On 2013-01-29 14:51, Borislav Petkov wrote:
> On Tue, Jan 29, 2013 at 01:37:59PM +0100, Jan Kiszka wrote:
>> 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" <da...@davemloft.net>
>> CC: sparcli...@vger.kernel.org
>> Signed-off-by: Jan Kiszka <jan.kis...@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..864962c
>> --- /dev/null
>> +++ b/scripts/gdb/percpu.py
>> @@ -0,0 +1,61 @@
>> +#
>> +# gdb helper commands and functions for Linux kernel debugging
>> +#
>> +# per-cpu tools
>
> This is actually a very cool thing for CPU guys: it can show what kind
> of hybrid CPUs they've been glueing together, like the following, for
> example:
>
> ...
> (gdb) p $lx_per_cpu("cpu_info").x86_virt_bits
> $5 = 48 '0'
> (gdb) p $lx_per_cpu("cpu_info").x86_vendor_id
> $6 = "GenuineIntel\000\000\000"
> (gdb) p $lx_per_cpu("cpu_info").x86_model_id
> $7 = "AMD Phenom(tm) 9550 Quad-Core Processor", '\000' <repeats 24 times>
> (gdb)
>
> Since when does Intel produce CPUs called "AMD Phenom(tm) 9550 Quad-Core
> Processor"? .. hahaha..
Let me guess: You are dumping a weird QEMU/KVM CPU, right?
>
>> +#
>> +# Copyright (c) Siemens AG, 2011-2013
>> +#
>> +# Authors:
>> +# Jan Kiszka <jan.kis...@siemens.com>
>> +#
>> +# This work is licensed under the terms of the GNU GPL version 2.
>> +#
>> +
>> +import gdb
>> +
>> +from utils import *
>> +from task import *
>> +
>> +MAX_CPUS = 4096
>> +
>> +def get_current_cpu():
>> + if get_gdbserver_type() == GDBSERVER_QEMU:
>> + return gdb.selected_thread().num - 1
>> + elif get_gdbserver_type() == GDBSERVER_KGDB:
>> + tid = gdb.selected_thread().ptid[2]
>> + if tid > (0x100000000 - MAX_CPUS - 2):
>> + return 0x100000000 - tid - 2
>> + else:
>> + return get_thread_info(get_task_by_pid(tid))['cpu']
>> + else:
>> + raise gdb.GdbError("Sorry, obtaining the current CPU is "
>> + "not yet supported with this gdb server.")
>> +
>> +def per_cpu(var_ptr, cpu):
>> + if cpu == -1:
>> + cpu = get_current_cpu()
>> + if is_target_arch("sparc:v9"):
>> + offset = gdb.parse_and_eval("trap_block[" + str(cpu) +
>> + "].__per_cpu_base")
>> + else:
>> + offset = gdb.parse_and_eval("__per_cpu_offset[" + str(cpu) +
>> + "]")
>> + pointer = var_ptr.cast(get_long_type()) + offset
>> + return pointer.cast(var_ptr.type).dereference()
>> +
>> +
>> +class PerCpu(gdb.Function):
>> + __doc__ = "Return per-cpu variable.\n" \
>> + "\n" \
>> + "$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."
>
>
> Ok, seriously now:
>
> apropos shows the "Return per-cpu... " line above. Have you found out
> which gdb command shows the rest? help and info both say "Undefined
> command".
help function lx_...
It took me a while to find this, too.
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
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