Provide __bss_start and _end symbols in grub-mkimage.

For this ensure that all bss sections are merged.

We need this to correctly prelink non-PE relocatable images.

diff --git a/include/grub/util/mkimage.h b/include/grub/util/mkimage.h
index 8169939a7accbac38aba26feb7a56a1c39db797d..25a49d5c34cf0e4cbf668a1563e561184c24a9cd 100644 (file)
--- a/include/grub/util/mkimage.h
+++ b/include/grub/util/mkimage.h
@@ -33,6 +33,8 @@ struct grub_mkimage_layout
   grub_size_t ia64_got_off;
   grub_size_t got_size;
   unsigned ia64jmpnum;
+  Elf_Addr bss_start;
+  Elf_Addr end;
 };
 
 /* Private header. Use only in mkimage-related sources.  */

diff --git a/util/grub-mkimagexx.c b/util/grub-mkimagexx.c
index 74f86f5df7cb1125e70985db2da56bf4ce4d5b33..433322d85c4f2aeb2ff4602d43ccd5c8c8caba5a 100644 (file)
--- a/util/grub-mkimagexx.c
+++ b/util/grub-mkimagexx.c
@@ -490,6 +490,7 @@ SUFFIX (relocate_symbols) (Elf_Ehdr *e, Elf_Shdr *sections,
                           Elf_Shdr *symtab_section, Elf_Addr *section_addresses,
                           Elf_Half section_entsize, Elf_Half num_sections,
                           void *jumpers, Elf_Addr jumpers_addr,
+                          Elf_Addr bss_start, Elf_Addr end,
                           const struct grub_install_image_target_desc *image_target)
 {
   Elf_Word symtab_size, sym_size, num_syms;
@@ -528,16 +529,22 @@ SUFFIX (relocate_symbols) (Elf_Ehdr *e, Elf_Shdr *sections,
         }
       else if (cur_index == STN_UNDEF)
        {
-         if (sym->st_name)
+         if (sym->st_name && grub_strcmp (name, "__bss_start"))
+           sym->st_value = bss_start;
+         else if (sym->st_name && grub_strcmp (name, "__end"))
+           sym->st_value = end;
+         else if (sym->st_name)
            grub_util_error ("undefined symbol %s", name);
          else
            continue;
        }
       else if (cur_index >= num_sections)
        grub_util_error ("section %d does not exist", cur_index);
-
-      sym->st_value = (grub_target_to_host (sym->st_value)
-                      + section_addresses[cur_index]);
+      else
+       {
+         sym->st_value = (grub_target_to_host (sym->st_value)
+                          + section_addresses[cur_index]);
+       }
 
       if (image_target->elf_target == EM_IA_64 && ELF_ST_TYPE (sym->st_info)
          == STT_FUNC)
@@ -1462,9 +1469,7 @@ SUFFIX (is_text_section) (Elf_Shdr *s, const struct grub_install_image_target_de
          == (SHF_EXECINSTR | SHF_ALLOC));
 }
 
-/* Determine if this section is a data section. This assumes that
-   BSS is also a data section, since the converter initializes BSS
-   when producing PE32 to avoid a bug in EFI implementations.  */
+/* Determine if this section is a data section.  */
 static int
 SUFFIX (is_data_section) (Elf_Shdr *s, const struct grub_install_image_target_desc *image_target)
 {
@@ -1472,7 +1477,16 @@ SUFFIX (is_data_section) (Elf_Shdr *s, const struct grub_install_image_target_de
       && grub_target_to_host32 (s->sh_type) != SHT_PROGBITS)
     return 0;
   return ((grub_target_to_host (s->sh_flags) & (SHF_EXECINSTR | SHF_ALLOC))
-         == SHF_ALLOC);
+         == SHF_ALLOC) && !(grub_target_to_host32 (s->sh_type) == SHT_NOBITS);
+}
+
+static int
+SUFFIX (is_bss_section) (Elf_Shdr *s, const struct grub_install_image_target_desc *image_target)
+{
+  if (!is_relocatable (image_target))
+    return 0;
+  return ((grub_target_to_host (s->sh_flags) & (SHF_EXECINSTR | SHF_ALLOC))
+         == SHF_ALLOC) && (grub_target_to_host32 (s->sh_type) == SHT_NOBITS);
 }
 
 /* Return if the ELF header is valid.  */
@@ -1492,6 +1506,32 @@ SUFFIX (check_elf_header) (Elf_Ehdr *e, size_t size, const struct grub_install_i
   return 1;
 }
 
+static Elf_Addr
+SUFFIX (put_section) (Elf_Shdr *s, int i,
+                     Elf_Addr current_address,
+                     Elf_Addr *section_addresses,
+                     const char *strtab,
+                     const struct grub_install_image_target_desc *image_target)
+{
+       Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
+       const char *name = strtab + grub_host_to_target32 (s->sh_name);
+
+       if (align)
+         current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
+                                     align)
+           - image_target->vaddr_offset;
+
+       grub_util_info ("locating the section %s at 0x%"
+                       GRUB_HOST_PRIxLONG_LONG,
+                       name, (unsigned long long) current_address);
+       if (!is_relocatable (image_target))
+         current_address = grub_host_to_target_addr (s->sh_addr)
+           - image_target->link_addr;
+       section_addresses[i] = current_address;
+       current_address += grub_host_to_target_addr (s->sh_size);
+       return current_address;
+}
+
 /* Locate section addresses by merging code sections and data sections
    into .text and .data, respectively. Return the array of section
    addresses.  */
@@ -1531,32 +1571,22 @@ SUFFIX (locate_sections) (const char *kernel_path,
        i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
     if (SUFFIX (is_text_section) (s, image_target))
       {
-       Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
-       const char *name = strtab + grub_host_to_target32 (s->sh_name);
-       if (align)
-         current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
-                                     align) - image_target->vaddr_offset;
-       grub_util_info ("locating the section %s at 0x%"
-                       GRUB_HOST_PRIxLONG_LONG,
-                       name, (unsigned long long) current_address);
-       if (image_target->id != IMAGE_EFI)
+       current_address = SUFFIX (put_section) (s, i,
+                                               current_address,
+                                               section_addresses,
+                                               strtab,
+                                               image_target);
+       if (!is_relocatable (image_target) &&
+           grub_host_to_target_addr (s->sh_addr) != image_target->link_addr)
          {
-           current_address = grub_host_to_target_addr (s->sh_addr)
-             - image_target->link_addr;
-           if (grub_host_to_target_addr (s->sh_addr)
-               != image_target->link_addr)
-             {
-               char *msg
-                 = grub_xasprintf (_("`%s' is miscompiled: its start address is 0x%llx"
-                                     " instead of 0x%llx: ld.gold bug?"),
-                                   kernel_path,
-                                   (unsigned long long) grub_host_to_target_addr (s->sh_addr),
-                                   (unsigned long long) image_target->link_addr);
-               grub_util_error ("%s", msg);
-             }
+           char *msg
+             = grub_xasprintf (_("`%s' is miscompiled: its start address is 0x%llx"
+                                 " instead of 0x%llx: ld.gold bug?"),
+                               kernel_path,
+                               (unsigned long long) grub_host_to_target_addr (s->sh_addr),
+                               (unsigned long long) image_target->link_addr);
+           grub_util_error ("%s", msg);
          }
-       section_addresses[i] = current_address;
-       current_address += grub_host_to_target_addr (s->sh_size);
       }
 
   current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
@@ -1569,27 +1599,31 @@ SUFFIX (locate_sections) (const char *kernel_path,
        i < num_sections;
        i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
     if (SUFFIX (is_data_section) (s, image_target))
-      {
-       Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
-       const char *name = strtab + grub_host_to_target32 (s->sh_name);
+      current_address = SUFFIX (put_section) (s, i,
+                                             current_address,
+                                             section_addresses,
+                                             strtab,
+                                             image_target);
 
-       if (align)
-         current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
-                                     align)
-           - image_target->vaddr_offset;
+  current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
+                             image_target->section_align) - image_target->vaddr_offset;
 
-       grub_util_info ("locating the section %s at 0x%"
-                       GRUB_HOST_PRIxLONG_LONG,
-                       name, (unsigned long long) current_address);
-       if (image_target->id != IMAGE_EFI)
-         current_address = grub_host_to_target_addr (s->sh_addr)
-           - image_target->link_addr;
-       section_addresses[i] = current_address;
-       current_address += grub_host_to_target_addr (s->sh_size);
-      }
+  layout->bss_start = current_address;
+  
+  /* .bss */
+  for (i = 0, s = sections;
+       i < num_sections;
+       i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
+    if (SUFFIX (is_bss_section) (s, image_target))
+      current_address = SUFFIX (put_section) (s, i,
+                                             current_address,
+                                             section_addresses,
+                                             strtab,
+                                             image_target);
 
   current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
                              image_target->section_align) - image_target->vaddr_offset;
+  layout->end = current_address;
   layout->kernel_size = current_address;
   return section_addresses;
 }
@@ -1789,8 +1823,11 @@ SUFFIX (grub_mkimage_load_image) (const char *kernel_path,
        i < num_sections;
        i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
     if (SUFFIX (is_data_section) (s, image_target)
+       || SUFFIX (is_bss_section) (s, image_target)
        || SUFFIX (is_text_section) (s, image_target))
       {
+       /* Explicitly initialize BSS
+          when producing PE32 to avoid a bug in EFI implementations. */
        if (grub_target_to_host32 (s->sh_type) == SHT_NOBITS)
          memset (out_img + section_addresses[i], 0,
                  grub_host_to_target_addr (s->sh_size));