Noratrieb/elven-forest
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sefault!!!

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This commit is contained in:
nora 2023-02-13 21:59:19 +01:00
parent d6daaea999
commit e2ca10426e
7 changed files with 192 additions and 60 deletions
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62
elven-wald/src/lib.rs
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@ -4,9 +4,9 @@ extern crate tracing;
use anyhow::{bail, Context, Result};
use clap::Parser;
use elven_parser::{
consts::{self as c, ShType, SHT_PROGBITS},
read::{ElfIdent, ElfReader, Offset},
write::{self, ElfWriter, SectionRelativeAbsoluteAddr, Section},
consts::{self as c, PhFlags, SectionIdx, ShType, PT_LOAD, SHT_PROGBITS},
read::{Addr, ElfIdent, ElfReader, Offset},
write::{self, ElfWriter, ProgramHeader, Section, SectionRelativeAbsoluteAddr},
};
use memmap2::Mmap;
use std::{
@ -58,19 +58,15 @@ pub fn run(opts: Opts) -> Result<()> {
let _start_sym = elf.symbol_by_name(b"_start")?;
let section = _start_sym.shndx;
let entry = SectionRelativeAbsoluteAddr {
section,
rel_offset: Offset(_start_sym.value.0),
};
write_output(text_content, entry)?;
write_output(text_content, _start_sym.value.0)?;
Ok(())
}
fn write_output(text: &[u8], entry: SectionRelativeAbsoluteAddr) -> Result<()> {
pub const BASE_EXEC_ADDR: Addr = Addr(0x400000); // whatever ld does
pub const DEFAULT_PROGRAM_HEADER_ALIGN_THAT_LD_USES_HERE: u64 = 0x1000;
fn write_output(text: &[u8], entry_offset_from_text: u64) -> Result<()> {
let ident = ElfIdent {
magic: *c::ELFMAG,
class: c::Class(c::ELFCLASS64),
@ -90,15 +86,51 @@ fn write_output(text: &[u8], entry: SectionRelativeAbsoluteAddr) -> Result<()> {
let mut write = ElfWriter::new(header);
let text_name = write.add_sh_string(b".text");
write.add_section(Section {
let text_section = write.add_section(Section {
name: text_name,
r#type: ShType(SHT_PROGBITS),
flags: 0,
fixed_entsize: None,
content: text.to_vec(),
});
})?;
write.set_entry(entry);
let elf_header_and_program_headers = ProgramHeader {
r#type: PT_LOAD.into(),
flags: PhFlags::PF_R,
offset: SectionRelativeAbsoluteAddr {
section: SectionIdx(0),
rel_offset: Offset(0),
},
vaddr: BASE_EXEC_ADDR,
paddr: BASE_EXEC_ADDR,
filesz: 176, // FIXME: Do not hardocde this lol
memsz: 176,
align: DEFAULT_PROGRAM_HEADER_ALIGN_THAT_LD_USES_HERE,
};
write.add_program_header(elf_header_and_program_headers);
let entry_addr = Addr(
BASE_EXEC_ADDR.0 + DEFAULT_PROGRAM_HEADER_ALIGN_THAT_LD_USES_HERE + entry_offset_from_text,
);
let text_program_header = ProgramHeader {
r#type: PT_LOAD.into(),
flags: PhFlags::PF_X | PhFlags::PF_R,
offset: SectionRelativeAbsoluteAddr {
section: text_section,
rel_offset: Offset(0),
},
vaddr: entry_addr,
paddr: entry_addr,
filesz: text.len() as u64,
memsz: text.len() as u64,
align: DEFAULT_PROGRAM_HEADER_ALIGN_THAT_LD_USES_HERE,
};
write.add_program_header(text_program_header);
write.set_entry(entry_addr);
let output = write.write().context("writing output file")?;