void show_code()

in kernel/dis.c [500:565]

• 60 lines of code
• 21 McCabe index (conditional complexity)

void show_code(struct pt_regs *regs)
{
	char *mode = user_mode(regs) ? "User" : "Krnl";
	unsigned char code[64];
	char buffer[128], *ptr;
	unsigned long addr;
	int start, end, opsize, hops, i;

	/* Get a snapshot of the 64 bytes surrounding the fault address. */
	for (start = 32; start && regs->psw.addr >= 34 - start; start -= 2) {
		addr = regs->psw.addr - 34 + start;
		if (copy_from_regs(regs, code + start - 2, (void *)addr, 2))
			break;
	}
	for (end = 32; end < 64; end += 2) {
		addr = regs->psw.addr + end - 32;
		if (copy_from_regs(regs, code + end, (void *)addr, 2))
			break;
	}
	/* Code snapshot useable ? */
	if ((regs->psw.addr & 1) || start >= end) {
		printk("%s Code: Bad PSW.\n", mode);
		return;
	}
	/* Find a starting point for the disassembly. */
	while (start < 32) {
		for (i = 0, hops = 0; start + i < 32 && hops < 3; hops++) {
			if (!find_insn(code + start + i))
				break;
			i += insn_length(code[start + i]);
		}
		if (start + i == 32)
			/* Looks good, sequence ends at PSW. */
			break;
		start += 2;
	}
	/* Decode the instructions. */
	ptr = buffer;
	ptr += sprintf(ptr, "%s Code:", mode);
	hops = 0;
	while (start < end && hops < 8) {
		opsize = insn_length(code[start]);
		if  (start + opsize == 32)
			*ptr++ = '#';
		else if (start == 32)
			*ptr++ = '>';
		else
			*ptr++ = ' ';
		addr = regs->psw.addr + start - 32;
		ptr += sprintf(ptr, "%px: ", (void *)addr);
		if (start + opsize >= end)
			break;
		for (i = 0; i < opsize; i++)
			ptr += sprintf(ptr, "%02x", code[start + i]);
		*ptr++ = '\t';
		if (i < 6)
			*ptr++ = '\t';
		ptr += print_insn(ptr, code + start, addr);
		start += opsize;
		pr_cont("%s", buffer);
		ptr = buffer;
		ptr += sprintf(ptr, "\n          ");
		hops++;
	}
	pr_cont("\n");
}