path: root/arch/arm
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authorDoug Anderson <armlinux@m.disordat.com>2015-09-02 03:39:19 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-10-03 16:36:45 +0100
commit001bf455d20645190beb98ff4ee450dfea1b7eb2 (patch)
tree00a39cbb4fff12bc55a9d9822275406ad6bd5cd7 /arch/arm
parent7e31210349e9e03a9a4dff31ab5f2bc83e8e84f5 (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')
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)
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)