[PATCH] powerpc: rtas_flash cannot be a module

[PATCH] powerpc: rtas_flash cannot be a module

[Anton Blanchard]

When trying to flash a machine via the update_flash command, I received the
following error:


    Restarting system.
    FLASH: kernel bug...flash list header addr above 4GB


The code in question has a comment that the flash list should be in
the kernel data and therefore under 4GB:

        /* NOTE: the "first" block list is a global var with no data
         * blocks in the kernel data segment.  We do this because
         * we want to ensure this block_list addr is under 4GB.
         */

Unfortunately the Kconfig option is marked tristate which means the variable
may not be in the kernel data and could be above 4GB.

Change RTAS_FLASH to a bool. If we are worried about kernel footprint we
could move the problem variables out of the module and export them.

Signed-off-by: Anton Blanchard <anton@samba.org>
---     

Index: linux-2.6/arch/powerpc/platforms/Kconfig
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/Kconfig	2010-06-09 15:44:53.635955260 +1000
+++ linux-2.6/arch/powerpc/platforms/Kconfig	2010-06-09 15:45:00.503453428 +1000
@@ -97,7 +97,7 @@ config RTAS_PROC
 	default y
 
 config RTAS_FLASH
-	tristate "Firmware flash interface"
+	bool "Firmware flash interface"
 	depends on PPC64 && RTAS_PROC
 
 config MMIO_NVRAM
Index: linux-2.6/arch/powerpc/configs/ppc64_defconfig
===================================================================
--- linux-2.6.orig/arch/powerpc/configs/ppc64_defconfig	2010-06-09 15:46:25.394704486 +1000
+++ linux-2.6/arch/powerpc/configs/ppc64_defconfig	2010-06-09 15:46:37.083454943 +1000
@@ -264,7 +264,7 @@ CONFIG_U3_DART=y
 CONFIG_PPC_RTAS=y
 CONFIG_RTAS_ERROR_LOGGING=y
 CONFIG_RTAS_PROC=y
-CONFIG_RTAS_FLASH=m
+CONFIG_RTAS_FLASH=y
 CONFIG_PPC_PMI=m
 CONFIG_MMIO_NVRAM=y
 CONFIG_MPIC_U3_HT_IRQS=y
Index: linux-2.6/arch/powerpc/configs/pseries_defconfig
===================================================================
--- linux-2.6.orig/arch/powerpc/configs/pseries_defconfig	2010-06-09 15:46:25.364703092 +1000
+++ linux-2.6/arch/powerpc/configs/pseries_defconfig	2010-06-09 15:46:31.723454300 +1000
@@ -213,7 +213,7 @@ CONFIG_PPC_I8259=y
 CONFIG_PPC_RTAS=y
 CONFIG_RTAS_ERROR_LOGGING=y
 CONFIG_RTAS_PROC=y
-CONFIG_RTAS_FLASH=m
+CONFIG_RTAS_FLASH=y
 # CONFIG_MMIO_NVRAM is not set
 CONFIG_IBMVIO=y
 CONFIG_IBMEBUS=y

Re: [PATCH] powerpc: rtas_flash cannot be a module

[Milton Miller]

On Wed, 9 Jun 2010 at about 16:01:10 +1000 Anton Blanchard wrote:
> 
> When trying to flash a machine via the update_flash command, I received the
> following error:
> 
> 
>     Restarting system.
>     FLASH: kernel bug...flash list header addr above 4GB
> 
> 
> The code in question has a comment that the flash list should be in
> the kernel data and therefore under 4GB:
> 
>         /* NOTE: the "first" block list is a global var with no data
>          * blocks in the kernel data segment.  We do this because
>          * we want to ensure this block_list addr is under 4GB.
>          */
> 
> Unfortunately the Kconfig option is marked tristate which means the variable
> may not be in the kernel data and could be above 4GB.

So we should use that rtas_data_buf with its lock ...

Oh look, the driver already uses that buffer for the call to verify_flash

untested patch to follow

milton

[PATCH] powerpc: rtas_flash needs to use rtas_data_buf

[Milton Miller]

When trying to flash a machine via the update_flash command, Anton received the
following error:


    Restarting system.
    FLASH: kernel bug...flash list header addr above 4GB


The code in question has a comment that the flash list should be in
the kernel data and therefore under 4GB:

        /* NOTE: the "first" block list is a global var with no data
         * blocks in the kernel data segment.  We do this because
         * we want to ensure this block_list addr is under 4GB.
         */

Unfortunately the Kconfig option is marked tristate which means the variable
may not be in the kernel data and could be above 4GB.

Instead of relying on the data segment being below 4GB, use the static
data buffer allocated by the kernel for use by rtas.  Since we don't
use the header struct directly anymore, convert it to a simple pointer.

Reported-By: Anton Blanchard <anton@samba.org>
Signed-Off-By: Milton Miller <miltonm@bga.com
---
not even compile tested, but at least code to backup the complaint

--- a/arch/powerpc/kernel/rtas_flash.c.orig	2010-06-11 01:56:26.658583560 +0000
+++ a/arch/powerpc/kernel/rtas_flash.c	2010-06-11 02:43:37.244966477 +0000
@@ -93,12 +93,8 @@ struct flash_block_list {
 	struct flash_block_list *next;
 	struct flash_block blocks[FLASH_BLOCKS_PER_NODE];
 };
-struct flash_block_list_header { /* just the header of flash_block_list */
-	unsigned long num_blocks;
-	struct flash_block_list *next;
-};
 
-static struct flash_block_list_header rtas_firmware_flash_list = {0, NULL};
+static struct flash_block_list *rtas_firmware_flash_list;
 
 /* Use slab cache to guarantee 4k alignment */
 static struct kmem_cache *flash_block_cache = NULL;
@@ -107,13 +103,14 @@ static struct kmem_cache *flash_block_ca
 
 /* Local copy of the flash block list.
  * We only allow one open of the flash proc file and create this
- * list as we go.  This list will be put in the
- * rtas_firmware_flash_list var once it is fully read.
+ * list as we go.  The rtas_firmware_flash_list varable will be
+ * set once the data is fully read.
  *
  * For convenience as we build the list we use virtual addrs,
  * we do not fill in the version number, and the length field
  * is treated as the number of entries currently in the block
- * (i.e. not a byte count).  This is all fixed on release.
+ * (i.e. not a byte count).  This is all fixed when calling 
+ * the flash routine.
  */
 
 /* Status int must be first member of struct */
@@ -200,16 +197,16 @@ static int rtas_flash_release(struct ino
 	if (uf->flist) {    
 		/* File was opened in write mode for a new flash attempt */
 		/* Clear saved list */
-		if (rtas_firmware_flash_list.next) {
-			free_flash_list(rtas_firmware_flash_list.next);
-			rtas_firmware_flash_list.next = NULL;
+		if (rtas_firmware_flash_list) {
+			free_flash_list(rtas_firmware_flash_list);
+			rtas_firmware_flash_list = NULL;
 		}
 
 		if (uf->status != FLASH_AUTH)  
 			uf->status = flash_list_valid(uf->flist);
 
 		if (uf->status == FLASH_IMG_READY) 
-			rtas_firmware_flash_list.next = uf->flist;
+			rtas_firmware_flash_list = uf->flist;
 		else
 			free_flash_list(uf->flist);
 
@@ -592,7 +589,7 @@ static void rtas_flash_firmware(int rebo
 	unsigned long rtas_block_list;
 	int i, status, update_token;
 
-	if (rtas_firmware_flash_list.next == NULL)
+	if (rtas_firmware_flash_list == NULL)
 		return;		/* nothing to do */
 
 	if (reboot_type != SYS_RESTART) {
@@ -609,20 +606,25 @@ static void rtas_flash_firmware(int rebo
 		return;
 	}
 
-	/* NOTE: the "first" block list is a global var with no data
-	 * blocks in the kernel data segment.  We do this because
-	 * we want to ensure this block_list addr is under 4GB.
+	/*
+	 * NOTE: the "first" block must be under 4GB, so we create
+	 * an entry with no data blocks in the reserved buffer in
+	 * the kernel data segment.
 	 */
-	rtas_firmware_flash_list.num_blocks = 0;
-	flist = (struct flash_block_list *)&rtas_firmware_flash_list;
+	spin_lock(&rtas_data_buf_lock);
+	flist = (struct rtas_flash_list *)&rtas_data_buf[0];
+	flist.num_blocks = 0;
+	flist.next = rtas_firmware_flash_list;
 	rtas_block_list = virt_to_abs(flist);
 	if (rtas_block_list >= 4UL*1024*1024*1024) {
 		printk(KERN_ALERT "FLASH: kernel bug...flash list header addr above 4GB\n");
+		spin_unlock(&rtas_data_buf_lock);
 		return;
 	}
 
 	printk(KERN_ALERT "FLASH: preparing saved firmware image for flash\n");
 	/* Update the block_list in place. */
+	rtas_firmware_flash_list = NULL; /* too hard to backout on error */
 	image_size = 0;
 	for (f = flist; f; f = next) {
 		/* Translate data addrs to absolute */
@@ -663,6 +665,7 @@ static void rtas_flash_firmware(int rebo
 		printk(KERN_ALERT "FLASH: unknown flash return code %d\n", status);
 		break;
 	}
+	spin_unlock(&rtas_data_buf_lock);
 }
 
 static void remove_flash_pde(struct proc_dir_entry *dp)

Re: [PATCH] powerpc: rtas_flash needs to use rtas_data_buf

[Anton Blanchard]

From: Milton Miller <miltonm@us.ibm.com>

When trying to flash a machine via the update_flash command, Anton received the
following error:


    Restarting system.
    FLASH: kernel bug...flash list header addr above 4GB


The code in question has a comment that the flash list should be in
the kernel data and therefore under 4GB:

        /* NOTE: the "first" block list is a global var with no data
         * blocks in the kernel data segment.  We do this because
         * we want to ensure this block_list addr is under 4GB.
         */

Unfortunately the Kconfig option is marked tristate which means the variable
may not be in the kernel data and could be above 4GB.

Instead of relying on the data segment being below 4GB, use the static
data buffer allocated by the kernel for use by rtas.  Since we don't
use the header struct directly anymore, convert it to a simple pointer.

Reported-By: Anton Blanchard <anton@samba.org>
Signed-Off-By: Milton Miller <miltonm@bga.com
Tested-By: Anton Blanchard <anton@samba.org>
---

Index: powerpc.git/arch/powerpc/kernel/rtas_flash.c
===================================================================
--- powerpc.git.orig/arch/powerpc/kernel/rtas_flash.c	2010-05-05 16:17:00.883456148 +1000
+++ powerpc.git/arch/powerpc/kernel/rtas_flash.c	2010-06-12 23:44:25.973458269 +1000
@@ -94,12 +94,8 @@ struct flash_block_list {
 	struct flash_block_list *next;
 	struct flash_block blocks[FLASH_BLOCKS_PER_NODE];
 };
-struct flash_block_list_header { /* just the header of flash_block_list */
-	unsigned long num_blocks;
-	struct flash_block_list *next;
-};
 
-static struct flash_block_list_header rtas_firmware_flash_list = {0, NULL};
+static struct flash_block_list *rtas_firmware_flash_list;
 
 /* Use slab cache to guarantee 4k alignment */
 static struct kmem_cache *flash_block_cache = NULL;
@@ -108,13 +104,14 @@ static struct kmem_cache *flash_block_ca
 
 /* Local copy of the flash block list.
  * We only allow one open of the flash proc file and create this
- * list as we go.  This list will be put in the
- * rtas_firmware_flash_list var once it is fully read.
+ * list as we go.  The rtas_firmware_flash_list varable will be
+ * set once the data is fully read.
  *
  * For convenience as we build the list we use virtual addrs,
  * we do not fill in the version number, and the length field
  * is treated as the number of entries currently in the block
- * (i.e. not a byte count).  This is all fixed on release.
+ * (i.e. not a byte count).  This is all fixed when calling 
+ * the flash routine.
  */
 
 /* Status int must be first member of struct */
@@ -201,16 +198,16 @@ static int rtas_flash_release(struct ino
 	if (uf->flist) {    
 		/* File was opened in write mode for a new flash attempt */
 		/* Clear saved list */
-		if (rtas_firmware_flash_list.next) {
-			free_flash_list(rtas_firmware_flash_list.next);
-			rtas_firmware_flash_list.next = NULL;
+		if (rtas_firmware_flash_list) {
+			free_flash_list(rtas_firmware_flash_list);
+			rtas_firmware_flash_list = NULL;
 		}
 
 		if (uf->status != FLASH_AUTH)  
 			uf->status = flash_list_valid(uf->flist);
 
 		if (uf->status == FLASH_IMG_READY) 
-			rtas_firmware_flash_list.next = uf->flist;
+			rtas_firmware_flash_list = uf->flist;
 		else
 			free_flash_list(uf->flist);
 
@@ -593,7 +590,7 @@ static void rtas_flash_firmware(int rebo
 	unsigned long rtas_block_list;
 	int i, status, update_token;
 
-	if (rtas_firmware_flash_list.next == NULL)
+	if (rtas_firmware_flash_list == NULL)
 		return;		/* nothing to do */
 
 	if (reboot_type != SYS_RESTART) {
@@ -610,20 +607,25 @@ static void rtas_flash_firmware(int rebo
 		return;
 	}
 
-	/* NOTE: the "first" block list is a global var with no data
-	 * blocks in the kernel data segment.  We do this because
-	 * we want to ensure this block_list addr is under 4GB.
+	/*
+	 * NOTE: the "first" block must be under 4GB, so we create
+	 * an entry with no data blocks in the reserved buffer in
+	 * the kernel data segment.
 	 */
-	rtas_firmware_flash_list.num_blocks = 0;
-	flist = (struct flash_block_list *)&rtas_firmware_flash_list;
+	spin_lock(&rtas_data_buf_lock);
+	flist = (struct flash_block_list *)&rtas_data_buf[0];
+	flist->num_blocks = 0;
+	flist->next = rtas_firmware_flash_list;
 	rtas_block_list = virt_to_abs(flist);
 	if (rtas_block_list >= 4UL*1024*1024*1024) {
 		printk(KERN_ALERT "FLASH: kernel bug...flash list header addr above 4GB\n");
+		spin_unlock(&rtas_data_buf_lock);
 		return;
 	}
 
 	printk(KERN_ALERT "FLASH: preparing saved firmware image for flash\n");
 	/* Update the block_list in place. */
+	rtas_firmware_flash_list = NULL; /* too hard to backout on error */
 	image_size = 0;
 	for (f = flist; f; f = next) {
 		/* Translate data addrs to absolute */
@@ -664,6 +666,7 @@ static void rtas_flash_firmware(int rebo
 		printk(KERN_ALERT "FLASH: unknown flash return code %d\n", status);
 		break;
 	}
+	spin_unlock(&rtas_data_buf_lock);
 }
 
 static void remove_flash_pde(struct proc_dir_entry *dp)

Re: [PATCH] powerpc: rtas_flash cannot be a module

[Anton Blanchard]

 
Hi,

> So we should use that rtas_data_buf with its lock ...
> 
> Oh look, the driver already uses that buffer for the call to verify_flash
> 
> untested patch to follow

Thanks, it built and tested OK with the following patch. Will send a
complete patch with these changes in a minute.

Anton

--- build/arch/powerpc/kernel/rtas_flash.c~	2010-06-12 09:06:43.000000000 -0400
+++ build/arch/powerpc/kernel/rtas_flash.c	2010-06-12 09:08:30.000000000 -0400
@@ -613,9 +613,9 @@
 	 * the kernel data segment.
 	 */
 	spin_lock(&rtas_data_buf_lock);
-	flist = (struct rtas_flash_list *)&rtas_data_buf[0];
-	flist.num_blocks = 0;
-	flist.next = rtas_firmware_flash_list;
+	flist = (struct flash_block_list *)&rtas_data_buf[0];
+	flist->num_blocks = 0;
+	flist->next = rtas_firmware_flash_list;
 	rtas_block_list = virt_to_abs(flist);
 	if (rtas_block_list >= 4UL*1024*1024*1024) {
 		printk(KERN_ALERT "FLASH: kernel bug...flash list header addr above 4GB\n");