4cdb7ba9b6
This patch extends the protection domain framework with an additional plugin to use Task-State Segment (TSS) structures to offload much of the work of switching protection domains to the CPU. This can save space compared to paging, since paging requires two 4KiB page tables and one 32-byte page table plus one whole-system TSS and an additional 32-byte data structure for each protection domain, whereas the approach implemented by this patch just requires a 128-byte data structure for each protection domain. Only a small number of protection domains will typically be used, so n * 128 < 8328 + (n * 32). For additional information, please refer to cpu/x86/mm/README.md. GCC 6 is introducing named address spaces for the FS and GS segments [1]. LLVM Clang also provides address spaces for the FS and GS segments [2]. This patch also adds support to the multi-segment X86 memory management subsystem for using these features instead of inline assembly blocks, which enables type checking to detect some address space mismatches. [1] https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html [2] http://llvm.org/releases/3.3/tools/clang/docs/LanguageExtensions.html#target-specific-extensions
93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
/*
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* Copyright (C) 2015-2016, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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OUTPUT_FORMAT("elf32-i386")
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ENTRY(start)
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SECTIONS {
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/*
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OS-Dev Wiki says it is common for kernels to start at 1M. Addresses before that
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are used by BIOS/EFI, the bootloader and memory-mapped I/O.
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The UEFI GenFw program inserts a 0x220-byte offset between the image base and
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the .text section. We add that same offset here to align the symbols in the
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UEFI DLL with those in the final UEFI binary to make debugging easier. We also
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apply 32-byte alignments to sections rather than more conventional 4K-byte
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alignments to avoid symbols being shifted from the intermediate DLL to the
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final UEFI image as would occur if the GenFw program shifted the .text section
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from a higher, 4K-aligned offset to the 0x220-byte offset from the image base.
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Such shifting may make debugging more difficult by preventing the DLL from
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being a directly-useful source of symbol information. The debugging symbols
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are not included in the final UEFI image. The GenFw program uses a minimum
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section alignment of 32 bytes, so smaller alignment granularities may also
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result in symbol perturbation.
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*/
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. = 1M + 0x220;
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.text ALIGN (32) :
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{
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KEEP(*(.multiboot))
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*(.boot_text)
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*(.text*)
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}
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.rodata ALIGN (32) :
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{
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*(.rodata*)
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_sdata_shared_isr = .;
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KEEP(*(.shared_isr_data*))
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_edata_shared_isr = .;
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}
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.data ALIGN (32) :
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{
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*(.data*)
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}
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.bss ALIGN (32) :
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{
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*(COMMON)
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*(.main_stack)
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*(.bss*)
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*(.gdt_bss_start)
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/*
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The other GDT-related sections defined in gdt.h are only used when
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protection domain support is enabled. Thus, they do not need to be
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included here.
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*/
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_ebss_gdt_addr = .;
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}
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_ebss_pre_dma_addr = ALIGN(32);
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}
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