68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
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#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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#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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* Location of anything goes memory for real mode.
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*
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* The MBR won't load program content beyond this address, so we have
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* room for buffers, page tables, etc. before we reach the stack frame.
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*/
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#ifndef REAL_SCRATCH_AREA
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#define REAL_SCRATCH_AREA 0x40000
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#endif
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/**
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* Location of real mode 64kb stack frame.
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*
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* This address was chosen because memory beyond 0x80000 can't be
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* accessed safely without consulting e820.
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*/
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#ifndef REAL_STACK_FRAME
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#define REAL_STACK_FRAME 0x70000
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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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