[PATCH] powerpc: Feed entire flattened device tree into the random pool

We feed the entire DMI table into the random pool to provide
better random data during early boot, so do the same with the
flattened device tree.

Signed-off-by: Anton Blanchard <redacted>
---

It might be worth doing this somewhere common, but the only place
I could find (unflatten_device_tree) is almost certainly too
early in the boot process.

diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 63d051f..6914851 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c

@@ -35,6 +35,7 @@
 #include <linux/percpu.h>
 #include <linux/memblock.h>
 #include <linux/of_platform.h>
+#include <linux/random.h>
 #include <asm/io.h>
 #include <asm/paca.h>
 #include <asm/prom.h>

@@ -752,3 +753,13 @@ void arch_setup_pdev_archdata(struct platform_device *pdev)
 	pdev->dev.dma_mask = &pdev->archdata.dma_mask;
  	set_dma_ops(&pdev->dev, &dma_direct_ops);
 }
+
+/* Feed entire flattened device tree into the random pool */
+static int __init add_fdt_randomness(void)
+{
+	add_device_randomness(initial_boot_params,
+			      initial_boot_params->totalsize);
+
+	return 0;
+}
+core_initcall(add_fdt_randomness);

On Thu, Jul 25, 2013 at 12:51:22PM +1000, Anton Blanchard wrote:

We feed the entire DMI table into the random pool to provide
better random data during early boot, so do the same with the
flattened device tree.

Signed-off-by: Anton Blanchard <redacted>
---

It might be worth doing this somewhere common, but the only place
I could find (unflatten_device_tree) is almost certainly too
early in the boot process.

Nice.

But why not put the initcall in drivers/of/fdt.c, that way it's not
early but it's still common ?

cheers

Hi Michael,

But why not put the initcall in drivers/of/fdt.c, that way it's not
early but it's still common ?

Good idea! How does this look? So long as it happens before
module_init(rand_initialize) we should be good.

Anton
--

We feed the entire DMI table into the random pool to provide
better random data during early boot, so do the same with the
flattened device tree.

Signed-off-by: Anton Blanchard <redacted>
---

v2: move to drivers/of/fdt.c as suggested by Michael Ellerman

Index: b/drivers/of/fdt.c
===================================================================

--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c

@@ -17,6 +17,7 @@
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
+#include <linux/random.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #ifdef CONFIG_PPC

@@ -714,3 +715,14 @@ void __init unflatten_device_tree(void)
 }
 
 #endif /* CONFIG_OF_EARLY_FLATTREE */
+
+/* Feed entire flattened device tree into the random pool */
+static int __init add_fdt_randomness(void)
+{
+	if (initial_boot_params)
+		add_device_randomness(initial_boot_params,
+				      initial_boot_params->totalsize);
+
+	return 0;
+}
+core_initcall(add_fdt_randomness);

On Thu, Jul 25, 2013 at 02:30:31PM +1000, Anton Blanchard wrote:

Hi Michael,

quoted

But why not put the initcall in drivers/of/fdt.c, that way it's not
early but it's still common ?

Good idea! How does this look? So long as it happens before
module_init(rand_initialize) we should be good.

This must be some strange new meaning of the word "random" of which I
was not previously aware.  But I guess it's marginally better than
nothing.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

On Thu, 25 Jul 2013 14:30:31 +1000, Anton Blanchard [off-list ref] wrote:

be32_to_cpu(initial_boot_params->totalsize);

g.

Hi,

be32_to_cpu(initial_boot_params->totalsize);

Ouch, thanks Grant.

Anton
--

We feed the entire DMI table into the random pool to provide
better random data during early boot, so do the same with the
flattened device tree.

Signed-off-by: Anton Blanchard <redacted>
---

v3: Fix endian issues as noted by Grant

Index: b/drivers/of/fdt.c
===================================================================

--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c

@@ -17,6 +17,7 @@
 #include <linux/string.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
+#include <linux/random.h>
 
 #include <asm/setup.h>  /* for COMMAND_LINE_SIZE */
 #ifdef CONFIG_PPC

@@ -714,3 +715,14 @@ void __init unflatten_device_tree(void)
 }
 
 #endif /* CONFIG_OF_EARLY_FLATTREE */
+
+/* Feed entire flattened device tree into the random pool */
+static int __init add_fdt_randomness(void)
+{
+	if (initial_boot_params)
+		add_device_randomness(initial_boot_params,
+				be32_to_cpu(initial_boot_params->totalsize));
+
+	return 0;
+}
+core_initcall(add_fdt_randomness);

On Mon, 29 Jul 2013 13:11:50 +1000, Anton Blanchard [off-list ref] wrote:

Hi,

quoted

be32_to_cpu(initial_boot_params->totalsize);

Ouch, thanks Grant.

Anton
--

We feed the entire DMI table into the random pool to provide
better random data during early boot, so do the same with the
flattened device tree.

Signed-off-by: Anton Blanchard <redacted>

Applied, thanks

g.