[compiler-rt] [scudo] Move getResidentPages function (PR #183138)

[Christopher Ferris via llvm-commits]

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@@ -131,6 +131,38 @@ void MemMapLinux::releaseAndZeroPagesToOSImpl(uptr From, uptr Size) {
   }
 }
 
+s64 MemMapLinux::getResidentPagesImpl(uptr From, uptr Size) {
+  unsigned char PageData[256];
+
+  uptr PageSize = getPageSizeCached();
+  uptr PageSizeLog = getPageSizeLogCached();
+
+  // Make sure the address is page aligned.
+  uptr CurrentAddress = From & ~(PageSize - 1);
+  uptr LastAddress = roundUp(From + Size, PageSize);
+  s64 ResidentPages = 0;
+  while (CurrentAddress < LastAddress) {
+    uptr Length = LastAddress - CurrentAddress;
+    if ((Length >> PageSizeLog) > sizeof(PageData)) {
+      Length = sizeof(PageData) << PageSizeLog;
+    }
+    if (mincore(reinterpret_cast<void *>(CurrentAddress), Length, PageData) ==
+        -1) {
+      ScopedString Str;
+      Str.append("mincore failed: %s\n", strerror(errno));
+      Str.output();
+      return 0;
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cferris1000 wrote:

This should be returning -1.

https://github.com/llvm/llvm-project/pull/183138