[sanitizer] Warn if allocator size exceeds max user virtual address

[thurstond]

This warns the user of incompatible configurations, such as 39-bit and 42-bit VMAs for AArch64 non-Android Linux ASan (#145259).

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Thurston Dang (thurstond)

Changes

This warns the user of incompatible configurations, such as 39-bit and 42-bit VMAs for AArch64 non-Android Linux ASan (#145259).

---

Full diff: https://github.com/llvm/llvm-project/pull/152428.diff

1 Files Affected:

• (modified) compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h (+12)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h b/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h
index 51ac1b6ae4975..56d40c19b0f0c 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary64.h
@@ -113,6 +113,18 @@ class SizeClassAllocator64 {
   // ~(uptr)0.
   void Init(s32 release_to_os_interval_ms, uptr heap_start = 0) {
     uptr TotalSpaceSize = kSpaceSize + AdditionalSize();
+
+    uptr MaxAddr = GetMaxUserVirtualAddress();
+    // VReport does not call the sanitizer allocator.
+    VReport(3, "Max user virtual address: 0x%zx\n", MaxAddr);
+    VReport(3, "Total space size for primary allocator: 0x%zx\n",
+            TotalSpaceSize);
+    if (TotalSpaceSize >= MaxAddr)
+      VReport(0, "Error: heap size %zx exceeds max user virtual address %zx\n",
+              TotalSpaceSize, MaxAddr);
+    // We can't easily adjust the requested heap size, because kSpaceSize is
+    // const (for optimization) and used throughout the code.
+
     PremappedHeap = heap_start != 0;
     if (PremappedHeap) {
       CHECK(!kUsingConstantSpaceBeg);

[fmayer]

it's not immediately clear what there is TO DO

[thurstond]

There is nothing to do in the immediate or even medium-term future. But suppose it's the year 2800: 256TB heaps are commonplace, this warning message keeps popping up. and you get woken from cryogenic sleep because you are the last-known maintainer of Android sanitizers; you'll be glad the TODO is there to hint that the check needs revising.

[fmayer]

i mean: if it says TODO, it should clearly state what there is to do. if it's just an explanation of the state of things, remove the TODO.

[thurstond]

I've revised it