[PATCH 2/2] arm64: efi: kaslr: Fix boot failure if efi_random_alloc() fails

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

If efi_random_alloc() fails, we still try to use EFI_KIMG_ALIGN
instead of MIN_KIMG_ALIGN to check the kernel image alignment,
which is incorrect, we need to fallback to MIN_KIMG_ALIGN (2M).

This removes the not-that-useful min_kimg_align helper and instead
uses the appropriate aligment in the respective call sites:

efi_random_alloc() always wants EFI_KIMG_ALIGN as this is only
used when kaslr is on, and all other cases go into alignment
check code which always need to check (and enforce) MIN_KIMG_ALIGN

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Fixes: 7c116db24d94 (efi/libstub/arm64: Retain 2MB kernel Image alignment if !KASLR)
---
 drivers/firmware/efi/libstub/arm64-stub.c | 27 ++++++++++-------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index 7bf0a7acae5e..e264ff90ba03 100644
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -34,18 +34,6 @@ efi_status_t check_platform_features(void)
 	return EFI_SUCCESS;
 }
 
-/*
- * Although relocatable kernels can fix up the misalignment with respect to
- * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of
- * sync with those recorded in the vmlinux when kaslr is disabled but the
- * image required relocation anyway. Therefore retain 2M alignment unless
- * KASLR is in use.
- */
-static u64 min_kimg_align(void)
-{
-	return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
-}
-
 efi_status_t handle_kernel_image(unsigned long *image_addr,
 				 unsigned long *image_size,
 				 unsigned long *reserve_addr,
@@ -84,15 +72,24 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		/*
 		 * If KASLR is enabled, and we have some randomness available,
 		 * locate the kernel at a randomized offset in physical memory.
+		 *
+		 * In that case, we don't need to preserve the 2M alignment
 		 */
-		status = efi_random_alloc(*reserve_size, min_kimg_align(),
+		status = efi_random_alloc(*reserve_size, EFI_KIMG_ALIGN,
 					  reserve_addr, phys_seed);
 	} else {
 		status = EFI_OUT_OF_RESOURCES;
 	}
 
 	if (status != EFI_SUCCESS) {
-		if (IS_ALIGNED((u64)_text, min_kimg_align())) {
+		/*
+		 * Although relocatable kernels can fix up the misalignment with respect to
+		 * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of
+		 * sync with those recorded in the vmlinux when kaslr is disabled but the
+		 * image required relocation anyway. Therefore retain 2M alignment unless
+		 * KASLR is in use.
+		 */
+		if (IS_ALIGNED((u64)_text, MIN_KIMG_ALIGN)) {
 			/*
 			 * Just execute from wherever we were loaded by the
 			 * UEFI PE/COFF loader if the alignment is suitable.
@@ -103,7 +100,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 
 		status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
-						    ULONG_MAX, min_kimg_align());
+						    ULONG_MAX, MIN_KIMG_ALIGN);
 
 		if (status != EFI_SUCCESS) {
 			efi_err("Failed to relocate kernel\n");




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