Rework the way jemalloc uses mmap(2) on FreeBSD.
This makes it directly use MAP_EXCL and MAP_ALIGNED() instead of weird workarounds involving mapping at random places and then unmapping parts of them.
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25
src/pages.c
25
src/pages.c
@ -180,6 +180,31 @@ pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
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assert(alignment >= PAGE);
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assert(ALIGNMENT_ADDR2BASE(addr, alignment) == addr);
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#if defined(__FreeBSD__) && defined(MAP_EXCL)
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/*
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* FreeBSD has mechanisms both to mmap at specific address without
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* touching existing mappings, and to mmap with specific alignment.
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*/
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{
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int prot = *commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
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int flags = mmap_flags;
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if (addr != NULL) {
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flags |= MAP_FIXED | MAP_EXCL;
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} else {
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unsigned alignment_bits = ffs_zu(alignment);
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assert(alignment_bits > 1);
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flags |= MAP_ALIGNED(alignment_bits - 1);
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}
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void *ret = mmap(addr, size, prot, flags, -1, 0);
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if (ret == MAP_FAILED) {
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ret = NULL;
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}
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return ret;
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}
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#endif
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/*
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* Ideally, there would be a way to specify alignment to mmap() (like
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* NetBSD has), but in the absence of such a feature, we have to work
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