kernel/vm_manager: Add overload of FindFreeRegion() that operates on a boundary

This will be necessary for making our TLS slot management slightly more
straightforward. This can also be utilized for other purposes in the
future.

We can implement the existing simpler overload in terms of this one
anyways, we just pass the beginning and end of the ASLR region as the
boundaries.

1 files changed, 21 insertions, 10 deletions

diff --git a/src/core/hle/kernel/vm_manager.cpp b/src/core/hle/kernel/vm_manager.cpp
index c929c2a52..3df5ccb7f 100644
--- a/src/core/hle/kernel/vm_manager.cpp
+++ b/src/core/hle/kernel/vm_manager.cpp
@@ -152,22 +152,33 @@ ResultVal<VMManager::VMAHandle> VMManager::MapBackingMemory(VAddr target, u8* me
 }
 
 ResultVal<VAddr> VMManager::FindFreeRegion(u64 size) const {
-    // Find the first Free VMA.
-    const VAddr base = GetASLRRegionBaseAddress();
-    const VMAHandle vma_handle = std::find_if(vma_map.begin(), vma_map.end(), [&](const auto& vma) {
-        if (vma.second.type != VMAType::Free)
-            return false;
+    return FindFreeRegion(GetASLRRegionBaseAddress(), GetASLRRegionEndAddress(), size);
+}
 
-        const VAddr vma_end = vma.second.base + vma.second.size;
-        return vma_end > base && vma_end >= base + size;
-    });
+ResultVal<VAddr> VMManager::FindFreeRegion(VAddr begin, VAddr end, u64 size) const {
+    ASSERT(begin < end);
+    ASSERT(size <= end - begin);
 
-    if (vma_handle == vma_map.end()) {
+    const VMAHandle vma_handle =
+        std::find_if(vma_map.begin(), vma_map.end(), [begin, end, size](const auto& vma) {
+            if (vma.second.type != VMAType::Free) {
+                return false;
+            }
+            const VAddr vma_base = vma.second.base;
+            const VAddr vma_end = vma_base + vma.second.size;
+            const VAddr assumed_base = (begin < vma_base) ? vma_base : begin;
+            const VAddr used_range = assumed_base + size;
+
+            return vma_base <= assumed_base && assumed_base < used_range && used_range < end &&
+                   used_range <= vma_end;
+        });
+
+    if (vma_handle == vma_map.cend()) {
         // TODO(Subv): Find the correct error code here.
         return ResultCode(-1);
     }
 
-    const VAddr target = std::max(base, vma_handle->second.base);
+    const VAddr target = std::max(begin, vma_handle->second.base);
     return MakeResult<VAddr>(target);
 }