If the UEFI firmware has loaded the kernel at the right alignment, and
we are running a relocatable kernel, there is no point in copying the
kernel to a different place in memory, and instead, we can just run it
in place.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
drivers/firmware/efi/libstub/arm64-stub.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 9254cd8ab2d3..d263f504dcf0 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -104,6 +104,15 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
(u32)phys_seed);
*image_addr = *reserve_addr + offset;
+ } else if (IS_ENABLED(CONFIG_RELOCATABLE) &&
+ IS_ALIGNED((u64)_text - TEXT_OFFSET, EFI_KIMG_ALIGN)) {
+ /*
+ * If we are relocatable and were loaded at a suitable offset,
+ * there is no need to do anything and we can just execute in
+ * place.
+ */
+ *image_addr = (u64)_text;
+ return EFI_SUCCESS;
} else {
/*
* Else, try a straight allocation at the preferred offset.
--
2.17.1
