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https://github.com/Atmosphere-NX/Atmosphere.git
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kern: put rela in bss
NOTE: This saves ~0x4000 of space at the cost of crimes against the linker script.
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parent
fba962ef11
commit
960ba52a43
4 changed files with 25 additions and 19 deletions
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@ -9,7 +9,6 @@ def align_up(val, algn):
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val += algn - 1
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return val - (val % algn)
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def main(argc, argv):
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if argc != 4:
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print('Usage: %s kernel_ldr.bin kernel.bin output.bin' % argv[0])
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@ -21,8 +20,15 @@ def main(argc, argv):
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kernel_metadata_offset = 4
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assert (kernel_metadata_offset <= len(kernel) - 0x40)
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assert (kernel[kernel_metadata_offset:kernel_metadata_offset + 4] == b'MSS0')
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kernel_end = up('<I', kernel[kernel_metadata_offset + 0x38:kernel_metadata_offset + 0x3C])[0]
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assert (kernel_end >= len(kernel))
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bss_start, bss_end, kernel_end = up('<III', kernel[kernel_metadata_offset + 0x30:kernel_metadata_offset + 0x3C])
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assert (bss_end >= bss_start)
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assert (bss_end == kernel_end)
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assert (len(kernel) <= kernel_end)
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if len(kernel) < kernel_end:
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kernel += b'\x00' * (kernel_end - len(kernel))
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assert (kernel_end == len(kernel))
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embedded_ini = b''
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try:
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@ -102,7 +102,7 @@ DEPENDS := $(OFILES:.o=.d)
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# main targets
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#---------------------------------------------------------------------------------
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$(OUTPUT).bin : $(OUTPUT).elf
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$(OBJCOPY) -S -O binary --set-section-flags .bss=alloc,load,contents $< $@
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$(OBJCOPY) -S -O binary $< $@
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@echo built ... $(notdir $@)
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$(OUTPUT).elf : $(OFILES)
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@ -113,9 +113,6 @@ SECTIONS
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.gnu_extab : ONLY_IF_RO { *(.gnu_extab*) } : rodata
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.dynamic : { *(.dynamic) } :rodata :dyn
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.dynsym : { *(.dynsym) } :rodata
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.dynstr : { *(.dynstr) } :rodata
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.rela.dyn : { *(.rela.*) } :rodata
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.hash : { *(.hash) } :rodata
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.gnu.hash : { *(.gnu.hash) } :rodata
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.gnu.version : { *(.gnu.version) } :rodata
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@ -152,18 +149,19 @@ SECTIONS
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{
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*(.data .data.* .gnu.linkonce.d.*)
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SORT(CONSTRUCTORS)
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. = ALIGN(8);
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} :data
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__bss_start__ = .;
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.bss ALIGN(8) :
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{
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*(.dynbss)
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*(.bss .bss.* .gnu.linkonce.b.*)
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*(COMMON)
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. = ALIGN(8);
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} : data
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. = ALIGN(0x1000);
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.rela.dyn : { *(.rela.*) } :data
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.bss ADDR(.rela.dyn) (NOLOAD) : {
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*(.dynbss)
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*(.bss .bss.* .gnu.linkonce.b.*)
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*(COMMON)
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. = ALIGN(0x1000);
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}
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__bss_end__ = .;
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@ -174,7 +172,7 @@ SECTIONS
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================== */
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/* Discard sections that difficult post-processing */
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/DISCARD/ : { *(.group .comment .note .interp .fini_array .fini_array.* .text._ZSt23__cmpexch_failure_orderSt12memory_order) }
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/DISCARD/ : { *(.group .comment .note .interp .fini_array .fini_array.* .dynsym .dynstr) }
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/* Stabs debugging sections. */
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.stab 0 : { *(.stab) }
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@ -207,13 +207,15 @@ namespace ams::kern::init::loader {
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/* NOTE: Nintendo does this only on 10.0.0+ */
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init_pt.PhysicallyRandomize(virtual_base_address + rx_offset, bss_end_offset - rx_offset, true);
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/* Clear kernel .bss. */
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std::memset(GetVoidPointer(virtual_base_address + bss_offset), 0, bss_end_offset - bss_offset);
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/* Apply relocations to the kernel. */
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const Elf::Dyn *kernel_dynamic = reinterpret_cast<const Elf::Dyn *>(GetInteger(virtual_base_address) + dynamic_offset);
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Elf::ApplyRelocations(GetInteger(virtual_base_address), kernel_dynamic);
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/* Clear kernel .bss. */
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/* NOTE: The kernel does this before applying relocations, but we do it after. */
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/* This allows us to place our relocations in space overlapping with .bss...and thereby reclaim the memory that would otherwise be wasted. */
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std::memset(GetVoidPointer(virtual_base_address + bss_offset), 0, bss_end_offset - bss_offset);
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/* Call the kernel's init array functions. */
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/* NOTE: The kernel does this after reprotecting .rodata, but we do it before. */
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/* This allows our global constructors to edit .rodata, which is valuable for editing the SVC tables to support older firmwares' ABIs. */
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