linux-kernel - [PATCH v2 06/13] irqchip: GICv3: ITS: LPI allocator

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1416336788-22634-7-git-send-email-marc.zyngier@arm.com>
Date:	Tue, 18 Nov 2014 18:53:01 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Will Deacon <will.deacon@....com>,
	Catalin marinas <catalin.marinas@....com>,
	Mark Rutland <mark.rutland@....com>,
	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Robert Richter <robert.richter@...iumnetworks.com>,
	"Yun Wu (Abel)" <wuyun.wu@...wei.com>
Subject: [PATCH v2 06/13] irqchip: GICv3: ITS: LPI allocator

LPIs are the type of interrupts that are used by the ITS. Given
the size of the namespace (anywhere between 16 and 32bit), interrupt
IDs are allocated in chunks of 32.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 drivers/irqchip/irq-gic-v3-its.c | 103 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index d24bebd..4154a16 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -586,3 +586,106 @@ static struct irq_chip its_irq_chip = {
 	.irq_eoi		= its_eoi_irq,
 	.irq_set_affinity	= its_set_affinity,
 };
+
+/*
+ * How we allocate LPIs:
+ *
+ * The GIC has id_bits bits for interrupt identifiers. From there, we
+ * must subtract 8192 which are reserved for SGIs/PPIs/SPIs. Then, as
+ * we allocate LPIs by chunks of 32, we can shift the whole thing by 5
+ * bits to the right.
+ *
+ * This gives us (((1UL << id_bits) - 8192) >> 5) possible allocations.
+ */
+#define IRQS_PER_CHUNK_SHIFT	5
+#define IRQS_PER_CHUNK		(1 << IRQS_PER_CHUNK_SHIFT)
+
+static unsigned long *lpi_bitmap;
+static u32 lpi_chunks;
+static DEFINE_SPINLOCK(lpi_lock);
+
+static int its_lpi_to_chunk(int lpi)
+{
+	return (lpi - 8192) >> IRQS_PER_CHUNK_SHIFT;
+}
+
+static int its_chunk_to_lpi(int chunk)
+{
+	return (chunk << IRQS_PER_CHUNK_SHIFT) + 8192;
+}
+
+static int its_lpi_init(u32 id_bits)
+{
+	lpi_chunks = its_lpi_to_chunk(1UL << id_bits);
+
+	lpi_bitmap = kzalloc(BITS_TO_LONGS(lpi_chunks) * sizeof(long),
+			     GFP_KERNEL);
+	if (!lpi_bitmap) {
+		lpi_chunks = 0;
+		return -ENOMEM;
+	}
+
+	pr_info("ITS: Allocated %d chunks for LPIs\n", (int)lpi_chunks);
+	return 0;
+}
+
+static unsigned long *its_lpi_alloc_chunks(int nr_irqs, int *base, int *nr_ids)
+{
+	unsigned long *bitmap = NULL;
+	int chunk_id;
+	int nr_chunks;
+	int i;
+
+	nr_chunks = DIV_ROUND_UP(nr_irqs, IRQS_PER_CHUNK);
+
+	spin_lock(&lpi_lock);
+
+	do {
+		chunk_id = bitmap_find_next_zero_area(lpi_bitmap, lpi_chunks,
+						      0, nr_chunks, 0);
+		if (chunk_id < lpi_chunks)
+			break;
+
+		nr_chunks--;
+	} while (nr_chunks > 0);
+
+	if (!nr_chunks)
+		goto out;
+
+	bitmap = kzalloc(BITS_TO_LONGS(nr_chunks * IRQS_PER_CHUNK) * sizeof (long),
+			 GFP_ATOMIC);
+	if (!bitmap)
+		goto out;
+
+	for (i = 0; i < nr_chunks; i++)
+		set_bit(chunk_id + i, lpi_bitmap);
+
+	*base = its_chunk_to_lpi(chunk_id);
+	*nr_ids = nr_chunks * IRQS_PER_CHUNK;
+
+out:
+	spin_unlock(&lpi_lock);
+
+	return bitmap;
+}
+
+static void its_lpi_free(unsigned long *bitmap, int base, int nr_ids)
+{
+	int lpi;
+
+	spin_lock(&lpi_lock);
+
+	for (lpi = base; lpi < (base + nr_ids); lpi += IRQS_PER_CHUNK) {
+		int chunk = its_lpi_to_chunk(lpi);
+		BUG_ON(chunk > lpi_chunks);
+		if (test_bit(chunk, lpi_bitmap)) {
+			clear_bit(chunk, lpi_bitmap);
+		} else {
+			pr_err("Bad LPI chunk %d\n", chunk);
+		}
+	}
+
+	spin_unlock(&lpi_lock);
+
+	kfree(bitmap);
+}
-- 
2.1.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/