Red Bear OS
0f6fe3f7ea
start() now emits single-char breadcrumbs (BS:0 through BS:5) via debug fd 1 after each major mprotect step, so serial output reveals exactly how far execution gets before any crash. The panic handler now attempts to open a fresh debug scheme handle if fd 1 write fails, ensuring panic messages are visible even when stdout was never set up successfully.
99 lines
2.7 KiB
Rust
99 lines
2.7 KiB
Rust
use syscall::flag::MapFlags;
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mod offsets {
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unsafe extern "C" {
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static __text_start: u8;
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static __text_end: u8;
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static __rodata_start: u8;
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static __rodata_end: u8;
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static __data_start: u8;
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static __bss_end: u8;
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}
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pub fn text() -> (usize, usize) {
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unsafe {
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(
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&__text_start as *const u8 as usize,
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&__text_end as *const u8 as usize,
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)
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}
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}
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pub fn rodata() -> (usize, usize) {
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unsafe {
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(
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&__rodata_start as *const u8 as usize,
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&__rodata_end as *const u8 as usize,
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)
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}
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}
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pub fn data_and_bss() -> (usize, usize) {
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unsafe {
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(
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&__data_start as *const u8 as usize,
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&__bss_end as *const u8 as usize,
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)
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}
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}
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}
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fn dbg(msg: &[u8]) {
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let _ = libredox::call::write(1, msg);
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}
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#[unsafe(no_mangle)]
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pub unsafe extern "C" fn start() -> ! {
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let (text_start, text_end) = offsets::text();
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let (rodata_start, rodata_end) = offsets::rodata();
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let (data_start, data_end) = offsets::data_and_bss();
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let debug_fd = syscall::UPPER_FDTBL_TAG + syscall::data::GlobalSchemes::Debug as usize;
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let _ = libredox::call::openat(debug_fd, "", syscall::O_RDONLY as i32, 0);
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let _ = libredox::call::openat(debug_fd, "", syscall::O_WRONLY as i32, 0);
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let _ = libredox::call::openat(debug_fd, "", syscall::O_WRONLY as i32, 0);
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dbg(b"BS:0\n");
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unsafe {
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let _ = syscall::mprotect(4096, 4096, MapFlags::PROT_READ | MapFlags::MAP_PRIVATE)
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.expect("mprotect failed for initfs header page");
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dbg(b"BS:1\n");
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let _ = syscall::mprotect(
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text_start,
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text_end - text_start,
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MapFlags::PROT_READ | MapFlags::PROT_EXEC | MapFlags::MAP_PRIVATE,
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)
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.expect("mprotect failed for .text");
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dbg(b"BS:2\n");
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let _ = syscall::mprotect(
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rodata_start,
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rodata_end - rodata_start,
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MapFlags::PROT_READ | MapFlags::MAP_PRIVATE,
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)
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.expect("mprotect failed for .rodata");
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dbg(b"BS:3\n");
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let _ = syscall::mprotect(
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data_start,
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data_end - data_start,
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MapFlags::PROT_READ | MapFlags::PROT_WRITE | MapFlags::MAP_PRIVATE,
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)
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.expect("mprotect failed for .data/.bss");
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dbg(b"BS:4\n");
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let _ = syscall::mprotect(
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data_end,
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crate::arch::STACK_START - data_end,
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MapFlags::PROT_READ | MapFlags::MAP_PRIVATE,
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)
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.expect("mprotect failed for rest of memory");
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}
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dbg(b"BS:5\n");
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crate::exec::main();
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}
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