EFI touchups for v5.7

Hello Ingo, Thomas,

Please pull the below into tip:efi/core - it is a pair of fixes for the code that has been queued up for v5.7

Thanks,
Ard.

The following changes since commit d5528d5e91041e68e8eab9792ce627705a0ed273:

partitions/efi: Fix partition name parsing in GUID partition entry (2020-03-08 10:00:09 +0100)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi.git efi-next

for you to fetch changes up to c6987a415f71352fe1483b09d8b0027ccf3b2175:

efi/libstub/arm: fix spurious message that an initrd was loaded (2020-03-29 09:48:42 +0200)

----------------------------------------------------------------
Some EFI followup fixes for v5.7:
- fix arm64 boot regression on broken, older versions of GRUB
- suppress spurious 'initrd loaded from command line' print

----------------------------------------------------------------
Ard Biesheuvel (2):
efi/libstub/arm64: avoid image_base value from efi_loaded_image efi/libstub/arm: fix spurious message that an initrd was loaded

 drivers/firmware/efi/libstub/arm-stub.c   | 2 +-
 drivers/firmware/efi/libstub/arm64-stub.c | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.

However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.

While at it, fix another issue in commit 9f9223778ef3, which may result in the unassigned image_addr to be misidentified as the preferred load offset of the kernel, which is unlikely but will cause a boot crash if it does occur.

Finally, let's add a warning if the _text vs. image_base discrepancy is detected, so we can tell more easily how widespread this issue actually is.

---
 drivers/firmware/efi/libstub/arm64-stub.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

index 9254cd8ab2d3..db0c1a9c1699 100644
@@ -116,6 +116,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		*image_addr = (unsigned long)_text;
 		if (*image_addr == preferred_offset)
 			return EFI_SUCCESS;
 

@@ -140,7 +141,11 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-	memcpy((void *)*image_addr, image->image_base, kernel_size);
+
+	if (image->image_base != _text)
+		pr_efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
+
+	memcpy((void *)*image_addr, _text, kernel_size);
 
 	return EFI_SUCCESS;
 }

2.17.1

Commit ec93fc371f014a6f ("efi/libstub: Add support for loading the initrd from a device path") added a diagnostic print to the ARM version of the EFI stub that reports whether an initrd has been loaded that was passed via the command line using initrd=. However, it failed to take into account that, for historical reasons, the file loading routines return EFI_SUCCESS when no file was found, and the only way to decide whether a file was loaded is to inspect the 'size' argument that is passed by reference. So let's inspect this returned size, to prevent the print from being emitted even if no initrd was loaded at all.

---
 drivers/firmware/efi/libstub/arm-stub.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 13559c7e6643..99a5cde7c2d8 100644
@@ -277,7 +277,7 @@ efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
 		} else if (status == EFI_NOT_FOUND) {
 			status = efi_load_initrd(image, &initrd_addr, &initrd_size,
 						 ULONG_MAX, max_addr);
-			if (status == EFI_SUCCESS)
+			if (status == EFI_SUCCESS && initrd_size > 0)
 				pr_efi("Loaded initrd from command line option\n");
 		}
 		if (status != EFI_SUCCESS)

2.17.1

Applied to tip:efi/core, thanks Ard!

Ingo