On Fri, Mar 02, 2018 at 06:01:31PM +0000, Will Deacon wrote: > On Thu, Mar 01, 2018 at 11:38:03AM -0800, Douglas Anderson wrote: > > This is the equivalent of commit 001bf455d206 ("ARM: 8428/1: kgdb: Fix > > registers on sleeping tasks") but for arm64. Nuff said. > > It's a pity that 001bf455d206 doesn't explain *why* past_pt_regs doesn't > work.
The task_pt_regs are the userspace regs at the highest address on the kernel stack: #define task_pt_regs(p) \ ((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1) ... for kernel tasks, that's meaningless, and for user tasks, that won't correspond to kernel state. > > diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c > > index 2122cd187f19..01285d4dcdc3 100644 > > --- a/arch/arm64/kernel/kgdb.c > > +++ b/arch/arm64/kernel/kgdb.c > > @@ -138,14 +138,26 @@ 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_struct *thread = &task->thread; > > + struct cpu_context *cpu_context = &thread->cpu_context; We can do this in one go: struct cpu_context *cpu_context = &task->thread.cpu_context; ... since we don't need the thread variable otherwise. > > > > /* Initialize to zero */ > > memset((char *)gdb_regs, 0, NUMREGBYTES); > > - thread_regs = task_pt_regs(task); > > - memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES); > > - /* Special case for PSTATE (check comments in asm/kgdb.h for details) */ > > - dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs); > > + > > + gdb_regs[19] = cpu_context->x19; > > + gdb_regs[20] = cpu_context->x20; > > + gdb_regs[21] = cpu_context->x21; > > + gdb_regs[22] = cpu_context->x22; > > + gdb_regs[23] = cpu_context->x23; > > + gdb_regs[24] = cpu_context->x24; > > + gdb_regs[25] = cpu_context->x25; > > + gdb_regs[26] = cpu_context->x26; > > + gdb_regs[27] = cpu_context->x27; > > + gdb_regs[28] = cpu_context->x28; > > + gdb_regs[29] = cpu_context->fp; > > + > > + gdb_regs[31] = cpu_context->sp; > > + gdb_regs[32] = cpu_context->pc; Are the other reg fields initialised elsewhere? We might want to zero them here. Thanks, Mark.