Implement vfork
This commit is contained in:
Jeremy Soller
parent
aa0fb28edc
commit
b3d980b9ac
2 changed files with 154 additions and 94 deletions
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@ -19,7 +19,7 @@ use scheme;
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use syscall;
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use syscall::data::Stat;
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use syscall::error::*;
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use syscall::flag::{CLONE_VM, CLONE_FS, CLONE_FILES, MAP_WRITE, MAP_WRITE_COMBINE, WNOHANG};
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use syscall::flag::{CLONE_VFORK, CLONE_VM, CLONE_FS, CLONE_FILES, MAP_WRITE, MAP_WRITE_COMBINE, WNOHANG};
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use syscall::validate::{validate_slice, validate_slice_mut};
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pub fn brk(address: usize) -> Result<usize> {
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@ -59,6 +59,7 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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let pid;
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{
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let arch;
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let vfork;
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let mut kfx_option = None;
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let mut kstack_option = None;
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let mut offset = 0;
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@ -227,6 +228,18 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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}
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}
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// If vfork, block the current process
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// This has to be done after the operations that may require context switches
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if flags & CLONE_VFORK == CLONE_VFORK {
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let contexts = context::contexts();
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let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
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let mut context = context_lock.write();
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context.status = context::Status::Blocked;
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vfork = true;
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} else {
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vfork = false;
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}
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// Set up new process
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{
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let mut contexts = context::contexts_mut();
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@ -235,6 +248,12 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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pid = context.id;
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context.ppid = ppid;
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context.status = context::Status::Runnable;
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context.vfork = vfork;
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context.arch = arch;
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let mut active_table = unsafe { ActivePageTable::new() };
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@ -246,6 +265,8 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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InactivePageTable::new(frame, &mut active_table, &mut temporary_page)
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};
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context.arch.set_page_table(unsafe { new_table.address() });
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// Copy kernel mapping
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{
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let frame = active_table.p4()[510].pointed_frame().expect("kernel table not mapped");
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@ -350,10 +371,6 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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context.env = env;
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context.files = files;
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context.arch.set_page_table(unsafe { new_table.address() });
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context.status = context::Status::Runnable;
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}
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}
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@ -365,14 +382,32 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
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pub fn exit(status: usize) -> ! {
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{
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let contexts = context::contexts();
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let context_lock = contexts.current().expect("tried to exit without context");
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let mut context = context_lock.write();
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context.image.clear();
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drop(context.heap.take());
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drop(context.stack.take());
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context.grants = Arc::new(Mutex::new(Vec::new()));
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context.files = Arc::new(Mutex::new(Vec::new()));
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context.status = context::Status::Exited(status);
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let (vfork, ppid) = {
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let context_lock = contexts.current().expect("tried to exit without context");
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let mut context = context_lock.write();
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context.image.clear();
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drop(context.heap.take());
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drop(context.stack.take());
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context.grants = Arc::new(Mutex::new(Vec::new()));
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context.files = Arc::new(Mutex::new(Vec::new()));
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context.status = context::Status::Exited(status);
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let vfork = context.vfork;
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context.vfork = false;
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(vfork, context.ppid)
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};
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if vfork {
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if let Some(context_lock) = contexts.get(ppid) {
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let mut context = context_lock.write();
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if context.status == context::Status::Blocked {
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context.status = context::Status::Runnable;
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} else {
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println!("{} not blocked for exit vfork unblock", ppid);
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}
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} else {
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println!("{} not found for exit vfork unblock", ppid);
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}
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}
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}
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unsafe { context::switch(); }
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@ -407,104 +442,123 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
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drop(arg_ptrs); // Drop so that usage is not allowed after unmapping context
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let contexts = context::contexts();
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let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
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let mut context = context_lock.write();
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let (vfork, ppid) = {
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let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
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let mut context = context_lock.write();
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// Unmap previous image and stack
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context.image.clear();
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drop(context.heap.take());
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drop(context.stack.take());
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context.grants = Arc::new(Mutex::new(Vec::new()));
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// Unmap previous image and stack
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context.image.clear();
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drop(context.heap.take());
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drop(context.stack.take());
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context.grants = Arc::new(Mutex::new(Vec::new()));
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for segment in elf.segments() {
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if segment.p_type == program_header::PT_LOAD {
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for segment in elf.segments() {
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if segment.p_type == program_header::PT_LOAD {
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let mut memory = context::memory::Memory::new(
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VirtualAddress::new(segment.p_vaddr as usize),
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segment.p_memsz as usize,
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entry::NO_EXECUTE | entry::WRITABLE,
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true,
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true
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);
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unsafe {
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// Copy file data
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memcpy(segment.p_vaddr as *mut u8,
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(elf.data.as_ptr() as usize + segment.p_offset as usize) as *const u8,
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segment.p_filesz as usize);
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}
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let mut flags = entry::NO_EXECUTE | entry::USER_ACCESSIBLE;
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if segment.p_flags & program_header::PF_R == program_header::PF_R {
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flags.insert(entry::PRESENT);
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}
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// W ^ X. If it is executable, do not allow it to be writable, even if requested
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if segment.p_flags & program_header::PF_X == program_header::PF_X {
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flags.remove(entry::NO_EXECUTE);
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} else if segment.p_flags & program_header::PF_W == program_header::PF_W {
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flags.insert(entry::WRITABLE);
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}
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memory.remap(flags, true);
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context.image.push(memory.to_shared());
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}
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}
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context.heap = Some(context::memory::Memory::new(
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VirtualAddress::new(arch::USER_HEAP_OFFSET),
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0,
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entry::NO_EXECUTE | entry::WRITABLE | entry::USER_ACCESSIBLE,
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true,
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true
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).to_shared());
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// Map stack
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context.stack = Some(context::memory::Memory::new(
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VirtualAddress::new(arch::USER_STACK_OFFSET),
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arch::USER_STACK_SIZE,
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entry::NO_EXECUTE | entry::WRITABLE | entry::USER_ACCESSIBLE,
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true,
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true
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));
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let mut arg_size = 0;
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for arg in args.iter().rev() {
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = arch::USER_ARG_OFFSET + arg_size; }
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = arg.len(); }
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arg_size += arg.len();
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}
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = args.len(); }
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if arg_size > 0 {
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let mut memory = context::memory::Memory::new(
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VirtualAddress::new(segment.p_vaddr as usize),
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segment.p_memsz as usize,
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VirtualAddress::new(arch::USER_ARG_OFFSET),
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arg_size,
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entry::NO_EXECUTE | entry::WRITABLE,
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true,
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true
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);
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unsafe {
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// Copy file data
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memcpy(segment.p_vaddr as *mut u8,
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(elf.data.as_ptr() as usize + segment.p_offset as usize) as *const u8,
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segment.p_filesz as usize);
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let mut arg_offset = 0;
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for arg in args.iter().rev() {
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unsafe {
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memcpy((arch::USER_ARG_OFFSET + arg_offset) as *mut u8,
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arg.as_ptr(),
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arg.len());
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}
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arg_offset += arg.len();
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}
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let mut flags = entry::NO_EXECUTE | entry::USER_ACCESSIBLE;
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if segment.p_flags & program_header::PF_R == program_header::PF_R {
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flags.insert(entry::PRESENT);
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}
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// W ^ X. If it is executable, do not allow it to be writable, even if requested
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if segment.p_flags & program_header::PF_X == program_header::PF_X {
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flags.remove(entry::NO_EXECUTE);
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} else if segment.p_flags & program_header::PF_W == program_header::PF_W {
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flags.insert(entry::WRITABLE);
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}
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memory.remap(flags, true);
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memory.remap(entry::NO_EXECUTE | entry::USER_ACCESSIBLE, true);
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context.image.push(memory.to_shared());
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}
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}
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context.heap = Some(context::memory::Memory::new(
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VirtualAddress::new(arch::USER_HEAP_OFFSET),
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0,
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entry::NO_EXECUTE | entry::WRITABLE | entry::USER_ACCESSIBLE,
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true,
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true
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).to_shared());
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let vfork = context.vfork;
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context.vfork = false;
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(vfork, context.ppid)
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};
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// Map stack
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context.stack = Some(context::memory::Memory::new(
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VirtualAddress::new(arch::USER_STACK_OFFSET),
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arch::USER_STACK_SIZE,
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entry::NO_EXECUTE | entry::WRITABLE | entry::USER_ACCESSIBLE,
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true,
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true
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));
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let mut arg_size = 0;
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for arg in args.iter().rev() {
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = arch::USER_ARG_OFFSET + arg_size; }
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = arg.len(); }
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arg_size += arg.len();
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}
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sp -= mem::size_of::<usize>();
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unsafe { *(sp as *mut usize) = args.len(); }
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if arg_size > 0 {
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let mut memory = context::memory::Memory::new(
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VirtualAddress::new(arch::USER_ARG_OFFSET),
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arg_size,
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entry::NO_EXECUTE | entry::WRITABLE,
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true,
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true
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);
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let mut arg_offset = 0;
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for arg in args.iter().rev() {
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unsafe {
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memcpy((arch::USER_ARG_OFFSET + arg_offset) as *mut u8,
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arg.as_ptr(),
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arg.len());
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if vfork {
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if let Some(context_lock) = contexts.get(ppid) {
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let mut context = context_lock.write();
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if context.status == context::Status::Blocked {
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context.status = context::Status::Runnable;
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} else {
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println!("{} not blocked for exec vfork unblock", ppid);
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}
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arg_offset += arg.len();
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} else {
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println!("{} not found for exec vfork unblock", ppid);
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}
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memory.remap(entry::NO_EXECUTE | entry::USER_ACCESSIBLE, true);
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context.image.push(memory.to_shared());
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}
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},
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Err(err) => {
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