linux-stable.git/arch/arm64/kernel, branch v4.9

KVM: arm64: Fix the issues when guest PMCCFILTR is configured

2016-11-18T09:06:58+00:00

KVM calls kvm_pmu_set_counter_event_type() when PMCCFILTR is configured.
But this function can't deals with PMCCFILTR correctly because the evtCount
bits of PMCCFILTR, which is reserved 0, conflits with the SW_INCR event
type of other PMXEVTYPER registers. To fix it, when eventsel == 0, this
function shouldn't return immediately; instead it needs to check further
if select_idx is ARMV8_PMU_CYCLE_IDX.

Another issue is that KVM shouldn't copy the eventsel bits of PMCCFILTER
blindly to attr.config. Instead it ought to convert the request to the
"cpu cycle" event type (i.e. 0x11).

To support this patch and to prevent duplicated definitions, a limited
set of ARMv8 perf event types were relocated from perf_event.c to
asm/perf_event.h.

Cc: stable@vger.kernel.org # 4.6+
Acked-by: Will Deacon 
Signed-off-by: Wei Huang 
Signed-off-by: Marc Zyngier

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2016-10-20T17:17:13+00:00

Pull arm64 fixes from Will Deacon:
 "Most of these are CC'd for stable, but there are a few fixing issues
  introduced during the recent merge window too.

  There's also a fix for the xgene PMU driver, but it seemed daft to
  send as a separate pull request, so I've included it here with the
  rest of the fixes.

   - Fix ACPI boot due to recent broken NUMA changes
   - Fix remote enabling of CPU features requiring PSTATE bit manipulation
   - Add address range check when emulating user cache maintenance
   - Fix LL/SC loops that allow compiler to introduce memory accesses
   - Fix recently added write_sysreg_s macro
   - Ensure MDCR_EL2 is initialised on qemu targets without a PMU
   - Avoid kaslr breakage due to MODVERSIONs and DYNAMIC_FTRACE
   - Correctly drive recent ld when building relocatable Image
   - Remove junk IS_ERR check from xgene PMU driver added during merge window
   - pr_cont fixes after core changes in the merge window"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: remove pr_cont abuse from mem_init
  arm64: fix show_regs fallout from KERN_CONT changes
  arm64: kernel: force ET_DYN ELF type for CONFIG_RELOCATABLE=y
  arm64: suspend: Reconfigure PSTATE after resume from idle
  arm64: mm: Set PSTATE.PAN from the cpu_enable_pan() call
  arm64: cpufeature: Schedule enable() calls instead of calling them via IPI
  arm64: Cortex-A53 errata workaround: check for kernel addresses
  arm64: percpu: rewrite ll/sc loops in assembly
  arm64: swp emulation: bound LL/SC retries before rescheduling
  arm64: sysreg: Fix use of XZR in write_sysreg_s
  arm64: kaslr: keep modules close to the kernel when DYNAMIC_FTRACE=y
  arm64: kernel: Init MDCR_EL2 even in the absence of a PMU
  perf: xgene: Remove bogus IS_ERR() check
  arm64: kernel: numa: fix ACPI boot cpu numa node mapping
  arm64: kaslr: fix breakage with CONFIG_MODVERSIONS=y

arm64: fix show_regs fallout from KERN_CONT changes

2016-10-20T14:27:56+00:00

Recently in commit 4bcc595ccd80decb ("printk: reinstate KERN_CONT for
printing continuation lines"), the behaviour of printk changed w.r.t.
KERN_CONT. Now, KERN_CONT is mandatory to continue existing lines.
Without this, prefixes are inserted, making output illegible, e.g.

[ 1007.069010] pc : [] lr : [] pstate: 40000145
[ 1007.076329] sp : ffff000008d53ec0
[ 1007.079606] x29: ffff000008d53ec0 [ 1007.082797] x28: 0000000080c50018
[ 1007.086160]
[ 1007.087630] x27: ffff000008e0c7f8 [ 1007.090820] x26: ffff80097631ca00
[ 1007.094183]
[ 1007.095653] x25: 0000000000000001 [ 1007.098843] x24: 000000ea68b61cac
[ 1007.102206]

... or when dumped with the userpace dmesg tool, which has slightly
different implicit newline behaviour. e.g.

[ 1007.069010] pc : [] lr : [] pstate: 40000145
[ 1007.076329] sp : ffff000008d53ec0
[ 1007.079606] x29: ffff000008d53ec0
[ 1007.082797] x28: 0000000080c50018
[ 1007.086160]
[ 1007.087630] x27: ffff000008e0c7f8
[ 1007.090820] x26: ffff80097631ca00
[ 1007.094183]
[ 1007.095653] x25: 0000000000000001
[ 1007.098843] x24: 000000ea68b61cac
[ 1007.102206]

We can't simply always use KERN_CONT for lines which may or may not be
continuations. That causes line prefixes (e.g. timestamps) to be
supressed, and the alignment of all but the first line will be broken.

For even more fun, we can't simply insert some dummy empty-string printk
calls, as GCC warns for an empty printk string, and even if we pass
KERN_DEFAULT explcitly to silence the warning, the prefix gets swallowed
unless there is an additional part to the string.

Instead, we must manually iterate over pairs of registers, which gives
us the legible output we want in either case, e.g.

[  169.771790] pc : [] lr : [] pstate: 40000145
[  169.779109] sp : ffff000008d53ec0
[  169.782386] x29: ffff000008d53ec0 x28: 0000000080c50018
[  169.787650] x27: ffff000008e0c7f8 x26: ffff80097631de00
[  169.792913] x25: 0000000000000001 x24: 00000027827b2cf4

Signed-off-by: Mark Rutland 
Cc: Catalin Marinas 
Cc: Will Deacon 
Signed-off-by: Will Deacon

arm64: suspend: Reconfigure PSTATE after resume from idle

2016-10-20T08:50:54+00:00

The suspend/resume path in kernel/sleep.S, as used by cpu-idle, does not
save/restore PSTATE. As a result of this cpufeatures that were detected
and have bits in PSTATE get lost when we resume from idle.

UAO gets set appropriately on the next context switch. PAN will be
re-enabled next time we return from user-space, but on a preemptible
kernel we may run work accessing user space before this point.

Add code to re-enable theses two features in __cpu_suspend_exit().
We re-use uao_thread_switch() passing current.

Signed-off-by: James Morse 
Cc: Lorenzo Pieralisi 
Signed-off-by: Will Deacon

arm64: cpufeature: Schedule enable() calls instead of calling them via IPI

2016-10-20T08:50:53+00:00

The enable() call for a cpufeature/errata is called using on_each_cpu().
This issues a cross-call IPI to get the work done. Implicitly, this
stashes the running PSTATE in SPSR when the CPU receives the IPI, and
restores it when we return. This means an enable() call can never modify
PSTATE.

To allow PAN to do this, change the on_each_cpu() call to use
stop_machine(). This schedules the work on each CPU which allows
us to modify PSTATE.

This involves changing the protype of all the enable() functions.

enable_cpu_capabilities() is called during boot and enables the feature
on all online CPUs. This path now uses stop_machine(). CPU features for
hotplug'd CPUs are enabled by verify_local_cpu_features() which only
acts on the local CPU, and can already modify the running PSTATE as it
is called from secondary_start_kernel().

Reported-by: Tony Thompson 
Reported-by: Vladimir Murzin 
Signed-off-by: James Morse 
Cc: Suzuki K Poulose 
Signed-off-by: Will Deacon

arm64: Cortex-A53 errata workaround: check for kernel addresses

2016-10-20T08:50:49+00:00

Commit 7dd01aef0557 ("arm64: trap userspace "dc cvau" cache operation on
errata-affected core") adds code to execute cache maintenance instructions
in the kernel on behalf of userland on CPUs with certain ARM CPU errata.
It turns out that the address hasn't been checked to be a valid user
space address, allowing userland to clean cache lines in kernel space.
Fix this by introducing an address check before executing the
instructions on behalf of userland.

Since the address doesn't come via a syscall parameter, we can't just
reject tagged pointers and instead have to remove the tag when checking
against the user address limit.

Cc: 
Fixes: 7dd01aef0557 ("arm64: trap userspace "dc cvau" cache operation on errata-affected core")
Reported-by: Kristina Martsenko 
Signed-off-by: Andre Przywara 
[will: rework commit message + replace access_ok with max_user_addr()]
Signed-off-by: Will Deacon

arm64: swp emulation: bound LL/SC retries before rescheduling

2016-10-19T14:37:23+00:00

If a CPU does not implement a global monitor for certain memory types,
then userspace can attempt a kernel DoS by issuing SWP instructions
targetting the problematic memory (for example, a framebuffer mapped
with non-cacheable attributes).

The SWP emulation code protects against these sorts of attacks by
checking for pending signals and potentially rescheduling when the STXR
instruction fails during the emulation. Whilst this is good for avoiding
livelock, it harms emulation of legitimate SWP instructions on CPUs
where forward progress is not guaranteed if there are memory accesses to
the same reservation granule (up to 2k) between the failing STXR and
the retry of the LDXR.

This patch solves the problem by retrying the STXR a bounded number of
times (4) before breaking out of the LL/SC loop and looking for
something else to do.

Cc: 
Fixes: bd35a4adc413 ("arm64: Port SWP/SWPB emulation support from arm")
Reviewed-by: Mark Rutland 
Signed-off-by: Will Deacon

arm64: kernel: Init MDCR_EL2 even in the absence of a PMU

2016-10-17T14:54:30+00:00

Commit f436b2ac90a0 ("arm64: kernel: fix architected PMU registers
unconditional access") made sure we wouldn't access unimplemented
PMU registers, but also left MDCR_EL2 uninitialized in that case,
leading to trap bits being potentially left set.

Make sure we always write something in that register.

Fixes: f436b2ac90a0 ("arm64: kernel: fix architected PMU registers unconditional access")
Cc: Lorenzo Pieralisi 
Cc: Will Deacon 
Cc: 
Signed-off-by: Marc Zyngier 
Signed-off-by: Will Deacon

arm64: kernel: numa: fix ACPI boot cpu numa node mapping

2016-10-17T14:49:23+00:00

Commit 7ba5f605f3a0 ("arm64/numa: remove the limitation that cpu0 must
bind to node0") removed the numa cpu<->node mapping restriction whereby
logical cpu 0 always corresponds to numa node 0; removing the
restriction was correct, in that it does not really exist in practice
but the commit only updated the early mapping of logical cpu 0 to its
real numa node for the DT boot path, missing the ACPI one, leading to
boot failures on ACPI systems owing to missing node<->cpu map for
logical cpu 0.

Fix the issue by updating the ACPI boot path with code that carries out
the early cpu<->node mapping also for the boot cpu (ie cpu 0), mirroring
what is currently done in the DT boot path.

Fixes: 7ba5f605f3a0 ("arm64/numa: remove the limitation that cpu0 must bind to node0")
Signed-off-by: Lorenzo Pieralisi 
Tested-by: Laszlo Ersek 
Reported-by: Laszlo Ersek 
Cc: Will Deacon 
Cc: Laszlo Ersek 
Cc: Hanjun Guo 
Cc: Andrew Jones 
Cc: Zhen Lei 
Cc: Catalin Marinas 
Signed-off-by: Will Deacon

kprobes: Unpoison stack in jprobe_return() for KASAN

2016-10-16T09:02:31+00:00

I observed false KSAN positives in the sctp code, when
sctp uses jprobe_return() in jsctp_sf_eat_sack().

The stray 0xf4 in shadow memory are stack redzones:

[     ] ==================================================================
[     ] BUG: KASAN: stack-out-of-bounds in memcmp+0xe9/0x150 at addr ffff88005e48f480
[     ] Read of size 1 by task syz-executor/18535
[     ] page:ffffea00017923c0 count:0 mapcount:0 mapping:          (null) index:0x0
[     ] flags: 0x1fffc0000000000()
[     ] page dumped because: kasan: bad access detected
[     ] CPU: 1 PID: 18535 Comm: syz-executor Not tainted 4.8.0+ #28
[     ] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[     ]  ffff88005e48f2d0 ffffffff82d2b849 ffffffff0bc91e90 fffffbfff10971e8
[     ]  ffffed000bc91e90 ffffed000bc91e90 0000000000000001 0000000000000000
[     ]  ffff88005e48f480 ffff88005e48f350 ffffffff817d3169 ffff88005e48f370
[     ] Call Trace:
[     ]  [] dump_stack+0x12e/0x185
[     ]  [] kasan_report+0x489/0x4b0
[     ]  [] __asan_report_load1_noabort+0x19/0x20
[     ]  [] memcmp+0xe9/0x150
[     ]  [] depot_save_stack+0x176/0x5c0
[     ]  [] save_stack+0xb1/0xd0
[     ]  [] kasan_slab_free+0x72/0xc0
[     ]  [] kfree+0xc8/0x2a0
[     ]  [] skb_free_head+0x79/0xb0
[     ]  [] skb_release_data+0x37a/0x420
[     ]  [] skb_release_all+0x4f/0x60
[     ]  [] consume_skb+0x138/0x370
[     ]  [] sctp_chunk_put+0xcb/0x180
[     ]  [] sctp_chunk_free+0x58/0x70
[     ]  [] sctp_inq_pop+0x68f/0xef0
[     ]  [] sctp_assoc_bh_rcv+0xd6/0x4b0
[     ]  [] sctp_inq_push+0x131/0x190
[     ]  [] sctp_backlog_rcv+0xe9/0xa20
[ ... ]
[     ] Memory state around the buggy address:
[     ]  ffff88005e48f380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[     ]  ffff88005e48f400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[     ] >ffff88005e48f480: f4 f4 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[     ]                    ^
[     ]  ffff88005e48f500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[     ]  ffff88005e48f580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[     ] ==================================================================

KASAN stack instrumentation poisons stack redzones on function entry
and unpoisons them on function exit. If a function exits abnormally
(e.g. with a longjmp like jprobe_return()), stack redzones are left
poisoned. Later this leads to random KASAN false reports.

Unpoison stack redzones in the frames we are going to jump over
before doing actual longjmp in jprobe_return().

Signed-off-by: Dmitry Vyukov 
Acked-by: Masami Hiramatsu 
Reviewed-by: Mark Rutland 
Cc: Mark Rutland 
Cc: Catalin Marinas 
Cc: Andrey Ryabinin 
Cc: Lorenzo Pieralisi 
Cc: Alexander Potapenko 
Cc: Will Deacon 
Cc: Andrew Morton 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: "David S. Miller" 
Cc: Masami Hiramatsu 
Cc: kasan-dev@googlegroups.com
Cc: surovegin@google.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1476454043-101898-1-git-send-email-dvyukov@google.com
Signed-off-by: Ingo Molnar