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    Subject[PATCH v4 12/13] scripts/gdb: Add internal helper and convenience function for per-cpu lookup
    Date
    This function allows to obtain a per-cpu variable, either of the current
    or an explicitly specified CPU.

    Note: sparc64 version is untested.

    CC: "David S. Miller" <davem@davemloft.net>
    CC: sparclinux@vger.kernel.org
    Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
    ---
    scripts/gdb/percpu.py | 61 ++++++++++++++++++++++++++++++++++++++++++++
    scripts/gdb/vmlinux-gdb.py | 1 +
    2 files changed, 62 insertions(+), 0 deletions(-)
    create mode 100644 scripts/gdb/percpu.py

    diff --git a/scripts/gdb/percpu.py b/scripts/gdb/percpu.py
    new file mode 100644
    index 0000000..e2556919
    --- /dev/null
    +++ b/scripts/gdb/percpu.py
    @@ -0,0 +1,61 @@
    +#
    +# gdb helper commands and functions for Linux kernel debugging
    +#
    +# per-cpu tools
    +#
    +# Copyright (c) Siemens AG, 2011, 2012
    +#
    +# Authors:
    +# Jan Kiszka <jan.kiszka@siemens.com>
    +#
    +# This work is licensed under the terms of the GNU GPL version 2.
    +#
    +
    +import gdb
    +
    +from utils import *
    +from task import *
    +
    +MAX_CPUS = 4096
    +
    +def get_current_cpu():
    + if get_gdbserver_type() == GDBSERVER_QEMU:
    + return gdb.selected_thread().num - 1
    + elif get_gdbserver_type() == GDBSERVER_KGDB:
    + tid = gdb.selected_thread().ptid[2]
    + if tid > (0x100000000 - MAX_CPUS - 2):
    + return 0x100000000 - tid - 2
    + else:
    + return get_thread_info(get_task_by_pid(tid))['cpu']
    + else:
    + raise gdb.GdbError("Sorry, obtaining the current CPU is "
    + "not yet supported with this gdb server.")
    +
    +def per_cpu(var_name, cpu):
    + var = gdb.parse_and_eval("&" + var_name)
    + if cpu == -1:
    + cpu = get_current_cpu()
    + if is_target_arch("sparc:v9"):
    + offset = gdb.parse_and_eval("trap_block[" + str(cpu) +
    + "].__per_cpu_base")
    + else:
    + offset = gdb.parse_and_eval("__per_cpu_offset[" + str(cpu) +
    + "]")
    + pointer = var.cast(get_long_type()) + offset
    + return pointer.cast(var.type).dereference()
    +
    +
    +class PerCpu(gdb.Function):
    + __doc__ = "Return per-cpu variable.\n" \
    + "\n" \
    + "$lx_per_cpu(\"VAR\"[, CPU]): Return the per-cpu variable called VAR for the\n" \
    + "given CPU number. If CPU is omitted, the CPU of the current context is used.\n" \
    + "Note that VAR has to be quoted as string."
    +
    + def __init__(self):
    + super(PerCpu, self).__init__("lx_per_cpu")
    +
    + def invoke(self, var_name, cpu = -1):
    + return per_cpu(var_name.string(), cpu)
    +
    +PerCpu()
    diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
    index e78b353..6606247 100644
    --- a/scripts/gdb/vmlinux-gdb.py
    +++ b/scripts/gdb/vmlinux-gdb.py
    @@ -25,3 +25,4 @@ else:
    import symbols
    import dmesg
    import task
    + import percpu
    --
    1.7.3.4


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