84 lines
3.0 KiB
C
84 lines
3.0 KiB
C
#include <assert.h>
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#include <errno.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include "io.h"
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#include "ir.h"
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#define ELF_HEADER_SIZE 0xb0
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size_t compile(void) {
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init();
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var code = lit(42);
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var call = lit(60);
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var args[2] = { call, code };
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syscall(2, args);
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return ELF_HEADER_SIZE;
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}
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static void write_elf(uint64_t entry_point) {
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uint64_t file_len = ftell(outfile);
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fseek(outfile, 0, SEEK_SET);
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// Hardcoded ELF header for statically-linked position-independent executable.
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// Since we only support Linux amd64 static PIE, there's no need to abstract over this for now.
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uint8_t elf_header[ELF_HEADER_SIZE] = {
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// ELF header
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0x7F, 'E', 'L', 'F', // ELF magic
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2, 1, 1, 3, 0, // 64-bit little-endian Linux, ELF version 1
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0, 0, 0, 0, 0, 0, 0, // padding
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3, 0, 0x3E, 0, 1, 0, 0, 0, // dynamic executable, amd64, ELF version 1 again
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0, 0, 0, 0, 0, 0, 0, 0, // PATCHME: entry point address
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0x40, 0, 0, 0, 0, 0, 0, 0, // program header table offset (immediately after ELF)
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0, 0, 0, 0, 0, 0, 0, 0, // section header table offset (none)
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0, 0, 0, 0, 0x40, 0, 0x38, 0, // flags (none), header sizes
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2, 0, 0, 0, 0, 0, 0, 0, // 2 segments, no sections
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// program header segment
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6, 0, 0, 0, 4, 0, 0, 0, // program header segment, readable
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0x40, 0, 0, 0, 0, 0, 0, 0, // immediately after ELF header
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0x40, 0, 0, 0, 0, 0, 0, 0, // virtual address
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0, 0, 0, 0, 0, 0, 0, 0, // physical address
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0x70, 0, 0, 0, 0, 0, 0, 0, // size in file (2 * size of program header)
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0x70, 0, 0, 0, 0, 0, 0, 0, // size in memory
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8, 0, 0, 0, 0, 0, 0, 0, // alignment
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// executable segment
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1, 0, 0, 0, 5, 0, 0, 0, // loadable segment, readable and executable
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0, 0, 0, 0, 0, 0, 0, 0, // whole file
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0, 0, 0, 0, 0, 0, 0, 0, // virtual address
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0, 0, 0, 0, 0, 0, 0, 0, // physical address
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0, 0, 0, 0, 0, 0, 0, 0, // PATCHME: size in file
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0, 0, 0, 0, 0, 0, 0, 0, // PATCHME: size in memory
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0, 0x10, 0, 0, 0, 0, 0, 0, // alignment (4K)
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};
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uint64_t ep = (uint64_t) entry_point;
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uint64_t fl = (uint64_t) file_len;
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memcpy(&elf_header[0x18], &entry_point, sizeof(uint64_t));
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memcpy(&elf_header[0x98], &file_len, sizeof(uint64_t));
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memcpy(&elf_header[0x98 + sizeof(uint64_t)], &file_len, sizeof(uint64_t));
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emit(elf_header, ELF_HEADER_SIZE);
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}
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int main(int argc, char** argv) {
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if (argc != 3) {
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fprintf(stderr, "usage: %s <output file> <source file>\n", argv[0]);
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exit(1);
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}
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open_files(argv[2], argv[1]);
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fseek(outfile, ELF_HEADER_SIZE, SEEK_SET);
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size_t entry_point = compile();
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write_elf((uint64_t) entry_point);
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close_files();
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return 0;
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}
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