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Pin grants that are used in UserScheme.

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This commit is contained in:
4lDO2
2023-07-02 15:29:06 +02:00
parent 954a8d00fe
commit b3a6a6744a
4 changed files with 58 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/context/memory.rs
+46 -11
View File
@@ -103,9 +103,12 @@ impl AddrSpace {
cow_file_ref.clone(),
)?,
// No, your temporary UserScheme mappings will not be kept across forks.
Provider::External { is_pinned_userscheme_borrow: true, .. } => continue,
// MAP_SHARED grants are retained by reference, across address space clones (across
// forks on monolithic kernels).
Provider::External { ref address_space, src_base } => Grant::borrow_grant(
Provider::External { ref address_space, src_base, .. } => Grant::borrow_grant(
Arc::clone(&address_space),
grant_base,
grant_base,
@@ -144,9 +147,15 @@ impl AddrSpace {
let mapper = &mut self.table.utable;
// TODO: Remove allocation (might require BTreeMap::set_key or interior mutability).
let regions = self.grants.conflicts(requested_span).map(|(base, info)| PageSpan::new(base, info.page_count)).collect::<Vec<_>>();
let regions = self.grants.conflicts(requested_span).map(|(base, info)| if info.is_pinned() {
Err(Error::new(EBUSY))
} else {
Ok(PageSpan::new(base, info.page_count))
}).collect::<Vec<_>>();
for grant_span_res in regions {
let grant_span = grant_span_res?;
for grant_span in regions {
let grant = self.grants.remove(grant_span.base).expect("grant cannot magically disappear while we hold the lock!");
//log::info!("Mprotecting {:#?} to {:#?} in {:#?}", grant, flags, grant_span);
let intersection = grant_span.intersection(requested_span);
@@ -177,17 +186,26 @@ impl AddrSpace {
}
Ok(())
}
pub fn munmap(mut self: RwLockWriteGuard<'_, Self>, mut requested_span: PageSpan) {
pub fn munmap(mut self: RwLockWriteGuard<'_, Self>, mut requested_span: PageSpan, unpin: bool) -> Result<()> {
let mut notify_files = Vec::new();
let mut flusher = PageFlushAll::new();
let this = &mut *self;
let next = |grants: &mut UserGrants, span: PageSpan| grants.conflicts(span).map(|(base, info)| PageSpan::new(base, info.page_count)).next();
let next = |grants: &mut UserGrants, span: PageSpan| grants.conflicts(span).map(|(base, info)| if info.is_pinned() && !unpin {
Err(Error::new(EBUSY))
} else {
Ok(PageSpan::new(base, info.page_count))
}).next();
while let Some(conflicting_span) = next(&mut this.grants, requested_span) {
let grant = this.grants.remove(conflicting_span.base).expect("conflicting region didn't exist");
while let Some(conflicting_span_res) = next(&mut this.grants, requested_span) {
let conflicting_span = conflicting_span_res?;
let mut grant = this.grants.remove(conflicting_span.base).expect("conflicting region didn't exist");
if unpin {
grant.info.unpin();
}
let intersection = conflicting_span.intersection(requested_span);
@@ -235,6 +253,8 @@ impl AddrSpace {
let _ = desc.into_inner().try_close();
}
}
Ok(())
}
pub fn mmap(&mut self, page: Option<Page>, page_count: NonZeroUsize, flags: MapFlags, map: impl FnOnce(Page, PageFlags<RmmA>, &mut PageMapper, &mut dyn Flusher<RmmA>) -> Result<Grant>) -> Result<Page> {
// Finally, the end of all "T0DO: Abstract with other grant creation"!
@@ -567,7 +587,7 @@ pub enum Provider {
PhysBorrowed { base: Frame },
/// The memory is borrowed directly from another address space.
External { address_space: Arc<RwLock<AddrSpace>>, src_base: Page },
External { address_space: Arc<RwLock<AddrSpace>>, src_base: Page, is_pinned_userscheme_borrow: bool },
FmapBorrowed { file_ref: GrantFileRef },
}
@@ -642,6 +662,7 @@ impl Grant {
provider: Provider::External {
src_base,
address_space: src_address_space_lock,
is_pinned_userscheme_borrow: false,
}
},
})
@@ -688,6 +709,7 @@ impl Grant {
dst_flusher: impl Flusher<RmmA>,
eager: bool,
allow_phys: bool,
is_pinned_userscheme_borrow: bool,
) -> Result<Grant> {
/*
if eager {
@@ -729,7 +751,7 @@ impl Grant {
page_count,
flags,
mapped: true,
provider: Provider::External { address_space: src_address_space_lock, src_base }
provider: Provider::External { address_space: src_address_space_lock, src_base, is_pinned_userscheme_borrow }
},
})
}
@@ -866,6 +888,8 @@ impl Grant {
PageSpan::new(self.base, self.info.page_count)
}
pub fn extract(mut self, span: PageSpan) -> Option<(Option<Grant>, Grant, Option<Grant>)> {
assert!(!self.info.is_pinned(), "forgot to enforce that UserScheme mappings cannot be split");
let (before_span, this_span, after_span) = self.span().slice(span);
let before_grant = before_span.map(|span| Grant {
@@ -875,9 +899,10 @@ impl Grant {
mapped: self.info.mapped,
page_count: span.count,
provider: match self.info.provider {
Provider::External { ref address_space, src_base } => Provider::External {
Provider::External { ref address_space, src_base, .. } => Provider::External {
address_space: Arc::clone(address_space),
src_base,
is_pinned_userscheme_borrow: false,
},
Provider::Allocated { ref cow_file_ref } => Provider::Allocated { cow_file_ref: cow_file_ref.clone() },
Provider::PhysBorrowed { ref base } => Provider::PhysBorrowed { base: base.clone() },
@@ -902,9 +927,10 @@ impl Grant {
provider: match self.info.provider {
// TODO: Adjust offset
Provider::Allocated { ref cow_file_ref } => Provider::Allocated { cow_file_ref: cow_file_ref.clone() },
Provider::External { ref address_space, src_base } => Provider::External {
Provider::External { ref address_space, src_base, .. } => Provider::External {
address_space: Arc::clone(address_space),
src_base,
is_pinned_userscheme_borrow: false,
},
Provider::PhysBorrowed { base } => Provider::PhysBorrowed { base: base.next_by(this_span.count) },
@@ -920,6 +946,15 @@ impl Grant {
}
}
impl GrantInfo {
pub fn is_pinned(&self) -> bool {
matches!(self.provider, Provider::External { is_pinned_userscheme_borrow: true, .. })
}
pub fn unpin(&mut self) {
if let Provider::External { ref mut is_pinned_userscheme_borrow, .. } = self.provider {
*is_pinned_userscheme_borrow = false;
}
}
pub fn flags(&self) -> PageFlags<RmmA> {
self.flags
}
src/scheme/proc.rs
+3 -2
View File
@@ -717,7 +717,7 @@ impl KernelScheme for ProcScheme {
dst_addr_space.mmap(requested_dst_page, src_page_count, map.flags, |dst_page, _flags, dst_mapper, dst_flusher| Grant::transfer(middle, dst_page, src_mapper, dst_mapper, InactiveFlusher::new(), dst_flusher))?
} else {
dst_addr_space.mmap(requested_dst_page, src_page_count, map.flags, |dst_page, flags, dst_mapper, flusher| Ok(Grant::borrow(Arc::clone(addrspace), src_addr_space, src_grant_span.base, dst_page, src_grant_span.count, flags, dst_mapper, flusher, true, true)?))?
dst_addr_space.mmap(requested_dst_page, src_page_count, map.flags, |dst_page, flags, dst_mapper, flusher| Ok(Grant::borrow(Arc::clone(addrspace), src_addr_space, src_grant_span.base, dst_page, src_grant_span.count, flags, dst_mapper, flusher, true, true, false)?))?
};
Ok(result_base.start_address().data())
@@ -897,7 +897,8 @@ impl KernelScheme for ProcScheme {
ADDRSPACE_OP_MUNMAP => {
let (page, page_count) = crate::syscall::validate_region(next()??, next()??)?;
addrspace.write().munmap(PageSpan::new(page, page_count));
let unpin = false;
addrspace.write().munmap(PageSpan::new(page, page_count), unpin)?;
}
ADDRSPACE_OP_MPROTECT => {
let (page, page_count) = crate::syscall::validate_region(next()??, next()??)?;
src/scheme/user.rs
+7 -2
View File
@@ -273,7 +273,11 @@ impl UserInner {
// BARs, but it doesn't make sense yet.)
let allow_phys = false;
Ok(Grant::borrow(Arc::clone(&cur_space_lock), &mut *cur_space_lock.write(), first_middle_src_page, dst_page, middle_page_count.get(), page_flags, mapper, flusher, eager, allow_phys)?)
// Deny any attempts by the scheme, to unmap these temporary pages. The only way to
// unmap them is to respond to the scheme socket.
let is_pinned_userscheme_borrow = true;
Ok(Grant::borrow(Arc::clone(&cur_space_lock), &mut *cur_space_lock.write(), first_middle_src_page, dst_page, middle_page_count.get(), page_flags, mapper, flusher, eager, allow_phys, is_pinned_userscheme_borrow)?)
})?;
}
@@ -579,7 +583,8 @@ impl<const READ: bool, const WRITE: bool> CaptureGuard<READ, WRITE> {
let (first_page, page_count, _offset) = page_range_containing(self.base, self.len);
space.write().munmap(PageSpan::new(first_page, page_count));
let unpin = true;
space.write().munmap(PageSpan::new(first_page, page_count), unpin)?;
result
}
src/syscall/fs.rs
+2 -1
View File
@@ -394,7 +394,8 @@ pub fn funmap(virtual_address: usize, length: usize) -> Result<usize> {
let addr_space = Arc::clone(context::current()?.read().addr_space()?);
let span = PageSpan::validate_nonempty(VirtualAddress::new(virtual_address), length_aligned).ok_or(Error::new(EINVAL))?;
addr_space.write().munmap(span);
let unpin = false;
addr_space.write().munmap(span, unpin)?;
Ok(0)
}