diff options
Diffstat (limited to 'pkg/sentry/fs/fsutil')
-rw-r--r-- | pkg/sentry/fs/fsutil/README.md | 17 | ||||
-rw-r--r-- | pkg/sentry/fs/fsutil/host_mappable.go | 10 | ||||
-rw-r--r-- | pkg/sentry/fs/fsutil/inode_cached.go | 28 |
3 files changed, 27 insertions, 28 deletions
diff --git a/pkg/sentry/fs/fsutil/README.md b/pkg/sentry/fs/fsutil/README.md index d3780e9fa..6e677890c 100644 --- a/pkg/sentry/fs/fsutil/README.md +++ b/pkg/sentry/fs/fsutil/README.md @@ -108,9 +108,9 @@ The host then sends a `SIGSEGV` to the sentry because the address range [`A`, `A`+8) is not mapped on the host. The `SIGSEGV` indicates that the memory was accessed writable. The sentry looks up the vma associated with [`A`, `A`+8), finds the file that was mapped and its `CachingInodeOperations`. It then calls -`CachingInodeOperations.MapInto` which allocates memory to back [`A`, `A`+8). It -may choose to allocate more memory (i.e. do "readahead") to minimize subsequent -faults. +`CachingInodeOperations.Translate` which allocates memory to back [`A`, `A`+8). +It may choose to allocate more memory (i.e. do "readahead") to minimize +subsequent faults. Memory that is allocated comes from a host tmpfs file (see `filemem.FileMem`). The host tmpfs file memory is brought up to date with the contents of the mapped @@ -138,12 +138,11 @@ memcpy(A, buffer, 4); ``` Since the first process has already mapped and accessed the same region of the -file writable, `CachingInodeOperations.MapInto` is called but re-maps the memory -that has already been allocated (because the host mapping can be invalidated at -any time) rather than allocating new memory. The address range [`A`, `A`+0x1000) -reflects the same cached view of the file as the first process sees. For -example, reading 8 bytes from the file from either process via read(2) starting -at offset 0 returns a consistent "bbbbaaaa". +file writable, `CachingInodeOperations.Translate` is called but returns the +memory that has already been allocated rather than allocating new memory. The +address range [`A`, `A`+0x1000) reflects the same cached view of the file as the +first process sees. For example, reading 8 bytes from the file from either +process via read(2) starting at offset 0 returns a consistent "bbbbaaaa". When this process no longer needs the shared memory, it may do: diff --git a/pkg/sentry/fs/fsutil/host_mappable.go b/pkg/sentry/fs/fsutil/host_mappable.go index 340f8d288..1bb5c6b6e 100644 --- a/pkg/sentry/fs/fsutil/host_mappable.go +++ b/pkg/sentry/fs/fsutil/host_mappable.go @@ -106,16 +106,16 @@ func (h *HostMappable) InvalidateUnsavable(ctx context.Context) error { return nil } -// MapInto implements platform.File.MapInto. -func (h *HostMappable) MapInto(as platform.AddressSpace, addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error { - return as.MapFile(addr, h.backingFile.FD(), fr, at, precommit) -} - // MapInternal implements platform.File.MapInternal. func (h *HostMappable) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { return h.hostFileMapper.MapInternal(fr, h.backingFile.FD(), at.Write) } +// FD implements platform.File.FD. +func (h *HostMappable) FD() int { + return h.backingFile.FD() +} + // IncRef implements platform.File.IncRef. func (h *HostMappable) IncRef(fr platform.FileRange) { mr := memmap.MappableRange{Start: fr.Start, End: fr.End} diff --git a/pkg/sentry/fs/fsutil/inode_cached.go b/pkg/sentry/fs/fsutil/inode_cached.go index e3b52e943..ef11676b8 100644 --- a/pkg/sentry/fs/fsutil/inode_cached.go +++ b/pkg/sentry/fs/fsutil/inode_cached.go @@ -835,20 +835,6 @@ func (c *CachingInodeOperations) InvalidateUnsavable(ctx context.Context) error return nil } -// MapInto implements platform.File.MapInto. This is used when we directly map -// an underlying host fd and CachingInodeOperations is used as the platform.File -// during translation. -func (c *CachingInodeOperations) MapInto(as platform.AddressSpace, addr usermem.Addr, fr platform.FileRange, at usermem.AccessType, precommit bool) error { - return as.MapFile(addr, c.backingFile.FD(), fr, at, precommit) -} - -// MapInternal implements platform.File.MapInternal. This is used when we -// directly map an underlying host fd and CachingInodeOperations is used as the -// platform.File during translation. -func (c *CachingInodeOperations) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { - return c.hostFileMapper.MapInternal(fr, c.backingFile.FD(), at.Write) -} - // IncRef implements platform.File.IncRef. This is used when we directly map an // underlying host fd and CachingInodeOperations is used as the platform.File // during translation. @@ -900,3 +886,17 @@ func (c *CachingInodeOperations) DecRef(fr platform.FileRange) { c.dataMu.Unlock() } + +// MapInternal implements platform.File.MapInternal. This is used when we +// directly map an underlying host fd and CachingInodeOperations is used as the +// platform.File during translation. +func (c *CachingInodeOperations) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { + return c.hostFileMapper.MapInternal(fr, c.backingFile.FD(), at.Write) +} + +// FD implements platform.File.FD. This is used when we directly map an +// underlying host fd and CachingInodeOperations is used as the platform.File +// during translation. +func (c *CachingInodeOperations) FD() int { + return c.backingFile.FD() +} |