linux-stable.git/arch, branch v5.0.7

ARM: shmobile: Fix R-Car Gen2 regulator quirk

2019-04-05T20:34:52+00:00

[ Upstream commit 5347a0203709d5039a74d7c94e23519eee478094 ]

The quirk code currently detects all compatible I2C chips with a shared
IRQ line on all I2C busses, adds them into a list, and registers a bus
notifier. For every chip for which the bus notifier triggers, the quirk
code performs I2C transfer on that I2C bus for all addresses in the list.
The problem is that this may generate transfers to non-existing chips on
systems with multiple I2C busses.

This patch adds a check to verify that the I2C bus to which the chip with
shared IRQ is attached to matches the I2C bus of the chip which triggered
the bus notifier and only starts the I2C transfer if they match.

Signed-off-by: Marek Vasut 
Tested-by: Nguyen Viet Dung 
Signed-off-by: Simon Horman 
Signed-off-by: Sasha Levin

x86/build: Mark per-CPU symbols as absolute explicitly for LLD

2019-04-05T20:34:52+00:00

[ Upstream commit d071ae09a4a1414c1433d5ae9908959a7325b0ad ]

Accessing per-CPU variables is done by finding the offset of the
variable in the per-CPU block and adding it to the address of the
respective CPU's block.

Section 3.10.8 of ld.bfd's documentation states:

  For expressions involving numbers, relative addresses and absolute
  addresses, ld follows these rules to evaluate terms:

  Other binary operations, that is, between two relative addresses
  not in the same section, or between a relative address and an
  absolute address, first convert any non-absolute term to an
  absolute address before applying the operator."

Note that LLVM's linker does not adhere to the GNU ld's implementation
and as such requires implicitly-absolute terms to be explicitly marked
as absolute in the linker script. If not, it fails currently with:

  ld.lld: error: ./arch/x86/kernel/vmlinux.lds:153: at least one side of the expression must be absolute
  ld.lld: error: ./arch/x86/kernel/vmlinux.lds:154: at least one side of the expression must be absolute
  Makefile:1040: recipe for target 'vmlinux' failed

This is not a functional change for ld.bfd which converts the term to an
absolute symbol anyways as specified above.

Based on a previous submission by Tri Vo .

Reported-by: Dmitry Golovin 
Signed-off-by: Rafael Ávila de Espíndola 
[ Update commit message per Boris' and Michael's suggestions. ]
Signed-off-by: Nick Desaulniers 
[ Massage commit message more, fix typos. ]
Signed-off-by: Borislav Petkov 
Tested-by: Dmitry Golovin 
Cc: "H. Peter Anvin" 
Cc: Andy Lutomirski 
Cc: Brijesh Singh 
Cc: Cao Jin 
Cc: Ingo Molnar 
Cc: Joerg Roedel 
Cc: Masahiro Yamada 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Cc: Tri Vo 
Cc: dima@golovin.in
Cc: morbo@google.com
Cc: x86-ml 
Link: https://lkml.kernel.org/r/20181219190145.252035-1-ndesaulniers@google.com
Signed-off-by: Sasha Levin

x86/build: Specify elf_i386 linker emulation explicitly for i386 objects

2019-04-05T20:34:51+00:00

[ Upstream commit 927185c124d62a9a4d35878d7f6d432a166b74e3 ]

The kernel uses the OUTPUT_FORMAT linker script command in it's linker
scripts. Most of the time, the -m option is passed to the linker with
correct architecture, but sometimes (at least for x86_64) the -m option
contradicts the OUTPUT_FORMAT directive.

Specifically, arch/x86/boot and arch/x86/realmode/rm produce i386 object
files, but are linked with the -m elf_x86_64 linker flag when building
for x86_64.

The GNU linker manpage doesn't explicitly state any tie-breakers between
-m and OUTPUT_FORMAT. But with BFD and Gold linkers, OUTPUT_FORMAT
overrides the emulation value specified with the -m option.

LLVM lld has a different behavior, however. When supplied with
contradicting -m and OUTPUT_FORMAT values it fails with the following
error message:

  ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64

Therefore, just add the correct -m after the incorrect one (it overrides
it), so the linker invocation looks like this:

  ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T \
    realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf

This is not a functional change for GNU ld, because (although not
explicitly documented) OUTPUT_FORMAT overrides -m EMULATION.

Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting
it in QEMU.

 [ bp: massage and clarify text. ]

Suggested-by: Dmitry Golovin 
Signed-off-by: George Rimar 
Signed-off-by: Tri Vo 
Signed-off-by: Borislav Petkov 
Tested-by: Tri Vo 
Tested-by: Nick Desaulniers 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Michael Matz 
Cc: Thomas Gleixner 
Cc: morbo@google.com
Cc: ndesaulniers@google.com
Cc: ruiu@google.com
Cc: x86-ml 
Link: https://lkml.kernel.org/r/20190111201012.71210-1-trong@android.com
Signed-off-by: Sasha Levin

powerpc/pseries: Perform full re-add of CPU for topology update post-migration

2019-04-05T20:34:46+00:00

[ Upstream commit 81b61324922c67f73813d8a9c175f3c153f6a1c6 ]

On pseries systems, performing a partition migration can result in
altering the nodes a CPU is assigned to on the destination system. For
exampl, pre-migration on the source system CPUs are in node 1 and 3,
post-migration on the destination system CPUs are in nodes 2 and 3.

Handling the node change for a CPU can cause corruption in the slab
cache if we hit a timing where a CPUs node is changed while cache_reap()
is invoked. The corruption occurs because the slab cache code appears
to rely on the CPU and slab cache pages being on the same node.

The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c
does not prevent us from hitting this scenario.

Changing the device tree property update notification handler that
recognizes an affinity change for a CPU to do a full DLPAR remove and
add of the CPU instead of dynamically changing its node resolves this
issue.

Signed-off-by: Nathan Fontenot 
Signed-off-by: Michael W. Bringmann 
Tested-by: Michael W. Bringmann 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

powerpc/64s: Clear on-stack exception marker upon exception return

2019-04-05T20:34:46+00:00

[ Upstream commit eddd0b332304d554ad6243942f87c2fcea98c56b ]

The ppc64 specific implementation of the reliable stacktracer,
save_stack_trace_tsk_reliable(), bails out and reports an "unreliable
trace" whenever it finds an exception frame on the stack. Stack frames
are classified as exception frames if the STACK_FRAME_REGS_MARKER
magic, as written by exception prologues, is found at a particular
location.

However, as observed by Joe Lawrence, it is possible in practice that
non-exception stack frames can alias with prior exception frames and
thus, that the reliable stacktracer can find a stale
STACK_FRAME_REGS_MARKER on the stack. It in turn falsely reports an
unreliable stacktrace and blocks any live patching transition to
finish. Said condition lasts until the stack frame is
overwritten/initialized by function call or other means.

In principle, we could mitigate this by making the exception frame
classification condition in save_stack_trace_tsk_reliable() stronger:
in addition to testing for STACK_FRAME_REGS_MARKER, we could also take
into account that for all exceptions executing on the kernel stack
  - their stack frames's backlink pointers always match what is saved
    in their pt_regs instance's ->gpr[1] slot and that
  - their exception frame size equals STACK_INT_FRAME_SIZE, a value
    uncommonly large for non-exception frames.

However, while these are currently true, relying on them would make
the reliable stacktrace implementation more sensitive towards future
changes in the exception entry code. Note that false negatives, i.e.
not detecting exception frames, would silently break the live patching
consistency model.

Furthermore, certain other places (diagnostic stacktraces, perf, xmon)
rely on STACK_FRAME_REGS_MARKER as well.

Make the exception exit code clear the on-stack
STACK_FRAME_REGS_MARKER for those exceptions running on the "normal"
kernel stack and returning to kernelspace: because the topmost frame
is ignored by the reliable stack tracer anyway, returns to userspace
don't need to take care of clearing the marker.

Furthermore, as I don't have the ability to test this on Book 3E or 32
bits, limit the change to Book 3S and 64 bits.

Fixes: df78d3f61480 ("powerpc/livepatch: Implement reliable stack tracing for the consistency model")
Reported-by: Joe Lawrence 
Signed-off-by: Nicolai Stange 
Signed-off-by: Joe Lawrence 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin

ARM: avoid Cortex-A9 livelock on tight dmb loops

2019-04-05T20:34:45+00:00

[ Upstream commit 5388a5b82199facacd3d7ac0d05aca6e8f902fed ]

machine_crash_nonpanic_core() does this:

	while (1)
		cpu_relax();

because the kernel has crashed, and we have no known safe way to deal
with the CPU.  So, we place the CPU into an infinite loop which we
expect it to never exit - at least not until the system as a whole is
reset by some method.

In the absence of erratum 754327, this code assembles to:

	b	.

In other words, an infinite loop.  When erratum 754327 is enabled,
this becomes:

1:	dmb
	b	1b

It has been observed that on some systems (eg, OMAP4) where, if a
crash is triggered, the system tries to kexec into the panic kernel,
but fails after taking the secondary CPU down - placing it into one
of these loops.  This causes the system to livelock, and the most
noticable effect is the system stops after issuing:

	Loading crashdump kernel...

to the system console.

The tested as working solution I came up with was to add wfe() to
these infinite loops thusly:

	while (1) {
		cpu_relax();
		wfe();
	}

which, without 754327 builds to:

1:	wfe
	b	1b

or with 754327 is enabled:

1:	dmb
	wfe
	b	1b

Adding "wfe" does two things depending on the environment we're running
under:
- where we're running on bare metal, and the processor implements
  "wfe", it stops us spinning endlessly in a loop where we're never
  going to do any useful work.
- if we're running in a VM, it allows the CPU to be given back to the
  hypervisor and rescheduled for other purposes (maybe a different VM)
  rather than wasting CPU cycles inside a crashed VM.

However, in light of erratum 794072, Will Deacon wanted to see 10 nops
as well - which is reasonable to cover the case where we have erratum
754327 enabled _and_ we have a processor that doesn't implement the
wfe hint.

So, we now end up with:

1:      wfe
        b       1b

when erratum 754327 is disabled, or:

1:      dmb
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        wfe
        b       1b

when erratum 754327 is enabled.  We also get the dmb + 10 nop
sequence elsewhere in the kernel, in terminating loops.

This is reasonable - it means we get the workaround for erratum
794072 when erratum 754327 is enabled, but still relinquish the dead
processor - either by placing it in a lower power mode when wfe is
implemented as such or by returning it to the hypervisior, or in the
case where wfe is a no-op, we use the workaround specified in erratum
794072 to avoid the problem.

These as two entirely orthogonal problems - the 10 nops addresses
erratum 794072, and the wfe is an optimisation that makes the system
more efficient when crashed either in terms of power consumption or
by allowing the host/other VMs to make use of the CPU.

I don't see any reason not to use kexec() inside a VM - it has the
potential to provide automated recovery from a failure of the VMs
kernel with the opportunity for saving a crashdump of the failure.
A panic() with a reboot timeout won't do that, and reading the
libvirt documentation, setting on_reboot to "preserve" won't either
(the documentation states "The preserve action for an on_reboot event
is treated as a destroy".)  Surely it has to be a good thing to
avoiding having CPUs spinning inside a VM that is doing no useful
work.

Acked-by: Will Deacon 
Signed-off-by: Russell King 
Signed-off-by: Sasha Levin

ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of

2019-04-05T20:34:45+00:00

[ Upstream commit 72cd4064fccaae15ab84d40d4be23667402df4ed ]

ARMv8M introduces support for Security extension to M class, among
other things it affects exception handling, especially, encoding of
EXC_RETURN.

The new bits have been added:

Bit [6]	Secure or Non-secure stack
Bit [5]	Default callee register stacking
Bit [0]	Exception Secure

which conflicts with hard-coded value of EXC_RETURN:

In fact, we only care of few bits:

Bit [3]	 Mode (0 - Handler, 1 - Thread)
Bit [2]	 Stack pointer selection (0 - Main, 1 - Process)

We can toggle only those bits and left other bits as they were on
exception entry.

It is basically, what patch does - saves EXC_RETURN when we do
transition form Thread to Handler mode (it is first svc), so later
saved value is used instead of EXC_RET_THREADMODE_PROCESSSTACK.

Signed-off-by: Vladimir Murzin 
Signed-off-by: Russell King 
Signed-off-by: Sasha Levin

ARM: dts: lpc32xx: Remove leading 0x and 0s from bindings notation

2019-04-05T20:34:44+00:00

[ Upstream commit 3e3380d0675d5e20b0af067d60cb947a4348bf9b ]

Improve the DTS files by removing all the leading "0x" and zeros to fix
the following dtc warnings:

Warning (unit_address_format): Node /XXX unit name should not have leading "0x"

and

Warning (unit_address_format): Node /XXX unit name should not have leading 0s

Converted using the following command:

find . -type f \( -iname *.dts -o -iname *.dtsi \) -exec sed -i -e "s/@\([0-9a-fA-FxX\.;:#]+\)\s*{/@\L\1 {/g" -e "s/@0x\(.*\) {/@\1 {/g" -e "s/@0+\(.*\) {/@\1 {/g" {} +

For simplicity, two sed expressions were used to solve each warnings
separately.

To make the regex expression more robust a few other issues were resolved,
namely setting unit-address to lower case, and adding a whitespace before
the opening curly brace:

https://elinux.org/Device_Tree_Linux#Linux_conventions

This will solve as a side effect warning:

Warning (simple_bus_reg): Node /XXX@ simple-bus unit address format error, expected ""

This is a follow up to commit 4c9847b7375a ("dt-bindings: Remove leading 0x from bindings notation")

Reported-by: David Daney 
Suggested-by: Rob Herring 
Signed-off-by: Mathieu Malaterre 
[vzapolskiy: fixed commit message to pass checkpatch.pl test]
Signed-off-by: Vladimir Zapolskiy 
Signed-off-by: Sasha Levin

perf/aux: Make perf_event accessible to setup_aux()

2019-04-05T20:34:42+00:00

[ Upstream commit 840018668ce2d96783356204ff282d6c9b0e5f66 ]

When pmu::setup_aux() is called the coresight PMU needs to know which
sink to use for the session by looking up the information in the
event's attr::config2 field.

As such simply replace the cpu information by the complete perf_event
structure and change all affected customers.

Signed-off-by: Mathieu Poirier 
Reviewed-by: Suzuki Poulouse 
Acked-by: Peter Zijlstra 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Alexei Starovoitov 
Cc: Greg Kroah-Hartman 
Cc: H. Peter Anvin 
Cc: Heiko Carstens 
Cc: Jiri Olsa 
Cc: Mark Rutland 
Cc: Martin Schwidefsky 
Cc: Namhyung Kim 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Link: http://lkml.kernel.org/r/20190131184714.20388-2-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo 
Signed-off-by: Sasha Levin

powerpc/ptrace: Mitigate potential Spectre v1

2019-04-05T20:34:42+00:00

[ Upstream commit ebb0e13ead2ddc186a80b1b0235deeefc5a1a667 ]

'regno' is directly controlled by user space, hence leading to a potential
exploitation of the Spectre variant 1 vulnerability.

On PTRACE_SETREGS and PTRACE_GETREGS requests, user space passes the
register number that would be read or written. This register number is
called 'regno' which is part of the 'addr' syscall parameter.

This 'regno' value is checked against the maximum pt_regs structure size,
and then used to dereference it, which matches the initial part of a
Spectre v1 (and Spectre v1.1) attack. The dereferenced value, then,
is returned to userspace in the GETREGS case.

This patch sanitizes 'regno' before using it to dereference pt_reg.

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Signed-off-by: Breno Leitao 
Acked-by: Gustavo A. R. Silva 
Signed-off-by: Michael Ellerman 
Signed-off-by: Sasha Levin