The gencore() and freecore() code in gencore.c is guarded by
POSTK_DEBUG_ARCH_DEP_18, so the call to these functions should
also be guarded, otherwise linking fails.
Previously the allocator would return all availble memory for a
request of 0 pages. This is rather counter-intuitive and left no
memory for subsequent allocations.
There is no good reason to map these low addresses (userspace could with
mmap fixed, but that is grounds for many exploits...);
the main advantage however is if we do a null deref or close to (0->foo)
within a pagefault we will get a panic stack instead of getting a hang
because we cannot get some locks.
- make should be $(MAKE)
- add + in front of rules spawning long-lasted make process in a
subshell. (This would not be needed with $(MAKE) -C .. target, but our
makefiles do not handle that because they use $(PWD))
- split the main 'all' rule as all 4 targets are independant
- fix dependencies where appropriate for parallelism
Extra, not speed-related changes:
- remove some double-colon for targets as they do not need it
This cuts build time from 5s to 1.5s on a laptop with -j4, and more
importantly from 85s to 35s on a KNL node.
As a bonus, the fixed dependencies removes the need to clean before
rebuilding all the time. Probably.
- myfree in pager.c was called with an argument, so add one to the
dummy definition
- pgoff is offset_t (unsigned) and doesn't need to be compared to 0
- clang says '*(int *)0 = 0' will be optimized away instead of keeping
the segfault without a volatile hint (?! that is wrong!), but it causes
no harm to add anyway.
This replaces the chained list used to keep track of all memory ranges
of a process by a standard rbtree (no need of interval tree here
because there is no overlap)
Accesses that were done directly through vm_range_list before were
replaced by lookup_process_memory_range, even full list scan (e.g.
coredump).
The full scans will thus be less efficient because calls to rb_next()
will not be inlined, but these are rarer calls that can probably afford
this compared to code simplicity.
The only reference to the actual backing structure left outside of
process.c is a call to rb_erase in xpmem_free_process_memory_range.
v2: fix lookup_process_memory_range with small start address
v3: make vm_range_insert error out properly
Panic does not lead to easy debug, all error paths
are handled to just return someting on error
v4: fix lookup_process_memory_range (again)
That optimistically going left was a more serious bug than just
last iteration, we could just pass by a match and continue down
the tree if the match was not a leaf.
v5: some users actually needed leftmost match, so restore behavior
without the breakage (hopefully)
