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This repository was archived by the owner on Nov 1, 2020. It is now read-only.
This repository was archived by the owner on Nov 1, 2020. It is now read-only.

Wasm: munmap possible problem #8330

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Wasm: munmap possible problem#8330
@yowl

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@yowl
yowl
opened on Sep 15, 2020

Emscripten basically maps mmap/munmap to malloc/free. The second parameter to munmap is effectively unused https://github.com/emscripten-core/emscripten/blob/3abb4a6993ef97d652eae673cd79ffcdf97732dd/src/library_syscall.js#L275 I think this means that

corert/src/Native/gc/unix/gcenv.unix.cpp

Lines 624 to 635 in a892bba

if (startPadding != 0)
{
int ret = munmap(pRetVal, startPadding);
assert(ret == 0);
}
size_t endPadding = alignedSize - (startPadding + size);
if (endPadding != 0)
{
int ret = munmap((void *)((size_t)pAlignedRetVal + size), endPadding);
assert(ret == 0);
}
is going to be a problem. startPadding never seems to be non zero, but endPadding often is.

If the alignment == OS_PAGE_SIZE for Wasm that might be a workaround, or maybe VirtualReserveInner and VirtualRelease that just went to malloc/free ?

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