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Added more comments to vmmap.rs
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@ruchjoshi-nyu
ruchjoshi-nyu authored Nov 11, 2024
1 parent ff4db4f commit a2c3e1f
Showing 1 changed file with 48 additions and 9 deletions.
57 changes: 48 additions & 9 deletions src/safeposix/vmmap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,7 @@ pub enum MemoryBackingType {
FileDescriptor(u64), // stores file descriptor addr
}

/// In the old native client based vmmap, we relied on the fd, shmid
/// fields.
///

/// An entry in the virtual memory map that contains fields such as page number, number of pages,
/// permissions, file offset, file size, shared memory ID, and backing fields to distinguish memory types.
#[derive(Clone, PartialEq, Eq, Debug)]
Expand All @@ -34,6 +32,9 @@ pub struct VmmapEntry {
pub backing: MemoryBackingType,
}


// Implement methods for VmmapEntry
// Constructor to create a new VmmapEntry
#[allow(dead_code)]
impl VmmapEntry {
pub fn new(
Expand All @@ -45,7 +46,7 @@ impl VmmapEntry {
removed: bool,
file_offset: i64,
file_size: i64,
cage_id: u64,
cage_id: u64, //This is the cage id to refer to for file backings
backing: MemoryBackingType,
) -> Self {
return VmmapEntry {
Expand All @@ -62,19 +63,18 @@ impl VmmapEntry {
};
}

// Placeholder method to get maximum protection (currrently incomplete)
fn max_prot(&self) -> i32 {
let flags = PROT_NONE;

flags
}

// Placeholder method for printing (currently does nothing)
fn print(&self) {}

// gonna have 3 types of memory:
// memory that has no memory backing
// things that are backed by fd -> represented by -1

// Leave todo
// Placeholder method to check file descriptor protection (currently does nothing)
fn check_fd_protection(&self, cage_id: i32) {
let _ = cage_id;
} // will call the microvisor, need to pass fd
Expand All @@ -85,6 +85,8 @@ impl VmmapEntry {
// allowing different Vmmap versions to share the same interface.
#[allow(dead_code)]
pub trait VmmapOps {

// Method to update a memory map entry
fn update(
&mut self,
page_num: u32,
Expand All @@ -99,8 +101,10 @@ pub trait VmmapOps {
cage_id: u64,
) -> Result<(), io::Error>;

// Method to add a new entry to the memory map
fn add_entry(&mut self, vmmap_entry_ref: VmmapEntry);

// Method to add an entry with override
fn add_entry_with_override(
&mut self,
page_num: u32,
Expand All @@ -114,44 +118,61 @@ pub trait VmmapOps {
cage_id: u64,
) -> Result<(), io::Error>;

// Method to change protection of a memory region
fn change_prot(&mut self, page_num: u32, npages: u32, new_prot: i32);

// Method to remove an entry from the memory map
fn remove_entry(&mut self, page_num: u32, npages: u32) -> Result<(), io::Error>;

// Method to check if a mapping exists
fn check_existing_mapping(&self, page_num: u32, npages: u32, prot: i32) -> bool;

// Method to check address mapping
fn check_addr_mapping(&mut self, page_num: u32, npages: u32, prot: i32) -> Option<u32>;

// Method to find a page in the memory map
fn find_page(&self, page_num: u32) -> Option<&VmmapEntry>;

// Method to find a mutable page in the memory map
fn find_page_mut(&mut self, page_num: u32) -> Option<&mut VmmapEntry>;

// Method to iterate over pages
fn find_page_iter(
&self,
page_num: u32,
) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &VmmapEntry)>;

// Method to iterate over mutable pages
fn find_page_iter_mut(
&mut self,
page_num: u32,
) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &mut VmmapEntry)>;


// Method to get the first entry in the memory map
fn first_entry(&self) -> Option<(&Interval<u32>, &VmmapEntry)>;

// Method to get the last entry in the memory map
fn last_entry(&self) -> Option<(&Interval<u32>, &VmmapEntry)>;

// Method to iterate over entries in both directions
fn double_ended_iter(&self) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &VmmapEntry)>;

// Method to iterate over mutable entries in both directions
fn double_ended_iter_mut(
&mut self,
) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &mut VmmapEntry)>;

// Method to find space in the memory map
fn find_space(&self, npages: u32) -> Option<Interval<u32>>;

// Method to find space above a hint
fn find_space_above_hint(&self, npages: u32, hint: u32) -> Option<Interval<u32>>;

// Method to find map space
fn find_map_space(&self, num_pages: u32, pages_per_map: u32) -> Option<Interval<u32>>;

// Method to find map space with a hint
fn find_map_space_with_hint(
&self,
num_pages: u32,
Expand All @@ -176,10 +197,12 @@ impl Vmmap {
}
}

// Method to round page number up to the nearest multiple of pages_per_map
fn round_page_num_up_to_map_multiple(&self, npages: u32, pages_per_map: u32) -> u32 {
(npages + pages_per_map - 1) & !(pages_per_map - 1)
}

// Method to truncate page number down to the nearest multiple of pages_per_map
fn trunc_page_num_down_to_map_multiple(&self, npages: u32, pages_per_map: u32) -> u32 {
npages & !(pages_per_map - 1)
}
Expand All @@ -201,6 +224,7 @@ impl VmmapOps for Vmmap {
);
}

// Method to add an entry with override, using update method
fn add_entry_with_override(
&mut self,
page_num: u32,
Expand Down Expand Up @@ -248,6 +272,7 @@ impl VmmapOps for Vmmap {
)
}

// Method to update a memory map entry, handling insertion and removal
fn update(
&mut self,
page_num: u32,
Expand Down Expand Up @@ -300,6 +325,7 @@ impl VmmapOps for Vmmap {
Ok(())
}

// Method to change protection of a memory region
fn change_prot(&mut self, page_num: u32, npages: u32, new_prot: i32) {
let new_region_end_page = page_num + npages;
let new_region_start_page = page_num;
Expand Down Expand Up @@ -331,6 +357,7 @@ impl VmmapOps for Vmmap {
}
}

// Method to check if a mapping exists
fn check_existing_mapping(&self, page_num: u32, npages: u32, prot: i32) -> bool {
let region_end_page = page_num + npages;
let region_interval = ie(page_num, region_end_page);
Expand Down Expand Up @@ -369,6 +396,7 @@ impl VmmapOps for Vmmap {
false
}

// Method to check address mapping, using cached entry if possible
fn check_addr_mapping(&mut self, page_num: u32, npages: u32, prot: i32) -> Option<u32> {
let region_end_page = page_num + npages;

Expand Down Expand Up @@ -422,32 +450,38 @@ impl VmmapOps for Vmmap {
None
}

//Method to find a page in the memory map
fn find_page(&self, page_num: u32) -> Option<&VmmapEntry> {
self.entries.get_at_point(page_num)
}

// Method to find a mutable page in the memory map
fn find_page_mut(&mut self, page_num: u32) -> Option<&mut VmmapEntry> {
self.entries.get_at_point_mut(page_num)
}

// Method to get the last entry in the memory map
fn last_entry(&self) -> Option<(&Interval<u32>, &VmmapEntry)> {
self.entries.last_key_value()
}

// Method to get the first entry in the memory map
fn first_entry(&self) -> Option<(&Interval<u32>, &VmmapEntry)> {
self.entries.first_key_value()
}

// Method to iterate over entries in both directions
fn double_ended_iter(&self) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &VmmapEntry)> {
self.entries.iter()
}

// Method to iterate over mutable entries in both directions
fn double_ended_iter_mut(
&mut self,
) -> impl DoubleEndedIterator<Item = (&Interval<u32>, &mut VmmapEntry)> {
self.entries.iter_mut()
}

// Method to iterate over pages, starting from a given page number
fn find_page_iter(
&self,
page_num: u32,
Expand All @@ -460,6 +494,7 @@ impl VmmapOps for Vmmap {
}
}

// Method to iterate over mutable pages, starting from a given page number
fn find_page_iter_mut(
&mut self,
page_num: u32,
Expand All @@ -473,6 +508,7 @@ impl VmmapOps for Vmmap {
}
}

// Method to find space in the memory map
fn find_space(&self, npages: u32) -> Option<Interval<u32>> {
let start = self.first_entry();
let end = self.last_entry();
Expand All @@ -498,6 +534,7 @@ impl VmmapOps for Vmmap {
None
}

// Method to find space above a hint
fn find_space_above_hint(&self, npages: u32, hint: u32) -> Option<Interval<u32>> {
let start = hint;
let end = self.last_entry();
Expand All @@ -519,6 +556,7 @@ impl VmmapOps for Vmmap {
None
}

// Method to find map space, rounding page numbers up to the nearest multiple of pages_per_map
fn find_map_space(&self, num_pages: u32, pages_per_map: u32) -> Option<Interval<u32>> {
let start = self.first_entry();
let end = self.last_entry();
Expand Down Expand Up @@ -551,6 +589,7 @@ impl VmmapOps for Vmmap {
None
}

// Method to find map space with a hint, rounding page numbers up to the nearest multiple of pages_per_map
fn find_map_space_with_hint(
&self,
num_pages: u32,
Expand Down

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