[Xen-devel] [GRUB2 PATCH v3 3/4] multiboot2: Do not pass memory maps to image if EFI boot services are enabled

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

Do not pass memory maps to image if it asked for EFI boot services.
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 already finish boot services.
If we keep boot services then it is easier to not provide maps. However,
if image needs memory maps and they are not provided by bootloader then
it should get them itself just before ExitBootServices() call.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
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 7591edc..ce68f48 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)
@@ -759,12 +759,13 @@ 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
@@ -780,18 +781,19 @@ 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;
@@ -890,27 +892,24 @@ 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


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