kern: simplify rela-in-bss impl

mesosphere/build_mesosphere.py

@@ -9,23 +9,6 @@ def align_up(val, algn):
     val += algn - 1
     return val - (val % algn)
 
-def find_rela(kernel, dynamic):
-    rela_offset, rela_size = (None, None)
-    while True:
-        dyn_type, dyn_val = up('<QQ', kernel[dynamic:dynamic+0x10])
-        if dyn_type == 0:
-            break
-        elif dyn_type == 7:
-            assert (rela_offset is None)
-            rela_offset = dyn_val
-        elif dyn_type == 8:
-            assert (rela_size is None)
-            rela_size = dyn_val
-        dynamic += 0x10
-    assert (rela_offset is not None)
-    assert (rela_size is not None)
-    return (rela_offset, rela_size)
-
 def main(argc, argv):
     if argc != 4:
         print('Usage: %s kernel_ldr.bin kernel.bin output.bin' % argv[0])
@@ -37,18 +20,14 @@ def main(argc, argv):
     kernel_metadata_offset = 4
     assert (kernel_metadata_offset <= len(kernel) - 0x40)
     assert (kernel[kernel_metadata_offset:kernel_metadata_offset + 4] == b'MSS0')
-    bss_start, bss_end, kernel_end, dynamic = up('<IIII', kernel[kernel_metadata_offset + 0x30:kernel_metadata_offset + 0x40])
+
+    bss_start, bss_end, kernel_end = up('<III', kernel[kernel_metadata_offset + 0x30:kernel_metadata_offset + 0x3C])
     assert (bss_end >= bss_start)
-    bss_size = bss_end - bss_start
     assert (bss_end == kernel_end)
-    assert (kernel_end <= len(kernel))
 
-    rela_offset, rela_size = find_rela(kernel, dynamic)
-    assert (rela_size == len(kernel) - kernel_end)
-    assert (bss_start <= rela_offset and rela_offset + rela_size <= bss_end)
-    assert (kernel[bss_start:bss_end] == (b'\x00'* bss_size))
-
-    kernel = kernel[:rela_offset] + kernel[bss_end:] + (b'\x00' * (bss_size - (rela_size + (rela_offset - bss_start))))
+    assert (len(kernel) <= kernel_end)
+    if len(kernel) < kernel_end:
+        kernel += b'\x00' * (kernel_end - len(kernel))
     assert (kernel_end == len(kernel))
 
     embedded_ini = b''

mesosphere/kernel/Makefile

@@ -102,7 +102,7 @@ DEPENDS	:=	$(OFILES:.o=.d)
 # main targets
 #---------------------------------------------------------------------------------
 $(OUTPUT).bin	:	$(OUTPUT).elf
-	$(OBJCOPY) -S -O binary --set-section-flags .bss=alloc,load,contents $< $@
+	$(OBJCOPY) -S -O binary $< $@
 	@echo built ... $(notdir $@)
 
 $(OUTPUT).elf	:	$(OFILES)

mesosphere/kernel/kernel.ld

@@ -154,16 +154,14 @@ SECTIONS
 
 	__bss_start__ = .;
 
-    OVERLAY : NOCROSSREFS {
-        .bss {
+    .rela.dyn : { *(.rela.*) } :data
+
+    .bss ADDR(.rela.dyn) (NOLOAD) : {
         *(.dynbss)
         *(.bss .bss.* .gnu.linkonce.b.*)
         *(COMMON)
         . = ALIGN(0x1000);
     }
-        .rela.dyn { *(.rela.*) }
-    } :data
-
 
 	__bss_end__ = .;