linux/arch
Doug Anderson 001bf455d2 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>
2015-10-03 16:36:45 +01:00
..
alpha Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-18 08:11:42 -07:00
arc genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
arm ARM: 8428/1: kgdb: Fix registers on sleeping tasks 2015-10-03 16:36:45 +01:00
arm64 Mostly stable material, a lot of ARM fixes. 2015-09-18 09:23:08 -07:00
avr32 genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
blackfin genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
c6x genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
cris CRISv10: delete unused lib/dmacopy.c 2015-09-05 00:56:51 +02:00
frv Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-03 15:46:07 -07:00
h8300 dma-mapping: consolidate dma_set_mask 2015-09-10 13:29:01 -07:00
hexagon Merge branch 'akpm' (patches from Andrew) 2015-09-10 18:19:42 -07:00
ia64 ia64: Enable userfaultfd and membarrier system calls 2015-09-15 16:22:45 -07:00
m32r lib/decompressors: use real out buf size for gunzip with kernel 2015-09-10 13:29:01 -07:00
m68k genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
metag genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
microblaze Merge branch 'akpm' (patches from Andrew) 2015-09-10 18:19:42 -07:00
mips Mostly stable material, a lot of ARM fixes. 2015-09-18 09:23:08 -07:00
mn10300 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-03 15:46:07 -07:00
nios2 nios2: add Max10 defconfig 2015-09-08 18:16:02 +08:00
openrisc dma-mapping: consolidate dma_set_mask 2015-09-10 13:29:01 -07:00
parisc parisc: Use platform_device_register_simple("rtc-generic") 2015-09-08 17:53:48 +02:00
powerpc Mostly stable material, a lot of ARM fixes. 2015-09-18 09:23:08 -07:00
s390 KVM: s390: Replace incorrect atomic_or with atomic_andnot 2015-09-16 17:01:06 +02:00
score Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 14:04:50 -07:00
sh genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
sparc genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
tile genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
um Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 14:04:50 -07:00
unicore32 genirq: Remove irq argument from irq flow handlers 2015-09-16 15:47:51 +02:00
x86 Mostly stable material, a lot of ARM fixes. 2015-09-18 09:23:08 -07:00
xtensa dma-mapping: consolidate dma_set_mask 2015-09-10 13:29:01 -07:00
.gitignore
Kconfig kexec: split kexec_load syscall from kexec core code 2015-09-10 13:29:01 -07:00