core: move relocation to embedded data region
The relocation sections are placed last in the linker script to be kept
out of the way for the other sections. The relocation sections are
interpreted by gen_tee_bin.py and converted into a more compact data
structure which is stored in the embedded data region.
For each relocation, only one 32-bit offset is kept. Compared to the
standard ELF format, the size of the relocation table is either halved
(Rel32 type: two 32-bit words per entry) or divided by 6 (Rel64 type:
three 64-bit words per entry).
Acked-by: Jerome Forissier <jerome@forissier.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/scripts/gen_tee_bin.py b/scripts/gen_tee_bin.py
index 675ae24..504d6b3 100755
--- a/scripts/gen_tee_bin.py
+++ b/scripts/gen_tee_bin.py
@@ -15,7 +15,10 @@
try:
from elftools.elf.elffile import ELFFile
from elftools.elf.constants import SH_FLAGS
+ from elftools.elf.enums import ENUM_RELOC_TYPE_ARM
+ from elftools.elf.enums import ENUM_RELOC_TYPE_AARCH64
from elftools.elf.sections import SymbolTableSection
+ from elftools.elf.relocation import RelocationSection
except ImportError:
print("""
@@ -117,12 +120,50 @@
if tee_pager_bin is None:
pad_to = get_symbol(elffile, '__data_end')['st_value']
dump_names = re.compile(
- r'^\.(text|rodata|got|data|ARM\.exidx|ARM\.extab|rel|rela)$')
+ r'^\.(text|rodata|got|data|ARM\.exidx|ARM\.extab)$')
tee_pager_bin = get_sections(elffile, pad_to, dump_names)
return tee_pager_bin
+def get_reloc_bin(elffile):
+ if get_arch_id(elffile) == 0:
+ exp_rel_type = ENUM_RELOC_TYPE_ARM['R_ARM_RELATIVE']
+ else:
+ exp_rel_type = ENUM_RELOC_TYPE_AARCH64['R_AARCH64_RELATIVE']
+
+ link_address = get_symbol(elffile, '__text_start')['st_value']
+
+ addrs = []
+ for section in elffile.iter_sections():
+ if not isinstance(section, RelocationSection):
+ continue
+ for rel in section.iter_relocations():
+ if rel['r_info_type'] == 0:
+ continue
+ if rel['r_info_type'] != exp_rel_type:
+ eprint("Unexpected relocation type 0x%x" %
+ rel['r_info_type'])
+ sys.exit(1)
+ addrs.append(rel['r_offset'] - link_address)
+
+ addrs.sort()
+ data = bytearray()
+ for a in addrs:
+ data += struct.pack('<I', a)
+
+ # Relocations has been reduced to only become the relative type with
+ # addend at the address (r_offset) of relocation, that is, increase by
+ # load_offset. The addresses (r_offset) are also sorted. The format is
+ # then:
+ # uint32_t: relocation #1
+ # uint32_t: relocation #2
+ # ...
+ # uint32_t: relocation #n
+
+ return data
+
+
def get_hashes_bin(elffile):
pageable_bin = get_pageable_bin(elffile)
if len(pageable_bin) % small_page_size != 0:
@@ -142,29 +183,40 @@
global tee_embdata_bin
if tee_embdata_bin is None:
hashes_bin = get_hashes_bin(elffile)
+ reloc_bin = get_reloc_bin(elffile)
- num_entries = 1
+ num_entries = 2
hash_offs = 2 * 4 + num_entries * (2 * 4)
hash_pad = round_up(len(hashes_bin), 8) - len(hashes_bin)
- total_len = hash_offs + len(hashes_bin) + hash_pad
+ reloc_offs = hash_offs + len(hashes_bin) + hash_pad
+ reloc_pad = round_up(len(reloc_bin), 8) - len(reloc_bin)
+ total_len = reloc_offs + len(reloc_bin) + reloc_pad
- tee_embdata_bin = struct.pack('<IIII', total_len, num_entries,
- hash_offs, len(hashes_bin))
+ tee_embdata_bin = struct.pack('<IIIIII', total_len, num_entries,
+ hash_offs, len(hashes_bin),
+ reloc_offs, len(reloc_bin))
tee_embdata_bin += hashes_bin + bytearray(hash_pad)
+ tee_embdata_bin += reloc_bin + bytearray(reloc_pad)
# The embedded data region is designed to be easy to extend when
# needed, it's formatted as:
- # +--------------------------------------------------------+
- # | uint32_t: Length of entire area including this field |
- # +--------------------------------------------------------+
- # | uint32_t: Number of entries "1" |
- # +--------------------------------------------------------+
- # | uint32_t: Offset of hashes from beginning of table |
- # +--------------------------------------------------------+
- # | uint32_t: Length of hashes |
- # +--------------------------------------------------------+
- # | Data of hashes + eventual padding |
- # +--------------------------------------------------------+
+ # +---------------------------------------------------------+
+ # | uint32_t: Length of entire area including this field |
+ # +---------------------------------------------------------+
+ # | uint32_t: Number of entries "2" |
+ # +---------------------------------------------------------+
+ # | uint32_t: Offset of hashes from beginning of table |
+ # +---------------------------------------------------------+
+ # | uint32_t: Length of hashes |
+ # +---------------------------------------------------------+
+ # | uint32_t: Offset of relocations from beginning of table |
+ # +---------------------------------------------------------+
+ # | uint32_t: Length of relocations |
+ # +---------------------------------------------------------+
+ # | Data of hashes + eventual padding |
+ # +---------------------------------------------------------+
+ # | Data of relocations + eventual padding |
+ # +---------------------------------------------------------+
return tee_embdata_bin