1 files changed, 86 insertions, 9 deletions
diff --git a/drivers/nvmem/rmem.c b/drivers/nvmem/rmem.c
index 7f907c5a445e..b39d628cb60a 100644
--- a/drivers/nvmem/rmem.c
+++ b/drivers/nvmem/rmem.c
@@ -3,28 +3,40 @@
  * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  */
 
+#include <linux/crc32.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/nvmem-provider.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 
 struct rmem {
 	struct device *dev;
 	struct nvmem_device *nvmem;
 	struct reserved_mem *mem;
+};
+
+struct rmem_match_data {
+	int (*checksum)(struct rmem *priv);
+};
 
-	phys_addr_t size;
+struct __packed rmem_eyeq5_header {
+	u32 magic;
+	u32 version;
+	u32 size;
 };
 
+#define RMEM_EYEQ5_MAGIC	((u32)0xDABBAD00)
+
 static int rmem_read(void *context, unsigned int offset,
 		     void *val, size_t bytes)
 {
 	struct rmem *priv = context;
-	size_t available = priv->mem->size;
-	loff_t off = offset;
 	void *addr;
-	int count;
+
+	if ((phys_addr_t)offset + bytes > priv->mem->size)
+		return -EIO;
 
 	/*
 	 * Only map the reserved memory at this point to avoid potential rogue
@@ -36,26 +48,79 @@ static int rmem_read(void *context, unsigned int offset,
 	 * An alternative would be setting the memory as RO, set_memory_ro(),
 	 * but as of Dec 2020 this isn't possible on arm64.
 	 */
-	addr = memremap(priv->mem->base, available, MEMREMAP_WB);
+	addr = memremap(priv->mem->base, priv->mem->size, MEMREMAP_WB);
 	if (!addr) {
 		dev_err(priv->dev, "Failed to remap memory region\n");
 		return -ENOMEM;
 	}
 
-	count = memory_read_from_buffer(val, bytes, &off, addr, available);
+	memcpy(val, addr + offset, bytes);
 
 	memunmap(addr);
 
-	if (count < 0)
-		return count;
+	return 0;
+}
+
+static int rmem_eyeq5_checksum(struct rmem *priv)
+{
+	void *buf __free(kfree) = NULL;
+	struct rmem_eyeq5_header header;
+	u32 computed_crc, *target_crc;
+	size_t data_size;
+	int ret;
+
+	ret = rmem_read(priv, 0, &header, sizeof(header));
+	if (ret)
+		return ret;
+
+	if (header.magic != RMEM_EYEQ5_MAGIC)
+		return -EINVAL;
+
+	/*
+	 * Avoid massive kmalloc() if header read is invalid;
+	 * the check would be done by the next rmem_read() anyway.
+	 */
+	if (header.size > priv->mem->size)
+		return -EINVAL;
+
+	/*
+	 *           0 +-------------------+
+	 *             | Header (12 bytes) | \
+	 *             +-------------------+ |
+	 *             |                   | | data to be CRCed
+	 *             |        ...        | |
+	 *             |                   | /
+	 *   data_size +-------------------+
+	 *             |   CRC (4 bytes)   |
+	 * header.size +-------------------+
+	 */
+
+	buf = kmalloc(header.size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = rmem_read(priv, 0, buf, header.size);
+	if (ret)
+		return ret;
 
-	return count == bytes ? 0 : -EIO;
+	data_size = header.size - sizeof(*target_crc);
+	target_crc = buf + data_size;
+	computed_crc = crc32(U32_MAX, buf, data_size) ^ U32_MAX;
+
+	if (computed_crc == *target_crc)
+		return 0;
+
+	dev_err(priv->dev,
+		"checksum failed: computed %#x, expected %#x, header (%#x, %#x, %#x)\n",
+		computed_crc, *target_crc, header.magic, header.version, header.size);
+	return -EINVAL;
 }
 
 static int rmem_probe(struct platform_device *pdev)
 {
 	struct nvmem_config config = { };
 	struct device *dev = &pdev->dev;
+	const struct rmem_match_data *match_data = device_get_match_data(dev);
 	struct reserved_mem *mem;
 	struct rmem *priv;
 
@@ -78,10 +143,22 @@ static int rmem_probe(struct platform_device *pdev)
 	config.size = mem->size;
 	config.reg_read = rmem_read;
 
+	if (match_data && match_data->checksum) {
+		int ret = match_data->checksum(priv);
+
+		if (ret)
+			return ret;
+	}
+
 	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
 }
 
+static const struct rmem_match_data rmem_eyeq5_match_data = {
+	.checksum = rmem_eyeq5_checksum,
+};
+
 static const struct of_device_id rmem_match[] = {
+	{ .compatible = "mobileye,eyeq5-bootloader-config", .data = &rmem_eyeq5_match_data },
 	{ .compatible = "nvmem-rmem", },
 	{ /* sentinel */ },
 };