On 3/2/2018 12:53 AM, AKASHI Takahiro wrote:
Tyler, Jeffrey,

[Note: This issue takes place in kexec, not kdump. So to be precise,
it is not the same phenomenon as what I addressed in [1],[2]:

On Thu, Mar 01, 2018 at 12:56:38PM -0500, Tyler Baicar wrote:

On 2/28/2018 9:50 PM, AKASHI Takahiro wrote:

On Wed, Feb 28, 2018 at 08:39:42AM -0700, Jeffrey Hugo wrote:
On 2/27/2018 11:19 PM, AKASHI Takahiro wrote:

# I missed catching your patch as its subject doesn't contain arm64.

On Fri, Feb 23, 2018 at 12:42:31PM -0700, Tyler Baicar wrote:
Currently on arm64 ESRT memory does not appear to be properly blocked off.
Upon successful initialization, ESRT prints out the memory region that it
exists in like:

esrt: Reserving ESRT space from 0x000000000a4c1c18 to 0x000000000a4c1cf0.

But then by dumping /proc/iomem this region appears as part of System RAM
rather than being reserved:

08f10000-0deeffff : System RAM

This causes issues when trying to kexec if the kernel is relocatable. When
kexec tries to execute, this memory can be selected to relocate the kernel to
which then overwrites all the ESRT information. Then when the kexec'd kernel
tries to initialize ESRT, it doesn't recognize the ESRT version number and
just returns from efi_esrt_init().
I'm not sure what is the root cause of your problem.
Do you have good confidence that the kernel (2nd kernel image in this case?)
really overwrite ESRT region?
According to my debug, yes.
Using JTAG, I was able to determine that the ESRT memory region was getting
overwritten by the secondary kernel in
kernel/arch/arm64/kernel/relocate_kernel.S - specifically the "copy_page"
line of arm64_relocate_new_kernel()

To my best knowledge, kexec is carefully designed not to do such a thing
as it allocates a temporary buffer for kernel image and copies it to the
final destination at the very end of the 1st kernel.

My guess is that kexec, or rather kexec-tools, tries to load the kernel image
at 0x8f80000 (or 0x9080000?, not sure) in your case. It may or may not be
overlapped with ESRT.
(Try "-d" option when executing kexec command for confirmation.)
With -d, I see

get_memory_ranges_iomem_cb: 0000000009611000 - 000000000e5fffff : System RAM

That overlaps the ESRT reservation -
[ 0.000000] esrt: Reserving ESRT space from 0x000000000b708718 to

Are you using initrd with kexec?
To make the things clear, can you show me, if possible, the followings:
I have attached all of these:
Many thanks.
According to the data, ESRT was overwritten by initrd, not the kernel image.
It doesn't matter to you though :)

The solution would be, as Ard suggested, that more information be
added to /proc/iomem.
I'm going to fix the issue as quickly as possible.
Great, thank you!! Please add us to the fix and we will gladly test it out.


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