Revert "efi/libstub: arm64: Relax 2M alignment again for relocatable kernels"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4VSGH
CVE: NA

--------------------------------

This reverts commit c6d2a109.

I got the following messages when booting kernel:

  EFI stub: Booting Linux Kernel...
  EFI stub: EFI_RNG_PROTOCOL unavailable, KASLR will be disabled
  EFI stub: Using DTB from configuration table
  EFI stub: Exiting boot services and installing virtual address map...

  ...

  [ 0.000000] CPU features: kernel page table isolation forced ON by KASLR
  [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI)
  [ 3.393380] KASLR disabled due to lack of seed

KPTI is forced on by KASLR, but in fact KASLR is not enabled, it's
because kaslr_offset() returns non-zero in kaslr_requires_kpti().

To avoid this problem, when efi kaslr is disabled, make image
MIN_KIMG_ALIGN align which is used to get KASLR offset in
primary_entry(), so kaslr_offset() will returns 0.
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/firmware/efi/libstub/arm64-stub.c

@@ -79,6 +79,18 @@ static bool check_image_region(u64 base, u64 size)
 	return ret;
 }
 
+/*
+ * 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,
@@ -89,16 +101,6 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	unsigned long kernel_size, kernel_memsize = 0;
 	u32 phys_seed = 0;
 
-	/*
-	 * 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 if KASLR was explicitly disabled, even if it was not
-	 * going to be activated to begin with.
-	 */
-	u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
-
 	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
 		if (!efi_nokaslr) {
 			status = efi_get_random_bytes(sizeof(phys_seed),
@@ -132,7 +134,7 @@ 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.
 		 */
-		status = efi_random_alloc(*reserve_size, min_kimg_align,
+		status = efi_random_alloc(*reserve_size, min_kimg_align(),
 					  reserve_addr, phys_seed);
 	} else {
 		status = EFI_OUT_OF_RESOURCES;
@@ -141,7 +143,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	if (status != EFI_SUCCESS) {
 		if (!check_image_region((u64)_text, kernel_memsize)) {
 			efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
-		} else if (IS_ALIGNED((u64)_text, min_kimg_align)) {
+		} else 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.
@@ -152,7 +154,7 @@ 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");