Kernel: Make Memory::Region::map() return KResult

..and use TRY() at the call sites to propagate errors. :^)

Kernel/Memory/AddressSpace.cpp

@@ -72,8 +72,7 @@ KResult AddressSpace::unmap_mmap_range(VirtualAddress addr, size_t size)
         for (auto* new_region : new_regions) {
             // TODO: Ideally we should do this in a way that can be rolled back on failure, as failing here
             // leaves the caller in an undefined state.
-            if (!new_region->map(page_directory()))
+            TRY(new_region->map(page_directory()));
-                return ENOMEM;
         }
 
         PerformanceManager::add_unmap_perf_event(Process::current(), range_to_unmap);
@@ -122,8 +121,7 @@ KResult AddressSpace::unmap_mmap_range(VirtualAddress addr, size_t size)
     for (auto* new_region : new_regions) {
         // TODO: Ideally we should do this in a way that can be rolled back on failure, as failing here
         // leaves the caller in an undefined state.
-        if (!new_region->map(page_directory()))
+        TRY(new_region->map(page_directory()));
-            return ENOMEM;
     }
 
     PerformanceManager::add_unmap_perf_event(Process::current(), range_to_unmap);
@@ -161,8 +159,7 @@ KResultOr<Region*> AddressSpace::allocate_region(VirtualRange const& range, Stri
     VERIFY(range.is_valid());
     auto vmobject = TRY(AnonymousVMObject::try_create_with_size(range.size(), strategy));
     auto region = TRY(Region::try_create_user_accessible(range, move(vmobject), 0, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, false));
-    if (!region->map(page_directory()))
+    TRY(region->map(page_directory()));
-        return ENOMEM;
     return add_region(move(region));
 }
 
@@ -185,8 +182,7 @@ KResultOr<Region*> AddressSpace::allocate_region_with_vmobject(VirtualRange cons
     offset_in_vmobject &= PAGE_MASK;
     auto region = TRY(Region::try_create_user_accessible(range, move(vmobject), offset_in_vmobject, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, shared));
     auto* added_region = TRY(add_region(move(region)));
-    if (!added_region->map(page_directory()))
+    TRY(added_region->map(page_directory()));
-        return ENOMEM;
     return added_region;
 }
 

Kernel/Memory/MemoryManager.cpp

@@ -730,8 +730,7 @@ KResultOr<NonnullOwnPtr<Region>> MemoryManager::allocate_kernel_region(PhysicalA
 KResultOr<NonnullOwnPtr<Region>> MemoryManager::allocate_kernel_region_with_vmobject(VirtualRange const& range, VMObject& vmobject, StringView name, Region::Access access, Region::Cacheable cacheable)
 {
     auto region = TRY(Region::try_create_kernel_only(range, vmobject, 0, KString::try_create(name), access, cacheable));
-    if (!region->map(kernel_page_directory()))
+    TRY(region->map(kernel_page_directory()));
-        return ENOMEM;
     return region;
 }
 

Kernel/Memory/Region.cpp

@@ -243,7 +243,7 @@ void Region::set_page_directory(PageDirectory& page_directory)
     m_page_directory = page_directory;
 }
 
-bool Region::map(PageDirectory& page_directory, ShouldFlushTLB should_flush_tlb)
+KResult Region::map(PageDirectory& page_directory, ShouldFlushTLB should_flush_tlb)
 {
     SpinlockLocker page_lock(page_directory.get_lock());
     SpinlockLocker lock(s_mm_lock);
@@ -263,16 +263,18 @@ bool Region::map(PageDirectory& page_directory, ShouldFlushTLB should_flush_tlb)
     if (page_index > 0) {
         if (should_flush_tlb == ShouldFlushTLB::Yes)
             MM.flush_tlb(m_page_directory, vaddr(), page_index);
-        return page_index == page_count();
+        if (page_index == page_count())
+            return KSuccess;
     }
-    return false;
+    return ENOMEM;
 }
 
 void Region::remap()
 {
     VERIFY(m_page_directory);
     auto result = map(*m_page_directory);
-    VERIFY(result);
+    if (result.is_error())
+        TODO();
 }
 
 PageFaultResponse Region::handle_fault(PageFault const& fault)

Kernel/Memory/Region.h

@@ -170,7 +170,7 @@ public:
     void set_executable(bool b) { set_access_bit(Access::Execute, b); }
 
     void set_page_directory(PageDirectory&);
-    [[nodiscard]] bool map(PageDirectory&, ShouldFlushTLB = ShouldFlushTLB::Yes);
+    KResult map(PageDirectory&, ShouldFlushTLB = ShouldFlushTLB::Yes);
     enum class ShouldDeallocateVirtualRange {
         No,
         Yes,

Kernel/Syscalls/fork.cpp

@@ -95,8 +95,7 @@ KResultOr<FlatPtr> Process::sys$fork(RegisterState& regs)
             dbgln_if(FORK_DEBUG, "fork: cloning Region({}) '{}' @ {}", region, region->name(), region->vaddr());
             auto region_clone = TRY(region->try_clone());
             auto* child_region = TRY(child->address_space().add_region(move(region_clone)));
-            if (!child_region->map(child->address_space().page_directory(), Memory::ShouldFlushTLB::No))
+            TRY(child_region->map(child->address_space().page_directory(), Memory::ShouldFlushTLB::No));
-                return ENOMEM;
 
             if (region == m_master_tls_region.unsafe_ptr())
                 child->m_master_tls_region = child_region;

Kernel/Syscalls/mmap.cpp

@@ -338,11 +338,9 @@ KResultOr<FlatPtr> Process::sys$mprotect(Userspace<void*> addr, size_t size, int
 
         // Map the new regions using our page directory (they were just allocated and don't have one).
         for (auto* adjacent_region : adjacent_regions) {
-            if (!adjacent_region->map(address_space().page_directory()))
+            TRY(adjacent_region->map(address_space().page_directory()));
-                return ENOMEM;
         }
-        if (!new_region->map(address_space().page_directory()))
+        TRY(new_region->map(address_space().page_directory()));
-            return ENOMEM;
         return 0;
     }
 
@@ -401,11 +399,9 @@ KResultOr<FlatPtr> Process::sys$mprotect(Userspace<void*> addr, size_t size, int
 
             // Map the new region using our page directory (they were just allocated and don't have one) if any.
             if (adjacent_regions.size())
-                if (!adjacent_regions[0]->map(address_space().page_directory()))
+                TRY(adjacent_regions[0]->map(address_space().page_directory()));
-                    return ENOMEM;
 
-            if (!new_region->map(address_space().page_directory()))
+            TRY(new_region->map(address_space().page_directory()));
-                return ENOMEM;
         }
 
         return 0;