1# 2# gdb helper commands and functions for Linux kernel debugging 3# 4# per-cpu tools 5# 6# Copyright (c) Siemens AG, 2011-2013 7# 8# Authors: 9# Jan Kiszka <jan.kiszka@siemens.com> 10# 11# This work is licensed under the terms of the GNU GPL version 2. 12# 13 14import gdb 15 16from linux import tasks, utils 17 18 19task_type = utils.CachedType("struct task_struct") 20 21 22MAX_CPUS = 4096 23 24 25def get_current_cpu(): 26 if utils.get_gdbserver_type() == utils.GDBSERVER_QEMU: 27 return gdb.selected_thread().num - 1 28 elif utils.get_gdbserver_type() == utils.GDBSERVER_KGDB: 29 tid = gdb.selected_thread().ptid[2] 30 if tid > (0x100000000 - MAX_CPUS - 2): 31 return 0x100000000 - tid - 2 32 else: 33 return tasks.get_thread_info(tasks.get_task_by_pid(tid))['cpu'] 34 else: 35 raise gdb.GdbError("Sorry, obtaining the current CPU is not yet " 36 "supported with this gdb server.") 37 38 39def per_cpu(var_ptr, cpu): 40 if cpu == -1: 41 cpu = get_current_cpu() 42 if utils.is_target_arch("sparc:v9"): 43 offset = gdb.parse_and_eval( 44 "trap_block[{0}].__per_cpu_base".format(str(cpu))) 45 else: 46 try: 47 offset = gdb.parse_and_eval( 48 "__per_cpu_offset[{0}]".format(str(cpu))) 49 except gdb.error: 50 # !CONFIG_SMP case 51 offset = 0 52 pointer = var_ptr.cast(utils.get_long_type()) + offset 53 return pointer.cast(var_ptr.type).dereference() 54 55 56cpu_mask = {} 57 58 59def cpu_mask_invalidate(event): 60 global cpu_mask 61 cpu_mask = {} 62 gdb.events.stop.disconnect(cpu_mask_invalidate) 63 if hasattr(gdb.events, 'new_objfile'): 64 gdb.events.new_objfile.disconnect(cpu_mask_invalidate) 65 66 67def cpu_list(mask_name): 68 global cpu_mask 69 mask = None 70 if mask_name in cpu_mask: 71 mask = cpu_mask[mask_name] 72 if mask is None: 73 mask = gdb.parse_and_eval(mask_name + ".bits") 74 if hasattr(gdb, 'events'): 75 cpu_mask[mask_name] = mask 76 gdb.events.stop.connect(cpu_mask_invalidate) 77 if hasattr(gdb.events, 'new_objfile'): 78 gdb.events.new_objfile.connect(cpu_mask_invalidate) 79 bits_per_entry = mask[0].type.sizeof * 8 80 num_entries = mask.type.sizeof * 8 / bits_per_entry 81 entry = -1 82 bits = 0 83 84 while True: 85 while bits == 0: 86 entry += 1 87 if entry == num_entries: 88 return 89 bits = mask[entry] 90 if bits != 0: 91 bit = 0 92 break 93 94 while bits & 1 == 0: 95 bits >>= 1 96 bit += 1 97 98 cpu = entry * bits_per_entry + bit 99 100 bits >>= 1 101 bit += 1 102 103 yield int(cpu) 104 105 106def each_online_cpu(): 107 for cpu in cpu_list("__cpu_online_mask"): 108 yield cpu 109 110 111def each_present_cpu(): 112 for cpu in cpu_list("__cpu_present_mask"): 113 yield cpu 114 115 116def each_possible_cpu(): 117 for cpu in cpu_list("__cpu_possible_mask"): 118 yield cpu 119 120 121def each_active_cpu(): 122 for cpu in cpu_list("__cpu_active_mask"): 123 yield cpu 124 125 126class LxCpus(gdb.Command): 127 """List CPU status arrays 128 129Displays the known state of each CPU based on the kernel masks 130and can help identify the state of hotplugged CPUs""" 131 132 def __init__(self): 133 super(LxCpus, self).__init__("lx-cpus", gdb.COMMAND_DATA) 134 135 def invoke(self, arg, from_tty): 136 gdb.write("Possible CPUs : {}\n".format(list(each_possible_cpu()))) 137 gdb.write("Present CPUs : {}\n".format(list(each_present_cpu()))) 138 gdb.write("Online CPUs : {}\n".format(list(each_online_cpu()))) 139 gdb.write("Active CPUs : {}\n".format(list(each_active_cpu()))) 140 141 142LxCpus() 143 144 145class PerCpu(gdb.Function): 146 """Return per-cpu variable. 147 148$lx_per_cpu("VAR"[, CPU]): Return the per-cpu variable called VAR for the 149given CPU number. If CPU is omitted, the CPU of the current context is used. 150Note that VAR has to be quoted as string.""" 151 152 def __init__(self): 153 super(PerCpu, self).__init__("lx_per_cpu") 154 155 def invoke(self, var_name, cpu=-1): 156 var_ptr = gdb.parse_and_eval("&" + var_name.string()) 157 return per_cpu(var_ptr, cpu) 158 159 160PerCpu() 161 162def get_current_task(cpu): 163 task_ptr_type = task_type.get_type().pointer() 164 165 if utils.is_target_arch("x86"): 166 if gdb.lookup_global_symbol("cpu_tasks"): 167 # This is a UML kernel, which stores the current task 168 # differently than other x86 sub architectures 169 var_ptr = gdb.parse_and_eval("(struct task_struct *)cpu_tasks[0].task") 170 return var_ptr.dereference() 171 else: 172 var_ptr = gdb.parse_and_eval("&pcpu_hot.current_task") 173 return per_cpu(var_ptr, cpu).dereference() 174 elif utils.is_target_arch("aarch64"): 175 current_task_addr = gdb.parse_and_eval("$SP_EL0") 176 if (current_task_addr >> 63) != 0: 177 current_task = current_task_addr.cast(task_ptr_type) 178 return current_task.dereference() 179 else: 180 raise gdb.GdbError("Sorry, obtaining the current task is not allowed " 181 "while running in userspace(EL0)") 182 else: 183 raise gdb.GdbError("Sorry, obtaining the current task is not yet " 184 "supported with this arch") 185 186class LxCurrentFunc(gdb.Function): 187 """Return current task. 188 189$lx_current([CPU]): Return the per-cpu task variable for the given CPU 190number. If CPU is omitted, the CPU of the current context is used.""" 191 192 def __init__(self): 193 super(LxCurrentFunc, self).__init__("lx_current") 194 195 def invoke(self, cpu=-1): 196 return get_current_task(cpu) 197 198 199LxCurrentFunc() 200