From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Peter Jones <pjones@redhat.com>
Date: Mon, 1 Aug 2022 14:06:30 -0400
Subject: [PATCH] efi: use enumerated array positions for our allocation
 choices

In our kernel allocator on EFI systems, we currently have a growing
amount of code that references the various allocation policies by
position in the array, and of course maintenance of this code scales
very poorly.

This patch changes them to be enumerated, so they're easier to refer to
farther along in the code without confusion.

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 grub-core/loader/i386/efi/linux.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
index 91ae274299..8daa070132 100644
--- a/grub-core/loader/i386/efi/linux.c
+++ b/grub-core/loader/i386/efi/linux.c
@@ -60,17 +60,26 @@ struct allocation_choice {
     grub_efi_allocate_type_t alloc_type;
 };
 
-static struct allocation_choice max_addresses[4] =
+enum {
+    KERNEL_PREF_ADDRESS,
+    KERNEL_4G_LIMIT,
+    KERNEL_NO_LIMIT,
+};
+
+static struct allocation_choice max_addresses[] =
   {
     /* the kernel overrides this one with pref_address and
      * GRUB_EFI_ALLOCATE_ADDRESS */
-    { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
+    [KERNEL_PREF_ADDRESS] =
+      { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
+    /* If the flag in params is set, this one gets changed to be above 4GB. */
+    [KERNEL_4G_LIMIT] =
+      { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
     /* this one is always below 4GB, which we still *prefer* even if the flag
      * is set. */
-    { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
-    /* If the flag in params is set, this one gets changed to be above 4GB. */
-    { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
-    { 0, 0 }
+    [KERNEL_NO_LIMIT] =
+      { GRUB_EFI_MAX_ALLOCATION_ADDRESS, GRUB_EFI_ALLOCATE_MAX_ADDRESS },
+    { NO_MEM, 0, 0 }
   };
 static struct allocation_choice saved_addresses[4];
 
@@ -405,7 +414,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   if (lh->xloadflags & LINUX_XLF_CAN_BE_LOADED_ABOVE_4G)
     {
       grub_dprintf ("linux", "Loading kernel above 4GB is supported; enabling.\n");
-      max_addresses[2].addr = GRUB_EFI_MAX_USABLE_ADDRESS;
+      max_addresses[KERNEL_NO_LIMIT].addr = GRUB_EFI_MAX_USABLE_ADDRESS;
     }
   else
     {
@@ -478,11 +487,11 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   grub_dprintf ("linux", "lh->pref_address: %p\n", (void *)(grub_addr_t)lh->pref_address);
   if (lh->pref_address < (grub_uint64_t)GRUB_EFI_MAX_ALLOCATION_ADDRESS)
     {
-      max_addresses[0].addr = lh->pref_address;
-      max_addresses[0].alloc_type = GRUB_EFI_ALLOCATE_ADDRESS;
+      max_addresses[KERNEL_PREF_ADDRESS].addr = lh->pref_address;
+      max_addresses[KERNEL_PREF_ADDRESS].alloc_type = GRUB_EFI_ALLOCATE_ADDRESS;
     }
-  max_addresses[1].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
-  max_addresses[2].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
+  max_addresses[KERNEL_4G_LIMIT].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
+  max_addresses[KERNEL_NO_LIMIT].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
   kernel_size = lh->init_size;
   kernel_mem = kernel_alloc (kernel_size, GRUB_EFI_RUNTIME_SERVICES_CODE,
 			     N_("can't allocate kernel"));