Kernel: Remove allocate_region() functions that don't take a Range

Let's force callers to provide a VM range when allocating a region.
This makes ENOMEM error handling more visible and removes implicit
VM allocation which felt a bit magical.

5 files changed, 41 insertions, 25 deletions

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index ef6b9728f0..17ce03bba2 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -150,14 +150,6 @@ KResultOr<Region*> Process::allocate_region(const Range& range, const String& na
     return &add_region(move(region));
 }
 
-KResultOr<Region*> Process::allocate_region(VirtualAddress vaddr, size_t size, const String& name, int prot, AllocationStrategy strategy)
-{
-    auto range = allocate_range(vaddr, size);
-    if (!range.is_valid())
-        return ENOMEM;
-    return allocate_region(range, name, prot, strategy);
-}
-
 KResultOr<Region*> Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool shared)
 {
     ASSERT(range.is_valid());
@@ -183,14 +175,6 @@ KResultOr<Region*> Process::allocate_region_with_vmobject(const Range& range, No
     return &region;
 }
 
-KResultOr<Region*> Process::allocate_region_with_vmobject(VirtualAddress vaddr, size_t size, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool shared)
-{
-    auto range = allocate_range(vaddr, size);
-    if (!range.is_valid())
-        return ENOMEM;
-    return allocate_region_with_vmobject(range, move(vmobject), offset_in_vmobject, name, prot, shared);
-}
-
 bool Process::deallocate_region(Region& region)
 {
     OwnPtr<Region> region_protector;
diff --git a/Kernel/Process.h b/Kernel/Process.h
index 9a49204f83..3acafcccbb 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -437,8 +437,6 @@ public:
         return m_euid == 0;
     }
 
-    KResultOr<Region*> allocate_region_with_vmobject(VirtualAddress, size_t, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot, bool shared);
-    KResultOr<Region*> allocate_region(VirtualAddress, size_t, const String& name, int prot = PROT_READ | PROT_WRITE, AllocationStrategy strategy = AllocationStrategy::Reserve);
     KResultOr<Region*> allocate_region_with_vmobject(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, const String& name, int prot, bool shared);
     KResultOr<Region*> allocate_region(const Range&, const String& name, int prot = PROT_READ | PROT_WRITE, AllocationStrategy strategy = AllocationStrategy::Reserve);
     bool deallocate_region(Region& region);
diff --git a/Kernel/Syscalls/execve.cpp b/Kernel/Syscalls/execve.cpp
index 182ecbb9d5..1348582663 100644
--- a/Kernel/Syscalls/execve.cpp
+++ b/Kernel/Syscalls/execve.cpp
@@ -184,7 +184,13 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
                 return IterationDecision::Break;
             }
 
-            auto region_or_error = allocate_region({}, program_header.size_in_memory(), String::formatted("{} (master-tls)", elf_name), PROT_READ | PROT_WRITE, AllocationStrategy::Reserve);
+            auto range = allocate_range({}, program_header.size_in_memory());
+            if (!range.is_valid()) {
+                ph_load_result = ENOMEM;
+                return IterationDecision::Break;
+            }
+
+            auto region_or_error = allocate_region(range, String::formatted("{} (master-tls)", elf_name), PROT_READ | PROT_WRITE, AllocationStrategy::Reserve);
             if (region_or_error.is_error()) {
                 ph_load_result = region_or_error.error();
                 return IterationDecision::Break;
@@ -219,7 +225,12 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
             if (program_header.is_writable())
                 prot |= PROT_WRITE;
             auto region_name = String::formatted("{} (data-{}{})", elf_name, program_header.is_readable() ? "r" : "", program_header.is_writable() ? "w" : "");
-            auto region_or_error = allocate_region(program_header.vaddr().offset(load_offset), program_header.size_in_memory(), move(region_name), prot, AllocationStrategy::Reserve);
+            auto range = allocate_range(program_header.vaddr().offset(load_offset), program_header.size_in_memory());
+            if (!range.is_valid()) {
+                ph_load_result = ENOMEM;
+                return IterationDecision::Break;
+            }
+            auto region_or_error = allocate_region(range, region_name, prot, AllocationStrategy::Reserve);
             if (region_or_error.is_error()) {
                 ph_load_result = region_or_error.error();
                 return IterationDecision::Break;
@@ -251,7 +262,12 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
             prot |= PROT_WRITE;
         if (program_header.is_executable())
             prot |= PROT_EXEC;
-        auto region_or_error = allocate_region_with_vmobject(program_header.vaddr().offset(load_offset), program_header.size_in_memory(), *vmobject, program_header.offset(), elf_name, prot, true);
+        auto range = allocate_range(program_header.vaddr().offset(load_offset), program_header.size_in_memory());
+        if (!range.is_valid()) {
+            ph_load_result = ENOMEM;
+            return IterationDecision::Break;
+        }
+        auto region_or_error = allocate_region_with_vmobject(range, *vmobject, program_header.offset(), elf_name, prot, true);
         if (region_or_error.is_error()) {
             ph_load_result = region_or_error.error();
             return IterationDecision::Break;
@@ -271,7 +287,13 @@ KResultOr<Process::LoadResult> Process::load_elf_object(FileDescription& object_
         return ENOEXEC;
     }
 
-    auto stack_region_or_error = allocate_region(VirtualAddress(), Thread::default_userspace_stack_size, "Stack (Main thread)", PROT_READ | PROT_WRITE, AllocationStrategy::Reserve);
+    auto stack_range = allocate_range({}, Thread::default_userspace_stack_size);
+    if (!stack_range.is_valid()) {
+        dbgln("do_exec: Failed to allocate VM range for stack");
+        return ENOMEM;
+    }
+
+    auto stack_region_or_error = allocate_region(stack_range, "Stack (Main thread)", PROT_READ | PROT_WRITE, AllocationStrategy::Reserve);
     if (stack_region_or_error.is_error())
         return stack_region_or_error.error();
     auto& stack_region = *stack_region_or_error.value();
diff --git a/Kernel/Syscalls/mmap.cpp b/Kernel/Syscalls/mmap.cpp
index 070233a841..b461893fc5 100644
--- a/Kernel/Syscalls/mmap.cpp
+++ b/Kernel/Syscalls/mmap.cpp
@@ -404,10 +404,14 @@ void* Process::sys$mremap(Userspace<const Syscall::SC_mremap_params*> user_param
         auto old_name = old_region->name();
         auto old_prot = region_access_flags_to_prot(old_region->access());
         NonnullRefPtr inode = static_cast<SharedInodeVMObject&>(old_region->vmobject()).inode();
+
+        // Unmap without deallocating the VM range since we're going to reuse it.
+        old_region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
         deallocate_region(*old_region);
 
         auto new_vmobject = PrivateInodeVMObject::create_with_inode(inode);
-        auto new_region_or_error = allocate_region_with_vmobject(range.base(), range.size(), new_vmobject, 0, old_name, old_prot, false);
+
+        auto new_region_or_error = allocate_region_with_vmobject(range, new_vmobject, 0, old_name, old_prot, false);
         if (new_region_or_error.is_error())
             return (void*)new_region_or_error.error().error();
         auto& new_region = *new_region_or_error.value();
@@ -439,7 +443,11 @@ void* Process::sys$allocate_tls(size_t size)
     });
     ASSERT(main_thread);
 
-    auto region_or_error = allocate_region({}, size, String(), PROT_READ | PROT_WRITE);
+    auto range = allocate_range({}, size);
+    if (!range.is_valid())
+        return (void*)-ENOMEM;
+
+    auto region_or_error = allocate_region(range, String(), PROT_READ | PROT_WRITE);
     if (region_or_error.is_error())
         return (void*)region_or_error.error().error();
 
diff --git a/Kernel/Thread.cpp b/Kernel/Thread.cpp
index c3640c3098..52fe586f0c 100644
--- a/Kernel/Thread.cpp
+++ b/Kernel/Thread.cpp
@@ -1041,7 +1041,11 @@ KResult Thread::make_thread_specific_region(Badge<Process>)
     if (!process().m_master_tls_region)
         return KSuccess;
 
-    auto region_or_error = process().allocate_region({}, thread_specific_region_size(), "Thread-specific", PROT_READ | PROT_WRITE);
+    auto range = process().allocate_range({}, thread_specific_region_size());
+    if (!range.is_valid())
+        return ENOMEM;
+
+    auto region_or_error = process().allocate_region(range, "Thread-specific", PROT_READ | PROT_WRITE);
     if (region_or_error.is_error())
         return region_or_error.error();