[RFC PATCH 0/2] ARM: kexec: Add dtb kexec support

[RFC PATCH 0/2] ARM: kexec: Add dtb kexec support

[Matthew Leach]

Currently the value of r2 that is passed to the new kernel when
performing a kexec() is hard coded to an address that is 16Kb before
the kernel image. A dtb file may be much larger and thus get corrupted
by the decompressor's page tables.

These patches, along with a set of kexec-tools patches, move the dtb
to a more sane location. The kernel will scan each segment for the dtb
magic within the first four bytes of each segment to identify the
physical address to pass through to the new kernel in r2.


Matthew Leach (2):
  ARM: kexec: scan for dtb magic in segments
  ARM: kexec: Check segment memory addresses

 arch/arm/kernel/machine_kexec.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

-- 
1.7.12

[RFC PATCH 1/2] ARM: kexec: scan for dtb magic in segments

[Matthew Leach]

This patch allows a dtb to be passed to a new kernel using the kexec
mechinism.

When loading segments from userspace, scan each segment's first four
bytes for the dtb magic. If this is found set the kexec_boot_atags
parameter to the relocate_kernel code to the phyical address of this
segment.

Cc: Simon Horman <horms@verge.net.au>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Matthew Leach <matthew.leach@arm.com>
---
 arch/arm/kernel/machine_kexec.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index dfcdb9f..a6bbc0f 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -9,6 +9,7 @@
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <asm/pgtable.h>
+#include <linux/of_fdt.h>
 #include <asm/pgalloc.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
@@ -32,6 +33,22 @@ static atomic_t waiting_for_crash_ipi;
 
 int machine_kexec_prepare(struct kimage *image)
 {
+	struct kexec_segment *current_segment;
+	__be32 header;
+	int i, err;
+
+	/* No segment at default ATAGs address. try to locate
+	 * a dtb using magic */
+	for (i = 0; i < image->nr_segments; i++) {
+		current_segment = &image->segment[i];
+
+		err = get_user(header, (__be32*)current_segment->buf);
+		if (err)
+			return err;
+
+		if (be32_to_cpu(header) == OF_DT_HEADER)
+			kexec_boot_atags = current_segment->mem;
+	}
 	return 0;
 }
 
@@ -122,7 +139,9 @@ void machine_kexec(struct kimage *image)
 	kexec_start_address = image->start;
 	kexec_indirection_page = page_list;
 	kexec_mach_type = machine_arch_type;
-	kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;
+	if (!kexec_boot_atags)
+		kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;
+
 
 	/* copy our kernel relocation code to the control code page */
 	memcpy(reboot_code_buffer,
-- 
1.7.12

[RFC PATCH 1/2] ARM: kexec: scan for dtb magic in segments

[Simon Horman]

On Thu, Sep 06, 2012 at 02:35:02PM +0100, Matthew Leach wrote:
> This patch allows a dtb to be passed to a new kernel using the kexec
> mechinism.
> 
> When loading segments from userspace, scan each segment's first four
> bytes for the dtb magic. If this is found set the kexec_boot_atags
> parameter to the relocate_kernel code to the phyical address of this
> segment.
> 
> Cc: Simon Horman <horms@verge.net.au>
> Reviewed-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Matthew Leach <matthew.leach@arm.com>
> ---

Reviewed-by: Simon Horman <horms@verge.net.au>

[RFC PATCH 2/2] ARM: kexec: Check segment memory addresses

[Matthew Leach]

Ensure that the memory regions that are set within the segments
correspond to physical contiguous memory regions.

Cc: Simon Horman <horms@verge.net.au>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Matthew Leach <matthew.leach@arm.com>
---
 arch/arm/kernel/machine_kexec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index a6bbc0f..524139a 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -8,6 +8,7 @@
 #include <linux/reboot.h>
 #include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/memblock.h>
 #include <asm/pgtable.h>
 #include <linux/of_fdt.h>
 #include <asm/pgalloc.h>
@@ -42,6 +43,12 @@ int machine_kexec_prepare(struct kimage *image)
 	for (i = 0; i < image->nr_segments; i++) {
 		current_segment = &image->segment[i];
 
+		err = memblock_is_region_memory(current_segment->mem,
+						current_segment->memsz);
+		if (err)
+			return - EINVAL;
+
+
 		err = get_user(header, (__be32*)current_segment->buf);
 		if (err)
 			return err;
-- 
1.7.12

[RFC PATCH 2/2] ARM: kexec: Check segment memory addresses

[Simon Horman]

On Thu, Sep 06, 2012 at 02:35:03PM +0100, Matthew Leach wrote:
> Ensure that the memory regions that are set within the segments
> correspond to physical contiguous memory regions.
> 
> Cc: Simon Horman <horms@verge.net.au>
> Reviewed-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Matthew Leach <matthew.leach@arm.com>
> ---

Reviewed-by: Simon Horman <horms@verge.net.au>

>  arch/arm/kernel/machine_kexec.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
> index a6bbc0f..524139a 100644
> --- a/arch/arm/kernel/machine_kexec.c
> +++ b/arch/arm/kernel/machine_kexec.c
> @@ -8,6 +8,7 @@
>  #include <linux/reboot.h>
>  #include <linux/io.h>
>  #include <linux/irq.h>
> +#include <linux/memblock.h>
>  #include <asm/pgtable.h>
>  #include <linux/of_fdt.h>
>  #include <asm/pgalloc.h>
> @@ -42,6 +43,12 @@ int machine_kexec_prepare(struct kimage *image)
>  	for (i = 0; i < image->nr_segments; i++) {
>  		current_segment = &image->segment[i];
>  
> +		err = memblock_is_region_memory(current_segment->mem,
> +						current_segment->memsz);
> +		if (err)
> +			return - EINVAL;
> +
> +
>  		err = get_user(header, (__be32*)current_segment->buf);
>  		if (err)
>  			return err;
> -- 
> 1.7.12
>