Subject: Re: [PATCH v4 0/5] ARM: decompressor: use by-VA cache maintenance for v7 cores

From: Tony Lindgren <[email-masked]>
Date: Wed, 26 Feb 2020 11:14:56 -0800

* Ard Biesheuvel <[email-masked]> [200226 16:58]:
> While making changes to the EFI stub startup code, I noticed that we are
> still doing set/way maintenance on the caches when booting on v7 cores.
> This works today on VMs by virtue of the fact that KVM traps set/way ops
> and cleans the whole address space by VA on behalf of the guest, and on
> most v7 hardware, the set/way ops are in fact sufficient when only one
> core is running, as there usually is no system cache. But on systems
> like SynQuacer, for which 32-bit firmware is available, the current cache
> maintenance only pushes the data out to the L3 system cache, where it
> is not visible to the CPU once it turns the MMU and caches off.
> 
> So instead, switch to the by-VA cache maintenance that the architecture
> requires for v7 and later (and ARM1176, as a side effect).
> 
> Changes since v3:
> - ensure that the region that is cleaned after self-relocation of the zImage
>   covers the appended DTB, if present

I gave these a try on top of the earlier "arm: fix Kbuild issue caused
by per-task stack protector GCC plugin" and booting still works for
me on armv7 including appended dtb:

Tested-by: Tony Lindgren <[email-masked]>

_______________________________________________
linux-arm-kernel mailing list
[email-masked]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel