Add support for /proc/self(pid)/maps

src/libos/src/fs/inode_file.rs

@@ -266,6 +266,10 @@ impl File for INodeFile {
 }
 
 impl INodeFile {
+    pub fn inode(&self) -> &Arc<dyn INode> {
+        &self.inode
+    }
+
     pub fn open(inode: Arc<dyn INode>, abs_path: &str, flags: u32) -> Result<Self> {
         let access_mode = AccessMode::from_u32(flags)?;
         if (access_mode.readable() && !inode.allow_read()?) {

src/libos/src/fs/procfs/pid/maps.rs

@@ -0,0 +1,134 @@
+use super::*;
+
+use crate::vm::{ChunkType, VMArea, VMPerms, VMRange};
+
+// This file is to implement /proc/self(pid)/maps file system.
+//
+// Print format:
+// vmrange_start-vmrange_end, permission, shared/private, offset, device ID, inode, pathname
+//
+// Example:
+// - cat /proc/self/maps
+// 555555554000-555555556000 r--p 00000000 08:12 39321752                   /usr/bin/cat
+// 555555556000-55555555b000 r-xp 00002000 08:12 39321752                   /usr/bin/cat
+// 55555555b000-55555555e000 r--p 00007000 08:12 39321752                   /usr/bin/cat
+// 55555555e000-55555555f000 r--p 00009000 08:12 39321752                   /usr/bin/cat
+// 55555555f000-555555560000 rw-p 0000a000 08:12 39321752                   /usr/bin/cat
+// 555555560000-555555581000 rw-p 00000000 00:00 0                          [heap]
+// 7ffff7536000-7ffff7558000 rw-p 00000000 00:00 0
+// 7ffff7558000-7ffff7dc8000 r--p 00000000 08:12 39322175                   /usr/lib/locale/locale-archive
+// 7ffff7dc8000-7ffff7dea000 r--p 00000000 08:12 39324754                   /usr/lib/x86_64-linux-gnu/libc-2.31.so
+// 7ffff7dea000-7ffff7f62000 r-xp 00022000 08:12 39324754                   /usr/lib/x86_64-linux-gnu/libc-2.31.so
+// 7ffff7f62000-7ffff7fb0000 r--p 0019a000 08:12 39324754                   /usr/lib/x86_64-linux-gnu/libc-2.31.so
+// 7ffff7fb0000-7ffff7fb4000 r--p 001e7000 08:12 39324754                   /usr/lib/x86_64-linux-gnu/libc-2.31.so
+// 7ffff7fb4000-7ffff7fb6000 rw-p 001eb000 08:12 39324754                   /usr/lib/x86_64-linux-gnu/libc-2.31.so
+// 7ffff7fb6000-7ffff7fbc000 rw-p 00000000 00:00 0
+// 7ffff7fcf000-7ffff7fd0000 r--p 00000000 08:12 39324750                   /usr/lib/x86_64-linux-gnu/ld-2.31.so
+// 7ffff7fd0000-7ffff7ff3000 r-xp 00001000 08:12 39324750                   /usr/lib/x86_64-linux-gnu/ld-2.31.so
+// 7ffff7ff3000-7ffff7ffb000 r--p 00024000 08:12 39324750                   /usr/lib/x86_64-linux-gnu/ld-2.31.so
+// 7ffff7ffc000-7ffff7ffd000 r--p 0002c000 08:12 39324750                   /usr/lib/x86_64-linux-gnu/ld-2.31.so
+// 7ffff7ffd000-7ffff7ffe000 rw-p 0002d000 08:12 39324750                   /usr/lib/x86_64-linux-gnu/ld-2.31.so
+// 7ffff7ffe000-7ffff7fff000 rw-p 00000000 00:00 0
+// 7ffffffde000-7ffffffff000 rw-p 00000000 00:00 0                          [stack]
+// 80000006b000-80000006f000 r--p 00000000 00:00 0                          [vvar]
+// 80000006f000-800000071000 r-xp 00000000 00:00 0                          [vdso]
+// ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]
+//
+// Known limitation:
+// - Device ID is not provided by FS
+// - Not shown in address order
+
+pub struct ProcMapsINode(ProcessRef);
+
+impl ProcMapsINode {
+    pub fn new(process_ref: &ProcessRef) -> Arc<dyn INode> {
+        Arc::new(File::new(Self(Arc::clone(process_ref))))
+    }
+}
+
+impl ProcINode for ProcMapsINode {
+    fn generate_data_in_bytes(&self) -> vfs::Result<Vec<u8>> {
+        let result_string = {
+            let main_thread = self.0.main_thread().unwrap();
+            let process_vm = main_thread.vm();
+            let heap_range = process_vm.heap_range();
+            let stack_range = process_vm.stack_range();
+
+            let process_vm_chunks = process_vm.mem_chunks().read().unwrap();
+            process_vm_chunks
+                .iter()
+                .map(|chunk| match chunk.internal() {
+                    ChunkType::SingleVMA(vma) => {
+                        let range = chunk.range();
+                        let heap_or_stack = if range == heap_range {
+                            Some(" [heap]")
+                        } else if range == stack_range {
+                            Some(" [stack]")
+                        } else {
+                            None
+                        };
+                        let vma = vma.lock().unwrap();
+                        get_output_for_vma(&vma, heap_or_stack)
+                    }
+                    ChunkType::MultiVMA(internal_manager) => {
+                        let internal = internal_manager.lock().unwrap();
+                        let vmas_list = internal.chunk_manager().vmas();
+                        vmas_list
+                            .iter()
+                            .map(|obj| get_output_for_vma(obj.vma(), None))
+                            .fold(String::new(), |acc, vma_info| acc + &vma_info)
+                    }
+                })
+                .fold(String::new(), |acc, vma_info| acc + &vma_info)
+        };
+
+        Ok(result_string.into_bytes())
+    }
+}
+
+fn get_output_for_vma(vma: &VMArea, heap_or_stack: Option<&str>) -> String {
+    let range = vma.range();
+    let perms = vma.perms();
+
+    let (file_path, offset, device_id, inode_num) = {
+        if let Some((file, offset)) = vma.init_file() {
+            let inode_file = file.as_inode_file().unwrap();
+            let file_path = inode_file.abs_path();
+            let inode_num = inode_file.inode().metadata().unwrap().inode;
+            let device_id = inode_file.inode().metadata().unwrap().dev;
+            (file_path, offset, device_id, inode_num)
+        } else if heap_or_stack.is_some() {
+            (heap_or_stack.unwrap(), 0, 0, 0)
+        } else {
+            ("", 0, 0, 0)
+        }
+    };
+
+    let shared = vma.writeback_file().is_some();
+    print_each_map(
+        range, perms, shared, offset, device_id, inode_num, file_path,
+    )
+}
+
+fn print_each_map(
+    range: &VMRange,
+    perms: VMPerms,
+    shared: bool,
+    offset: usize,
+    device_id: usize,
+    inode_num: usize,
+    file_path: &str,
+) -> String {
+    let result_str = format!(
+        "{:x}-{:x} {}{} {:08x} {} {}      {}\n",
+        range.start(),
+        range.end(),
+        perms.display(),
+        if shared { "s" } else { "p" },
+        offset,
+        device_id,
+        inode_num,
+        file_path
+    );
+    result_str
+}

src/libos/src/fs/procfs/pid/mod.rs

@@ -7,6 +7,7 @@ use self::comm::ProcCommINode;
 use self::cwd::ProcCwdSymINode;
 use self::exe::ProcExeSymINode;
 use self::fd::LockedProcFdDirINode;
+use self::maps::ProcMapsINode;
 use self::root::ProcRootSymINode;
 use self::stat::ProcStatINode;
 
@@ -15,6 +16,7 @@ mod comm;
 mod cwd;
 mod exe;
 mod fd;
+mod maps;
 mod root;
 mod stat;
 
@@ -60,6 +62,9 @@ impl LockedPidDirINode {
         // stat
         let stat_inode = ProcStatINode::new(&file.process_ref);
         file.entries.insert(String::from("stat"), stat_inode);
+        // maps
+        let maps_inode = ProcMapsINode::new(&file.process_ref);
+        file.entries.insert(String::from("maps"), maps_inode);
 
         Ok(())
     }

src/libos/src/process/do_spawn/exec_loader.rs

@@ -1,6 +1,6 @@
 use super::super::elf_file::*;
 use super::ThreadRef;
-use crate::fs::{FileMode, INodeExt};
+use crate::fs::{AsINodeFile, FileMode, INodeExt};
 use crate::prelude::*;
 use rcore_fs::vfs::{FileType, INode, Metadata};
 use std::ffi::CString;
@@ -13,10 +13,10 @@ use std::ffi::CString;
 pub fn load_exec_file_hdr_to_vec(
     file_path: &str,
     current_ref: &ThreadRef,
-) -> Result<(Option<String>, Arc<dyn INode>, Vec<u8>, ElfHeader)> {
+) -> Result<(Option<String>, FileRef, Vec<u8>, ElfHeader)> {
-    let (inode, file_buf, elf_hdr) = load_file_hdr_to_vec(&file_path, current_ref)?;
+    let (file_ref, file_buf, elf_hdr) = load_file_hdr_to_vec(&file_path, current_ref)?;
     if elf_hdr.is_some() {
-        Ok((None, inode, file_buf, elf_hdr.unwrap()))
+        Ok((None, file_ref, file_buf, elf_hdr.unwrap()))
     } else {
         // loaded file is not Elf format, try script file
         if !is_script_file(&file_buf) {
@@ -30,14 +30,14 @@ pub fn load_exec_file_hdr_to_vec(
                 "libos doesn't support executing binaries from \"/host\" directory"
             );
         }
-        let (interp_inode, interp_buf, interp_hdr) =
+        let (interp_file, interp_buf, interp_hdr) =
             load_file_hdr_to_vec(&interpreter_path, current_ref)?;
         let interp_hdr = if interp_hdr.is_none() {
             return_errno!(ENOEXEC, "scrip interpreter is not ELF format");
         } else {
             interp_hdr.unwrap()
         };
-        Ok((Some(interpreter_path), interp_inode, interp_buf, interp_hdr))
+        Ok((Some(interpreter_path), interp_file, interp_buf, interp_hdr))
     }
 }
 
@@ -72,13 +72,13 @@ fn parse_script_interpreter(file_buf: &Vec<u8>) -> Result<String> {
 pub fn load_file_hdr_to_vec(
     file_path: &str,
     current_ref: &ThreadRef,
-) -> Result<(Arc<dyn INode>, Vec<u8>, Option<ElfHeader>)> {
+) -> Result<(FileRef, Vec<u8>, Option<ElfHeader>)> {
-    let inode = current_ref
+    let file_ref = current_ref
         .fs()
         .read()
         .unwrap()
-        .lookup_inode(file_path)
+        .open_file(file_path, 0, FileMode::S_IRUSR)?;
-        .map_err(|e| errno!(e.errno(), "cannot find the file"))?;
+    let inode = file_ref.as_inode_file()?.inode();
 
     // Make sure the final file to exec is not a directory
     let metadata = inode.metadata()?;
@@ -105,12 +105,12 @@ pub fn load_file_hdr_to_vec(
         .read_elf64_lazy_as_vec()
         .map_err(|e| errno!(e.errno(), "failed to read the file"))?;
 
-    let elf_header = ElfFile::parse_elf_hdr(&inode, &mut file_buf);
+    let elf_header = ElfFile::parse_elf_hdr(&file_ref, &mut file_buf);
     if let Ok(elf_header) = elf_header {
-        Ok((inode, file_buf, Some(elf_header)))
+        Ok((file_ref, file_buf, Some(elf_header)))
     } else {
         // this file is not ELF format or there is something wrong when parsing
         warn!("parse elf header error = {}", elf_header.err().unwrap());
-        Ok((inode, file_buf, None))
+        Ok((file_ref, file_buf, None))
     }
 }

src/libos/src/process/do_spawn/mod.rs

@@ -166,7 +166,7 @@ fn new_process_common(
     parent_process: Option<ProcessRef>,
 ) -> Result<ProcessRef> {
     let mut argv = argv.clone().to_vec();
-    let (is_script, elf_inode, mut elf_buf, elf_header) =
+    let (is_script, elf_file, mut elf_buf, elf_header) =
         load_exec_file_hdr_to_vec(file_path, current_ref)?;
 
     // elf_path might be different from file_path because file_path could lead to a script text file.
@@ -182,13 +182,13 @@ fn new_process_common(
         file_path.to_string()
     };
 
-    let exec_elf_hdr = ElfFile::new(&elf_inode, &mut elf_buf, elf_header)
+    let exec_elf_hdr = ElfFile::new(&elf_file, &mut elf_buf, elf_header)
         .cause_err(|e| errno!(e.errno(), "invalid executable"))?;
     let ldso_path = exec_elf_hdr
         .elf_interpreter()
         .ok_or_else(|| errno!(EINVAL, "cannot find the interpreter segment"))?;
     trace!("ldso_path = {:?}", ldso_path);
-    let (ldso_inode, mut ldso_elf_hdr_buf, ldso_elf_header) =
+    let (ldso_file, mut ldso_elf_hdr_buf, ldso_elf_header) =
         load_file_hdr_to_vec(ldso_path, current_ref)
             .cause_err(|e| errno!(e.errno(), "cannot load ld.so"))?;
     let ldso_elf_header = if ldso_elf_header.is_none() {
@@ -196,7 +196,7 @@ fn new_process_common(
     } else {
         ldso_elf_header.unwrap()
     };
-    let ldso_elf_hdr = ElfFile::new(&ldso_inode, &mut ldso_elf_hdr_buf, ldso_elf_header)
+    let ldso_elf_hdr = ElfFile::new(&ldso_file, &mut ldso_elf_hdr_buf, ldso_elf_header)
         .cause_err(|e| errno!(e.errno(), "invalid ld.so"))?;
 
     let new_process_ref = {

src/libos/src/process/elf_file.rs

@@ -15,7 +15,7 @@ const ELF64_HDR_SIZE: usize = 64;
 pub struct ElfFile<'a> {
     elf_buf: &'a [u8],
     elf_inner: Elf<'a>,
-    file_inode: &'a Arc<dyn INode>,
+    file_ref: &'a FileRef,
 }
 
 impl<'a> Debug for ElfFile<'a> {
@@ -30,7 +30,7 @@ impl<'a> Debug for ElfFile<'a> {
 
 impl<'a> ElfFile<'a> {
     pub fn new(
-        file_inode: &'a Arc<dyn INode>,
+        file_ref: &'a FileRef,
         mut elf_buf: &'a mut [u8],
         header: ElfHeader,
     ) -> Result<ElfFile<'a>> {
@@ -64,7 +64,7 @@ impl<'a> ElfFile<'a> {
                     intepreter_offset,
                     intepreter_count
                 );
-                file_inode.read_at(
+                file_ref.read_at(
                     intepreter_offset,
                     &mut elf_buf[intepreter_offset..intepreter_offset + intepreter_count],
                 );
@@ -87,7 +87,7 @@ impl<'a> ElfFile<'a> {
         Ok(ElfFile {
             elf_buf,
             elf_inner,
-            file_inode,
+            file_ref,
         })
     }
 
@@ -107,11 +107,11 @@ impl<'a> ElfFile<'a> {
         self.elf_buf
     }
 
-    pub fn file_inode(&self) -> &Arc<dyn INode> {
+    pub fn file_ref(&self) -> &FileRef {
-        self.file_inode
+        self.file_ref
     }
 
-    pub fn parse_elf_hdr(inode: &Arc<dyn INode>, elf_buf: &mut Vec<u8>) -> Result<ElfHeader> {
+    pub fn parse_elf_hdr(elf_file: &FileRef, elf_buf: &mut Vec<u8>) -> Result<ElfHeader> {
         // TODO: Sanity check the number of program headers..
         let mut phdr_start = 0;
         let mut phdr_end = 0;
@@ -130,7 +130,7 @@ impl<'a> ElfFile<'a> {
         }
 
         let program_hdr_table_size = elf_hdr.e_phnum * elf_hdr.e_phentsize;
-        inode.read_at(
+        elf_file.read_at(
             elf_hdr.e_phoff as usize,
             &mut elf_buf[hdr_size..hdr_size + (program_hdr_table_size as usize)],
         )?;

src/libos/src/vm/chunk.rs

@@ -93,11 +93,10 @@ impl Chunk {
     }
 
     pub fn new_single_vma_chunk(vm_range: &VMRange, options: &VMMapOptions) -> Result<Self> {
-        let writeback_file = options.writeback_file().clone();
         let vm_area = VMArea::new(
             vm_range.clone(),
             *options.perms(),
-            writeback_file,
+            options.initializer().backed_file(),
             DUMMY_CHUNK_PROCESS_ID,
         );
         // Initialize the memory of the new range
@@ -178,7 +177,7 @@ impl Chunk {
         if internal_manager.chunk_manager().free_size() < options.size() {
             return_errno!(ENOMEM, "no enough size without trying. try other chunks");
         }
-        internal_manager.chunk_manager().mmap(options)
+        internal_manager.chunk_manager_mut().mmap(options)
     }
 
     pub fn is_single_vma(&self) -> bool {
@@ -279,7 +278,11 @@ impl ChunkInternal {
         self.process_set.insert(pid);
     }
 
-    pub fn chunk_manager(&mut self) -> &mut ChunkManager {
+    pub fn chunk_manager(&self) -> &ChunkManager {
+        &self.chunk_manager
+    }
+
+    pub fn chunk_manager_mut(&mut self) -> &mut ChunkManager {
         &mut self.chunk_manager
     }
 

src/libos/src/vm/mod.rs

@@ -75,9 +75,10 @@ mod vm_util;
 
 use self::vm_layout::VMLayout;
 
-pub use self::chunk::ChunkRef;
+pub use self::chunk::{ChunkRef, ChunkType};
 pub use self::process_vm::{MMapFlags, MRemapFlags, MSyncFlags, ProcessVM, ProcessVMBuilder};
 pub use self::user_space_vm::USER_SPACE_VM_MANAGER;
+pub use self::vm_area::VMArea;
 pub use self::vm_perms::VMPerms;
 pub use self::vm_range::VMRange;
 pub use self::vm_util::{VMInitializer, VMMapOptionsBuilder};

src/libos/src/vm/process_vm.rs

@@ -7,7 +7,9 @@ use super::process::elf_file::{ElfFile, ProgramHeaderExt};
 use super::user_space_vm::USER_SPACE_VM_MANAGER;
 use super::vm_area::VMArea;
 use super::vm_perms::VMPerms;
-use super::vm_util::{VMInitializer, VMMapAddr, VMMapOptions, VMMapOptionsBuilder, VMRemapOptions};
+use super::vm_util::{
+    FileBacked, VMInitializer, VMMapAddr, VMMapOptions, VMMapOptionsBuilder, VMRemapOptions,
+};
 use std::collections::HashSet;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
@@ -117,7 +119,9 @@ impl<'a, 'b> ProcessVMBuilder<'a, 'b> {
                     .size(elf_layout.size())
                     .align(elf_layout.align())
                     .perms(VMPerms::ALL) // set it to read | write | exec for simplicity
-                    .initializer(VMInitializer::DoNothing())
+                    .initializer(VMInitializer::ElfSpecific {
+                        elf_file: elf_file.file_ref().clone(),
+                    })
                     .build()
                     .map_err(|e| {
                         &self.handle_error_when_init(&chunks);
@@ -244,7 +248,7 @@ impl<'a, 'b> ProcessVMBuilder<'a, 'b> {
                 }
 
                 // Bytes of file_size length are loaded from the ELF file
-                elf_file.file_inode().read_at(
+                elf_file.file_ref().read_at(
                     file_offset,
                     &mut elf_proc_buf[mem_start_offset..mem_start_offset + file_size],
                 );
@@ -318,6 +322,14 @@ impl ProcessVM {
         &self.mem_chunks
     }
 
+    pub fn stack_range(&self) -> &VMRange {
+        &self.stack_range
+    }
+
+    pub fn heap_range(&self) -> &VMRange {
+        &self.heap_range
+    }
+
     pub fn add_mem_chunk(&self, chunk: ChunkRef) {
         let mut mem_chunks = self.mem_chunks.write().unwrap();
         mem_chunks.insert(chunk);
@@ -488,28 +500,22 @@ impl ProcessVM {
                 VMInitializer::DoNothing()
             } else {
                 let file_ref = current!().file(fd)?;
-                VMInitializer::LoadFromFile {
+                // Only shared, file-backed memory mappings have write-back files
-                    file: file_ref,
+                let need_write_back = if flags.contains(MMapFlags::MAP_SHARED) {
-                    offset: offset,
+                    true
+                } else {
+                    false
+                };
+                VMInitializer::FileBacked {
+                    file: FileBacked::new(file_ref, offset, need_write_back),
                 }
             }
         };
-        // Only shared, file-backed memory mappings have write-back files
-        let writeback_file = if flags.contains(MMapFlags::MAP_SHARED) {
-            if let VMInitializer::LoadFromFile { file, offset } = &initializer {
-                Some((file.clone(), *offset))
-            } else {
-                None
-            }
-        } else {
-            None
-        };
         let mmap_options = VMMapOptionsBuilder::default()
             .size(size)
             .addr(addr_option)
             .perms(perms)
             .initializer(initializer)
-            .writeback_file(writeback_file)
             .build()?;
         let mmap_addr = USER_SPACE_VM_MANAGER.mmap(&mmap_options)?;
         Ok(mmap_addr)

src/libos/src/vm/vm_area.rs

@@ -2,6 +2,7 @@ use std::ops::{Deref, DerefMut};
 
 use super::vm_perms::VMPerms;
 use super::vm_range::VMRange;
+use super::vm_util::FileBacked;
 use super::*;
 
 use intrusive_collections::rbtree::{Link, RBTree};
@@ -11,7 +12,7 @@ use intrusive_collections::{intrusive_adapter, KeyAdapter};
 pub struct VMArea {
     range: VMRange,
     perms: VMPerms,
-    writeback_file: Option<(FileRef, usize)>,
+    file_backed: Option<FileBacked>,
     pid: pid_t,
 }
 
@@ -19,13 +20,13 @@ impl VMArea {
     pub fn new(
         range: VMRange,
         perms: VMPerms,
-        writeback_file: Option<(FileRef, usize)>,
+        file_backed: Option<FileBacked>,
         pid: pid_t,
     ) -> Self {
         Self {
             range,
             perms,
-            writeback_file,
+            file_backed,
             pid,
         }
     }
@@ -38,20 +39,25 @@ impl VMArea {
         new_perms: VMPerms,
         pid: pid_t,
     ) -> Self {
-        let new_writeback_file = vma.writeback_file.as_ref().map(|(file, file_offset)| {
+        let new_backed_file = vma.file_backed.as_ref().map(|file| {
-            let new_file = file.clone();
+            let mut new_file = file.clone();
+            let file_offset = file.offset();
 
             let new_file_offset = if vma.start() < new_range.start() {
                 let vma_offset = new_range.start() - vma.start();
-                *file_offset + vma_offset
+                file_offset + vma_offset
             } else {
                 let vma_offset = vma.start() - new_range.start();
-                debug_assert!(*file_offset >= vma_offset);
+                debug_assert!(file_offset >= vma_offset);
-                *file_offset - vma_offset
+                file_offset - vma_offset
             };
-            (new_file, new_file_offset)
+
+            new_file.set_offset(new_file_offset);
+
+            new_file
         });
-        Self::new(new_range, new_perms, new_writeback_file, pid)
+
+        Self::new(new_range, new_perms, new_backed_file, pid)
     }
 
     pub fn perms(&self) -> VMPerms {
@@ -66,8 +72,20 @@ impl VMArea {
         self.pid
     }
 
-    pub fn writeback_file(&self) -> &Option<(FileRef, usize)> {
+    pub fn init_file(&self) -> Option<(&FileRef, usize)> {
-        &self.writeback_file
+        if let Some(file) = &self.file_backed {
+            Some(file.init_file())
+        } else {
+            None
+        }
+    }
+
+    pub fn writeback_file(&self) -> Option<(&FileRef, usize)> {
+        if let Some(file) = &self.file_backed {
+            file.writeback_file()
+        } else {
+            None
+        }
     }
 
     pub fn set_perms(&mut self, new_perms: VMPerms) {
@@ -103,15 +121,19 @@ impl VMArea {
         let old_start = self.start();
         self.range.set_start(new_start);
 
-        // If the updates to the VMA needs to write back to a file, then the
+        if let Some(file) = self.file_backed.as_mut() {
-        // file offset must be adjusted according to the new start address.
+            if !file.need_write_back() {
-        if let Some((_, offset)) = self.writeback_file.as_mut() {
+                return;
+            }
+            // If the updates to the VMA needs to write back to a file, then the
+            // file offset must be adjusted according to the new start address.
+            let offset = file.offset();
             if old_start < new_start {
-                *offset += new_start - old_start;
+                file.set_offset(offset + (new_start - old_start));
             } else {
                 // The caller must guarantee that the new start makes sense
-                debug_assert!(*offset >= old_start - new_start);
+                debug_assert!(offset >= old_start - new_start);
-                *offset -= old_start - new_start;
+                file.set_offset(offset - (old_start - new_start));
             }
         }
     }
@@ -223,22 +245,3 @@ impl VMAObj {
         &self.vma
     }
 }
-
-impl VMArea {
-    pub fn new_obj(
-        range: VMRange,
-        perms: VMPerms,
-        writeback_file: Option<(FileRef, usize)>,
-        pid: pid_t,
-    ) -> Box<VMAObj> {
-        Box::new(VMAObj {
-            link: Link::new(),
-            vma: VMArea {
-                range,
-                perms,
-                writeback_file,
-                pid,
-            },
-        })
-    }
-}

src/libos/src/vm/vm_chunk_manager.rs

@@ -116,9 +116,13 @@ impl ChunkManager {
             .free_manager
             .find_free_range_internal(size, align, addr)?;
         let new_addr = new_range.start();
-        let writeback_file = options.writeback_file().clone();
         let current_pid = current!().process().pid();
-        let new_vma = VMArea::new(new_range, *options.perms(), writeback_file, current_pid);
+        let new_vma = VMArea::new(
+            new_range,
+            *options.perms(),
+            options.initializer().backed_file(),
+            current_pid,
+        );
 
         // Initialize the memory of the new range
         let buf = unsafe { new_vma.as_slice_mut() };
@@ -416,7 +420,7 @@ impl ChunkManager {
 
     /// Same as flush_vma, except that an extra condition on the file needs to satisfy.
     pub fn flush_file_vma_with_cond<F: Fn(&FileRef) -> bool>(vma: &VMArea, cond_fn: F) {
-        let (file, file_offset) = match vma.writeback_file().as_ref() {
+        let (file, file_offset) = match vma.writeback_file() {
             None => return,
             Some((file_and_offset)) => file_and_offset,
         };
@@ -430,7 +434,7 @@ impl ChunkManager {
         if !cond_fn(file) {
             return;
         }
-        file.write_at(*file_offset, unsafe { vma.as_slice() });
+        file.write_at(file_offset, unsafe { vma.as_slice() });
     }
 
     pub fn find_mmap_region(&self, addr: usize) -> Result<VMRange> {

src/libos/src/vm/vm_manager.rs

@@ -184,7 +184,11 @@ impl VMManager {
                         "mmap with addr in existing default chunk: {:?}",
                         chunk.range()
                     );
-                    return chunk_internal.lock().unwrap().chunk_manager().mmap(options);
+                    return chunk_internal
+                        .lock()
+                        .unwrap()
+                        .chunk_manager_mut()
+                        .mmap(options);
                 }
                 ChunkType::SingleVMA(_) => {
                     match addr {
@@ -287,7 +291,7 @@ impl VMManager {
                         ChunkType::MultiVMA(manager) => manager
                             .lock()
                             .unwrap()
-                            .chunk_manager()
+                            .chunk_manager_mut()
                             .munmap_range(munmap_range)?,
                     }
                 }
@@ -307,7 +311,7 @@ impl VMManager {
                 return manager
                     .lock()
                     .unwrap()
-                    .chunk_manager()
+                    .chunk_manager_mut()
                     .munmap_range(munmap_range);
             }
             ChunkType::SingleVMA(_) => {
@@ -353,7 +357,7 @@ impl VMManager {
                 return manager
                     .lock()
                     .unwrap()
-                    .chunk_manager()
+                    .chunk_manager_mut()
                     .mprotect(addr, size, perms);
             }
             ChunkType::SingleVMA(_) => {
@@ -383,7 +387,7 @@ impl VMManager {
                 return manager
                     .lock()
                     .unwrap()
-                    .chunk_manager()
+                    .chunk_manager_mut()
                     .msync_by_range(&sync_range);
             }
             ChunkType::SingleVMA(vma) => {
@@ -405,7 +409,7 @@ impl VMManager {
                     manager
                         .lock()
                         .unwrap()
-                        .chunk_manager()
+                        .chunk_manager_mut()
                         .msync_by_file(sync_file);
                 }
                 ChunkType::SingleVMA(vma) => {
@@ -452,7 +456,7 @@ impl VMManager {
             ChunkType::MultiVMA(manager) => manager
                 .lock()
                 .unwrap()
-                .chunk_manager()
+                .chunk_manager_mut()
                 .parse_mremap_options(options),
             ChunkType::SingleVMA(vma) => {
                 self.parse_mremap_options_for_single_vma_chunk(options, vma)

src/libos/src/vm/vm_perms.rs

@@ -55,6 +55,26 @@ impl VMPerms {
             assert!(sgx_status == sgx_status_t::SGX_SUCCESS && retval == 0);
         }
     }
+
+    pub fn display(&self) -> String {
+        let mut str = String::new();
+        if self.can_read() {
+            str += "r";
+        } else {
+            str += "-";
+        }
+        if self.can_write() {
+            str += "w";
+        } else {
+            str += "-";
+        }
+        if self.can_execute() {
+            str += "x";
+        } else {
+            str += "-";
+        }
+        str
+    }
 }
 
 impl Default for VMPerms {

src/libos/src/vm/vm_util.rs

@@ -1,9 +1,8 @@
 use super::*;
 
-// use super::vm_area::VMArea;
-// use super::free_space_manager::VMFreeSpaceManager;
 use super::vm_area::*;
 use super::vm_perms::VMPerms;
+use crate::fs::FileMode;
 use std::collections::BTreeSet;
 
 use intrusive_collections::rbtree::{Link, RBTree};
@@ -18,15 +17,19 @@ pub enum VMInitializer {
     CopyFrom {
         range: VMRange,
     },
-    LoadFromFile {
+    FileBacked {
-        file: FileRef,
+        file: FileBacked,
-        offset: usize,
+    },
+    // For ELF files, there is specical handling to not copy all the contents of the file. This is only used for tracking.
+    ElfSpecific {
+        elf_file: FileRef,
     },
     // For file-backed mremap which may move from old range to new range and read extra bytes from file
     CopyOldAndReadNew {
         old_range: VMRange,
         file: FileRef,
         offset: usize, // read file from this offset
+        new_writeback_file: FileBacked,
     },
 }
 
@@ -39,7 +42,7 @@ impl Default for VMInitializer {
 impl VMInitializer {
     pub fn init_slice(&self, buf: &mut [u8]) -> Result<()> {
         match self {
-            VMInitializer::DoNothing() => {
+            VMInitializer::DoNothing() | VMInitializer::ElfSpecific { .. } => {
                 // Do nothing
             }
             VMInitializer::FillZeros() => {
@@ -55,10 +58,11 @@ impl VMInitializer {
                     *b = 0;
                 }
             }
-            VMInitializer::LoadFromFile { file, offset } => {
+            VMInitializer::FileBacked { file } => {
                 // TODO: make sure that read_at does not move file cursor
                 let len = file
-                    .read_at(*offset, buf)
+                    .file_ref()
+                    .read_at(file.offset(), buf)
                     .cause_err(|_| errno!(EACCES, "failed to init memory from file"))?;
                 for b in &mut buf[len..] {
                     *b = 0;
@@ -68,6 +72,7 @@ impl VMInitializer {
                 old_range,
                 file,
                 offset,
+                new_writeback_file,
             } => {
                 // TODO: Handle old_range with non-readable subrange
                 let src_slice = unsafe { old_range.as_slice() };
@@ -85,6 +90,66 @@ impl VMInitializer {
         }
         Ok(())
     }
+
+    pub fn backed_file(&self) -> Option<FileBacked> {
+        match self {
+            VMInitializer::ElfSpecific { elf_file } => {
+                let file_ref = elf_file.clone();
+                Some(FileBacked::new(file_ref, 0, false))
+            }
+            VMInitializer::FileBacked { file } => Some(file.clone()),
+            VMInitializer::CopyOldAndReadNew {
+                new_writeback_file, ..
+            } => Some(new_writeback_file.clone()),
+            _ => None,
+        }
+    }
+}
+
+// This struct is used to record file-backed memory type.
+#[derive(Debug, Clone)]
+pub struct FileBacked {
+    file: FileRef,
+    offset: usize,
+    write_back: bool,
+}
+
+impl FileBacked {
+    pub fn new(file: FileRef, offset: usize, write_back: bool) -> Self {
+        Self {
+            file,
+            offset,
+            write_back,
+        }
+    }
+
+    pub fn file_ref(&self) -> &FileRef {
+        &self.file
+    }
+
+    pub fn offset(&self) -> usize {
+        self.offset
+    }
+
+    pub fn set_offset(&mut self, offset: usize) {
+        self.offset = offset;
+    }
+
+    pub fn need_write_back(&self) -> bool {
+        self.write_back
+    }
+
+    pub fn init_file(&self) -> (&FileRef, usize) {
+        (&self.file, self.offset)
+    }
+
+    pub fn writeback_file(&self) -> Option<(&FileRef, usize)> {
+        if self.write_back {
+            Some((&self.file, self.offset))
+        } else {
+            None
+        }
+    }
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -118,8 +183,6 @@ pub struct VMMapOptions {
     perms: VMPerms,
     addr: VMMapAddr,
     initializer: VMInitializer,
-    // The content of the VMA can be written back to a given file at a given offset
-    writeback_file: Option<(FileRef, usize)>,
 }
 
 // VMMapOptionsBuilder is generated automatically, except the build function
@@ -165,14 +228,12 @@ impl VMMapOptionsBuilder {
             Some(initializer) => initializer.clone(),
             None => VMInitializer::default(),
         };
-        let writeback_file = self.writeback_file.take().unwrap_or_default();
         Ok(VMMapOptions {
             size,
             align,
             perms,
             addr,
             initializer,
-            writeback_file,
         })
     }
 }
@@ -197,10 +258,6 @@ impl VMMapOptions {
     pub fn initializer(&self) -> &VMInitializer {
         &self.initializer
     }
-
-    pub fn writeback_file(&self) -> &Option<(FileRef, usize)> {
-        &self.writeback_file
-    }
 }
 
 #[derive(Clone, Copy, PartialEq)]
@@ -375,17 +432,18 @@ pub trait VMRemapParser {
             }
             (MRemapFlags::None, VMRemapSizeType::Growing, Some((backed_file, offset))) => {
                 // Update writeback file offset
-                let new_writeback_file = Some((backed_file.clone(), offset + vma.size()));
+                let vm_initializer_for_new_range = VMInitializer::FileBacked {
-                let vm_initializer_for_new_range = VMInitializer::LoadFromFile {
+                    file: FileBacked::new(
-                    file: backed_file.clone(),
+                        backed_file.clone(),
-                    offset: offset + vma.size(), // file-backed mremap should start from the end of previous mmap/mremap file
+                        offset + vma.size(), // file-backed mremap should start from the end of previous mmap/mremap file
+                        true,
+                    ),
                 };
                 let mmap_opts = VMMapOptionsBuilder::default()
                     .size(new_size - old_size)
                     .addr(VMMapAddr::Need(old_range.end()))
                     .perms(perms)
                     .initializer(vm_initializer_for_new_range)
-                    .writeback_file(new_writeback_file)
                     .build()?;
                 let ret_addr = Some(old_addr);
                 (Some(mmap_opts), ret_addr)
@@ -421,18 +479,18 @@ pub trait VMRemapParser {
                     VMRange::new_with_size(old_addr + old_size, new_size - old_size)?;
                 if self.is_free_range(&prefered_new_range) {
                     // Don't need to move the old range
-                    let vm_initializer_for_new_range = VMInitializer::LoadFromFile {
+                    let vm_initializer_for_new_range = VMInitializer::FileBacked {
-                        file: backed_file.clone(),
+                        file: FileBacked::new(
-                        offset: offset + vma.size(), // file-backed mremap should start from the end of previous mmap/mremap file
+                            backed_file.clone(),
+                            offset + vma.size(), // file-backed mremap should start from the end of previous mmap/mremap file
+                            true,
+                        ),
                     };
-                    // Write back file should start from new offset
-                    let new_writeback_file = Some((backed_file.clone(), offset + vma.size()));
                     let mmap_ops = VMMapOptionsBuilder::default()
                         .size(prefered_new_range.size())
                         .addr(VMMapAddr::Need(prefered_new_range.start()))
                         .perms(perms)
                         .initializer(vm_initializer_for_new_range)
-                        .writeback_file(new_writeback_file)
                         .build()?;
                     (Some(mmap_ops), Some(old_addr))
                 } else {
@@ -441,19 +499,19 @@ pub trait VMRemapParser {
                         let copy_end = vma.end();
                         let copy_range = VMRange::new(old_range.start(), copy_end)?;
                         let reread_file_start_offset = copy_end - vma.start();
+                        let new_writeback_file = FileBacked::new(backed_file.clone(), offset, true);
                         VMInitializer::CopyOldAndReadNew {
                             old_range: copy_range,
                             file: backed_file.clone(),
                             offset: reread_file_start_offset,
+                            new_writeback_file: new_writeback_file,
                         }
                     };
-                    let new_writeback_file = Some((backed_file.clone(), *offset));
                     let mmap_ops = VMMapOptionsBuilder::default()
                         .size(new_size)
                         .addr(VMMapAddr::Any)
                         .perms(perms)
                         .initializer(vm_initializer_for_new_range)
-                        .writeback_file(new_writeback_file)
                         .build()?;
                     // Cannot determine the returned address for now, which can only be obtained after calling mmap
                     let ret_addr = None;
@@ -476,19 +534,19 @@ pub trait VMRemapParser {
                     let copy_end = vma.end();
                     let copy_range = VMRange::new(old_range.start(), copy_end)?;
                     let reread_file_start_offset = copy_end - vma.start();
+                    let new_writeback_file = FileBacked::new(backed_file.clone(), offset, true);
                     VMInitializer::CopyOldAndReadNew {
                         old_range: copy_range,
                         file: backed_file.clone(),
                         offset: reread_file_start_offset,
+                        new_writeback_file: new_writeback_file,
                     }
                 };
-                let new_writeback_file = Some((backed_file.clone(), *offset));
                 let mmap_opts = VMMapOptionsBuilder::default()
                     .size(new_size)
                     .addr(VMMapAddr::Force(new_addr))
                     .perms(perms)
                     .initializer(vm_initializer_for_new_range)
-                    .writeback_file(new_writeback_file)
                     .build()?;
                 let ret_addr = Some(new_addr);
                 (Some(mmap_opts), ret_addr)

test/procfs/main.c

@@ -44,6 +44,7 @@ static int test_read_from_procfs(const char *proc_inode) {
         }
     } while (len == sizeof(buf));
     close(fd);
+    printf("test read from %s:\n%s\n", proc_inode, buf);
     return 0;
 }
 
@@ -89,6 +90,15 @@ static int test_readlink_from_proc_self_cwd() {
     return 0;
 }
 
+static int test_read_from_proc_self_maps() {
+    const char *proc_maps = "/proc/self/maps";
+
+    if (test_read_from_procfs(proc_maps) < 0) {
+        THROW_ERROR("failed to read the cpuinfo");
+    }
+    return 0;
+}
+
 static int test_readlink_from_proc_self_root() {
     char root_buf[PATH_MAX] = { 0 };
     const char *proc_root = "/proc/self/root";
@@ -282,6 +292,7 @@ static test_case_t test_cases[] = {
     TEST_CASE(test_readdir_root),
     TEST_CASE(test_readdir_self),
     TEST_CASE(test_readdir_self_fd),
+    TEST_CASE(test_read_from_proc_self_maps),
 };
 
 int main(int argc, const char *argv[]) {