86 lines
2.6 KiB
Rust
86 lines
2.6 KiB
Rust
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use abi::{
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error::Error,
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mem::{MappingFlags, MappingSource},
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};
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use super::TlsImage;
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// Variant II TLS layout:
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//
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// ... [ MODULE ] [ MODULE ] [ MODULE ] [ TCB ]
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// | | | |
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// | | | |
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// off3 off2 off1 tp
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/// Creates a new TLS image in the process memory, copying data from the TLS master copy (if any).
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/// Returns the resulting thread pointer.
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pub fn clone_tls(image: &TlsImage, tcb_size: usize) -> Result<(usize, usize), Error> {
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// Basically, the layout is:
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// * align(image.full_size) below the TP
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// * tcb_size starting with the TP
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// If the caller asked for no TCB to be placed, just reserve two words, the first one
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// will be used to put the self-pointer
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let tcb_size = if tcb_size < size_of::<usize>() * 2 {
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size_of::<usize>() * 2
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} else {
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(tcb_size + size_of::<usize>() - 1) & !(size_of::<usize>() - 1)
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};
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if !image.align.is_power_of_two() {
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panic!("TLS layout not aligned to a power of two: {}", image.align);
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}
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if image.align > 0x1000 {
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todo!("Cannot yet handle TLS block alignmnent larger than page size")
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}
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let align = image.align;
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let aligned_size = (image.full_size + tcb_size + align - 1) & !(align - 1);
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let page_aligned_size = (aligned_size + 0xFFf) & !0xFFF;
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let base = unsafe {
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crate::sys::map_memory(
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None,
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page_aligned_size,
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MappingFlags::WRITE,
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&MappingSource::Anonymous,
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)
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}?;
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let ptr = core::ptr::with_exposed_provenance_mut::<u8>(base);
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let module_data = unsafe { core::slice::from_raw_parts_mut(ptr, image.full_size) };
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let tcb = unsafe { core::slice::from_raw_parts_mut(ptr.add(image.full_size), tcb_size) };
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// Clone the Master Copy, if any
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let data_size = if let Some(master_copy) = image.master_copy {
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let source = unsafe { master_copy.as_ref() };
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module_data[..source.len()].copy_from_slice(source);
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source.len()
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} else {
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0
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};
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// Zero the rest
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module_data[data_size..image.full_size].fill(0);
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// Place the self-pointer to point at the TP itself
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let tp = base + image.full_size;
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assert_eq!(
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tp % size_of::<usize>(),
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0,
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"TLS self-pointer should at least be word-aligned"
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);
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tcb[..size_of::<usize>()].copy_from_slice(&tp.to_ne_bytes());
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// Zero the TCB after the self-pointer
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tcb[size_of::<usize>()..].fill(0);
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Ok((base, tp))
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}
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// In Variant II, the TP points directly at the TCB start
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pub(super) fn get_tcb_raw(tp: usize) -> *mut u8 {
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core::ptr::with_exposed_provenance_mut(tp)
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}
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