In the past, this allocator seems to have allocated things larger than
a page seperately. Much of this code was removed at some point (perhaps
along with sbrk() used) so remove the rest. Instead, keep allocating in
power-of-two bins up to FIRST_BUCKET_SIZE << (NBUCKETS - 1). If we want
something more efficent, we should use a fancier allocator.
While here, remove some vestages of sbrk() use. Most importantly, don't
try to page align the pagepool since it's always page aligned by mmap().
Reviewed by: kib
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D21453
In Seventh Edition UNIX, the last pointer passed to free() was
guaranteed to not actually have been freed allowing memory to be
"compacted" via the following pattern:
free(foo);
foo = realloc(foo, newsize);
Further, Andrew Koenig reports in "C Traps and Pitfalls" that the
original realloc() implementation required this pattern.
The C standard is clear that this is Undefined Behavior. Modern
allocators don't support it and no portable code could rely on it so
remove this support.
Note: the removed implementation contains an off-by-one error and if
an item isn't found on the freelist, then twice as much memory as the
largest possible allocation will be copied.
Reviewed by: kib, imp
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D21296
Use roundup2() and rounddown2() instead of inlining them.
Get rid of the fd local variable, use literal -1 for the mmap argument.
Use MAP_FAILED as mmap(2) failure indicator.
After that, apply some style.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
- Remove dead and most likely rotten MALLOC_DEBUG, MSTAT, and RCHECK options.
- Remove unused headers.
- Remove one case of undefined behavior where left shift could overflow.
It is impossible on practice for rtld and libthr consumer.
PR: 237577
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
