Re: [PATCH v3 4/5] x86/xen: Avoid relocatable quantities in Xen ELF notes

Jason Andryuk
2024-10-09T17:16:44Z

On 2024-10-09 12:04, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Xen puts virtual and physical addresses into ELF notes that are treated
> by the linker as relocatable by default. Doing so is not only pointless,
> given that the ELF notes are only intended for consumption by Xen before
> the kernel boots. It is also a KASLR leak, given that the kernel's ELF
> notes are exposed via the world readable /sys/kernel/notes.
>
> So emit these constants in a way that prevents the linker from marking
> them as relocatable. This involves place-relative relocations (which
> subtract their own virtual address from the symbol value) and linker
> provided absolute symbols that add the address of the place to the
> desired value.
>
> Tested-by: Jason Andryuk <jason.andryuk@amd.com>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

Thanks,
Jason