asmlinkage void kernel_unaligned_trap()

in kernel/unaligned_64.c [306:394]

• 76 lines of code
• 20 McCabe index (conditional complexity)

asmlinkage void kernel_unaligned_trap(struct pt_regs *regs, unsigned int insn)
{
	enum direction dir = decode_direction(insn);
	int size = decode_access_size(regs, insn);
	int orig_asi, asi;

	current_thread_info()->kern_una_regs = regs;
	current_thread_info()->kern_una_insn = insn;

	orig_asi = asi = decode_asi(insn, regs);

	/* If this is a {get,put}_user() on an unaligned userspace pointer,
	 * just signal a fault and do not log the event.
	 */
	if (asi == ASI_AIUS) {
		kernel_mna_trap_fault(0);
		return;
	}

	log_unaligned(regs);

	if (!ok_for_kernel(insn) || dir == both) {
		printk("Unsupported unaligned load/store trap for kernel "
		       "at <%016lx>.\n", regs->tpc);
		unaligned_panic("Kernel does fpu/atomic "
				"unaligned load/store.", regs);

		kernel_mna_trap_fault(0);
	} else {
		unsigned long addr, *reg_addr;
		int err;

		addr = compute_effective_address(regs, insn,
						 ((insn >> 25) & 0x1f));
		perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, addr);
		switch (asi) {
		case ASI_NL:
		case ASI_AIUPL:
		case ASI_AIUSL:
		case ASI_PL:
		case ASI_SL:
		case ASI_PNFL:
		case ASI_SNFL:
			asi &= ~0x08;
			break;
		}
		switch (dir) {
		case load:
			reg_addr = fetch_reg_addr(((insn>>25)&0x1f), regs);
			err = do_int_load(reg_addr, size,
					  (unsigned long *) addr,
					  decode_signedness(insn), asi);
			if (likely(!err) && unlikely(asi != orig_asi)) {
				unsigned long val_in = *reg_addr;
				switch (size) {
				case 2:
					val_in = swab16(val_in);
					break;
				case 4:
					val_in = swab32(val_in);
					break;
				case 8:
					val_in = swab64(val_in);
					break;
				case 16:
				default:
					BUG();
					break;
				}
				*reg_addr = val_in;
			}
			break;

		case store:
			err = do_int_store(((insn>>25)&0x1f), size,
					   (unsigned long *) addr, regs,
					   asi, orig_asi);
			break;

		default:
			panic("Impossible kernel unaligned trap.");
			/* Not reached... */
		}
		if (unlikely(err))
			kernel_mna_trap_fault(1);
		else
			advance(regs);
	}
}