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Aligned program heap (#11657)

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This commit is contained in:
Jack May
2020-08-17 09:49:21 -07:00
committed by GitHub
parent 7f108f373a
commit f8606fca4f
2 changed files with 39 additions and 3 deletions
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9
programs/bpf_loader/src/allocator_bump.rs
View File

@ -25,7 +25,14 @@ impl BPFAllocator {
impl Alloc for BPFAllocator {
fn alloc(&mut self, layout: Layout) -> Result<u64, AllocErr> {
if self.pos.saturating_add(layout.size() as u64) <= self.len {
let bytes_to_align = (self.pos as *const u8).align_offset(layout.align()) as u64;
if self
.pos
.saturating_add(layout.size() as u64)
.saturating_add(bytes_to_align)
<= self.len
{
self.pos += bytes_to_align;
let addr = self.start + self.pos;
self.pos += layout.size() as u64;
Ok(addr)

33
programs/bpf_loader/src/syscalls.rs
View File

@ -329,7 +329,10 @@ impl SyscallObject<BPFError> for SyscallSolAllocFree {
_ro_regions: &[MemoryRegion],
_rw_regions: &[MemoryRegion],
) -> Result<u64, EbpfError<BPFError>> {
let layout = Layout::from_size_align(size as usize, align_of::<u8>()).unwrap();
let layout = match Layout::from_size_align(size as usize, align_of::<u128>()) {
Ok(layout) => layout,
Err(_) => return Ok(0),
};
if free_addr == 0 {
match self.allocator.alloc(layout) {
Ok(addr) => Ok(addr as u64),
@ -1095,6 +1098,12 @@ mod tests {
.unwrap(),
0
);
assert_eq!(
syscall
.call(u64::MAX, 0, 0, 0, 0, ro_regions, rw_regions)
.unwrap(),
0
);
}
// many small allocs
{
@ -1104,7 +1113,7 @@ mod tests {
let mut syscall = SyscallSolAllocFree {
allocator: BPFAllocator::new(heap, MM_HEAP_START),
};
for _ in 0..100 {
for _ in 0..12 {
assert_ne!(
syscall.call(1, 0, 0, 0, 0, ro_regions, rw_regions).unwrap(),
0
@ -1117,5 +1126,25 @@ mod tests {
0
);
}
// aligned allocs
fn check_alignment<T>() {
let heap = vec![0_u8; 100];
let ro_regions = &[MemoryRegion::default()];
let rw_regions = &[MemoryRegion::new_from_slice(&heap, MM_HEAP_START)];
let mut syscall = SyscallSolAllocFree {
allocator: BPFAllocator::new(heap, MM_HEAP_START),
};
let address = syscall
.call(size_of::<u8>() as u64, 0, 0, 0, 0, ro_regions, rw_regions)
.unwrap();
assert_ne!(address, 0);
assert_eq!((address as *const u8).align_offset(align_of::<u8>()), 0);
}
check_alignment::<u8>();
check_alignment::<u16>();
check_alignment::<u32>();
check_alignment::<u64>();
check_alignment::<u128>();
}
}