arm64 uses SP_EL0 to save the current task_struct address. While running in EL0, SP_EL0 is clobbered by userspace. So if the upper bit is not 1 (not TTBR1), the current address is invalid. This patch checks the upper bit of SP_EL0, if the upper bit is 1, lx_current() of arm64 will return the derefrence of current task. Otherwise, lx_current() will tell users they are running in userspace(EL0). While arm64 is running in EL0, it is actually pointless to print current task as the memory of kernel space is not accessible in EL0. Link: https://lkml.kernel.org/r/20210314203444.15188-3-song.bao.hua@hisilicon.com Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kieran Bingham <kbingham@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
194 lines
5.2 KiB
Python
194 lines
5.2 KiB
Python
#
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# gdb helper commands and functions for Linux kernel debugging
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#
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# per-cpu tools
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#
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# Copyright (c) Siemens AG, 2011-2013
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#
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# Authors:
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# Jan Kiszka <jan.kiszka@siemens.com>
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#
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# This work is licensed under the terms of the GNU GPL version 2.
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#
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import gdb
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from linux import tasks, utils
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task_type = utils.CachedType("struct task_struct")
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MAX_CPUS = 4096
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def get_current_cpu():
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if utils.get_gdbserver_type() == utils.GDBSERVER_QEMU:
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return gdb.selected_thread().num - 1
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elif utils.get_gdbserver_type() == utils.GDBSERVER_KGDB:
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tid = gdb.selected_thread().ptid[2]
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if tid > (0x100000000 - MAX_CPUS - 2):
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return 0x100000000 - tid - 2
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else:
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return tasks.get_thread_info(tasks.get_task_by_pid(tid))['cpu']
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else:
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raise gdb.GdbError("Sorry, obtaining the current CPU is not yet "
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"supported with this gdb server.")
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def per_cpu(var_ptr, cpu):
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if cpu == -1:
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cpu = get_current_cpu()
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if utils.is_target_arch("sparc:v9"):
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offset = gdb.parse_and_eval(
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"trap_block[{0}].__per_cpu_base".format(str(cpu)))
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else:
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try:
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offset = gdb.parse_and_eval(
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"__per_cpu_offset[{0}]".format(str(cpu)))
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except gdb.error:
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# !CONFIG_SMP case
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offset = 0
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pointer = var_ptr.cast(utils.get_long_type()) + offset
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return pointer.cast(var_ptr.type).dereference()
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cpu_mask = {}
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def cpu_mask_invalidate(event):
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global cpu_mask
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cpu_mask = {}
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gdb.events.stop.disconnect(cpu_mask_invalidate)
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if hasattr(gdb.events, 'new_objfile'):
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gdb.events.new_objfile.disconnect(cpu_mask_invalidate)
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def cpu_list(mask_name):
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global cpu_mask
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mask = None
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if mask_name in cpu_mask:
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mask = cpu_mask[mask_name]
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if mask is None:
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mask = gdb.parse_and_eval(mask_name + ".bits")
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if hasattr(gdb, 'events'):
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cpu_mask[mask_name] = mask
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gdb.events.stop.connect(cpu_mask_invalidate)
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if hasattr(gdb.events, 'new_objfile'):
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gdb.events.new_objfile.connect(cpu_mask_invalidate)
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bits_per_entry = mask[0].type.sizeof * 8
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num_entries = mask.type.sizeof * 8 / bits_per_entry
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entry = -1
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bits = 0
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while True:
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while bits == 0:
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entry += 1
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if entry == num_entries:
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return
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bits = mask[entry]
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if bits != 0:
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bit = 0
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break
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while bits & 1 == 0:
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bits >>= 1
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bit += 1
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cpu = entry * bits_per_entry + bit
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bits >>= 1
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bit += 1
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yield int(cpu)
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def each_online_cpu():
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for cpu in cpu_list("__cpu_online_mask"):
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yield cpu
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def each_present_cpu():
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for cpu in cpu_list("__cpu_present_mask"):
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yield cpu
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def each_possible_cpu():
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for cpu in cpu_list("__cpu_possible_mask"):
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yield cpu
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def each_active_cpu():
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for cpu in cpu_list("__cpu_active_mask"):
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yield cpu
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class LxCpus(gdb.Command):
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"""List CPU status arrays
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Displays the known state of each CPU based on the kernel masks
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and can help identify the state of hotplugged CPUs"""
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def __init__(self):
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super(LxCpus, self).__init__("lx-cpus", gdb.COMMAND_DATA)
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def invoke(self, arg, from_tty):
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gdb.write("Possible CPUs : {}\n".format(list(each_possible_cpu())))
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gdb.write("Present CPUs : {}\n".format(list(each_present_cpu())))
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gdb.write("Online CPUs : {}\n".format(list(each_online_cpu())))
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gdb.write("Active CPUs : {}\n".format(list(each_active_cpu())))
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LxCpus()
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class PerCpu(gdb.Function):
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"""Return per-cpu variable.
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$lx_per_cpu("VAR"[, CPU]): Return the per-cpu variable called VAR for the
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given CPU number. If CPU is omitted, the CPU of the current context is used.
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Note that VAR has to be quoted as string."""
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def __init__(self):
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super(PerCpu, self).__init__("lx_per_cpu")
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def invoke(self, var_name, cpu=-1):
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var_ptr = gdb.parse_and_eval("&" + var_name.string())
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return per_cpu(var_ptr, cpu)
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PerCpu()
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def get_current_task(cpu):
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task_ptr_type = task_type.get_type().pointer()
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if utils.is_target_arch("x86"):
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var_ptr = gdb.parse_and_eval("¤t_task")
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return per_cpu(var_ptr, cpu).dereference()
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elif utils.is_target_arch("aarch64"):
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current_task_addr = gdb.parse_and_eval("$SP_EL0")
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if((current_task_addr >> 63) != 0):
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current_task = current_task_addr.cast(task_ptr_type)
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return current_task.dereference()
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else:
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raise gdb.GdbError("Sorry, obtaining the current task is not allowed "
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"while running in userspace(EL0)")
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else:
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raise gdb.GdbError("Sorry, obtaining the current task is not yet "
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"supported with this arch")
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class LxCurrentFunc(gdb.Function):
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"""Return current task.
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$lx_current([CPU]): Return the per-cpu task variable for the given CPU
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number. If CPU is omitted, the CPU of the current context is used."""
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def __init__(self):
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super(LxCurrentFunc, self).__init__("lx_current")
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def invoke(self, cpu=-1):
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return get_current_task(cpu)
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LxCurrentFunc()
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