Right now, we enable the CR4.FSGSBASE bit on CPUs which support the
facility (Ivy and later), to allow usermode to read fs and gs bases
without syscalls. This bit also controls the write access to bases
from userspace, but WRFSBASE and WRGSBASE instructions currently
cannot be used, because return path from both exceptions or interrupts
overrides bases with the values from pcb.
Supporting the instructions is useful because this means that usermode
can implement green-threads completely in userspace without issuing
syscalls to change all of the machine context.
Support is implemented by saving the fs base and user gs base when
PCB_FULL_IRET flag is set. The flag is set on the context switch,
which potentially causes clobber of the bases due to activation of
another context, and when explicit modification of the user context by
a syscall or exception handler is performed. In particular, the patch
moves setting of the flag before syscalls change context.
The changes to doreti_exit and PUSH_FRAME to clear PCB_FULL_IRET on
entry from userspace can be considered a bug fixes on its own.
Reviewed by: jhb (previous version)
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
Differential revision: https://reviews.freebsd.org/D12023
- Use more relevant name 'signo' instead of 'i' for the local variable
which contains a signal number to send for the current exception.
- Eliminate two labels 'userout' and 'out' which point to the very end
of the trap() function. Instead use return directly.
- Re-indent the prot_fault_translation block by reducing if() nesting.
- Some more monor style changes.
Requested and reviewed by: bde
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
This helps simplify the code in kern_shutdown.c and reduces the number
of globally visible functions.
No functional change intended.
Reviewed by: cem, def
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11603
dump_start() and dump_finish() are responsible for writing kernel dump
headers, optionally writing the key when encryption is enabled, and
initializing the initial offset into the dump device.
Also remove the unused dump_pad(), and make some functions static now that
they're only called from kern_shutdown.c.
No functional change intended.
Reviewed by: cem, def
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11584
Add an option to dynamically rebalance interrupts across cores
(hw.intrbalance); off by default.
The goal is to minimize preemption. By placing interrupt sources on distinct
CPUs, ithreads get preferentially scheduled on distinct CPUs. Overall
preemption is reduced and latency is reduced. In our workflow it reduced
"fighting" between two high-frequency interrupt sources. Reduced latency
was proven by, e.g., SPEC2008.
Submitted by: jeff@ (earlier version)
Reviewed by: kib@
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D10435
Intel SGX allows to manage isolated compartments "Enclaves" in user VA
space. Enclaves memory is part of processor reserved memory (PRM) and
always encrypted. This allows to protect user application code and data
from upper privilege levels including OS kernel.
This includes SGX driver and optional linux ioctl compatibility layer.
Intel SGX SDK for FreeBSD is also available.
Note this requires support from hardware (available since late Intel
Skylake CPUs).
Many thanks to Robert Watson for support and Konstantin Belousov
for code review.
Project wiki: https://wiki.freebsd.org/Intel_SGX.
Reviewed by: kib
Relnotes: yes
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D11113
It is quite useful when double fault is not caused by a stack overflow.
Tested by: pho (as part of the larger patch)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
reduces diff between amd64 and i386. Also, it fixes a regression introduced
in r322076, i.e., identify_hypervisor() failed to identify some hypervisors.
This function assumes cpu_feature2 is already initialized.
Reported by: dexuan
Tested by: dexuan
libefivar expects opening /dev/efi to indicate if the we can make efi
runtime calls. With a null routine, it was always succeeding leading
efi_variables_supported() to return the wrong value. Only succeed if
we have an efi_runtime table. Also, while I'm hear, out of an
abundance of caution, add a likely redundant check to make sure
efi_systbl is not NULL before dereferencing it. I know it can't be
NULL if efi_cfgtbl is non-NULL, but the compiler doesn't.
but it was broken since r273800 (and r278522, its MFC to stable/10) because
identify_cpu() is called too late, i.e., after init_param1().
MFC after: 3 days
Some C wrappers for x86 instructions do not touch global memory and only act
on their arguments; they can be marked __pure2, aka __const__. Without this
annotation, Clang 3.9.1 is not intelligent enough on its own to grok that
these functions are __const__.
Submitted by: Anton Rang <anton.rang AT isilon.com>
Sponsored by: Dell EMC Isilon
Similar to r321899, reduce sv_maxuser by one page inside of CloudABI.
This ensures that the stack, the vDSO and any allocations cannot touch
the top page of user virtual memory.
Considering that CloudABI userspace is completely oblivious to virtual
memory layout, don't bother making this conditional based on the CPU of
the running system.
Reviewed by: kib, truckman
Differential Revision: https://reviews.freebsd.org/D11808
when a signal is not intended to be sent.
The variable holding the signal number to send is left uninitialized,
which sometimes triggers invalid signal checks.
For NMI, a return to usermode without ast processing is done. On the
other hand, for spurious dtrace probe interrupt it is usermode which
triggered the interrupt, so handle it through userret() as any other
fault.
Reported by: Nils Beyer <nbe@renzel.net>
PR: 221151
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
from the top of user memory to one page lower on machines with the
Ryzen (AMD Family 17h) CPU. This pushes ps_strings and the stack
down by one page as well. On Ryzen there is some sort of interaction
between code running at the top of user memory address space and
interrupts that can cause FreeBSD to either hang or silently reset.
This sounds similar to the problem found with DragonFly BSD that
was fixed with this commit:
https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/b48dd28447fc8ef62fbc963accd301557fd9ac20
but our signal trampoline location was already lower than the address
that DragonFly moved their signal trampoline to. It also does not
appear to be related to SMT as described here:
https://www.phoronix.com/forums/forum/hardware/processors-memory/955368-some-ryzen-linux-users-are-facing-issues-with-heavy-compilation-loads?p=955498#post955498
"Hi, Matt Dillon here. Yes, I did find what I believe to be a
hardware issue with Ryzen related to concurrent operations. In a
nutshell, for any given hyperthread pair, if one hyperthread is
in a cpu-bound loop of any kind (can be in user mode), and the
other hyperthread is returning from an interrupt via IRETQ, the
hyperthread issuing the IRETQ can stall indefinitely until the
other hyperthread with the cpu-bound loop pauses (aka HLT until
next interrupt). After this situation occurs, the system appears
to destabilize. The situation does not occur if the cpu-bound
loop is on a different core than the core doing the IRETQ. The
%rip the IRETQ returns to (e.g. userland %rip address) matters a
*LOT*. The problem occurs more often with high %rip addresses
such as near the top of the user stack, which is where DragonFly's
signal trampoline traditionally resides. So a user program taking
a signal on one thread while another thread is cpu-bound can cause
this behavior. Changing the location of the signal trampoline
makes it more difficult to reproduce the problem. I have not
been because the able to completely mitigate it. When a cpu-thread
stalls in this manner it appears to stall INSIDE the microcode
for IRETQ. It doesn't make it to the return pc, and the cpu thread
cannot take any IPIs or other hardware interrupts while in this
state."
since the system instability has been observed on FreeBSD with SMT
disabled. Interrupts to appear to play a factor since running a
signal-intensive process on the first CPU core, which handles most
of the interrupts on my machine, is far more likely to trigger the
problem than running such a process on any other core.
Also lower sv_maxuser to prevent a malicious user from using mmap()
to load and execute code in the top page of user memory that was made
available when the shared page was moved down.
Make the same changes to the 64-bit Linux emulator.
PR: 219399
Reported by: nbe@renzel.net
Reviewed by: kib
Reviewed by: dchagin (previous version)
Tested by: nbe@renzel.net (earlier version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D11780
The removed release stores are not needed since stores are totally
ordered on i386 and amd64.
Reviewed by: alc, kib (previous revision)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D11790
add support for explicitly requesting that pmap_enter() create a 2MB page
mapping. (Essentially, this feature allows the machine-independent layer to
create superpage mappings preemptively, and not wait for automatic promotion
to occur.)
Export pmap_ps_enabled() to the machine-independent layer.
Add a flag to pmap_pv_insert_pde() that specifies whether it should fail or
reclaim a PV entry when one is not available.
Refactor pmap_enter_pde() into two functions, one by the same name, that is
a general-purpose function for creating PDE PG_PS mappings, and another,
pmap_enter_2mpage(), that is used to prefault 2MB read- and/or execute-only
mappings for execve(2), mmap(2), and shmat(2).
Submitted by: Yufeng Zhou <yz70@rice.edu> (an earlier version)
Reviewed by: kib, markj
Tested by: pho
MFC after: 10 days
Differential Revision: https://reviews.freebsd.org/D11556
Pollution from counter.h made __pcpu visible in amd64/pmap.c. Delete
the existing extern decl of __pcpu in amd64/pmap.c and avoid referring
to that symbol, instead accessing the pcpu region via PCPU_SET macros.
Also delete an unused extern decl of __pcpu from mp_x86.c.
Reviewed by: kib
Approved by: markj (mentor)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11666
this file. Previously, half of the pointers to a vm_page being used as
a page directory page were named "pdpg" and the rest were named "mpde".
Discussed with: kib
MFC after: 1 week
pmap_remove_ptes(). (This new function will also be used by an upcoming
change to pmap_enter() that adds support for psind == 1 mappings.)
Submitted by: Yufeng Zhou <yz70@rice.edu> (an earlier version)
Reviewed by: kib, markj
MFC after: 1 week
The mutex protecting access to the registered realtime clock should not be
overloaded to protect access to the atrtc hardware, which might not even be
the registered rtc. More importantly, the resettodr mutex needs to be
eliminated to remove locking/sleeping restrictions on clock drivers, and
that can't happen if MD code for amd64 depends on it. This change moves the
protection into what's really being protected: access to the atrtc date and
time registers.
This change also adds protection when the clock is accessed from
xentimer_settime(), which bypasses the resettodr locking.
Differential Revision: https://reviews.freebsd.org/D11483
Implement the MMC/SD/SDIO protocol within a CAM framework. CAM's
flexible queueing will make it easier to write non-storage drivers
than the legacy stack. SDIO drivers from both the kernel and as
userland daemons are possible, though much of that functionality will
come later.
Some of the CAM integration isn't complete (there are sleeps in the
device probe state machine, for example), but those minor issues can
be improved in-tree more easily than out of tree and shouldn't gate
progress on other fronts. Appologies to reviews if specific items
have been overlooked.
Submitted by: Ilya Bakulin
Reviewed by: emaste, imp, mav, adrian, ian
Differential Review: https://reviews.freebsd.org/D4761
merge with first commit, various compile hacks.
amdvi_cmp_wait: gcc complained about a malformed string behind an ifdef.
struct amdvi_dte: widen the type of the first reserved bitfield so that
the packed representation would not cross an alignment boundary for that
type. Apparently that causes in-tree gcc (4.2) to insert padding
(despite packed, resulting in a wrong structure definition), and causes
more modern gcc to emit a warning.
ivrs_hdr_iterate_tbl: delete a misleading check about header length
being less than 0 (the type is unsigned) and replace it with a check
that the length doesn't exceed the table size.
Reviewed by: anish, grehan
Approved by: markj (mentor)
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D11485
start address is not required to be page aligned. However, the loop
within pmap_invalidate_cache_range() that performs the actual cache
line invalidations requires that the starting address be truncated to
a multiple of the cache line size. This change corrects an error in
that truncation.
Submitted by: Brett Gutstein <bgutstein@rice.edu>
Reviewed by: kib
MFC after: 1 week
--Remove special-case handling of sparc64 bus_dmamap* functions.
Replace with a more generic mechanism that allows MD busdma
implementations to generate inline mapping functions by
defining WANT_INLINE_DMAMAP in <machine/bus_dma.h>. This
is currently useful for sparc64, x86, and arm64, which all
implement non-load dmamap operations as simple wrappers
around map objects which may be bus- or device-specific.
--Remove NULL-checked bus_dmamap macros. Implement the
equivalent NULL checks in the inlined x86 implementation.
For non-x86 platforms, these checks are a minor pessimization
as those platforms do not currently allow NULL maps. NULL
maps were originally allowed on arm64, which appears to have
been the motivation behind adding arm[64]-specific barriers
to bus_dma.h, but that support was removed in r299463.
--Simplify the internal interface used by the bus_dmamap_load*
variants and move it to bus_dma_internal.h
--Fix some drivers that directly include sys/bus_dma.h
despite the recommendations of bus_dma(9)
Reviewed by: kib (previous revision), marius
Differential Revision: https://reviews.freebsd.org/D10729
struct thread.
For all architectures, the syscall trap handlers have to allocate the
structure on the stack. The structure takes 88 bytes on 64bit arches
which is not negligible. Also, it cannot be easily found by other
code, which e.g. caused duplication of some members of the structure
to struct thread already. The change removes td_dbg_sc_code and
td_dbg_sc_nargs which were directly copied from syscall_args.
The structure is put into the copied on fork part of the struct thread
to make the syscall arguments information correct in the child after
fork.
This move will also allow several more uses shortly.
Reviewed by: jhb (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
X-Differential revision: https://reviews.freebsd.org/D11080
from machine/proc.h, consistently on all architectures.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
X-Differential revision: https://reviews.freebsd.org/D11080
pmap_enter() by implementing a single return path. Otherwise, the
duplication will only increase with the upcoming support for psind == 1.
Reviewed by: kib (some time ago)
prevents one from running eg clang built with debug; the new one is
arbitrary (equal to MAXDSIZ) and... well, should be quite future-proof.
Same fix might be applicable to other 64 bit architectures; I'll ask
their respective maintainers to make sure it won't break anything.
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D10758
