Add simplified mmap() and munmap() syscalls.

.gitignore

@@ -1 +1,6 @@
 *.swp
+Serenity.config
+Serenity.creator
+Serenity.creator.user
+Serenity.files
+Serenity.includes

Kernel/Syscall.cpp

@@ -90,6 +90,10 @@ DWORD handle(DWORD function, DWORD arg1, DWORD arg2, DWORD arg3)
  return current->sys$getpid();
  case Syscall::PosixWaitpid:
  return current->sys$waitpid((pid_t)arg1);
+ case Syscall::PosixMmap:
+ return (dword)current->sys$mmap((void*)arg1, (size_t)arg2);
+ case Syscall::PosixMunmap:
+ return current->sys$munmap((void*)arg1, (size_t)arg2);
  case Syscall::PosixExit:
  cli();
  locker.unlock();

Kernel/Syscall.h

@@ -24,6 +24,8 @@ enum Function {
  PosixGetgid = 0x1992,
  PosixGetpid = 0x1993,
  PosixWaitpid = 0x1994,
+ PosixMmap = 0x1995,
+ PosixMunmap = 0x1996,
 };
 
 void initialize();

Kernel/Task.cpp

@@ -120,6 +120,49 @@ Task::Region* Task::allocateRegion(size_t size, String&& name)
  return m_regions.last().ptr();
 }
 
+bool Task::deallocateRegion(Region& region)
+{
+ for (size_t i = 0; i < m_regions.size(); ++i) {
+ if (m_regions[i].ptr() == &region) {
+ // FIXME: This seems racy.
+ MemoryManager::the().unmapRegion(*this, region);
+ m_regions.remove(i);
+ return true;
+ }
+ }
+ return false;
+}
+
+Task::Region* Task::regionFromRange(LinearAddress laddr, size_t size)
+{
+ for (auto& region : m_regions) {
+ if (region->linearAddress == laddr && region->size == size)
+ return region.ptr();
+ }
+ return nullptr;
+}
+
+void* Task::sys$mmap(void* addr, size_t size)
+{
+ // FIXME: Implement mapping at a client-preferred address.
+ ASSERT(addr == nullptr);
+ auto* region = allocateRegion(size, "mmap");
+ if (!region)
+ return (void*)-1;
+ MemoryManager::the().mapRegion(*this, *region);
+ return (void*)region->linearAddress.get();
+}
+
+int Task::sys$munmap(void* addr, size_t size)
+{
+ auto* region = regionFromRange(LinearAddress((dword)addr), size);
+ if (!region)
+ return -1;
+ if (!deallocateRegion(*region))
+ return -1;
+ return 0;
+}
+
 int Task::sys$spawn(const char* path)
 {
  auto* child = Task::create(path, m_uid, m_gid);

Kernel/Task.h

@@ -99,6 +99,8 @@ class Task : public InlineLinkedListNode<Task> {
  void sys$exit(int status);
  int sys$spawn(const char* path);
  pid_t sys$waitpid(pid_t);
+ void* sys$mmap(void*, size_t size);
+ int sys$munmap(void*, size_t size);
 
  struct
  {
@@ -160,6 +162,9 @@ class Task : public InlineLinkedListNode<Task> {
  String name;
  };
  Region* allocateRegion(size_t, String&& name);
+ bool deallocateRegion(Region& region);
+
+ Region* regionFromRange(LinearAddress, size_t);
 
  Vector<OwnPtr<Region>> m_regions;
 

Kernel/sync-sh

@@ -3,5 +3,6 @@ mount -o loop _fs_contents mnt/
 cp ../Userland/sh mnt/bin/sh
 cp ../Userland/id mnt/bin/id
 cp ../Userland/ps mnt/bin/ps
+cp ../Userland/ls mnt/bin/ls
 umount mnt
 sync

LibC/Makefile

@@ -3,6 +3,7 @@ OBJS = \
  unistd.o \
  string.o \
  process.o \
+ mman.o \
  entry.o
 
 LIBRARY = LibC.a

LibC/mman.cpp

@@ -0,0 +1,16 @@
+#include "mman.h"
+#include <Kernel/Syscall.h>
+
+extern "C" {
+
+void* mmap(void* addr, size_t size)
+{
+ return (void*)Syscall::invoke(Syscall::PosixMmap, (dword)addr, (dword)size);
+}
+
+int munmap(void* addr, size_t size)
+{
+ return Syscall::invoke(Syscall::PosixMunmap, (dword)addr, (dword)size);
+}
+
+}

LibC/mman.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "types.h"
+
+extern "C" {
+
+void* mmap(void*, size_t);
+int munmap(void*, size_t);
+
+}

Userland/.gitignore

@@ -1,4 +1,5 @@
 id
 sh
 ps
+ls
 *.o

Userland/Makefile

@@ -1,12 +1,14 @@
 OBJS = \
  id.o \
  sh.o \
- ps.o
+ ps.o \
+ ls.o
 
 APPS = \
  id \
  sh \
- ps
+ ps \
+ ls
 
 ARCH_FLAGS =
 STANDARD_FLAGS = -std=c++17 -nostdinc++ -nostdlib
@@ -35,6 +37,9 @@ sh: sh.o
 ps: ps.o
  $(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 
+ls: ls.o
+ $(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
+
 .cpp.o:
  @echo "CXX $<"; $(CXX) $(CXXFLAGS) -o $@ -c $<
 

Userland/ls.cpp

@@ -0,0 +1,21 @@
+#include <LibC/stdio.h>
+#include <LibC/unistd.h>
+#include <LibC/mman.h>
+
+int main(int c, char** v)
+{
+ int fd = open("/");
+ if (fd == -1) {
+ printf("failed to open / :(\n");
+ return 1;
+ }
+
+ byte* memory = (byte*)mmap(nullptr, 16384);
+ printf("%p\n", memory);
+ memory[0] = 'H';
+ memory[1] = 'i';
+ memory[2] = '!';
+ memory[3] = '\0';
+ printf("%p : %s\n", memory, memory);
+ return 0;
+}