[GRUB2 PATCH v6 3/4 - FOR COMMIT] multiboot2: Do not pass memory maps to image if EFI boot services are enabled

[Daniel Kiper]

If image requested EFI boot services then skip multiboot2 memory maps.
Main reason for not providing maps is because they will likely be
invalid. We do a few allocations after filling them, e.g. for relocator
needs. Usually we do not care as we would have finished boot services.
If we keep boot services then it is easier/safer to not provide maps.
However, if image needs memory maps and they are not provided by bootloader
then it should get itself just before ExitBootServices() call.

Signed-off-by: Daniel Kiper <address@hidden>
Reviewed-by: Konrad Rzeszutek Wilk <address@hidden>
---
v5 - suggestions/fixes:
   - improve commit message
     (suggested by Konrad Rzeszutek Wilk).

v3 - suggestions/fixes:
   - improve commit message
     (suggested by Konrad Rzeszutek Wilk and Vladimir 'phcoder' Serbinenko).
---
 grub-core/loader/multiboot_mbi2.c |   71 ++++++++++++++++++-------------------
 1 file changed, 35 insertions(+), 36 deletions(-)

diff --git a/grub-core/loader/multiboot_mbi2.c 
b/grub-core/loader/multiboot_mbi2.c
index 6c04402..ad1553b 100644
--- a/grub-core/loader/multiboot_mbi2.c
+++ b/grub-core/loader/multiboot_mbi2.c
@@ -390,7 +390,7 @@ static grub_size_t
 grub_multiboot_get_mbi_size (void)
 {
 #ifdef GRUB_MACHINE_EFI
-  if (!efi_mmap_size)
+  if (!keep_bs && !efi_mmap_size)
     find_efi_mmap_size ();    
 #endif
   return 2 * sizeof (grub_uint32_t) + sizeof (struct multiboot_tag)
@@ -755,12 +755,13 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
       }
   }
 
-  {
-    struct multiboot_tag_mmap *tag = (struct multiboot_tag_mmap *) ptrorig;
-    grub_fill_multiboot_mmap (tag);
-    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
-      / sizeof (grub_properly_aligned_t);
-  }
+  if (!keep_bs)
+    {
+      struct multiboot_tag_mmap *tag = (struct multiboot_tag_mmap *) ptrorig;
+      grub_fill_multiboot_mmap (tag);
+      ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
+       / sizeof (grub_properly_aligned_t);
+    }
 
   {
     struct multiboot_tag_elf_sections *tag
@@ -776,18 +777,19 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
       / sizeof (grub_properly_aligned_t);
   }
 
-  {
-    struct multiboot_tag_basic_meminfo *tag
-      = (struct multiboot_tag_basic_meminfo *) ptrorig;
-    tag->type = MULTIBOOT_TAG_TYPE_BASIC_MEMINFO;
-    tag->size = sizeof (struct multiboot_tag_basic_meminfo); 
+  if (!keep_bs)
+    {
+      struct multiboot_tag_basic_meminfo *tag
+       = (struct multiboot_tag_basic_meminfo *) ptrorig;
+      tag->type = MULTIBOOT_TAG_TYPE_BASIC_MEMINFO;
+      tag->size = sizeof (struct multiboot_tag_basic_meminfo);
 
-    /* Convert from bytes to kilobytes.  */
-    tag->mem_lower = grub_mmap_get_lower () / 1024;
-    tag->mem_upper = grub_mmap_get_upper () / 1024;
-    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
-       / sizeof (grub_properly_aligned_t);
-  }
+      /* Convert from bytes to kilobytes.  */
+      tag->mem_lower = grub_mmap_get_lower () / 1024;
+      tag->mem_upper = grub_mmap_get_upper () / 1024;
+      ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
+       / sizeof (grub_properly_aligned_t);
+    }
 
   {
     struct grub_net_network_level_interface *net;
@@ -886,27 +888,24 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
     grub_efi_uintn_t efi_desc_size;
     grub_efi_uint32_t efi_desc_version;
 
-    tag->type = MULTIBOOT_TAG_TYPE_EFI_MMAP;
-    tag->size = sizeof (*tag) + efi_mmap_size;
-
     if (!keep_bs)
-      err = grub_efi_finish_boot_services (&efi_mmap_size, tag->efi_mmap, NULL,
-                                          &efi_desc_size, &efi_desc_version);
-    else
       {
-       if (grub_efi_get_memory_map (&efi_mmap_size, (void *) tag->efi_mmap,
-                                    NULL,
-                                    &efi_desc_size, &efi_desc_version) <= 0)
-         err = grub_error (GRUB_ERR_IO, "couldn't retrieve memory map");
+       tag->type = MULTIBOOT_TAG_TYPE_EFI_MMAP;
+       tag->size = sizeof (*tag) + efi_mmap_size;
+
+       err = grub_efi_finish_boot_services (&efi_mmap_size, tag->efi_mmap, 
NULL,
+                                            &efi_desc_size, &efi_desc_version);
+
+       if (err)
+         return err;
+
+       tag->descr_size = efi_desc_size;
+       tag->descr_vers = efi_desc_version;
+       tag->size = sizeof (*tag) + efi_mmap_size;
+
+       ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
+         / sizeof (grub_properly_aligned_t);
       }
-    if (err)
-      return err;
-    tag->descr_size = efi_desc_size;
-    tag->descr_vers = efi_desc_version;
-    tag->size = sizeof (*tag) + efi_mmap_size;
-
-    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
-      / sizeof (grub_properly_aligned_t);
   }
 
   if (keep_bs)
-- 
1.7.10.4