[PATCH] powerpc/crash: adjust the elfcorehdr size

[PATCH] powerpc/crash: adjust the elfcorehdr size

[Sourabh Jain]

With crash hotplug support enabled, additional memory is allocated to
the elfcorehdr kexec segment to accommodate resources added during
memory hotplug events. However, the kdump FDT is not updated with the
same size, which can result in elfcorehdr corruption in the kdump
kernel.

Update elf_headers_sz (the kimage member representing the size of the
elfcorehdr kexec segment) to reflect the total memory allocated for the
elfcorehdr segment instead of the elfcorehdr buffer size at the time of
kdump load. This allows of_kexec_alloc_and_setup_fdt() to reserve the
full elfcorehdr memory in the kdump FDT and prevents elfcorehdr
corruption.

Fixes: 849599b702ef8 ("powerpc/crash: add crash memory hotplug support")
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/kexec/file_load_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index e7ef8b2a2554..ed76326f4b57 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -460,7 +460,7 @@ static int load_elfcorehdr_segment(struct kimage *image, struct kexec_buf *kbuf)
 	}
 
 	image->elf_load_addr = kbuf->mem;
-	image->elf_headers_sz = headers_sz;
+	image->elf_headers_sz = kbuf->memsz;
 	image->elf_headers = headers;
 out:
 	kfree(cmem);
-- 
2.52.0

Re: [PATCH] powerpc/crash: adjust the elfcorehdr size

[Hari Bathini]

On 18/02/26 10:31 am, Sourabh Jain wrote:
> With crash hotplug support enabled, additional memory is allocated to
> the elfcorehdr kexec segment to accommodate resources added during
> memory hotplug events. However, the kdump FDT is not updated with the
> same size, which can result in elfcorehdr corruption in the kdump
> kernel.
> 
> Update elf_headers_sz (the kimage member representing the size of the
> elfcorehdr kexec segment) to reflect the total memory allocated for the
> elfcorehdr segment instead of the elfcorehdr buffer size at the time of
> kdump load. This allows of_kexec_alloc_and_setup_fdt() to reserve the
> full elfcorehdr memory in the kdump FDT and prevents elfcorehdr
> corruption.
> 
> Fixes: 849599b702ef8 ("powerpc/crash: add crash memory hotplug support")
> Cc: Hari Bathini <hbathini@linux.ibm.com>
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
> ---
>   arch/powerpc/kexec/file_load_64.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> index e7ef8b2a2554..ed76326f4b57 100644
> --- a/arch/powerpc/kexec/file_load_64.c
> +++ b/arch/powerpc/kexec/file_load_64.c
> @@ -460,7 +460,7 @@ static int load_elfcorehdr_segment(struct kimage *image, struct kexec_buf *kbuf)
>   	}
>   
>   	image->elf_load_addr = kbuf->mem;

> -	image->elf_headers_sz = headers_sz;
> +	image->elf_headers_sz = kbuf->memsz;

A comment here explaining why memsz is used instead of headers_sz and
also, another comment where memsz is set, as to why extra memory size
is accounted under it, improves readability...

Regardless..

Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>

Re: [PATCH] powerpc/crash: adjust the elfcorehdr size

[Sourabh Jain]

On 20/02/26 15:54, Hari Bathini wrote:
>
>
> On 18/02/26 10:31 am, Sourabh Jain wrote:
>> With crash hotplug support enabled, additional memory is allocated to
>> the elfcorehdr kexec segment to accommodate resources added during
>> memory hotplug events. However, the kdump FDT is not updated with the
>> same size, which can result in elfcorehdr corruption in the kdump
>> kernel.
>>
>> Update elf_headers_sz (the kimage member representing the size of the
>> elfcorehdr kexec segment) to reflect the total memory allocated for the
>> elfcorehdr segment instead of the elfcorehdr buffer size at the time of
>> kdump load. This allows of_kexec_alloc_and_setup_fdt() to reserve the
>> full elfcorehdr memory in the kdump FDT and prevents elfcorehdr
>> corruption.
>>
>> Fixes: 849599b702ef8 ("powerpc/crash: add crash memory hotplug support")
>> Cc: Hari Bathini <hbathini@linux.ibm.com>
>> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
>> Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
>> Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
>> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
>> ---
>>   arch/powerpc/kexec/file_load_64.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/kexec/file_load_64.c 
>> b/arch/powerpc/kexec/file_load_64.c
>> index e7ef8b2a2554..ed76326f4b57 100644
>> --- a/arch/powerpc/kexec/file_load_64.c
>> +++ b/arch/powerpc/kexec/file_load_64.c
>> @@ -460,7 +460,7 @@ static int load_elfcorehdr_segment(struct kimage 
>> *image, struct kexec_buf *kbuf)
>>       }
>>         image->elf_load_addr = kbuf->mem;
>
>> -    image->elf_headers_sz = headers_sz;
>> +    image->elf_headers_sz = kbuf->memsz;
>
> A comment here explaining why memsz is used instead of headers_sz and
> also, another comment where memsz is set, as to why extra memory size
> is accounted under it, improves readability...

Sure I will update the commit message in the next version.

>
> Regardless..
>
> Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Thanks for the review.

- Sourabh Jain