static ssize_t ctxid_masks_store()

in coresight/coresight-etm4x-sysfs.c [1964:2067]

• 65 lines of code
• 18 McCabe index (conditional complexity)

static ssize_t ctxid_masks_store(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t size)
{
	u8 i, j, maskbyte;
	unsigned long val1, val2, mask;
	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
	struct etmv4_config *config = &drvdata->config;
	int nr_inputs;

	/*
	 * Don't use contextID tracing if coming from a PID namespace.  See
	 * comment in ctxid_pid_store().
	 */
	if (task_active_pid_ns(current) != &init_pid_ns)
		return -EINVAL;

	/*
	 * only implemented when ctxid tracing is enabled, i.e. at least one
	 * ctxid comparator is implemented and ctxid is greater than 0 bits
	 * in length
	 */
	if (!drvdata->ctxid_size || !drvdata->numcidc)
		return -EINVAL;
	/* one mask if <= 4 comparators, two for up to 8 */
	nr_inputs = sscanf(buf, "%lx %lx", &val1, &val2);
	if ((drvdata->numcidc > 4) && (nr_inputs != 2))
		return -EINVAL;

	spin_lock(&drvdata->spinlock);
	/*
	 * each byte[0..3] controls mask value applied to ctxid
	 * comparator[0..3]
	 */
	switch (drvdata->numcidc) {
	case 0x1:
		/* COMP0, bits[7:0] */
		config->ctxid_mask0 = val1 & 0xFF;
		break;
	case 0x2:
		/* COMP1, bits[15:8] */
		config->ctxid_mask0 = val1 & 0xFFFF;
		break;
	case 0x3:
		/* COMP2, bits[23:16] */
		config->ctxid_mask0 = val1 & 0xFFFFFF;
		break;
	case 0x4:
		 /* COMP3, bits[31:24] */
		config->ctxid_mask0 = val1;
		break;
	case 0x5:
		/* COMP4, bits[7:0] */
		config->ctxid_mask0 = val1;
		config->ctxid_mask1 = val2 & 0xFF;
		break;
	case 0x6:
		/* COMP5, bits[15:8] */
		config->ctxid_mask0 = val1;
		config->ctxid_mask1 = val2 & 0xFFFF;
		break;
	case 0x7:
		/* COMP6, bits[23:16] */
		config->ctxid_mask0 = val1;
		config->ctxid_mask1 = val2 & 0xFFFFFF;
		break;
	case 0x8:
		/* COMP7, bits[31:24] */
		config->ctxid_mask0 = val1;
		config->ctxid_mask1 = val2;
		break;
	default:
		break;
	}
	/*
	 * If software sets a mask bit to 1, it must program relevant byte
	 * of ctxid comparator value 0x0, otherwise behavior is unpredictable.
	 * For example, if bit[3] of ctxid_mask0 is 1, we must clear bits[31:24]
	 * of ctxid comparator0 value (corresponding to byte 0) register.
	 */
	mask = config->ctxid_mask0;
	for (i = 0; i < drvdata->numcidc; i++) {
		/* mask value of corresponding ctxid comparator */
		maskbyte = mask & ETMv4_EVENT_MASK;
		/*
		 * each bit corresponds to a byte of respective ctxid comparator
		 * value register
		 */
		for (j = 0; j < 8; j++) {
			if (maskbyte & 1)
				config->ctxid_pid[i] &= ~(0xFFUL << (j * 8));
			maskbyte >>= 1;
		}
		/* Select the next ctxid comparator mask value */
		if (i == 3)
			/* ctxid comparators[4-7] */
			mask = config->ctxid_mask1;
		else
			mask >>= 0x8;
	}

	spin_unlock(&drvdata->spinlock);
	return size;
}