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kern: simplify rela-in-bss impl

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This commit is contained in:
Michael Scire 2021-10-08 12:46:23 -07:00
parent cfc54dbc88
commit dc52da2819
3 changed files with 13 additions and 36 deletions
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31
mesosphere/build_mesosphere.py
View file

@ -9,23 +9,6 @@ def align_up(val, algn):
val += algn - 1 val += algn - 1
return val - (val % algn) 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): def main(argc, argv):
if argc != 4: if argc != 4:
print('Usage: %s kernel_ldr.bin kernel.bin output.bin' % argv[0]) print('Usage: %s kernel_ldr.bin kernel.bin output.bin' % argv[0])
@ -37,18 +20,14 @@ def main(argc, argv):
kernel_metadata_offset = 4 kernel_metadata_offset = 4
assert (kernel_metadata_offset <= len(kernel) - 0x40) assert (kernel_metadata_offset <= len(kernel) - 0x40)
assert (kernel[kernel_metadata_offset:kernel_metadata_offset + 4] == b'MSS0') 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) assert (bss_end >= bss_start)
bss_size = bss_end - bss_start
assert (bss_end == kernel_end) assert (bss_end == kernel_end)
assert (kernel_end <= len(kernel))
rela_offset, rela_size = find_rela(kernel, dynamic) assert (len(kernel) <= kernel_end)
assert (rela_size == len(kernel) - kernel_end) if len(kernel) < kernel_end:
assert (bss_start <= rela_offset and rela_offset + rela_size <= bss_end) kernel += b'\x00' * (kernel_end - len(kernel))
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 (kernel_end == len(kernel)) assert (kernel_end == len(kernel))
embedded_ini = b'' embedded_ini = b''

2
mesosphere/kernel/Makefile
View file

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

8
mesosphere/kernel/kernel.ld
View file

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