diff --git a/mesosphere/build_mesosphere.py b/mesosphere/build_mesosphere.py index ed85e3282..b64fba912 100644 --- a/mesosphere/build_mesosphere.py +++ b/mesosphere/build_mesosphere.py @@ -9,6 +9,22 @@ 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('= len(kernel)) + bss_start, bss_end, kernel_end, dynamic = up('= 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 (kernel_end == len(kernel)) embedded_ini = b'' try: diff --git a/mesosphere/kernel/kernel.ld b/mesosphere/kernel/kernel.ld index 739fed35e..8d7da0ff0 100644 --- a/mesosphere/kernel/kernel.ld +++ b/mesosphere/kernel/kernel.ld @@ -113,9 +113,6 @@ SECTIONS .gnu_extab : ONLY_IF_RO { *(.gnu_extab*) } : rodata .dynamic : { *(.dynamic) } :rodata :dyn - .dynsym : { *(.dynsym) } :rodata - .dynstr : { *(.dynstr) } :rodata - .rela.dyn : { *(.rela.*) } :rodata .hash : { *(.hash) } :rodata .gnu.hash : { *(.gnu.hash) } :rodata .gnu.version : { *(.gnu.version) } :rodata @@ -152,18 +149,21 @@ SECTIONS { *(.data .data.* .gnu.linkonce.d.*) SORT(CONSTRUCTORS) + . = ALIGN(8); } :data __bss_start__ = .; - .bss ALIGN(8) : - { - *(.dynbss) - *(.bss .bss.* .gnu.linkonce.b.*) - *(COMMON) - . = ALIGN(8); - } : data - . = ALIGN(0x1000); + OVERLAY : NOCROSSREFS { + .bss { + *(.dynbss) + *(.bss .bss.* .gnu.linkonce.b.*) + *(COMMON) + . = ALIGN(0x1000); + } + .rela.dyn { *(.rela.*) } + } :data + __bss_end__ = .; @@ -174,7 +174,7 @@ SECTIONS ================== */ /* Discard sections that difficult post-processing */ - /DISCARD/ : { *(.group .comment .note .interp .fini_array .fini_array.* .text._ZSt23__cmpexch_failure_orderSt12memory_order) } + /DISCARD/ : { *(.group .comment .note .interp .fini_array .fini_array.* .dynsym .dynstr) } /* Stabs debugging sections. */ .stab 0 : { *(.stab) } diff --git a/mesosphere/kernel_ldr/source/kern_init_loader.cpp b/mesosphere/kernel_ldr/source/kern_init_loader.cpp index ad75f04eb..24c21a363 100644 --- a/mesosphere/kernel_ldr/source/kern_init_loader.cpp +++ b/mesosphere/kernel_ldr/source/kern_init_loader.cpp @@ -207,13 +207,15 @@ namespace ams::kern::init::loader { /* NOTE: Nintendo does this only on 10.0.0+ */ init_pt.PhysicallyRandomize(virtual_base_address + rx_offset, bss_end_offset - rx_offset, true); - /* Clear kernel .bss. */ - std::memset(GetVoidPointer(virtual_base_address + bss_offset), 0, bss_end_offset - bss_offset); - /* Apply relocations to the kernel. */ const Elf::Dyn *kernel_dynamic = reinterpret_cast(GetInteger(virtual_base_address) + dynamic_offset); Elf::ApplyRelocations(GetInteger(virtual_base_address), kernel_dynamic); + /* Clear kernel .bss. */ + /* NOTE: The kernel does this before applying relocations, but we do it after. */ + /* This allows us to place our relocations in space overlapping with .bss...and thereby reclaim the memory that would otherwise be wasted. */ + std::memset(GetVoidPointer(virtual_base_address + bss_offset), 0, bss_end_offset - bss_offset); + /* Call the kernel's init array functions. */ /* NOTE: The kernel does this after reprotecting .rodata, but we do it before. */ /* This allows our global constructors to edit .rodata, which is valuable for editing the SVC tables to support older firmwares' ABIs. */