------------------------------------------------
  0 |  IDL  |   0 |    0 |   0x87f000 | 0x81108c <rollback>
  1 |  IDL  |   1 |    0 |   0x881000 | 0x81108c <rollback>
  2 |  BLK  |   0 |    8 |    0xd6000 | 0x81108c <rollback>
  3 |  BLK  |   0 |   16 |    0xf8000 | 0x81108c <rollback>
  4 |  RUN  |   1 |    8 |   0x10e000 | 0x981ee8 <thread_func1+40>
  5 |  RUN  |   0 |    8 |   0x124000 | 0x981e98 <thread_func2+40>

Investigate state of specific task:

(gdb) print $hermit_task_by_id(2)
$1 = {id = 2, status = 3, last_core = 0, last_stack_pointer = 0x107e60, stack = 0xf8000, ist_addr = 0xe7000, flags = 0 '\000', 
  prio = 16 '\020', timeout = 883, start_tick = 207, heap = 0x0, parent = 0, next = 0x0, prev = 0x0, tls_addr = 12204928, 
  tls_size = 24, lwip_err = 0, signal_handler = 0x0, fpu = {fsave = {cwd = 0, swd = 0, twd = 0, fip = 0, fcs = 0, foo = 0, fos = 0, 
      st_space = {0 <repeats 20 times>}, status = 0}, fxsave = {cwd = 0, swd = 0, twd = 0, fop = 0, {{rip = 0, rdp = 0}, {fip = 0, 
          fcs = 0, foo = 0, fos = 0}}, mxcsr = 0, mxcsr_mask = 0, st_space = {0 <repeats 32 times>}, xmm_space = {
        0 <repeats 64 times>}, padding = {0 <repeats 12 times>}, {padding1 = {0 <repeats 12 times>}, sw_reserved = {
          0 <repeats 12 times>}}}, xsave = {fxsave = {cwd = 0, swd = 0, twd = 0, fop = 0, {{rip = 0, rdp = 0}, {fip = 0, fcs = 0, 
            foo = 0, fos = 0}}, mxcsr = 0, mxcsr_mask = 0, st_space = {0 <repeats 32 times>}, xmm_space = {0 <repeats 64 times>}, 
        padding = {0 <repeats 12 times>}, {padding1 = {0 <repeats 12 times>}, sw_reserved = {0 <repeats 12 times>}}}, hdr = {
        xstate_bv = 0, xcomp_bv = 0, reserved = {0, 0, 0, 0, 0, 0}}, ymmh = {ymmh_space = {0 <repeats 64 times>}}}}}

Show registered signal handlers (by hermit_signal(signal_handler_t handler)). Note that these are not signal handlers registered by newlib (signal(int sig, _sig_func_ptr func)).

(gdb) hermit-ls-sighandler
 ID | Signal Handler
------------------------------
  0 | 0x0
  1 | 0x0
  2 | 0x989660 <signal_dispatcher>
  3 | 0x0
  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