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Your Actually Portable Executables now contains a simple virtual memory that works similarly to the Linux Kernel in the sense that it maps your physical memory to negative addresses. This is needed to support mmap() and malloc(). This functionality has zero code size impact. For example the MODE=tiny LIFE.COM executable is still only 12KB in size. The APE bootloader code has also been simplified to improve readibility and further elevate the elegance by which we're able to support so many platforms thereby enhancing verifiability so that we may engender trust in this bootloading process.
49 lines
1.9 KiB
C
49 lines
1.9 KiB
C
#ifndef COSMOPOLITAN_APE_RELOCATIONS_H_
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#define COSMOPOLITAN_APE_RELOCATIONS_H_
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/*─────────────────────────────────────────────────────────────────────────────╗
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│ αcτµαlly pδrταblε εxεcµταblε § relocations │
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╚──────────────────────────────────────────────────────────────────────────────╝
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One of the things αcτµαlly pδrταblε εxεcµταblε does a good job
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abstracting, is how a program needs to exist at three addresses
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simultaneously during the early stages of the loading process.
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By default, the linker calculates all symbols using virtual addresses.
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In some cases it's necessary to use addend macros that change virtual
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addresses into the other two types: physical and real. */
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#define IMAGE_BASE_REAL 0x2000
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#ifndef IMAGE_BASE_VIRTUAL
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#define IMAGE_BASE_VIRTUAL 0x400000
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#endif
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#ifndef IMAGE_BASE_PHYSICAL
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#define IMAGE_BASE_PHYSICAL 0x100000
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#endif
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/**
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* Returns Relative Virtual Address.
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*/
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#define RVA(x) ((x) - (IMAGE_BASE_VIRTUAL))
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/**
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* Adjusts virtual address so it's relative to load address.
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*/
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#define PHYSICAL(x) ((x) - (IMAGE_BASE_VIRTUAL - IMAGE_BASE_PHYSICAL))
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/**
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* Makes high-entropy read-only addresses relocatable in real mode.
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*/
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#define REAL(x) ((x) - (IMAGE_BASE_VIRTUAL - IMAGE_BASE_REAL))
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#if IMAGE_BASE_VIRTUAL % 0x200000 != 0
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#error "IMAGE_BASE_VIRTUAL must be 2mb aligned"
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#endif
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#if IMAGE_BASE_PHYSICAL % 0x1000 != 0
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#error "IMAGE_BASE_PHYSICAL must be 4kb aligned"
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#endif
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#if IMAGE_BASE_REAL % 0x1000 != 0
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#error "IMAGE_BASE_REAL must be 4kb aligned"
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#endif
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#endif /* COSMOPOLITAN_APE_RELOCATIONS_H_ */
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