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powerpc: Feed entire flattened device tree into the random pool

PATCH In review Anton Blanchard 4 participants 7 messages Jul 25, 2013 – Aug 29, 2013

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PowerPC Device tree
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Anton Blanchard

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#0 lore raw

PATCH 1/1 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 <[email protected]>

---

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.

arch/powerpc/kernel/setup-common.c +11 -0
index 63d051f..6914851 100644
@@ -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);
#1 lore raw
Quoted 11 lines · Anton Blanchard

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 <[email protected]>

---

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

author
#2 lore raw

PATCH 1/1 of: Feed entire flattened device tree into the random pool

Hi Michael,

Quoted 2 lines

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 <[email protected]>

---

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

drivers/of/fdt.c +12 -0
Index: 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);
#3 lore raw

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

Quoted 8 lines · Anton Blanchard

Hi Michael,

Quoted 2 lines

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.

Signature · 4 lines
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#4 lore raw

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

In reply to Anton Blanchard
Quoted 34 lines · Anton Blanchard

Hi Michael,

Quoted 2 lines

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 <[email protected]>

---

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

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

drivers/of/fdt.c +1 -0
@@ -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

drivers/of/fdt.c void __init unflatten_device_tree(void) · line 724

Quoted 10 lines
drivers/of/fdt.c +7 -0
@@ -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);

be32_to_cpu(initial_boot_params->totalsize);

g.

author
#5 lore raw

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

Hi,

Quoted 1 line

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 <[email protected]>

---

v3: Fix endian issues as noted by Grant

drivers/of/fdt.c +12 -0
Index: 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);
Applied
#6 lore raw

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

Quoted 7 lines · Anton Blanchard

Hi,

Quoted 1 line

be32_to_cpu(initial_boot_params->totalsize);

Ouch, thanks Grant.

Quoted 8 lines

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 <[email protected]>

Applied, thanks

g.