Quite some time ago the interrupt entry stubs for unused vectors in the
system vector range got removed and directly mapped to the spurious
interrupt vector entry point.
Sounds reasonable, but it's subtly broken. The spurious interrupt vector
entry point pushes vector number 0xFF on the stack which makes the whole
logic in __smp_spurious_interrupt() pointless.
As a consequence any spurious interrupt which comes from a vector != 0xFF
is treated as a real spurious interrupt (vector 0xFF) and not
acknowledged. That subsequently stalls all interrupt vectors of equal and
lower priority, which brings the system to a grinding halt.
This can happen because even on 64-bit the system vector space is not
guaranteed to be fully populated. A full compile time handling of the
unused vectors is not possible because quite some of them are conditonally
populated at runtime.
Bring the entry stubs back, which wastes 160 bytes if all stubs are unused,
but gains the proper handling back. There is no point to selectively spare
some of the stubs which are known at compile time as the required code in
the IDT management would be way larger and convoluted.
Do not route the spurious entries through common_interrupt and do_IRQ() as
the original code did. Route it to smp_spurious_interrupt() which evaluates
the vector number and acts accordingly now that the real vector numbers are
handed in.
Fixup the pr_warn so the actual spurious vector (0xff) is clearly
distiguished from the other vectors and also note for the vectored case
whether it was pending in the ISR or not.
"Spurious APIC interrupt (vector 0xFF) on CPU#0, should never happen."
"Spurious interrupt vector 0xed on CPU#1. Acked."
"Spurious interrupt vector 0xee on CPU#1. Not pending!."
Fixes: 2414e021ac ("x86: Avoid building unused IRQ entry stubs")
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jan Beulich <jbeulich@suse.com>
Link: https://lkml.kernel.org/r/20190628111440.550568228@linutronix.de
Since the rework of the vector management, warnings about spurious
interrupts have been reported. Robert provided some more information and
did an initial analysis. The following situation leads to these warnings:
CPU 0 CPU 1 IO_APIC
interrupt is raised
sent to CPU1
Unable to handle
immediately
(interrupts off,
deep idle delay)
mask()
...
free()
shutdown()
synchronize_irq()
clear_vector()
do_IRQ()
-> vector is clear
Before the rework the vector entries of legacy interrupts were statically
assigned and occupied precious vector space while most of them were
unused. Due to that the above situation was handled silently because the
vector was handled and the core handler of the assigned interrupt
descriptor noticed that it is shut down and returned.
While this has been usually observed with legacy interrupts, this situation
is not limited to them. Any other interrupt source, e.g. MSI, can cause the
same issue.
After adding proper synchronization for level triggered interrupts, this
can only happen for edge triggered interrupts where the IO-APIC obviously
cannot provide information about interrupts in flight.
While the spurious warning is actually harmless in this case it worries
users and driver developers.
Handle it gracefully by marking the vector entry as VECTOR_SHUTDOWN instead
of VECTOR_UNUSED when the vector is freed up.
If that above late handling happens the spurious detector will not complain
and switch the entry to VECTOR_UNUSED. Any subsequent spurious interrupt on
that line will trigger the spurious warning as before.
Fixes: 464d12309e ("x86/vector: Switch IOAPIC to global reservation mode")
Reported-by: Robert Hodaszi <Robert.Hodaszi@digi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>-
Tested-by: Robert Hodaszi <Robert.Hodaszi@digi.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190628111440.459647741@linutronix.de
Doing the indirection through macros for the regs accessors just
makes them harder to read, so implement the helpers directly.
Note that only the helpers actually used are implemented now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Recent Intel chipsets including Skylake and ApolloLake have a special
ITSSPRC register which allows the 8254 PIT to be gated. When gated, the
8254 registers can still be programmed as normal, but there are no IRQ0
timer interrupts.
Some products such as the Connex L1430 and exone go Rugged E11 use this
register to ship with the PIT gated by default. This causes Linux to fail
to boot:
Kernel panic - not syncing: IO-APIC + timer doesn't work! Boot with
apic=debug and send a report.
The panic happens before the framebuffer is initialized, so to the user, it
appears as an early boot hang on a black screen.
Affected products typically have a BIOS option that can be used to enable
the 8254 and make Linux work (Chipset -> South Cluster Configuration ->
Miscellaneous Configuration -> 8254 Clock Gating), however it would be best
to make Linux support the no-8254 case.
Modern sytems allow to discover the TSC and local APIC timer frequencies,
so the calibration against the PIT is not required. These systems have
always running timers and the local APIC timer works also in deep power
states.
So the setup of the PIT including the IO-APIC timer interrupt delivery
checks are a pointless exercise.
Skip the PIT setup and the IO-APIC timer interrupt checks on these systems,
which avoids the panic caused by non ticking PITs and also speeds up the
boot process.
Thanks to Daniel for providing the changelog, initial analysis of the
problem and testing against a variety of machines.
Reported-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: linux@endlessm.com
Cc: rafael.j.wysocki@intel.com
Cc: hdegoede@redhat.com
Link: https://lkml.kernel.org/r/20190628072307.24678-1-drake@endlessm.com
The x86 vdso implementation on which the generic vdso library is based on
has subtle (unfortunately undocumented) twists:
1) The code assumes that the clocksource mask is U64_MAX which means that
no bits are masked. Which is true for any valid x86 VDSO clocksource.
Stupidly it still did the mask operation for no reason and at the wrong
place right after reading the clocksource.
2) It contains a sanity check to catch the case where slightly
unsynchronized TSC values can be observed which would cause the delta
calculation to make a huge jump. It therefore checks whether the
current TSC value is larger than the value on which the current
conversion is based on. If it's not larger the base value is used to
prevent time jumps.
#1 Is not only stupid for the X86 case because it does the masking for no
reason it is also completely wrong for clocksources with a smaller mask
which can legitimately wrap around during a conversion period. The core
timekeeping code does it correct by applying the mask after the delta
calculation:
(now - base) & mask
#2 is equally broken for clocksources which have smaller masks and can wrap
around during a conversion period because there the now > base check is
just wrong and causes stale time stamps and time going backwards issues.
Unbreak it by:
1) Removing the mask operation from the clocksource read which makes the
fallback detection work for all clocksources
2) Replacing the conditional delta calculation with a overrideable inline
function.
#2 could reuse clocksource_delta() from the timekeeping code but that
results in a significant performance hit for the x86 VSDO. The timekeeping
core code must have the non optimized version as it has to operate
correctly with clocksources which have smaller masks as well to handle the
case where TSC is discarded as timekeeper clocksource and replaced by HPET
or pmtimer. For the VDSO there is no replacement clocksource. If TSC is
unusable the syscall is enforced which does the right thing.
To accommodate to the needs of various architectures provide an
override-able inline function which defaults to the regular delta
calculation with masking:
(now - base) & mask
Override it for x86 with the non-masking and checking version.
This unbreaks the ARM64 syscall fallback operation, allows to use
clocksources with arbitrary width and preserves the performance
optimization for x86.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: catalin.marinas@arm.com
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux@armlinux.org.uk
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: paul.burton@mips.com
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: salyzyn@android.com
Cc: pcc@google.com
Cc: shuah@kernel.org
Cc: 0x7f454c46@gmail.com
Cc: linux@rasmusvillemoes.dk
Cc: huw@codeweavers.com
Cc: sthotton@marvell.com
Cc: andre.przywara@arm.com
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1906261159230.32342@nanos.tec.linutronix.de
Currently pt_regs on x86_32 has an oddity in that kernel regs
(!user_mode(regs)) are short two entries (esp/ss). This means that any
code trying to use them (typically: regs->sp) needs to jump through
some unfortunate hoops.
Change the entry code to fix this up and create a full pt_regs frame.
This then simplifies various trampolines in ftrace and kprobes, the
stack unwinder, ptrace, kdump and kgdb.
Much thanks to Josh for help with the cleanups!
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for wider use, move the ENCODE_FRAME_POINTER macros to
a common header and provide inline asm versions.
These macros are used to encode a pt_regs frame for the unwinder; see
unwind_frame.c:decode_frame_pointer().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
umwait or tpause allows the processor to enter a light-weight
power/performance optimized state (C0.1 state) or an improved
power/performance optimized state (C0.2 state) for a period specified by
the instruction or until the system time limit or until a store to the
monitored address range in umwait.
IA32_UMWAIT_CONTROL MSR register allows the OS to enable/disable C0.2 on
the processor and to set the maximum time the processor can reside in C0.1
or C0.2.
By default C0.2 is enabled so the user wait instructions can enter the
C0.2 state to save more power with slower wakeup time.
Andy Lutomirski proposed to set the maximum umwait time to 100000 cycles by
default. A quote from Andy:
"What I want to avoid is the case where it works dramatically differently
on NO_HZ_FULL systems as compared to everything else. Also, UMWAIT may
behave a bit differently if the max timeout is hit, and I'd like that
path to get exercised widely by making it happen even on default
configs."
A sysfs interface to adjust the time and the C0.2 enablement is provided in
a follow up change.
[ tglx: Renamed MSR_IA32_UMWAIT_CONTROL_MAX_TIME to
MSR_IA32_UMWAIT_CONTROL_TIME_MASK because the constant is used as
mask throughout the code.
Massaged comments and changelog ]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov" <bp@alien8.de>
Cc: "H Peter Anvin" <hpa@zytor.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/1560994438-235698-3-git-send-email-fenghua.yu@intel.com
umonitor, umwait, and tpause are a set of user wait instructions.
umonitor arms address monitoring hardware using an address. The
address range is determined by using CPUID.0x5. A store to
an address within the specified address range triggers the
monitoring hardware to wake up the processor waiting in umwait.
umwait instructs the processor to enter an implementation-dependent
optimized state while monitoring a range of addresses. The optimized
state may be either a light-weight power/performance optimized state
(C0.1 state) or an improved power/performance optimized state
(C0.2 state).
tpause instructs the processor to enter an implementation-dependent
optimized state C0.1 or C0.2 state and wake up when time-stamp counter
reaches specified timeout.
The three instructions may be executed at any privilege level.
The instructions provide power saving method while waiting in
user space. Additionally, they can allow a sibling hyperthread to
make faster progress while this thread is waiting. One example of an
application usage of umwait is when waiting for input data from another
application, such as a user level multi-threaded packet processing
engine.
Availability of the user wait instructions is indicated by the presence
of the CPUID feature flag WAITPKG CPUID.0x07.0x0:ECX[5].
Detailed information on the instructions and CPUID feature WAITPKG flag
can be found in the latest Intel Architecture Instruction Set Extensions
and Future Features Programming Reference and Intel 64 and IA-32
Architectures Software Developer's Manual.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: "Borislav Petkov" <bp@alien8.de>
Cc: "H Peter Anvin" <hpa@zytor.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>
Cc: "Tony Luck" <tony.luck@intel.com>
Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/1560994438-235698-2-git-send-email-fenghua.yu@intel.com
Several recent exploits have used direct calls to the native_write_cr4()
function to disable SMEP and SMAP before then continuing their exploits
using userspace memory access.
Direct calls of this form can be mitigate by pinning bits of CR4 so that
they cannot be changed through a common function. This is not intended to
be a general ROP protection (which would require CFI to defend against
properly), but rather a way to avoid trivial direct function calling (or
CFI bypasses via a matching function prototype) as seen in:
https://googleprojectzero.blogspot.com/2017/05/exploiting-linux-kernel-via-packet.html
(https://github.com/xairy/kernel-exploits/tree/master/CVE-2017-7308)
The goals of this change:
- Pin specific bits (SMEP, SMAP, and UMIP) when writing CR4.
- Avoid setting the bits too early (they must become pinned only after
CPU feature detection and selection has finished).
- Pinning mask needs to be read-only during normal runtime.
- Pinning needs to be checked after write to validate the cr4 state
Using __ro_after_init on the mask is done so it can't be first disabled
with a malicious write.
Since these bits are global state (once established by the boot CPU and
kernel boot parameters), they are safe to write to secondary CPUs before
those CPUs have finished feature detection. As such, the bits are set at
the first cr4 write, so that cr4 write bugs can be detected (instead of
silently papered over). This uses a few bytes less storage of a location we
don't have: read-only per-CPU data.
A check is performed after the register write because an attack could just
skip directly to the register write. Such a direct jump is possible because
of how this function may be built by the compiler (especially due to the
removal of frame pointers) where it doesn't add a stack frame (function
exit may only be a retq without pops) which is sufficient for trivial
exploitation like in the timer overwrites mentioned above).
The asm argument constraints gain the "+" modifier to convince the compiler
that it shouldn't make ordering assumptions about the arguments or memory,
and treat them as changed.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: kernel-hardening@lists.openwall.com
Link: https://lkml.kernel.org/r/20190618045503.39105-3-keescook@chromium.org
Add cpu feature conditional FSGSBASE access to the relevant helper
functions. That allows to accelerate certain FS/GS base operations in
subsequent changes.
Note, that while possible, the user space entry/exit GSBASE operations are
not going to use the new FSGSBASE instructions. The reason is that it would
require additional storage for the user space value which adds more
complexity to the low level code and experiments have shown marginal
benefit. This may be revisited later but for now the SWAPGS based handling
in the entry code is preserved except for the paranoid entry/exit code.
To preserve the SWAPGS entry mechanism introduce __[rd|wr]gsbase_inactive()
helpers. Note, for Xen PV, paravirt hooks can be added later as they might
allow a very efficient but different implementation.
[ tglx: Massaged changelog ]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lkml.kernel.org/r/1557309753-24073-7-git-send-email-chang.seok.bae@intel.com
This cleanly handles arches who do not yet define clone3.
clone3() was initially placed under __ARCH_WANT_SYS_CLONE under the
assumption that this would cleanly handle all architectures. It does
not.
Architectures such as nios2 or h8300 simply take the asm-generic syscall
definitions and generate their syscall table from it. Since they don't
define __ARCH_WANT_SYS_CLONE the build would fail complaining about
sys_clone3 missing. The reason this doesn't happen for legacy clone is
that nios2 and h8300 provide assembly stubs for sys_clone. This seems to
be done for architectural reasons.
The build failures for nios2 and h8300 were caught int -next luckily.
The solution is to define __ARCH_WANT_SYS_CLONE3 that architectures can
add. Additionally, we need a cond_syscall(clone3) for architectures such
as nios2 or h8300 that generate their syscall table in the way I
explained above.
Fixes: 8f3220a806 ("arch: wire-up clone3() syscall")
Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Adrian Reber <adrian@lisas.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Per commit 1b6269db3f ("KVM: VMX: Handle NMIs before enabling
interrupts and preemption"), NMIs are handled directly in vmx_vcpu_run()
to "make sure we handle NMI on the current cpu, and that we don't
service maskable interrupts before non-maskable ones". The other
exceptions handled by complete_atomic_exit(), e.g. async #PF and #MC,
have similar requirements, and are located there to avoid extra VMREADs
since VMX bins hardware exceptions and NMIs into a single exit reason.
Clean up the code and eliminate the vaguely named complete_atomic_exit()
by moving the interrupts-disabled exception and NMI handling into the
existing handle_external_intrs() callback, and rename the callback to
a more appropriate name. Rename VMexit handlers throughout so that the
atomic and non-atomic counterparts have similar names.
In addition to improving code readability, this also ensures the NMI
handler is run with the host's debug registers loaded in the unlikely
event that the user is debugging NMIs. Accuracy of the last_guest_tsc
field is also improved when handling NMIs (and #MCs) as the handler
will run after updating said field.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
[Naming cleanups. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Make it available to AMD hosts as well, just in case someone is trying
to use an Intel processor's CPUID setup.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add an MSRs which allows the guest to disable
host polling (specifically the cpuidle-haltpoll,
when performing polling in the guest, disables
host side polling).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Nadav reported that since the this_cpu_*() ops got asm-volatile
constraints on, code generation suffered for do_IRQ(), but since this
is all with IRQs disabled we can use __this_cpu_*().
smp_x86_platform_ipi 234 222 -12,+0
smp_kvm_posted_intr_ipi 74 66 -8,+0
smp_kvm_posted_intr_wakeup_ipi 86 78 -8,+0
smp_apic_timer_interrupt 292 284 -8,+0
smp_kvm_posted_intr_nested_ipi 74 66 -8,+0
do_IRQ 195 187 -8,+0
Reported-by: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recent probing at the Linux Kernel Memory Model uncovered a
'surprise'. Strongly ordered architectures where the atomic RmW
primitive implies full memory ordering and
smp_mb__{before,after}_atomic() are a simple barrier() (such as x86)
fail for:
*x = 1;
atomic_inc(u);
smp_mb__after_atomic();
r0 = *y;
Because, while the atomic_inc() implies memory order, it
(surprisingly) does not provide a compiler barrier. This then allows
the compiler to re-order like so:
atomic_inc(u);
*x = 1;
smp_mb__after_atomic();
r0 = *y;
Which the CPU is then allowed to re-order (under TSO rules) like:
atomic_inc(u);
r0 = *y;
*x = 1;
And this very much was not intended. Therefore strengthen the atomic
RmW ops to include a compiler barrier.
NOTE: atomic_{or,and,xor} and the bitops already had the compiler
barrier.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the jump label of a static key is transformed via the arch
specific function:
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
The new approach (batch mode) uses two arch functions, the first has the
same arguments of the arch_jump_label_transform(), and is the function:
bool arch_jump_label_transform_queue(struct jump_entry *entry,
enum jump_label_type type)
Rather than transforming the code, it adds the jump_entry in a queue of
entries to be updated. This functions returns true in the case of a
successful enqueue of an entry. If it returns false, the caller must to
apply the queue and then try to queue again, for instance, because the
queue is full.
This function expects the caller to sort the entries by the address before
enqueueuing then. This is already done by the arch independent code, though.
After queuing all jump_entries, the function:
void arch_jump_label_transform_apply(void)
Applies the changes in the queue.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/57b4caa654bad7e3b066301c9a9ae233dea065b5.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the patch of an address is done in three steps:
-- Pseudo-code #1 - Current implementation ---
1) add an int3 trap to the address that will be patched
sync cores (send IPI to all other CPUs)
2) update all but the first byte of the patched range
sync cores (send IPI to all other CPUs)
3) replace the first byte (int3) by the first byte of replacing opcode
sync cores (send IPI to all other CPUs)
-- Pseudo-code #1 ---
When a static key has more than one entry, these steps are called once for
each entry. The number of IPIs then is linear with regard to the number 'n' of
entries of a key: O(n*3), which is O(n).
This algorithm works fine for the update of a single key. But we think
it is possible to optimize the case in which a static key has more than
one entry. For instance, the sched_schedstats jump label has 56 entries
in my (updated) fedora kernel, resulting in 168 IPIs for each CPU in
which the thread that is enabling the key is _not_ running.
With this patch, rather than receiving a single patch to be processed, a vector
of patches is passed, enabling the rewrite of the pseudo-code #1 in this
way:
-- Pseudo-code #2 - This patch ---
1) for each patch in the vector:
add an int3 trap to the address that will be patched
sync cores (send IPI to all other CPUs)
2) for each patch in the vector:
update all but the first byte of the patched range
sync cores (send IPI to all other CPUs)
3) for each patch in the vector:
replace the first byte (int3) by the first byte of replacing opcode
sync cores (send IPI to all other CPUs)
-- Pseudo-code #2 - This patch ---
Doing the update in this way, the number of IPI becomes O(3) with regard
to the number of keys, which is O(1).
The batch mode is done with the function text_poke_bp_batch(), that receives
two arguments: a vector of "struct text_to_poke", and the number of entries
in the vector.
The vector must be sorted by the addr field of the text_to_poke structure,
enabling the binary search of a handler in the poke_int3_handler function
(a fast path).
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/ca506ed52584c80f64de23f6f55ca288e5d079de.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 fixes from Thomas Gleixner:
"The accumulated fixes from this and last week:
- Fix vmalloc TLB flush and map range calculations which lead to
stale TLBs, spurious faults and other hard to diagnose issues.
- Use fault_in_pages_writable() for prefaulting the user stack in the
FPU code as it's less fragile than the current solution
- Use the PF_KTHREAD flag when checking for a kernel thread instead
of current->mm as the latter can give the wrong answer due to
use_mm()
- Compute the vmemmap size correctly for KASLR and 5-Level paging.
Otherwise this can end up with a way too small vmemmap area.
- Make KASAN and 5-level paging work again by making sure that all
invalid bits are masked out when computing the P4D offset. This
worked before but got broken recently when the LDT remap area was
moved.
- Prevent a NULL pointer dereference in the resource control code
which can be triggered with certain mount options when the
requested resource is not available.
- Enforce ordering of microcode loading vs. perf initialization on
secondary CPUs. Otherwise perf tries to access a non-existing MSR
as the boot CPU marked it as available.
- Don't stop the resource control group walk early otherwise the
control bitmaps are not updated correctly and become inconsistent.
- Unbreak kgdb by returning 0 on success from
kgdb_arch_set_breakpoint() instead of an error code.
- Add more Icelake CPU model defines so depending changes can be
queued in other trees"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode, cpuhotplug: Add a microcode loader CPU hotplug callback
x86/kasan: Fix boot with 5-level paging and KASAN
x86/fpu: Don't use current->mm to check for a kthread
x86/kgdb: Return 0 from kgdb_arch_set_breakpoint()
x86/resctrl: Prevent NULL pointer dereference when local MBM is disabled
x86/resctrl: Don't stop walking closids when a locksetup group is found
x86/fpu: Update kernel's FPU state before using for the fsave header
x86/mm/KASLR: Compute the size of the vmemmap section properly
x86/fpu: Use fault_in_pages_writeable() for pre-faulting
x86/CPU: Add more Icelake model numbers
mm/vmalloc: Avoid rare case of flushing TLB with weird arguments
mm/vmalloc: Fix calculation of direct map addr range
