4lDO2
50 lines
2.0 KiB
Rust
50 lines
2.0 KiB
Rust
use syscall::flag::MapFlags;
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mod offsets {
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extern "C" {
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// text (R-X)
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static __text_start: u8;
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static __text_end: u8;
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// rodata (R--)
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static __rodata_start: u8;
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static __rodata_end: u8;
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// data+bss (RW-)
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static __data_start: u8;
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static __bss_end: u8;
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static __end: u8;
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}
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pub fn text() -> (usize, usize) {
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unsafe { (&__text_start as *const u8 as usize, &__text_end as *const u8 as usize) }
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}
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pub fn rodata() -> (usize, usize) {
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unsafe { (&__rodata_start as *const u8 as usize, &__rodata_end as *const u8 as usize) }
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}
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pub fn data_and_bss() -> (usize, usize) {
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unsafe { (&__data_start as *const u8 as usize, &__bss_end as *const u8 as usize) }
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}
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}
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#[no_mangle]
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pub unsafe extern "C" fn start() -> ! {
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// Remap self, from the previous RWX
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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 _ = syscall::open("debug:", syscall::O_RDONLY); // stdin
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let _ = syscall::open("debug:", syscall::O_WRONLY); // stdout
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let _ = syscall::open("debug:", syscall::O_WRONLY); // stderr
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// TODO: PROT_NONE
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let _ = syscall::mprotect(0, 4096, MapFlags::PROT_READ | MapFlags::MAP_PRIVATE).expect("mprotect failed for NULL page");
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let _ = syscall::mprotect(text_start, text_end - text_start, MapFlags::PROT_READ | MapFlags::PROT_EXEC | MapFlags::MAP_PRIVATE).expect("mprotect failed for .text");
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let _ = syscall::mprotect(rodata_start, rodata_end - rodata_start, MapFlags::PROT_READ | MapFlags::MAP_PRIVATE).expect("mprotect failed for .rodata");
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let _ = syscall::mprotect(data_start, data_end - data_start, MapFlags::PROT_READ | MapFlags::PROT_WRITE | MapFlags::MAP_PRIVATE).expect("mprotect failed for .data/.bss");
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let _ = syscall::mprotect(data_end, crate::arch::STACK_START - data_end, MapFlags::PROT_READ | MapFlags::MAP_PRIVATE).expect("mprotect failed for rest of memory");
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crate::exec::main();
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}
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