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| author | Doug Anderson <armlinux@m.disordat.com> | 2015-09-02 03:39:19 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-10-03 16:36:45 +0100 |
| commit | 001bf455d20645190beb98ff4ee450dfea1b7eb2 (patch) | |
| tree | 00a39cbb4fff12bc55a9d9822275406ad6bd5cd7 /arch/arm | |
| parent | 7e31210349e9e03a9a4dff31ab5f2bc83e8e84f5 (diff) | |
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 'arch/arm')
| -rw-r--r-- | arch/arm/kernel/kgdb.c | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index fd9eefce0a7b..9232caee7060 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -74,7 +74,7 @@ int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) { - struct pt_regs *thread_regs; + struct thread_info *ti; int regno; /* Just making sure... */ @@ -86,24 +86,17 @@ sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) gdb_regs[regno] = 0; /* Otherwise, we have only some registers from switch_to() */ - thread_regs = task_pt_regs(task); - gdb_regs[_R0] = thread_regs->ARM_r0; - gdb_regs[_R1] = thread_regs->ARM_r1; - gdb_regs[_R2] = thread_regs->ARM_r2; - gdb_regs[_R3] = thread_regs->ARM_r3; - gdb_regs[_R4] = thread_regs->ARM_r4; - gdb_regs[_R5] = thread_regs->ARM_r5; - gdb_regs[_R6] = thread_regs->ARM_r6; - gdb_regs[_R7] = thread_regs->ARM_r7; - gdb_regs[_R8] = thread_regs->ARM_r8; - gdb_regs[_R9] = thread_regs->ARM_r9; - gdb_regs[_R10] = thread_regs->ARM_r10; - gdb_regs[_FP] = thread_regs->ARM_fp; - gdb_regs[_IP] = thread_regs->ARM_ip; - gdb_regs[_SPT] = thread_regs->ARM_sp; - gdb_regs[_LR] = thread_regs->ARM_lr; - gdb_regs[_PC] = thread_regs->ARM_pc; - gdb_regs[_CPSR] = thread_regs->ARM_cpsr; + ti = task_thread_info(task); + gdb_regs[_R4] = ti->cpu_context.r4; + gdb_regs[_R5] = ti->cpu_context.r5; + gdb_regs[_R6] = ti->cpu_context.r6; + gdb_regs[_R7] = ti->cpu_context.r7; + gdb_regs[_R8] = ti->cpu_context.r8; + gdb_regs[_R9] = ti->cpu_context.r9; + gdb_regs[_R10] = ti->cpu_context.sl; + gdb_regs[_FP] = ti->cpu_context.fp; + gdb_regs[_SPT] = ti->cpu_context.sp; + gdb_regs[_PC] = ti->cpu_context.pc; } void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) |