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author | Doug Anderson <armlinux@m.disordat.com> | 2015-09-02 03:39:19 +0100 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-10-03 16:36:45 +0100 |
commit | 001bf455d20645190beb98ff4ee450dfea1b7eb2 (patch) | |
tree | 00a39cbb4fff12bc55a9d9822275406ad6bd5cd7 /virt | |
parent | 7e31210349e9e03a9a4dff31ab5f2bc83e8e84f5 (diff) | |
download | op-kernel-dev-001bf455d20645190beb98ff4ee450dfea1b7eb2.zip op-kernel-dev-001bf455d20645190beb98ff4ee450dfea1b7eb2.tar.gz |
ARM: 8428/1: kgdb: Fix registers on sleeping tasks
Dumping registers from other sleeping tasks in KGDB was totally
failing for me. All registers were reported as 0 in many cases.
The code was using task_pt_regs(task) to try to get other thread
registers. This doesn't appear to be the right place to look. From
my tests, I saw non-zero values in this structure when we were looking
at a kernel thread that had a userspace task associated with it, but
it contained the register values from the userspace task. So even in
the cases where registers weren't reported as 0 we were still not
showing the right thing.
Instead of using task_pt_regs(task) let's use task_thread_info(task).
This is the same place that is referred to when doing a dump of all
sleeping task stacks (kdb_show_stack() -> show_stack() ->
dump_backtrace() -> unwind_backtrace() -> thread_saved_sp()).
As further evidence that this is the right thing to do, you can find
the following comment in "gdbstub.c" right before it calls
sleeping_thread_to_gdb_regs():
Pull stuff saved during switch_to; nothing else is accessible (or
even particularly relevant). This should be enough for a stack
trace.
...and if you look at switch_to() it only saves r4-r11, sp and lr.
Those are the same registers that I'm getting out of the
task_thread_info().
With this change you can use "info thread" to see all tasks in the
kernel and you can switch to other tasks and examine them in gdb.
Signed-off-by: Doug Anderson <dianders@chromium.org>
Tested-by: Stephen Boyd <sboyd@codeurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'virt')
0 files changed, 0 insertions, 0 deletions