linux-stable.git/arch/mips/kernel, branch v4.12.2

MIPS: Avoid accidental raw backtrace

2017-06-30T02:42:15+00:00

Since commit 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with
usermode") show_backtrace() invokes the raw backtracer when
cp0_status & ST0_KSU indicates user mode to fix issues on EVA kernels
where user and kernel address spaces overlap.

However this is used by show_stack() which creates its own pt_regs on
the stack and leaves cp0_status uninitialised in most of the code paths.
This results in the non deterministic use of the raw back tracer
depending on the previous stack content.

show_stack() deals exclusively with kernel mode stacks anyway, so
explicitly initialise regs.cp0_status to KSU_KERNEL (i.e. 0) to ensure
we get a useful backtrace.

Fixes: 81a76d7119f6 ("MIPS: Avoid using unwind_stack() with usermode")
Signed-off-by: James Hogan 
Cc: linux-mips@linux-mips.org
Cc:  # 3.15+
Patchwork: https://patchwork.linux-mips.org/patch/16656/
Signed-off-by: Ralf Baechle

MIPS: Fix IRQ tracing & lockdep when rescheduling

2017-06-30T02:40:18+00:00

When the scheduler sets TIF_NEED_RESCHED & we call into the scheduler
from arch/mips/kernel/entry.S we disable interrupts. This is true
regardless of whether we reach work_resched from syscall_exit_work,
resume_userspace or by looping after calling schedule(). Although we
disable interrupts in these paths we don't call trace_hardirqs_off()
before calling into C code which may acquire locks, and we therefore
leave lockdep with an inconsistent view of whether interrupts are
disabled or not when CONFIG_PROVE_LOCKING & CONFIG_DEBUG_LOCKDEP are
both enabled.

Without tracing this interrupt state lockdep will print warnings such
as the following once a task returns from a syscall via
syscall_exit_partial with TIF_NEED_RESCHED set:

[   49.927678] ------------[ cut here ]------------
[   49.934445] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3687 check_flags.part.41+0x1dc/0x1e8
[   49.946031] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)
[   49.946355] CPU: 0 PID: 1 Comm: init Not tainted 4.10.0-00439-gc9fd5d362289-dirty #197
[   49.963505] Stack : 0000000000000000 ffffffff81bb5d6a 0000000000000006 ffffffff801ce9c4
[   49.974431]         0000000000000000 0000000000000000 0000000000000000 000000000000004a
[   49.985300]         ffffffff80b7e487 ffffffff80a24498 a8000000ff160000 ffffffff80ede8b8
[   49.996194]         0000000000000001 0000000000000000 0000000000000000 0000000077c8030c
[   50.007063]         000000007fd8a510 ffffffff801cd45c 0000000000000000 a8000000ff127c88
[   50.017945]         0000000000000000 ffffffff801cf928 0000000000000001 ffffffff80a24498
[   50.028827]         0000000000000000 0000000000000001 0000000000000000 0000000000000000
[   50.039688]         0000000000000000 a8000000ff127bd0 0000000000000000 ffffffff805509bc
[   50.050575]         00000000140084e0 0000000000000000 0000000000000000 0000000000040a00
[   50.061448]         0000000000000000 ffffffff8010e1b0 0000000000000000 ffffffff805509bc
[   50.072327]         ...
[   50.076087] Call Trace:
[   50.079869] [] show_stack+0x80/0xa8
[   50.086577] [] dump_stack+0x10c/0x190
[   50.093498] [] __warn+0xf0/0x108
[   50.099889] [] warn_slowpath_fmt+0x3c/0x48
[   50.107241] [] check_flags.part.41+0x1dc/0x1e8
[   50.114961] [] lock_is_held_type+0x8c/0xb0
[   50.122291] [] __schedule+0x8c0/0x10f8
[   50.129221] [] schedule+0x30/0x98
[   50.135659] [] work_resched+0x8/0x34
[   50.142397] ---[ end trace 0cb4f6ef5b99fe21 ]---
[   50.148405] possible reason: unannotated irqs-off.
[   50.154600] irq event stamp: 400463
[   50.159566] hardirqs last  enabled at (400463): [] _raw_spin_unlock_irqrestore+0x40/0xa8
[   50.171981] hardirqs last disabled at (400462): [] _raw_spin_lock_irqsave+0x30/0xb0
[   50.183897] softirqs last  enabled at (400450): [] __do_softirq+0x4ac/0x6a8
[   50.195015] softirqs last disabled at (400425): [] irq_exit+0x110/0x128

Fix this by using the TRACE_IRQS_OFF macro to call trace_hardirqs_off()
when CONFIG_TRACE_IRQFLAGS is enabled. This is done before invoking
schedule() following the work_resched label because:

 1) Interrupts are disabled regardless of the path we take to reach
    work_resched() & schedule().

 2) Performing the tracing here avoids the need to do it in paths which
    disable interrupts but don't call out to C code before hitting a
    path which uses the RESTORE_SOME macro that will call
    trace_hardirqs_on() or trace_hardirqs_off() as appropriate.

We call trace_hardirqs_on() using the TRACE_IRQS_ON macro before calling
syscall_trace_leave() for similar reasons, ensuring that lockdep has a
consistent view of state after we re-enable interrupts.

Signed-off-by: Paul Burton 
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: linux-mips@linux-mips.org
Cc: stable 
Patchwork: https://patchwork.linux-mips.org/patch/15385/
Signed-off-by: Ralf Baechle

MIPS: pm-cps: Drop manual cache-line alignment of ready_count

2017-06-30T02:38:55+00:00

We allocate memory for a ready_count variable per-CPU, which is accessed
via a cached non-coherent TLB mapping to perform synchronisation between
threads within the core using LL/SC instructions. In order to ensure
that the variable is contained within its own data cache line we
allocate 2 lines worth of memory & align the resulting pointer to a line
boundary. This is however unnecessary, since kmalloc is guaranteed to
return memory which is at least cache-line aligned (see
ARCH_DMA_MINALIGN). Stop the redundant manual alignment.

Besides cleaning up the code & avoiding needless work, this has the side
effect of avoiding an arithmetic error found by Bryan on 64 bit systems
due to the 32 bit size of the former dlinesz. This led the ready_count
variable to have its upper 32b cleared erroneously for MIPS64 kernels,
causing problems when ready_count was later used on MIPS64 via cpuidle.

Signed-off-by: Paul Burton 
Fixes: 3179d37ee1ed ("MIPS: pm-cps: add PM state entry code for CPS systems")
Reported-by: Bryan O'Donoghue 
Reviewed-by: Bryan O'Donoghue 
Tested-by: Bryan O'Donoghue 
Cc: linux-mips@linux-mips.org
Cc: stable  # v3.16+
Patchwork: https://patchwork.linux-mips.org/patch/15383/
Signed-off-by: Ralf Baechle

MIPS: head: Reorder instructions missing a delay slot

2017-06-27T21:35:21+00:00

In this sequence the 'move' is assumed in the delay slot of the 'beq',
but head.S is in reorder mode and the former gets pushed one 'nop'
farther by the assembler.

The corrected behavior made booting with an UHI supplied dtb erratic.

Fixes: 15f37e158892 ("MIPS: store the appended dtb address in a variable")
Signed-off-by: Karl Beldan 
Reviewed-by: James Hogan 
Cc: Jonas Gorski 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16614/
Signed-off-by: Ralf Baechle

MIPS: Fix bnezc/jialc return address calculation

2017-06-15T09:47:42+00:00

The code handling the pop76 opcode (ie. bnezc & jialc instructions) in
__compute_return_epc_for_insn() needs to set the value of $31 in the
jialc case, which is encoded with rs = 0. However its check to
differentiate bnezc (rs != 0) from jialc (rs = 0) was unfortunately
backwards, meaning that if we emulate a bnezc instruction we clobber $31
& if we emulate a jialc instruction it actually behaves like a jic
instruction.

Fix this by inverting the check of rs to match the way the instructions
are actually encoded.

Signed-off-by: Paul Burton 
Fixes: 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC instructions")
Cc: stable  # v4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16178/
Signed-off-by: Ralf Baechle

MIPS: ftrace: fix init functions tracing

2017-06-08T12:51:59+00:00

Since introduction of tracing for init functions the in_kernel_space()
check is no longer correct, as it ignores the init sections. As a
result, when probes are inserted (and disabled) in the init functions,
a branch instruction is inserted instead of a nop, which is likely to
result in random crashes during boot.

Remove the MIPS-specific in_kernel_space() method and replace it with a
generic core_kernel_text() that also checks for init sections during
system boot stage.

Fixes: 42c269c88dc1 ("ftrace: Allow for function tracing to record init functions on boot up")
Signed-off-by: Marcin Nowakowski 
Tested-by: Matt Redfearn 
Cc: Steven Rostedt 
Cc: Ingo Molnar 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16092/
Signed-off-by: Ralf Baechle

MIPS: perf: Remove incorrect odd/even counter handling for I6400

2017-06-08T12:51:58+00:00

All performance counters on I6400 (odd and even) are capable of counting
any of the available events, so drop current logic of using the extra
bit to determine which counter to use.

Signed-off-by: Marcin Nowakowski 
Fixes: 4e88a8621301 ("MIPS: Add cases for CPU_I6400")
Fixes: fd716fca10fc ("MIPS: perf: Fix I6400 event numbers")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15991/
Signed-off-by: Ralf Baechle

kthread: fix boot hang (regression) on MIPS/OpenRISC

2017-05-29T16:40:54+00:00

This fixes a regression in commit 4d6501dce079 where I didn't notice
that MIPS and OpenRISC were reinitialising p->{set,clear}_child_tid to
NULL after our initialisation in copy_process().

We can simply get rid of the arch-specific initialisation here since it
is now always done in copy_process() before hitting copy_thread{,_tls}().

Review notes:

 - As far as I can tell, copy_process() is the only user of
   copy_thread_tls(), which is the only caller of copy_thread() for
   architectures that don't implement copy_thread_tls().

 - After this patch, there is no arch-specific code touching
   p->set_child_tid or p->clear_child_tid whatsoever.

 - It may look like MIPS/OpenRISC wanted to always have these fields be
   NULL, but that's not true, as copy_process() would unconditionally
   set them again _after_ calling copy_thread_tls() before commit
   4d6501dce079.

Fixes: 4d6501dce079c1eb6bf0b1d8f528a5e81770109e ("kthread: Fix use-after-free if kthread fork fails")
Reported-by: Guenter Roeck 
Tested-by: Guenter Roeck  # MIPS only
Acked-by: Stafford Horne 
Acked-by: Oleg Nesterov 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc: Jonas Bonn 
Cc: Stefan Kristiansson 
Cc: openrisc@lists.librecores.org
Cc: Jamie Iles 
Cc: Thomas Gleixner 
Signed-off-by: Vegard Nossum 
Signed-off-by: Linus Torvalds

Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

2017-05-12T16:56:30+00:00

Pull MIPS updates from James Hogan:
 "math-emu:
   - Add missing clearing of BLTZALL and BGEZALL emulation counters
   - Fix BC1EQZ and BC1NEZ condition handling
   - Fix BLEZL and BGTZL identification

  BPF:
   - Add JIT support for SKF_AD_HATYPE
   - Use unsigned access for unsigned SKB fields
   - Quit clobbering callee saved registers in JIT code
   - Fix multiple problems in JIT skb access helpers

  Loongson 3:
   - Select MIPS_L1_CACHE_SHIFT_6

  Octeon:
   - Remove vestiges of CONFIG_CAVIUM_OCTEON_2ND_KERNEL
   - Remove unused L2C types and macros.
   - Remove unused SLI types and macros.
   - Fix compile error when USB is not enabled.
   - Octeon: Remove unused PCIERCX types and macros.
   - Octeon: Clean up platform code.

  SNI:
   - Remove recursive include of cpu-feature-overrides.h

  Sibyte:
   - Export symbol periph_rev to sb1250-mac network driver.
   - Fix Kconfig warning.

  Generic platform:
   - Enable Root FS on NFS in generic_defconfig

  SMP-MT:
   - Use CPU interrupt controller IPI IRQ domain support

  UASM:
   - Add support for LHU for uasm.
   - Remove needless ISA abstraction

  mm:
   - Add 48-bit VA space and 4-level page tables for 4K pages.

  PCI:
   - Add controllers before the specified head

  irqchip driver for MIPS CPU:
   - Replace magic 0x100 with IE_SW0
   - Prepare for non-legacy IRQ domains
   - Introduce IPI IRQ domain support

  MAINTAINERS:
   - Update email-id of Rahul Bedarkar

  NET:
   - sb1250-mac: Add missing MODULE_LICENSE()

  CPUFREQ:
   - Loongson2: drop set_cpus_allowed_ptr()

  Misc:
   - Disable Werror when W= is set
   - Opt into HAVE_COPY_THREAD_TLS
   - Enable GENERIC_CPU_AUTOPROBE
   - Use common outgoing-CPU-notification code
   - Remove dead define of ST_OFF
   - Remove CONFIG_ARCH_HAS_ILOG2_U{32,64}
   - Stengthen IPI IRQ domain sanity check
   - Remove confusing else statement in __do_page_fault()
   - Don't unnecessarily include kmalloc.h into .
   - Delete unused definition of SMP_CACHE_SHIFT.
   - Delete redundant definition of SMP_CACHE_BYTES"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (39 commits)
  MIPS: Sibyte: Fix Kconfig warning.
  MIPS: Sibyte: Export symbol periph_rev to sb1250-mac network driver.
  NET: sb1250-mac: Add missing MODULE_LICENSE()
  MAINTAINERS: Update email-id of Rahul Bedarkar
  MIPS: Remove confusing else statement in __do_page_fault()
  MIPS: Stengthen IPI IRQ domain sanity check
  MIPS: smp-mt: Use CPU interrupt controller IPI IRQ domain support
  irqchip: mips-cpu: Introduce IPI IRQ domain support
  irqchip: mips-cpu: Prepare for non-legacy IRQ domains
  irqchip: mips-cpu: Replace magic 0x100 with IE_SW0
  MIPS: Remove CONFIG_ARCH_HAS_ILOG2_U{32,64}
  MIPS: generic: Enable Root FS on NFS in generic_defconfig
  MIPS: mach-rm: Remove recursive include of cpu-feature-overrides.h
  MIPS: Opt into HAVE_COPY_THREAD_TLS
  CPUFREQ: Loongson2: drop set_cpus_allowed_ptr()
  MIPS: uasm: Remove needless ISA abstraction
  MIPS: Remove dead define of ST_OFF
  MIPS: Use common outgoing-CPU-notification code
  MIPS: math-emu: Fix BC1EQZ and BC1NEZ condition handling
  MIPS: r2-on-r6-emu: Clear BLTZALL and BGEZALL debugfs counters
  ...

Merge branch 'akpm' (patches from Andrew)

2017-05-09T01:17:56+00:00

Merge more updates from Andrew Morton:

 - the rest of MM

 - various misc things

 - procfs updates

 - lib/ updates

 - checkpatch updates

 - kdump/kexec updates

 - add kvmalloc helpers, use them

 - time helper updates for Y2038 issues. We're almost ready to remove
   current_fs_time() but that awaits a btrfs merge.

 - add tracepoints to DAX

* emailed patches from Andrew Morton : (114 commits)
  drivers/staging/ccree/ssi_hash.c: fix build with gcc-4.4.4
  selftests/vm: add a test for virtual address range mapping
  dax: add tracepoint to dax_insert_mapping()
  dax: add tracepoint to dax_writeback_one()
  dax: add tracepoints to dax_writeback_mapping_range()
  dax: add tracepoints to dax_load_hole()
  dax: add tracepoints to dax_pfn_mkwrite()
  dax: add tracepoints to dax_iomap_pte_fault()
  mtd: nand: nandsim: convert to memalloc_noreclaim_*()
  treewide: convert PF_MEMALLOC manipulations to new helpers
  mm: introduce memalloc_noreclaim_{save,restore}
  mm: prevent potential recursive reclaim due to clearing PF_MEMALLOC
  mm/huge_memory.c: deposit a pgtable for DAX PMD faults when required
  mm/huge_memory.c: use zap_deposited_table() more
  time: delete CURRENT_TIME_SEC and CURRENT_TIME
  gfs2: replace CURRENT_TIME with current_time
  apparmorfs: replace CURRENT_TIME with current_time()
  lustre: replace CURRENT_TIME macro
  fs: ubifs: replace CURRENT_TIME_SEC with current_time
  fs: ufs: use ktime_get_real_ts64() for birthtime
  ...