Re: [RESEND PATCH v2 0/2] efi/libstub: Ensure instruction cache coherency after kernel relocation

[Huacai Chen]

On Tue, Apr 28, 2026 at 7:07 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
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> On Mon, 27 Apr 2026, at 18:11, Ard Biesheuvel wrote:
> > On Mon, 27 Apr 2026, at 10:47, WANG Rui wrote:
> >> Changes since [v1]:
> >>   * Move efi_cache_sync_image() after check_platform_features(), matching arm64.
> >>   * Add "()" after function name in the subject.
> >>
> >> The EFI stub relocates the kernel image by copying it to a new memory
> >> location using memcpy(). On architectures where the instruction and data
> >> caches are not automatically coherent, the copied instructions may not be
> >> visible to the instruction fetch unit without explicit cache maintenance.
> >>
> >> This series adds the missing call to efi_cache_sync_image() in the generic
> >> relocation path, and provides a LoongArch implementation using the ibar
> >> instruction to ensure instruction fetches observe the updated contents.
> >>
> >> [v1]: https://lore.kernel.org/loongarch/20260427034451.717817-1-r@xxxxxx
> >>
> >> WANG Rui (2):
> >>   efi/loongarch: Implement efi_cache_sync_image
> >>   efi/libstub: Synchronize instruction cache after kernel relocation
> >>
> >
> > Queued up in efi/urgent - thanks.
Maybe this series should cc stable?

Huacai

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> This breaks the ARM build.
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> Since LoongArch is the only remaining user of efi_relocate_kernel(), I'll move it into drivers/firmware/efi/libstub/loongarch-stub.c first, and fix up these patches accordingly afterwards (no need to resend anything)
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