[PATCH] of: unflatten_and_copy: handle NULL initial_boot_params

[PATCH] of: unflatten_and_copy: handle NULL initial_boot_params

[James Hogan]

Check whether initial_boot_params is NULL before dereferencing it in
unflatten_and_copy_device_tree() for the case where no device tree is
available but the arch can still boot to a minimal usable system without
it.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arch@vger.kernel.org
---
 drivers/of/fdt.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 2fa024b97c43..ac4983955e6d 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -922,8 +922,14 @@ void __init unflatten_device_tree(void)
  */
 void __init unflatten_and_copy_device_tree(void)
 {
-	int size = __be32_to_cpu(initial_boot_params->totalsize);
-	void *dt = early_init_dt_alloc_memory_arch(size,
+	int size;
+	void *dt;
+
+	if (!initial_boot_params)
+		return;
+
+	size = __be32_to_cpu(initial_boot_params->totalsize);
+	dt = early_init_dt_alloc_memory_arch(size,
 		__alignof__(struct boot_param_header));
 
 	if (dt) {
-- 
1.8.1.2

Re: [PATCH] of: unflatten_and_copy: handle NULL initial_boot_params

[Grant Likely]

On Tue, 19 Nov 2013 12:58:12 +0000, James Hogan <james.hogan@imgtec.com> wrote:
> Check whether initial_boot_params is NULL before dereferencing it in
> unflatten_and_copy_device_tree() for the case where no device tree is
> available but the arch can still boot to a minimal usable system without
> it.
> 
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> Cc: Grant Likely <grant.likely@linaro.org>
> Cc: Rob Herring <rob.herring@calxeda.com>
> Cc: devicetree@vger.kernel.org
> Cc: linux-arch@vger.kernel.org
> ---
>  drivers/of/fdt.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 2fa024b97c43..ac4983955e6d 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -922,8 +922,14 @@ void __init unflatten_device_tree(void)
>   */
>  void __init unflatten_and_copy_device_tree(void)
>  {
> -	int size = __be32_to_cpu(initial_boot_params->totalsize);
> -	void *dt = early_init_dt_alloc_memory_arch(size,
> +	int size;
> +	void *dt;
> +
> +	if (!initial_boot_params)
> +		return;

Worth logging a message for those who can obtain the kernel log
buffer?

Otherwise:

Acked-by: Grant Likely <grant.likely@linaro.org>

But see my comments on Geert's "dt: Handle passed/built-in DT selection
in early_init_dt_scan()" patch.

g.

Re: [PATCH] of: unflatten_and_copy: handle NULL initial_boot_params

[James Hogan]

On 21/11/13 12:39, Grant Likely wrote:
> On Tue, 19 Nov 2013 12:58:12 +0000, James Hogan <james.hogan@imgtec.com> wrote:
>> Check whether initial_boot_params is NULL before dereferencing it in
>> unflatten_and_copy_device_tree() for the case where no device tree is
>> available but the arch can still boot to a minimal usable system without
>> it.
>>
>> Signed-off-by: James Hogan <james.hogan@imgtec.com>
>> Cc: Grant Likely <grant.likely@linaro.org>
>> Cc: Rob Herring <rob.herring@calxeda.com>
>> Cc: devicetree@vger.kernel.org
>> Cc: linux-arch@vger.kernel.org
>> ---
>>  drivers/of/fdt.c | 10 ++++++++--
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index 2fa024b97c43..ac4983955e6d 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -922,8 +922,14 @@ void __init unflatten_device_tree(void)
>>   */
>>  void __init unflatten_and_copy_device_tree(void)
>>  {
>> -	int size = __be32_to_cpu(initial_boot_params->totalsize);
>> -	void *dt = early_init_dt_alloc_memory_arch(size,
>> +	int size;
>> +	void *dt;
>> +
>> +	if (!initial_boot_params)
>> +		return;
> 
> Worth logging a message for those who can obtain the kernel log
> buffer?

Yes, sounds reasonable (especially since for Meta the platform name detected from DT doesn't get logged in this case and I still get the console out via JTAG probe).
I'll post a v2 adding this:

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index ac4983955e6d..758b4f8b30b7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -925,8 +925,10 @@ void __init unflatten_and_copy_device_tree(void)
 	int size;
 	void *dt;
 
-	if (!initial_boot_params)
+	if (!initial_boot_params) {
+		pr_warn("No valid device tree found, continuing without\n");
 		return;
+	}
 
 	size = __be32_to_cpu(initial_boot_params->totalsize);
 	dt = early_init_dt_alloc_memory_arch(size,

> Otherwise:
> 
> Acked-by: Grant Likely <grant.likely@linaro.org>

Thanks
James