From 0b5a915725f20545cbe44fa94feb2c6c6f08f421 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 9 Mar 2021 11:30:20 +0100
Subject: [PATCH] UserspaceEmulator: Keep the MMU regions list sorted

---
 Userland/DevTools/UserspaceEmulator/SoftMMU.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Userland/DevTools/UserspaceEmulator/SoftMMU.cpp b/Userland/DevTools/UserspaceEmulator/SoftMMU.cpp
index 7d42a8eb24..0d56f73bb0 100644
--- a/Userland/DevTools/UserspaceEmulator/SoftMMU.cpp
+++ b/Userland/DevTools/UserspaceEmulator/SoftMMU.cpp
@@ -30,6 +30,7 @@
 #include "Report.h"
 #include <AK/ByteBuffer.h>
 #include <AK/Memory.h>
+#include <AK/QuickSort.h>
 
 namespace UserspaceEmulator {
 
@@ -49,6 +50,7 @@ void SoftMMU::add_region(NonnullOwnPtr<Region> region)
     }
 
     m_regions.append(move(region));
+    quick_sort((Vector<OwnPtr<Region>>&)m_regions, [](auto& a, auto& b) { return a->base() < b->base(); });
 }
 
 void SoftMMU::remove_region(Region& region)
@@ -80,17 +82,27 @@ void SoftMMU::ensure_split_at(X86::LogicalAddress address)
     // If we get here, we know that the page exists and belongs to a region, that there is
     // a previous page, and that it belongs to the same region.
     VERIFY(is<MmapRegion>(m_page_to_region_map[page_index]));
-    MmapRegion* old_region = static_cast<MmapRegion*>(m_page_to_region_map[page_index]);
+    auto* old_region = static_cast<MmapRegion*>(m_page_to_region_map[page_index]);
+
+    //dbgln("splitting at {:p}", address.offset());
+    //dbgln("    old region: {:p}-{:p}", old_region->base(), old_region->end() - 1);
+
     NonnullOwnPtr<MmapRegion> new_region = old_region->split_at(VirtualAddress(offset));
+    //dbgln("    new region: {:p}-{:p}", new_region->base(), new_region->end() - 1);
+    //dbgln(" up old region: {:p}-{:p}", old_region->base(), old_region->end() - 1);
 
     size_t first_page_in_region = new_region->base() / PAGE_SIZE;
     size_t last_page_in_region = (new_region->base() + new_region->size() - 1) / PAGE_SIZE;
+
+    //dbgln("  @ remapping pages {} thru {}", first_page_in_region, last_page_in_region);
+
     for (size_t page = first_page_in_region; page <= last_page_in_region; ++page) {
         VERIFY(m_page_to_region_map[page] == old_region);
         m_page_to_region_map[page] = new_region.ptr();
     }
 
     m_regions.append(move(new_region));
+    quick_sort((Vector<OwnPtr<Region>>&)m_regions, [](auto& a, auto& b) { return a->base() < b->base(); });
 }
 
 void SoftMMU::set_tls_region(NonnullOwnPtr<Region> region)