diff mbox series

[V2] nvmem: brcm_nvram: store a copy of NVRAM content

Message ID 20231026073440.6724-1-zajec5@gmail.com (mailing list archive)
State New, archived
Headers show
Series [V2] nvmem: brcm_nvram: store a copy of NVRAM content | expand

Commit Message

Rafał Miłecki Oct. 26, 2023, 7:34 a.m. UTC
From: Rafał Miłecki <rafal@milecki.pl>

This driver uses MMIO access for reading NVRAM from a flash device.
Underneath there is a flash controller that reads data and provides
mapping window.

Using MMIO interface affects controller configuration and may break real
controller driver. It was reported by multiple users of devices with
NVRAM stored on NAND.

Modify driver to read & cache NVRAM content during init and use that
copy to provide NVMEM data when requested. On NAND flashes due to their
alignment NVRAM partitions can be quite big (1 MiB and more) while
actual NVRAM content stays quite small (usually 16 to 32 KiB). To avoid
allocating so much memory check for actual data length.

Link: https://lore.kernel.org/linux-mtd/CACna6rwf3_9QVjYcM+847biTX=K0EoWXuXcSMkJO1Vy_5vmVqA@mail.gmail.com/
Fixes: 3fef9ed0627a ("nvmem: brcm_nvram: new driver exposing Broadcom's NVRAM")
Cc: Arınç ÜNAL <arinc.unal@arinc9.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Minialize amount of allocated memory (check for actual data length)

 drivers/nvmem/brcm_nvram.c | 131 ++++++++++++++++++++++++++-----------
 1 file changed, 91 insertions(+), 40 deletions(-)

Comments

Arınç ÜNAL Oct. 26, 2023, 7:55 a.m. UTC | #1
On 26.10.2023 10:34, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> This driver uses MMIO access for reading NVRAM from a flash device.
> Underneath there is a flash controller that reads data and provides
> mapping window.
> 
> Using MMIO interface affects controller configuration and may break real
> controller driver. It was reported by multiple users of devices with
> NVRAM stored on NAND.
> 
> Modify driver to read & cache NVRAM content during init and use that
> copy to provide NVMEM data when requested. On NAND flashes due to their
> alignment NVRAM partitions can be quite big (1 MiB and more) while
> actual NVRAM content stays quite small (usually 16 to 32 KiB). To avoid
> allocating so much memory check for actual data length.
> 
> Link: https://lore.kernel.org/linux-mtd/CACna6rwf3_9QVjYcM+847biTX=K0EoWXuXcSMkJO1Vy_5vmVqA@mail.gmail.com/
> Fixes: 3fef9ed0627a ("nvmem: brcm_nvram: new driver exposing Broadcom's NVRAM")
> Cc: Arınç ÜNAL <arinc.unal@arinc9.com>
> Cc: Florian Fainelli <florian.fainelli@broadcom.com>
> Cc: Scott Branden <scott.branden@broadcom.com>
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

Acked-by: Arınç ÜNAL <arinc.unal@arinc9.com>

Arınç
kernel test robot Oct. 26, 2023, 11:31 a.m. UTC | #2
Hi Rafał,

kernel test robot noticed the following build warnings:

[auto build test WARNING on soc/for-next]
[also build test WARNING on linus/master v6.6-rc7 next-20231026]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Rafa-Mi-ecki/nvmem-brcm_nvram-store-a-copy-of-NVRAM-content/20231026-153630
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
patch link:    https://lore.kernel.org/r/20231026073440.6724-1-zajec5%40gmail.com
patch subject: [PATCH V2] nvmem: brcm_nvram: store a copy of NVRAM content
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231026/202310261904.cWDKcVh8-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231026/202310261904.cWDKcVh8-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310261904.cWDKcVh8-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/nvmem/brcm_nvram.c:36: warning: Function parameter or member 'dev' not described in 'brcm_nvram'
>> drivers/nvmem/brcm_nvram.c:36: warning: Function parameter or member 'cells' not described in 'brcm_nvram'
>> drivers/nvmem/brcm_nvram.c:36: warning: Function parameter or member 'ncells' not described in 'brcm_nvram'


vim +36 drivers/nvmem/brcm_nvram.c

3fef9ed0627af3 Rafał Miłecki 2021-03-30  19  
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  20  /**
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  21   * struct brcm_nvram - driver state internal struct
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  22   *
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  23   * @nvmem_size:		Size of the whole space available for NVRAM
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  24   * @data:		NVRAM data copy stored to avoid poking underlaying flash controller
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  25   * @data_len:		NVRAM data size
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  26   * @padding_byte:	Padding value used to fill remaining space
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  27   */
3fef9ed0627af3 Rafał Miłecki 2021-03-30  28  struct brcm_nvram {
3fef9ed0627af3 Rafał Miłecki 2021-03-30  29  	struct device *dev;
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  30  	size_t nvmem_size;
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  31  	uint8_t *data;
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  32  	size_t data_len;
6bb6c90c7bc5bb Rafał Miłecki 2023-10-26  33  	uint8_t padding_byte;
6e977eaa8280e9 Rafał Miłecki 2022-02-25  34  	struct nvmem_cell_info *cells;
6e977eaa8280e9 Rafał Miłecki 2022-02-25  35  	int ncells;
6e977eaa8280e9 Rafał Miłecki 2022-02-25 @36  };
6e977eaa8280e9 Rafał Miłecki 2022-02-25  37
diff mbox series

Patch

diff --git a/drivers/nvmem/brcm_nvram.c b/drivers/nvmem/brcm_nvram.c
index 9737104f3b76..fbd133732bba 100644
--- a/drivers/nvmem/brcm_nvram.c
+++ b/drivers/nvmem/brcm_nvram.c
@@ -17,9 +17,20 @@ 
 
 #define NVRAM_MAGIC			"FLSH"
 
+/**
+ * struct brcm_nvram - driver state internal struct
+ *
+ * @nvmem_size:		Size of the whole space available for NVRAM
+ * @data:		NVRAM data copy stored to avoid poking underlaying flash controller
+ * @data_len:		NVRAM data size
+ * @padding_byte:	Padding value used to fill remaining space
+ */
 struct brcm_nvram {
 	struct device *dev;
-	void __iomem *base;
+	size_t nvmem_size;
+	uint8_t *data;
+	size_t data_len;
+	uint8_t padding_byte;
 	struct nvmem_cell_info *cells;
 	int ncells;
 };
@@ -36,10 +47,47 @@  static int brcm_nvram_read(void *context, unsigned int offset, void *val,
 			   size_t bytes)
 {
 	struct brcm_nvram *priv = context;
-	u8 *dst = val;
+	size_t to_copy;
+
+	if (offset + bytes > priv->data_len)
+		to_copy = max_t(ssize_t, (ssize_t)priv->data_len - offset, 0);
+	else
+		to_copy = bytes;
+
+	memcpy(val, priv->data + offset, to_copy);
+
+	memset((uint8_t *)val + to_copy, priv->padding_byte, bytes - to_copy);
+
+	return 0;
+}
+
+static int brcm_nvram_copy_data(struct brcm_nvram *priv, struct platform_device *pdev)
+{
+	struct resource *res;
+	void __iomem *base;
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	priv->nvmem_size = resource_size(res);
+
+	priv->padding_byte = readb(base + priv->nvmem_size - 1);
+	for (priv->data_len = priv->nvmem_size;
+	     priv->data_len;
+	     priv->data_len--) {
+		if (readb(base + priv->data_len - 1) != priv->padding_byte)
+			break;
+	}
+	WARN(priv->data_len > SZ_128K, "Unexpected (big) NVRAM size: %zu B\n", priv->data_len);
+
+	priv->data = devm_kzalloc(priv->dev, priv->data_len, GFP_KERNEL);
+	if (!priv->data)
+		return -ENOMEM;
+
+	memcpy_fromio(priv->data, base, priv->data_len);
 
-	while (bytes--)
-		*dst++ = readb(priv->base + offset++);
+	bcm47xx_nvram_init_from_iomem(base, priv->data_len);
 
 	return 0;
 }
@@ -67,8 +115,13 @@  static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
 				size_t len)
 {
 	struct device *dev = priv->dev;
-	char *var, *value, *eq;
+	char *var, *value;
+	uint8_t tmp;
 	int idx;
+	int err = 0;
+
+	tmp = priv->data[len - 1];
+	priv->data[len - 1] = '\0';
 
 	priv->ncells = 0;
 	for (var = data + sizeof(struct brcm_nvram_header);
@@ -78,67 +131,68 @@  static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
 	}
 
 	priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
-	if (!priv->cells)
-		return -ENOMEM;
+	if (!priv->cells) {
+		err = -ENOMEM;
+		goto out;
+	}
 
 	for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
 	     var < (char *)data + len && *var;
 	     var = value + strlen(value) + 1, idx++) {
+		char *eq, *name;
+
 		eq = strchr(var, '=');
 		if (!eq)
 			break;
 		*eq = '\0';
+		name = devm_kstrdup(dev, var, GFP_KERNEL);
+		*eq = '=';
+		if (!name) {
+			err = -ENOMEM;
+			goto out;
+		}
 		value = eq + 1;
 
-		priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
-		if (!priv->cells[idx].name)
-			return -ENOMEM;
+		priv->cells[idx].name = name;
 		priv->cells[idx].offset = value - (char *)data;
 		priv->cells[idx].bytes = strlen(value);
 		priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
-		if (!strcmp(var, "et0macaddr") ||
-		    !strcmp(var, "et1macaddr") ||
-		    !strcmp(var, "et2macaddr")) {
+		if (!strcmp(name, "et0macaddr") ||
+		    !strcmp(name, "et1macaddr") ||
+		    !strcmp(name, "et2macaddr")) {
 			priv->cells[idx].raw_len = strlen(value);
 			priv->cells[idx].bytes = ETH_ALEN;
 			priv->cells[idx].read_post_process = brcm_nvram_read_post_process_macaddr;
 		}
 	}
 
-	return 0;
+out:
+	priv->data[len - 1] = tmp;
+	return err;
 }
 
 static int brcm_nvram_parse(struct brcm_nvram *priv)
 {
+	struct brcm_nvram_header *header = (struct brcm_nvram_header *)priv->data;
 	struct device *dev = priv->dev;
-	struct brcm_nvram_header header;
-	uint8_t *data;
 	size_t len;
 	int err;
 
-	memcpy_fromio(&header, priv->base, sizeof(header));
-
-	if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
+	if (memcmp(header->magic, NVRAM_MAGIC, 4)) {
 		dev_err(dev, "Invalid NVRAM magic\n");
 		return -EINVAL;
 	}
 
-	len = le32_to_cpu(header.len);
-
-	data = kzalloc(len, GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
-
-	memcpy_fromio(data, priv->base, len);
-	data[len - 1] = '\0';
-
-	err = brcm_nvram_add_cells(priv, data, len);
-	if (err) {
-		dev_err(dev, "Failed to add cells: %d\n", err);
-		return err;
+	len = le32_to_cpu(header->len);
+	if (len > priv->nvmem_size) {
+		dev_err(dev, "NVRAM length (%zd) exceeds mapped size (%zd)\n", len,
+			priv->nvmem_size);
+		return -EINVAL;
 	}
 
-	kfree(data);
+	err = brcm_nvram_add_cells(priv, priv->data, len);
+	if (err)
+		dev_err(dev, "Failed to add cells: %d\n", err);
 
 	return 0;
 }
@@ -150,7 +204,6 @@  static int brcm_nvram_probe(struct platform_device *pdev)
 		.reg_read = brcm_nvram_read,
 	};
 	struct device *dev = &pdev->dev;
-	struct resource *res;
 	struct brcm_nvram *priv;
 	int err;
 
@@ -159,21 +212,19 @@  static int brcm_nvram_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	priv->dev = dev;
 
-	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
-	if (IS_ERR(priv->base))
-		return PTR_ERR(priv->base);
+	err = brcm_nvram_copy_data(priv, pdev);
+	if (err)
+		return err;
 
 	err = brcm_nvram_parse(priv);
 	if (err)
 		return err;
 
-	bcm47xx_nvram_init_from_iomem(priv->base, resource_size(res));
-
 	config.dev = dev;
 	config.cells = priv->cells;
 	config.ncells = priv->ncells;
 	config.priv = priv;
-	config.size = resource_size(res);
+	config.size = priv->nvmem_size;
 
 	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
 }