In acpi_table_parse(), pointer of the table to pass to handler() is
checked before handler() called, so remove all the duplicate NULL
check in the handler function.
CC: Tony Luck <tony.luck@intel.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We currently allow any process to use rdpmc. This significantly
weakens the protection offered by PR_TSC_DISABLED, and it could be
helpful to users attempting to exploit timing attacks.
Since we can't enable access to individual counters, use a very
coarse heuristic to limit access to rdpmc: allow access only when
a perf_event is mmapped. This protects seccomp sandboxes.
There is plenty of room to further tighen these restrictions. For
example, this allows rdpmc for any x86_pmu event, but it's only
useful for self-monitoring tasks.
As a side effect, cap_user_rdpmc will now be false for AMD uncore
events. This isn't a real regression, since .event_idx is disabled
for these events anyway for the time being. Whenever that gets
re-added, the cap_user_rdpmc code can be adjusted or refactored
accordingly.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vince Weaver <vince@deater.net>
Cc: "hillf.zj" <hillf.zj@alibaba-inc.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/a2bdb3cf3a1d70c26980d7c6dddfbaa69f3182bf.1414190806.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename CONFIG_LIVE_PATCHING to CONFIG_LIVEPATCH to make the naming of
the config and the code more consistent.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Add support for specifying PCI based UARTs for earlyprintk
using a syntax like "earlyprintk=pciserial,00:18.1,115200",
where 00:18.1 is the BDF of a UART device.
[Slightly tidied from Stuart's original patch]
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Intel Moorestown platform support was removed few years ago. This is a follow
up which removes Moorestown specific code for the serial devices. It includes
mrst_max3110 and earlyprintk bits.
This was used on SFI (Medfield, Clovertrail) based platforms as well, though
new ones use normal serial interface for the console service.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We used to optimize rescheduling and audit on syscall exit. Now
that the full slow path is reasonably fast, remove these
optimizations. Syscall exit auditing is now handled exclusively by
syscall_trace_leave.
This adds something like 10ns to the previously optimized paths on
my computer, presumably due mostly to SAVE_REST / RESTORE_REST.
I think that we should eventually replace both the syscall and
non-paranoid interrupt exit slow paths with a pair of C functions
along the lines of the syscall entry hooks.
Link: http://lkml.kernel.org/r/22f2aa4a0361707a5cfb1de9d45260b39965dead.1421453410.git.luto@amacapital.net
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
The x86_64 entry code currently jumps through complex and
inconsistent hoops to try to minimize the impact of syscall exit
work. For a true fast-path syscall, almost nothing needs to be
done, so returning is just a check for exit work and sysret. For a
full slow-path return from a syscall, the C exit hook is invoked if
needed and we join the iret path.
Using iret to return to userspace is very slow, so the entry code
has accumulated various special cases to try to do certain forms of
exit work without invoking iret. This is error-prone, since it
duplicates assembly code paths, and it's dangerous, since sysret
can malfunction in interesting ways if used carelessly. It's
also inefficient, since a lot of useful cases aren't optimized
and therefore force an iret out of a combination of paranoia and
the fact that no one has bothered to write even more asm code
to avoid it.
I would argue that this approach is backwards. Rather than trying
to avoid the iret path, we should instead try to make the iret path
fast. Under a specific set of conditions, iret is unnecessary. In
particular, if RIP==RCX, RFLAGS==R11, RIP is canonical, RF is not
set, and both SS and CS are as expected, then
movq 32(%rsp),%rsp;sysret does the same thing as iret. This set of
conditions is nearly always satisfied on return from syscalls, and
it can even occasionally be satisfied on return from an irq.
Even with the careful checks for sysret applicability, this cuts
nearly 80ns off of the overhead from syscalls with unoptimized exit
work. This includes tracing and context tracking, and any return
that invokes KVM's user return notifier. For example, the cost of
getpid with CONFIG_CONTEXT_TRACKING_FORCE=y drops from ~360ns to
~280ns on my computer.
This may allow the removal and even eventual conversion to C
of a respectable amount of exit asm.
This may require further tweaking to give the full benefit on Xen.
It may be worthwhile to adjust signal delivery and exec to try hit
the sysret path.
This does not optimize returns to 32-bit userspace. Making the same
optimization for CS == __USER32_CS is conceptually straightforward,
but it will require some tedious code to handle the differences
between sysretl and sysexitl.
Link: http://lkml.kernel.org/r/71428f63e681e1b4aa1a781e3ef7c27f027d1103.1421453410.git.luto@amacapital.net
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
context_tracking_user_exit() has no effect if in_interrupt() returns true,
so ist_enter() didn't work. Fix it by calling exception_enter(), and thus
context_tracking_user_exit(), before incrementing the preempt count.
This also adds an assertion that will catch the problem reliably if
CONFIG_PROVE_RCU=y to help prevent the bug from being reintroduced.
Link: http://lkml.kernel.org/r/261ebee6aee55a4724746d0d7024697013c40a08.1422709102.git.luto@amacapital.net
Fixes: 9592747538 x86, traps: Track entry into and exit from IST context
Reported-and-tested-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
The new hw_breakpoint bits are now ready for v3.20, merge them
into the main branch, to avoid conflicts.
Conflicts:
tools/perf/Documentation/perf-record.txt
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86/entry enhancements from Andy Lutomirski:
" This is my accumulated x86 entry work, part 1, for 3.20. The meat
of this is an IST rework. When an IST exception interrupts user
space, we will handle it on the per-thread kernel stack instead of
on the IST stack. This sounds messy, but it actually simplifies the
IST entry/exit code, because it eliminates some ugly games we used
to play in order to handle rescheduling, signal delivery, etc on the
way out of an IST exception.
The IST rework introduces proper context tracking to IST exception
handlers. I haven't seen any bug reports, but the old code could
have incorrectly treated an IST exception handler as an RCU extended
quiescent state.
The memory failure change (included in this pull request with
Borislav and Tony's permission) eliminates a bunch of code that
is no longer needed now that user memory failure handlers are
called in process context.
Finally, this includes a few on Denys' uncontroversial and Obviously
Correct (tm) cleanups.
The IST and memory failure changes have been in -next for a while.
LKML references:
IST rework:
http://lkml.kernel.org/r/cover.1416604491.git.luto@amacapital.net
Memory failure change:
http://lkml.kernel.org/r/54ab2ffa301102cd6e@agluck-desk.sc.intel.com
Denys' cleanups:
http://lkml.kernel.org/r/1420927210-19738-1-git-send-email-dvlasenk@redhat.com
"
This tree semantically depends on and is based on the following RCU commit:
734d168013 ("rcu: Make rcu_nmi_enter() handle nesting")
... and for that reason won't be pushed upstream before the RCU bits hit Linus's tree.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commits 65cef1311d ("x86, microcode: Add a disable chicken bit") and
a18a0f6850 ("x86, microcode: Don't initialize microcode code on
paravirt") allow microcode driver skip initialization when microcode
loading is not permitted.
However, they don't prevent the driver from being loaded since the
init code returns 0. If at some point later the driver gets unloaded
this will result in an oops while trying to deregister the (never
registered) device.
To avoid this, make init code return an error on paravirt or when
microcode loading is disabled. The driver will then never be loaded.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: http://lkml.kernel.org/r/1422411669-25147-1-git-send-email-boris.ostrovsky@oracle.com
Reported-by: James Digwall <james@dingwall.me.uk>
Cc: stable@vger.kernel.org # 3.18
Signed-off-by: Borislav Petkov <bp@suse.de>
Pull x86 fixes from Thomas Gleixner:
"Hopefully the last round of fixes for 3.19
- regression fix for the LDT changes
- regression fix for XEN interrupt handling caused by the APIC
changes
- regression fixes for the PAT changes
- last minute fixes for new the MPX support
- regression fix for 32bit UP
- fix for a long standing relocation issue on 64bit tagged for stable
- functional fix for the Hyper-V clocksource tagged for stable
- downgrade of a pr_err which tends to confuse users
Looks a bit on the large side, but almost half of it are valuable
comments"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tsc: Change Fast TSC calibration failed from error to info
x86/apic: Re-enable PCI_MSI support for non-SMP X86_32
x86, mm: Change cachemode exports to non-gpl
x86, tls: Interpret an all-zero struct user_desc as "no segment"
x86, tls, ldt: Stop checking lm in LDT_empty
x86, mpx: Strictly enforce empty prctl() args
x86, mpx: Fix potential performance issue on unmaps
x86, mpx: Explicitly disable 32-bit MPX support on 64-bit kernels
x86, hyperv: Mark the Hyper-V clocksource as being continuous
x86: Don't rely on VMWare emulating PAT MSR correctly
x86, irq: Properly tag virtualization entry in /proc/interrupts
x86, boot: Skip relocs when load address unchanged
x86/xen: Override ACPI IRQ management callback __acpi_unregister_gsi
ACPI: pci: Do not clear pci_dev->irq in acpi_pci_irq_disable()
x86/xen: Treat SCI interrupt as normal GSI interrupt
The Witcher 2 did something like this to allocate a TLS segment index:
struct user_desc u_info;
bzero(&u_info, sizeof(u_info));
u_info.entry_number = (uint32_t)-1;
syscall(SYS_set_thread_area, &u_info);
Strictly speaking, this code was never correct. It should have set
read_exec_only and seg_not_present to 1 to indicate that it wanted
to find a free slot without putting anything there, or it should
have put something sensible in the TLS slot if it wanted to allocate
a TLS entry for real. The actual effect of this code was to
allocate a bogus segment that could be used to exploit espfix.
The set_thread_area hardening patches changed the behavior, causing
set_thread_area to return -EINVAL and crashing the game.
This changes set_thread_area to interpret this as a request to find
a free slot and to leave it empty, which isn't *quite* what the game
expects but should be close enough to keep it working. In
particular, using the code above to allocate two segments will
allocate the same segment both times.
According to FrostbittenKing on Github, this fixes The Witcher 2.
If this somehow still causes problems, we could instead allocate
a limit==0 32-bit data segment, but that seems rather ugly to me.
Fixes: 41bdc78544 x86/tls: Validate TLS entries to protect espfix
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: stable@vger.kernel.org
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/0cb251abe1ff0958b8e468a9a9a905b80ae3a746.1421954363.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull module and param fixes from Rusty Russell:
"Surprising number of fixes this merge window :(
The first two are minor fallout from the param rework which went in
this merge window.
The next three are a series which fixes a longstanding (but never
previously reported and unlikely , so no CC stable) race between
kallsyms and freeing the init section.
Finally, a minor cleanup as our module refcount will now be -1 during
unload"
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
module: make module_refcount() a signed integer.
module: fix race in kallsyms resolution during module load success.
module: remove mod arg from module_free, rename module_memfree().
module_arch_freeing_init(): new hook for archs before module->module_init freed.
param: fix uninitialized read with CONFIG_DEBUG_LOCK_ALLOC
param: initialize store function to NULL if not available.
smpboot is very creative with the ways to disable ioapic.
smpboot_clear_io_apic() smpboot_clear_io_apic_irqs() and
disable_ioapic_support() serve a similar purpose.
smpboot_clear_io_apic_irqs() is the most useless of all
functions as it clears a variable which has not been setup yet.
Aside of that it has the same ifdef mess and conditionals around the
ioapic related code, which can now be removed.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20150115211703.650280684@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
