arm64/debug: Fix registers on sleeping tasks

This is the equivalent of commit 001bf455 ("ARM: 8428/1: kgdb: Fix
registers on sleeping tasks") but for arm64.  Nuff said.

...well, perhaps I could also add that task_pt_regs are userspace
registers and that's not what kgdb is supposed to be reporting.  We're
supposed to be reporting kernel registers.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/kernel/kgdb.c

@@ -138,14 +138,25 @@ 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 cpu_context *cpu_context = &task->thread.cpu_context;
 
 	/* 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;
 }
 
 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)