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Rework the way jemalloc uses mmap(2) on FreeBSD.

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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.
This commit is contained in:
Edward Tomasz Napierala 2018-06-23 06:51:33 +01:00 committed by David Goldblatt
parent 676cdd6679
commit f80c97e477
1 changed files with 25 additions and 0 deletions
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25
src/pages.c
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@ -180,6 +180,31 @@ pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
assert(alignment >= PAGE);
assert(ALIGNMENT_ADDR2BASE(addr, alignment) == addr);
#if defined(__FreeBSD__) && defined(MAP_EXCL)
/*
* FreeBSD has mechanisms both to mmap at specific address without
* touching existing mappings, and to mmap with specific alignment.
*/
{
int prot = *commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
int flags = mmap_flags;
if (addr != NULL) {
flags |= MAP_FIXED | MAP_EXCL;
} else {
unsigned alignment_bits = ffs_zu(alignment);
assert(alignment_bits > 1);
flags |= MAP_ALIGNED(alignment_bits - 1);
}
void *ret = mmap(addr, size, prot, flags, -1, 0);
if (ret == MAP_FAILED) {
ret = NULL;
}
return ret;
}
#endif
/*
* Ideally, there would be a way to specify alignment to mmap() (like
* NetBSD has), but in the absence of such a feature, we have to work