Hojun-Cho
1657bdeda3
C bootstrap (phases 0-9):
cmd/wwc, cmd/6c, cmd/6a, cmd/6l, cmd/ww, rt, lib/*.
ww-side self-host (phase 10):
selfhost/cmd/wwc — ww-cgen frontend; bootstrap fixed point.
selfhost/cmd/6a — assembler; byte-identical to C 6a (test 991).
selfhost/cmd/6l — linker w/ archive (.a) support; byte-identical
to C 6l (test 992).
selfhost/cmd/ww — driver (build/run/version); byte-identical to
C ww (test 993).
make test: 15/15. make bootstrap: ww2.s == ww3.s, ww2.o == ww3.o,
ww2 == ww3 byte-identical, with the full ww-tooled chain.
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
/*
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* out.c — emit a static ELF64 executable.
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*
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* Layout (file order):
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* [0..64) ELF header
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* [64..120) program header (one PT_LOAD)
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* [120..0x1000) zero pad
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* [0x1000..) .text bytes
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*
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* The single PT_LOAD covers the whole file, R+X. No interpreter,
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* no dynamic, no .bss yet. Entry point is the address of the
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* symbol named "_start" (or whatever main supplies via -e).
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*/
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#include "l.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define ET_EXEC 2
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#define EM_X86_64 62
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#define EV_CURRENT 1
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#define ELFCLASS64 2
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#define ELFDATA2LSB 1
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#define PT_LOAD 1
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#define PF_X 1
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#define PF_W 2
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#define PF_R 4
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#pragma pack(push, 1)
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typedef struct {
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u8 e_ident[16];
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u16 e_type, e_machine;
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u32 e_version;
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u64 e_entry, e_phoff, e_shoff;
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u32 e_flags;
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u16 e_ehsize, e_phentsize, e_phnum, e_shentsize, e_shnum, e_shstrndx;
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} Ehdr;
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typedef struct {
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u32 p_type, p_flags;
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u64 p_offset, p_vaddr, p_paddr;
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u64 p_filesz, p_memsz, p_align;
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} Phdr;
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#pragma pack(pop)
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int
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l_emit_elf(Lnk *l, FILE *f, u64 base, u64 entry)
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{
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const u64 text_off = 0x1000;
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const u64 text_va = base + text_off;
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const u64 filesz = text_off + l->textlen;
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Ehdr eh = {0};
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memcpy(eh.e_ident, "\x7f""ELF", 4);
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eh.e_ident[4] = ELFCLASS64;
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eh.e_ident[5] = ELFDATA2LSB;
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eh.e_ident[6] = EV_CURRENT;
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eh.e_type = ET_EXEC;
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eh.e_machine = EM_X86_64;
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eh.e_version = EV_CURRENT;
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eh.e_entry = entry;
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eh.e_phoff = sizeof(Ehdr);
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eh.e_ehsize = sizeof(Ehdr);
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eh.e_phentsize = sizeof(Phdr);
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eh.e_phnum = 1;
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(void)text_va;
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Phdr ph = {0};
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ph.p_type = PT_LOAD;
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ph.p_flags = PF_R | PF_X;
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ph.p_offset = 0;
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ph.p_vaddr = base;
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ph.p_paddr = base;
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ph.p_filesz = filesz;
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ph.p_memsz = filesz;
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ph.p_align = 0x1000;
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fwrite(&eh, 1, sizeof eh, f);
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fwrite(&ph, 1, sizeof ph, f);
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/* pad to text_off */
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long here = ftell(f);
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for (long i = here; i < (long)text_off; i++) fputc(0, f);
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if (l->textlen) fwrite(l->text, 1, l->textlen, f);
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return 0;
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}
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