efi: Free malloc regions on exit

When we exit grub, we don't free all the memory that we allocated earlier
for our heap region. This can cause problems with setups where you try
to descend the boot order using "exit" entries, such as PXE -> HD boot
scenarios.

Signed-off-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/kern/efi/init.c

@@ -80,4 +80,5 @@ grub_efi_fini (void)
 {
   grub_efidisk_fini ();
   grub_console_fini ();
+  grub_efi_memory_fini ();
 }

grub-core/kern/efi/mm.c

@@ -49,6 +49,70 @@ static grub_efi_uintn_t finish_desc_size;
 static grub_efi_uint32_t finish_desc_version;
 int grub_efi_is_finished = 0;
 
+/*
+ * We need to roll back EFI allocations on exit. Remember allocations that
+ * we'll free on exit.
+ */
+struct efi_allocation;
+struct efi_allocation {
+	grub_efi_physical_address_t address;
+	grub_efi_uint64_t pages;
+	struct efi_allocation *next;
+};
+static struct efi_allocation *efi_allocated_memory;
+
+static void
+grub_efi_store_alloc (grub_efi_physical_address_t address,
+                         grub_efi_uintn_t pages)
+{
+  grub_efi_boot_services_t *b;
+  struct efi_allocation *alloc;
+  grub_efi_status_t status;
+
+  b = grub_efi_system_table->boot_services;
+  status = efi_call_3 (b->allocate_pool, GRUB_EFI_LOADER_DATA,
+                           sizeof(*alloc), (void**)&alloc);
+
+  if (status == GRUB_EFI_SUCCESS)
+    {
+      alloc->next = efi_allocated_memory;
+      alloc->address = address;
+      alloc->pages = pages;
+      efi_allocated_memory = alloc;
+    }
+  else
+      grub_printf ("Could not malloc memory to remember EFI allocation. "
+                   "Exiting GRUB won't free all memory.\n");
+}
+
+static void
+grub_efi_drop_alloc (grub_efi_physical_address_t address,
+                           grub_efi_uintn_t pages)
+{
+  struct efi_allocation *ea, *eap;
+  grub_efi_boot_services_t *b;
+
+  b = grub_efi_system_table->boot_services;
+
+  for (eap = NULL, ea = efi_allocated_memory; ea; eap = ea, ea = ea->next)
+    {
+      if (ea->address != address || ea->pages != pages)
+         continue;
+
+      /* Remove the current entry from the list. */
+      if (eap)
+        eap->next = ea->next;
+      else
+        efi_allocated_memory = ea->next;
+
+      /* Then free the memory backing it. */
+      efi_call_1 (b->free_pool, ea);
+
+      /* And leave, we're done. */
+      break;
+    }
+}
+
 /* Allocate pages. Return the pointer to the first of allocated pages.  */
 void *
 grub_efi_allocate_pages_real (grub_efi_physical_address_t address,
@@ -79,6 +143,8 @@ grub_efi_allocate_pages_real (grub_efi_physical_address_t address,
 	return 0;
     }
 
+  grub_efi_store_alloc (address, pages);
+
   return (void *) ((grub_addr_t) address);
 }
 
@@ -108,6 +174,8 @@ grub_efi_free_pages (grub_efi_physical_address_t address,
 
   b = grub_efi_system_table->boot_services;
   efi_call_2 (b->free_pages, address, pages);
+
+  grub_efi_drop_alloc (address, pages);
 }
 
 #if defined (__i386__) || defined (__x86_64__)
@@ -422,6 +490,20 @@ add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
     grub_fatal ("too little memory");
 }
 
+void
+grub_efi_memory_fini (void)
+{
+  /*
+   * Free all stale allocations. grub_efi_free_pages() will remove
+   * the found entry from the list and it will always find the first
+   * list entry (efi_allocated_memory is the list start). Hence we
+   * remove all entries from the list until none is left altogether.
+   */
+  while (efi_allocated_memory)
+      grub_efi_free_pages (efi_allocated_memory->address,
+                           efi_allocated_memory->pages);
+}
+
 #if 0
 /* Print the memory map.  */
 static void

include/grub/efi/efi.h

@@ -55,6 +55,7 @@ EXPORT_FUNC(grub_efi_get_memory_map) (grub_efi_uintn_t *memory_map_size,
 				      grub_efi_uintn_t *map_key,
 				      grub_efi_uintn_t *descriptor_size,
 				      grub_efi_uint32_t *descriptor_version);
+void grub_efi_memory_fini (void);
 grub_efi_loaded_image_t *EXPORT_FUNC(grub_efi_get_loaded_image) (grub_efi_handle_t image_handle);
 void EXPORT_FUNC(grub_efi_print_device_path) (grub_efi_device_path_t *dp);
 char *EXPORT_FUNC(grub_efi_get_filename) (grub_efi_device_path_t *dp);