Current code doesn't check size of elf sections and may perform needless
actions of zero-sized memory allocation and similar.
The bigger issue is that alignment requirement of a zero-sized section
gets effectively applied to the next section if it has smaller alignment
requirement. But other tools, like gdb and consequently kgdb,
completely ignore zero-sized sections and thus may map symbols to
addresses differently.
Zero-sized sections are not typical in general.
Their typical (only, even) cause in FreeBSD modules is inline assembly that
creates custom sections which is found in pcpu.h and vnet.h. Mere inclusion
of one of those header files produces a custom section in elf output.
If there is no actual use for the section in a given module, then the
section remains empty.
Better solution is to avoid creating zero-sized sections altogether,
which is in plans.
Preloaded modules are handled in boot code (load_elf_obj.c), while
dynamically loaded modules are handled by kernel (link_elf_obj.c).
Based on code by: np
MFC after: 3 weeks
At present the cpufreq sysctl handler for current level setting would
allocate and deallocate a temporary buffer of 24KB even to handle a
read-only query. This puts unnecessary load on memory subsystem when
current level is checked frequently, e.g. when the likes of powerd
and system monitoring software are running.
Change the strategy to allocating a long-lived buffer for handling the
requests.
Reviewed by: njl
MFC after: 2 weeks
taskqueues, more than one task can be running simultaneously.
Also make taskqueue_run(9) static to the file, since there are no
consumers in the base kernel and the function signature needs to change
with this fix.
Remove mention of taskqueue_run(9) and taskqueue_run_fast(9) from the
taskqueue(9) man page.
Reviewed by: jhb
Approved by: zml (mentor)
name of 32bit sibling architecture instead of the host one. Do the
same for hw.machine on amd64.
Add a safety belt debug.adaptive_machine_arch sysctl, to turn the
substitution off.
Reviewed by: jhb, nwhitehorn
MFC after: 2 weeks
is not defined at all because KTR_GEN is still a valid class and some
traces may fit in. Default to 0, instead, and block any tracing.
As long as this is a POLA violation (some thirdy-part code, even if
that may be a questionable choice, could be rely on that feature) a
MFC possibility might be carefully evaluated.
Sponsored by: Sandvine Incorporated
lengths. Make MI wrapper code to validate periods in request. Make kernel
clock management code to honor these hardware limitations while choosing hz,
stathz and profhz values.
machines which can clearly afford the memory.
This is a somewhat conservative version of the patch - more fine tuning may be
necessary.
Idea from: Thread on hackers@
Discussed with: alc
- Simplify ktrstruct() calling convention by having ktrstruct() use
strlen() rather than requiring the caller to hand-code the length of
constant strings.
MFC after: 1 month
most one call to pmap_qremove(), and thus one TLB shootdown, instead of one
call and TLB shootdown per page.
Simplify the interface to vm_hold_free_pages().
MFC after: 3 weeks
was needed at preliminary version of the patch, where number of CPU ticks
was divided strictly on 16 seconds. Final code instead uses real interval
duration, so precise interval should not be important. Same time aliasing
issues around second boundary causes false positives, periodically logging
useless "t_delta ... too long/short" messages when HZ set below 256.
the maintenance of vm_pageout_deficit can be localized to just two places:
vm_page_alloc() and vm_pageout_scan().
This change also corrects an off-by-one error in the maintenance of
vm_pageout_deficit. Historically, the buffer cache functions, allocbuf()
and vm_hold_load_pages(), have not taken into account that vm_page_alloc()
already increments vm_pageout_deficit by one.
Reviewed by: kib
- Fix a bug where thread may be in sleeping state but the wchan won't
be set, leading to an empty container for sleepq_type(). [0]
Sponsored by: Sandvine Incorporated
[0] Submitted by: Bryan Venteicher
<bryanv at daemoninthecloset dot org>
MFC after: 3 days
X-MFC: 209577
There are special cases where tty_rel_free() can be called twice in a
row, namely when closing and revoking the TTY at the same moment. Only
call destroy_dev_sched_cb() once.
Reported by: Jeremie Le Hen
MFC after: 1 week
specify the increment of vm_pageout_deficit when sleeping due to page
shortage. Then, in allocbuf(), the code to allocate pages when extending
vmio buffer can be replaced by a call to vm_page_grab().
Suggested and reviewed by: alc
MFC after: 2 weeks
numbers. This change adds a new function alloc_unr_specific() which
returns the requested unit number if it is free. If the number is
already allocated or out of the range, -1 is returned.
Update alloc_unr(9) manual page accordingly and add a MLINK for
alloc_unr_specific(9).
Discussed on: freebsd-hackers
one or more mappings to the bogus page must be replaced, call pmap_qenter()
just once. Previously, pmap_qenter() was called for each mapping to the
bogus page.
MFC after: 3 weeks
- Rename tdsignal() to tdsendsignal() and make it private to kern_sig.c.
- Add tdsignal() and tdksignal() routines that mirror psignal() and
pksignal() except that they accept a thread as an argument instead of
a process. They send a signal to a specific thread rather than to an
individual process.
Reviewed by: kib
shm syscalls, and initial check for the number of allocated segments
in the module deinitialization code, the following might happen:
after the check for active segment, while waiting for threads to
leave some other syscall, shmget(2) is called. Then, we can end
up with the shared segment that cannot be detached since sysvshm
module is unloaded.
Prevent the leak by rechecking and disclaiming a reference to the vm
object owned by sysvshm module, that might have grown during the drain.
Tested by: pho
Reviewed by: jhb
MFC after: 1 month
