[compiler-rt] [scudo] Avoid splitting aligned allocations on Trusty (PR #69281)
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llvm-commits at lists.llvm.org
Wed Feb 7 13:50:52 PST 2024
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@@ -122,7 +122,28 @@ bool mapSecondary(const Options &Options, uptr CommitBase, uptr CommitSize,
Flags |= MAP_RESIZABLE;
Flags |= MAP_ALLOWNOMEM;
- const uptr MaxUnusedCacheBytes = MaxUnusedCachePages * getPageSizeCached();
+ const uptr PageSize = getPageSizeCached();
+ if (SCUDO_TRUSTY) {
+ /*
+ * On Trusty we need AllocPos to be usable for shared memory, which cannot
+ * cross multiple mappings. This means we need to split around AllocPos
+ * and not over it. We can only do this if the address is page-aligned.
+ */
+ const uptr TaggedSize = AllocPos - CommitBase;
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ChiaHungDuan wrote:
Per discussion, I think we may still want `TaggedSize != 0` or `DCHECK_NE(TaggedSize, 0u)`. Or we don't need them anymore?
https://github.com/llvm/llvm-project/pull/69281
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