linux-stable.git/arch/mips, branch v4.18.2

Merge tag 'mips_fixes_4.18_5' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux

2018-07-28T19:32:28+00:00

Pull MIPS fix from Paul Burton:
 "Here's one more MIPS fix, reverting an errata workaround that was
  merged for v4.18-rc2 but has since been found to cause system hangs on
  some BCM4718A1-based systems by the OpenWRT project"

* tag 'mips_fixes_4.18_5' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  Revert "MIPS: BCM47XX: Enable 74K Core ExternalSync for PCIe erratum"

Revert "MIPS: BCM47XX: Enable 74K Core ExternalSync for PCIe erratum"

2018-07-27T17:07:32+00:00

This reverts commit 2a027b47dba6 ("MIPS: BCM47XX: Enable 74K Core
ExternalSync for PCIe erratum").

Enabling ExternalSync caused a regression for BCM4718A1 (used e.g. in
Netgear E3000 and ASUS RT-N16): it simply hangs during PCIe
initialization. It's likely that BCM4717A1 is also affected.

I didn't notice that earlier as the only BCM47XX devices with PCIe I
own are:
1) BCM4706 with 2 x 14e4:4331
2) BCM4706 with 14e4:4360 and 14e4:4331
it appears that BCM4706 is unaffected.

While BCM5300X-ES300-RDS.pdf seems to document that erratum and its
workarounds (according to quotes provided by Tokunori) it seems not even
Broadcom follows them.

According to the provided info Broadcom should define CONF7_ES in their
SDK's mipsinc.h and implement workaround in the si_mips_init(). Checking
both didn't reveal such code. It *could* mean Broadcom also had some
problems with the given workaround.

Signed-off-by: Rafał Miłecki 
Signed-off-by: Paul Burton 
Reported-by: Michael Marley 
Patchwork: https://patchwork.linux-mips.org/patch/20032/
URL: https://bugs.openwrt.org/index.php?do=details&task_id=1688
Cc: Tokunori Ikegami 
Cc: Hauke Mehrtens 
Cc: Chris Packham 
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org

MIPS: ath79: fix register address in ath79_ddr_wb_flush()

2018-07-20T17:17:04+00:00

ath79_ddr_wb_flush_base has the type void __iomem *, so register offsets
need to be a multiple of 4 in order to access the intended register.

Signed-off-by: Felix Fietkau 
Signed-off-by: John Crispin 
Signed-off-by: Paul Burton 
Fixes: 24b0e3e84fbf ("MIPS: ath79: Improve the DDR controller interface")
Patchwork: https://patchwork.linux-mips.org/patch/19912/
Cc: Alban Bedel 
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # 4.2+

MIPS: Fix off-by-one in pci_resource_to_user()

2018-07-16T15:22:31+00:00

The MIPS implementation of pci_resource_to_user() introduced in v3.12 by
commit 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci
memory space properly") incorrectly sets *end to the address of the
byte after the resource, rather than the last byte of the resource.

This results in userland seeing resources as a byte larger than they
actually are, for example a 32 byte BAR will be reported by a tool such
as lspci as being 33 bytes in size:

    Region 2: I/O ports at 1000 [disabled] [size=33]

Correct this by subtracting one from the calculated end address,
reporting the correct address to userland.

Signed-off-by: Paul Burton 
Reported-by: Rui Wang 
Fixes: 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci memory space properly")
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: Wolfgang Grandegger 
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v3.12+
Patchwork: https://patchwork.linux-mips.org/patch/19829/

MIPS: Fix ioremap() RAM check

2018-07-05T21:43:21+00:00

We currently attempt to check whether a physical address range provided
to __ioremap() may be in use by the page allocator by examining the
value of PageReserved for each page in the region - lowmem pages not
marked reserved are presumed to be in use by the page allocator, and
requests to ioremap them fail.

The way we check this has been broken since commit 92923ca3aace ("mm:
meminit: only set page reserved in the memblock region"), because
memblock will typically not have any knowledge of non-RAM pages and
therefore those pages will not have the PageReserved flag set. Thus when
we attempt to ioremap a region outside of RAM we incorrectly fail
believing that the region is RAM that may be in use.

In most cases ioremap() on MIPS will take a fast-path to use the
unmapped kseg1 or xkphys virtual address spaces and never hit this path,
so the only way to hit it is for a MIPS32 system to attempt to ioremap()
an address range in lowmem with flags other than _CACHE_UNCACHED.
Perhaps the most straightforward way to do this is using
ioremap_uncached_accelerated(), which is how the problem was discovered.

Fix this by making use of walk_system_ram_range() to test the address
range provided to __ioremap() against only RAM pages, rather than all
lowmem pages. This means that if we have a lowmem I/O region, which is
very common for MIPS systems, we're free to ioremap() address ranges
within it. A nice bonus is that the test is no longer limited to lowmem.

The approach here matches the way x86 performed the same test after
commit c81c8a1eeede ("x86, ioremap: Speed up check for RAM pages") until
x86 moved towards a slightly more complicated check using walk_mem_res()
for unrelated reasons with commit 0e4c12b45aa8 ("x86/mm, resource: Use
PAGE_KERNEL protection for ioremap of memory pages").

Signed-off-by: Paul Burton 
Reported-by: Serge Semin 
Tested-by: Serge Semin 
Fixes: 92923ca3aace ("mm: meminit: only set page reserved in the memblock region")
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.2+
Patchwork: https://patchwork.linux-mips.org/patch/19786/

MIPS: Use async IPIs for arch_trigger_cpumask_backtrace()

2018-06-28T21:14:41+00:00

The current MIPS implementation of arch_trigger_cpumask_backtrace() is
broken because it attempts to use synchronous IPIs despite the fact that
it may be run with interrupts disabled.

This means that when arch_trigger_cpumask_backtrace() is invoked, for
example by the RCU CPU stall watchdog, we may:

  - Deadlock due to use of synchronous IPIs with interrupts disabled,
    causing the CPU that's attempting to generate the backtrace output
    to hang itself.

  - Not succeed in generating the desired output from remote CPUs.

  - Produce warnings about this from smp_call_function_many(), for
    example:

    [42760.526910] INFO: rcu_sched detected stalls on CPUs/tasks:
    [42760.535755]  0-...!: (1 GPs behind) idle=ade/140000000000000/0 softirq=526944/526945 fqs=0
    [42760.547874]  1-...!: (0 ticks this GP) idle=e4a/140000000000000/0 softirq=547885/547885 fqs=0
    [42760.559869]  (detected by 2, t=2162 jiffies, g=266689, c=266688, q=33)
    [42760.568927] ------------[ cut here ]------------
    [42760.576146] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:416 smp_call_function_many+0x88/0x20c
    [42760.587839] Modules linked in:
    [42760.593152] CPU: 2 PID: 1216 Comm: sh Not tainted 4.15.4-00373-gee058bb4d0c2 #2
    [42760.603767] Stack : 8e09bd20 8e09bd20 8e09bd20 fffffff0 00000007 00000006 00000000 8e09bca8
    [42760.616937]         95b2b379 95b2b379 807a0080 00000007 81944518 0000018a 00000032 00000000
    [42760.630095]         00000000 00000030 80000000 00000000 806eca74 00000009 8017e2b8 000001a0
    [42760.643169]         00000000 00000002 00000000 8e09baa4 00000008 808b8008 86d69080 8e09bca0
    [42760.656282]         8e09ad50 805e20aa 00000000 00000000 00000000 8017e2b8 00000009 801070ca
    [42760.669424]         ...
    [42760.673919] Call Trace:
    [42760.678672] [<27fde568>] show_stack+0x70/0xf0
    [42760.685417] [<84751641>] dump_stack+0xaa/0xd0
    [42760.692188] [<699d671c>] __warn+0x80/0x92
    [42760.698549] [<68915d41>] warn_slowpath_null+0x28/0x36
    [42760.705912] [] smp_call_function_many+0x88/0x20c
    [42760.713696] [<6bbdfc2a>] arch_trigger_cpumask_backtrace+0x30/0x4a
    [42760.722216] [] rcu_dump_cpu_stacks+0x6a/0x98
    [42760.729580] [<796e7629>] rcu_check_callbacks+0x672/0x6ac
    [42760.737476] [<059b3b43>] update_process_times+0x18/0x34
    [42760.744981] [<6eb94941>] tick_sched_handle.isra.5+0x26/0x38
    [42760.752793] [<478d3d70>] tick_sched_timer+0x1c/0x50
    [42760.759882] [] __hrtimer_run_queues+0xc6/0x226
    [42760.767418] [] hrtimer_interrupt+0x88/0x19a
    [42760.775031] [<6765a19e>] gic_compare_interrupt+0x2e/0x3a
    [42760.782761] [<0558bf5f>] handle_percpu_devid_irq+0x78/0x168
    [42760.790795] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
    [42760.798117] [<1b6d462c>] gic_handle_local_int+0x38/0x86
    [42760.805545] [] gic_irq_dispatch+0xa/0x14
    [42760.812534] [<90c11ba2>] generic_handle_irq+0x1e/0x2c
    [42760.820086] [] do_IRQ+0x16/0x20
    [42760.826274] [<9aef3ce6>] plat_irq_dispatch+0x62/0x94
    [42760.833458] [<6a94b53c>] except_vec_vi_end+0x70/0x78
    [42760.840655] [<22284043>] smp_call_function_many+0x1ba/0x20c
    [42760.848501] [<54022b58>] smp_call_function+0x1e/0x2c
    [42760.855693] [] flush_tlb_mm+0x2a/0x98
    [42760.862730] [<0844cdd0>] tlb_flush_mmu+0x1c/0x44
    [42760.869628] [] arch_tlb_finish_mmu+0x26/0x3e
    [42760.877021] [<1aeaaf74>] tlb_finish_mmu+0x18/0x66
    [42760.883907] [] exit_mmap+0x76/0xea
    [42760.890428] [] mmput+0x80/0x11a
    [42760.896632] [] do_exit+0x1f4/0x80c
    [42760.903158] [] do_group_exit+0x20/0x7e
    [42760.909990] [<13fa8d54>] __wake_up_parent+0x0/0x1e
    [42760.917045] [<46cf89d0>] smp_call_function_many+0x1a2/0x20c
    [42760.924893] [<8c21a93b>] syscall_common+0x14/0x1c
    [42760.931765] ---[ end trace 02aa09da9dc52a60 ]---
    [42760.938342] ------------[ cut here ]------------
    [42760.945311] WARNING: CPU: 2 PID: 1216 at kernel/smp.c:291 smp_call_function_single+0xee/0xf8
    ...

This patch switches MIPS' arch_trigger_cpumask_backtrace() to use async
IPIs & smp_call_function_single_async() in order to resolve this
problem. We ensure use of the pre-allocated call_single_data_t
structures is serialized by maintaining a cpumask indicating that
they're busy, and refusing to attempt to send an IPI when a CPU's bit is
set in this mask. This should only happen if a CPU hasn't responded to a
previous backtrace IPI - ie. if it's hung - and we print a warning to
the console in this case.

I've marked this for stable branches as far back as v4.9, to which it
applies cleanly. Strictly speaking the faulty MIPS implementation can be
traced further back to commit 856839b76836 ("MIPS: Add
arch_trigger_all_cpu_backtrace() function") in v3.19, but kernel
versions v3.19 through v4.8 will require further work to backport due to
the rework performed in commit 9a01c3ed5cdb ("nmi_backtrace: add more
trigger_*_cpu_backtrace() methods").

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/19597/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: Huacai Chen 
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.9+
Fixes: 856839b76836 ("MIPS: Add arch_trigger_all_cpu_backtrace() function")
Fixes: 9a01c3ed5cdb ("nmi_backtrace: add more trigger_*_cpu_backtrace() methods")

MIPS: Call dump_stack() from show_regs()

2018-06-28T18:48:54+00:00

The generic nmi_cpu_backtrace() function calls show_regs() when a struct
pt_regs is available, and dump_stack() otherwise. If we were to make use
of the generic nmi_cpu_backtrace() with MIPS' current implementation of
show_regs() this would mean that we see only register data with no
accompanying stack information, in contrast with our current
implementation which calls dump_stack() regardless of whether register
state is available.

In preparation for making use of the generic nmi_cpu_backtrace() to
implement arch_trigger_cpumask_backtrace(), have our implementation of
show_regs() call dump_stack() and drop the explicit dump_stack() call in
arch_dump_stack() which is invoked by arch_trigger_cpumask_backtrace().

This will allow the output we produce to remain the same after a later
patch switches to using nmi_cpu_backtrace(). It may mean that we produce
extra stack output in other uses of show_regs(), but this:

  1) Seems harmless.
  2) Is good for consistency between arch_trigger_cpumask_backtrace()
     and other users of show_regs().
  3) Matches the behaviour of the ARM & PowerPC architectures.

Marked for stable back to v4.9 as a prerequisite of the following patch
"MIPS: Call dump_stack() from show_regs()".

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/19596/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: Huacai Chen 
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.9+

MIPS: Add ksig argument to rseq_{signal_deliver,handle_notify_resume}

2018-06-24T17:33:03+00:00

Commit 784e0300fe9f ("rseq: Avoid infinite recursion when delivering
SIGSEGV") added a new ksig argument to the rseq_signal_deliver() &
rseq_handle_notify_resume() functions, and was merged in v4.18-rc2.
Meanwhile MIPS support for restartable sequences was also merged in
v4.18-rc2 with commit 9ea141ad5471 ("MIPS: Add support for restartable
sequences"), and therefore didn't get updated for the API change.

This results in build failures like the following:

    CC      arch/mips/kernel/signal.o
  arch/mips/kernel/signal.c: In function 'handle_signal':
  arch/mips/kernel/signal.c:804:22: error: passing argument 1 of
    'rseq_signal_deliver' from incompatible pointer type
    [-Werror=incompatible-pointer-types]
    rseq_signal_deliver(regs);
                        ^~~~
  In file included from ./include/linux/context_tracking.h:5,
                   from arch/mips/kernel/signal.c:12:
  ./include/linux/sched.h:1811:56: note: expected 'struct ksignal *' but
    argument is of type 'struct pt_regs *'
    static inline void rseq_signal_deliver(struct ksignal *ksig,
                                           ~~~~~~~~~~~~~~~~^~~~
  arch/mips/kernel/signal.c:804:2: error: too few arguments to function
    'rseq_signal_deliver'
    rseq_signal_deliver(regs);
    ^~~~~~~~~~~~~~~~~~~

Fix this by adding the ksig argument as was done for other architectures
in commit 784e0300fe9f ("rseq: Avoid infinite recursion when delivering
SIGSEGV").

Signed-off-by: Paul Burton 
Acked-by: Mathieu Desnoyers 
Patchwork: https://patchwork.linux-mips.org/patch/19603/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: Peter Zijlstra 
Cc: Paul E. McKenney 
Cc: Boqun Feng 
Cc: Will Deacon 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org

MIPS: Wire up io_pgetevents syscall

2018-06-20T04:14:29+00:00

Wire up the io_pgetevents syscall that was introduced by commit
7a074e96dee6 ("aio: implement io_pgetevents").

Signed-off-by: Paul Burton 
Patchwork: https://patchwork.linux-mips.org/patch/19593/
Cc: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org

MIPS: Wire up the restartable sequences (rseq) syscall

2018-06-20T04:14:09+00:00

Wire up the restartable sequences (rseq) syscall for MIPS. This was
introduced by commit d7822b1e24f2 ("rseq: Introduce restartable
sequences system call") & MIPS now supports the prerequisites.

Signed-off-by: Paul Burton 
Reviewed-by: James Hogan 
Patchwork: https://patchwork.linux-mips.org/patch/19525/
Cc: Ralf Baechle 
Cc: Mathieu Desnoyers 
Cc: Peter Zijlstra 
Cc: Paul E. McKenney 
Cc: Boqun Feng 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org