linux-stable.git/arch/parisc/kernel, branch linux-4.3.y

parisc: Fix syscall restarts

2016-02-19T22:28:28+00:00

commit 71a71fb5374a23be36a91981b5614590b9e722c3 upstream.

On parisc syscalls which are interrupted by signals sometimes failed to
restart and instead returned -ENOSYS which in the worst case lead to
userspace crashes.
A similiar problem existed on MIPS and was fixed by commit e967ef02
("MIPS: Fix restart of indirect syscalls").

On parisc the current syscall restart code assumes that all syscall
callers load the syscall number in the delay slot of the ble
instruction. That's how it is e.g. done in the unistd.h header file:
	ble 0x100(%sr2, %r0)
	ldi #syscall_nr, %r20
Because of that assumption the current code never restored %r20 before
returning to userspace.

This assumption is at least not true for code which uses the glibc
syscall() function, which instead uses this syntax:
	ble 0x100(%sr2, %r0)
	copy regX, %r20
where regX depend on how the compiler optimizes the code and register
usage.

This patch fixes this problem by adding code to analyze how the syscall
number is loaded in the delay branch and - if needed - copy the syscall
number to regX prior returning to userspace for the syscall restart.

Signed-off-by: Helge Deller 
Cc: Mathieu Desnoyers 
Signed-off-by: Greg Kroah-Hartman

parisc: Use platform_device_register_simple("rtc-generic")

2015-09-08T15:53:48+00:00

Signed-off-by: Helge Deller

parisc: Drop CONFIG_SMP around update_cr16_clocksource()

2015-09-08T15:53:03+00:00

No need to use CONFIG_SMP around update_cr16_clocksource(). It checks for
num_online_cpus() beeing greater than 1, which is always 1 in UP builds.

Signed-off-by: Helge Deller

parisc: Use double word condition in 64bit CAS operation

2015-09-08T14:15:54+00:00

The attached change fixes the condition used in the "sub" instruction.
A double word comparison is needed.  This fixes the 64-bit LWS CAS
operation on 64-bit kernels.

I can now enable 64-bit atomic support in GCC.

Cc: 
Signed-off-by: John David Anglin 
Signed-off-by: Helge Deller

parisc: Filter out spurious interrupts in PA-RISC irq handler

2015-09-08T13:31:16+00:00

When detecting a serial port on newer PA-RISC machines (with iosapic) we have a
long way to go to find the right IRQ line, registering it, then registering the
serial port and the irq handler for the serial port. During this phase spurious
interrupts for the serial port may happen which then crashes the kernel because
the action handler might not have been set up yet.

So, basically it's a race condition between the serial port hardware and the
CPU which sets up the necessary fields in the irq sructs. The main reason for
this race is, that we unmask the serial port irqs too early without having set
up everything properly before (which isn't easily possible because we need the
IRQ number to register the serial ports).

This patch is a work-around for this problem. It adds checks to the CPU irq
handler to verify if the IRQ action field has been initialized already. If not,
we just skip this interrupt (which isn't critical for a serial port at bootup).
The real fix would probably involve rewriting all PA-RISC specific IRQ code
(for CPU, IOSAPIC, GSC and EISA) to use IRQ domains with proper parenting of
the irq chips and proper irq enabling along this line.

This bug has been in the PA-RISC port since the beginning, but the crashes
happened very rarely with currently used hardware.  But on the latest machine
which I bought (a C8000 workstation), which uses the fastest CPUs (4 x PA8900,
1GHz) and which has the largest possible L1 cache size (64MB each), the kernel
crashed at every boot because of this race. So, without this patch the machine
would currently be unuseable.

For the record, here is the flow logic:
1. serial_init_chip() in 8250_gsc.c calls iosapic_serial_irq().
2. iosapic_serial_irq() calls txn_alloc_irq() to find the irq.
3. iosapic_serial_irq() calls cpu_claim_irq() to register the CPU irq
4. cpu_claim_irq() unmasks the CPU irq (which it shouldn't!)
5. serial_init_chip() then registers the 8250 port.
Problems:
- In step 4 the CPU irq shouldn't have been registered yet, but after step 5
- If serial irq happens between 4 and 5 have finished, the kernel will crash

Signed-off-by: Helge Deller

parisc/irq: Use access helper irq_data_get_affinity_mask()

2015-07-31T20:20:04+00:00

Use access helper irq_data_get_affinity_mask() to hide implementation
details of struct irq_desc.

Signed-off-by: Jiang Liu 
Cc: Konrad Rzeszutek Wilk 
Cc: Tony Luck 
Cc: Bjorn Helgaas 
Cc: Benjamin Herrenschmidt 
Cc: Randy Dunlap 
Cc: Yinghai Lu 
Cc: Borislav Petkov 
Cc: James E.J. Bottomley 
Cc: Helge Deller 
Link: http://lkml.kernel.org/r/1433145945-789-24-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner

parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results

2015-07-10T19:47:47+00:00

The increased use of pdtlb/pitlb instructions seemed to increase the
frequency of random segmentation faults building packages. Further, we
had a number of cases where TLB inserts would repeatedly fail and all
forward progress would stop. The Haskell ghc package caused a lot of
trouble in this area. The final indication of a race in pte handling was
this syslog entry on sibaris (C8000):

 swap_free: Unused swap offset entry 00000004
 BUG: Bad page map in process mysqld  pte:00000100 pmd:019bbec5
 addr:00000000ec464000 vm_flags:00100073 anon_vma:0000000221023828 mapping: (null) index:ec464
 CPU: 1 PID: 9176 Comm: mysqld Not tainted 4.0.0-2-parisc64-smp #1 Debian 4.0.5-1
 Backtrace:
  [<0000000040173eb0>] show_stack+0x20/0x38
  [<0000000040444424>] dump_stack+0x9c/0x110
  [<00000000402a0d38>] print_bad_pte+0x1a8/0x278
  [<00000000402a28b8>] unmap_single_vma+0x3d8/0x770
  [<00000000402a4090>] zap_page_range+0xf0/0x198
  [<00000000402ba2a4>] SyS_madvise+0x404/0x8c0

Note that the pte value is 0 except for the accessed bit 0x100. This bit
shouldn't be set without the present bit.

It should be noted that the madvise system call is probably a trigger for many
of the random segmentation faults.

In looking at the kernel code, I found the following problems:

1) The pte_clear define didn't take TLB lock when clearing a pte.
2) We didn't test pte present bit inside lock in exception support.
3) The pte and tlb locks needed to merged in order to ensure consistency
between page table and TLB. This also has the effect of serializing TLB
broadcasts on SMP systems.

The attached change implements the above and a few other tweaks to try
to improve performance. Based on the timing code, TLB purges are very
slow (e.g., ~ 209 cycles per page on rp3440). Thus, I think it
beneficial to test the split_tlb variable to avoid duplicate purges.
Probably, all PA 2.0 machines have combined TLBs.

I dropped using __flush_tlb_range in flush_tlb_mm as I realized all
applications and most threads have a stack size that is too large to
make this useful. I added some comments to this effect.

Since implementing 1 through 3, I haven't had any random segmentation
faults on mx3210 (rp3440) in about one week of building code and running
as a Debian buildd.

Signed-off-by: John David Anglin 
Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: Helge Deller

Merge tag 'module_init-device_initcall-v4.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2015-07-02T17:30:48+00:00

Pull module_init replacement part one from Paul Gortmaker:
 "Replace module_init with equivalent device_initcall in non modules.

  This series of commits converts non-modular code that is using the
  module_init() call to hook itself into the system to instead use
  device_initcall().

  The conversion is a runtime no-op, since module_init actually becomes
  __initcall in the non-modular case, and that in turn gets mapped onto
  device_initcall.  A couple files show a larger negative diffstat,
  representing ones that had a module_exit function that we remove here
  vs previously relying on the linker to dispose of it.

  We make this conversion now, so that we can relocate module_init from
  init.h into module.h in the future.

  The files changed here are just limited to those that would otherwise
  have to add module.h to obviously non-modular code, in order to avoid
  a compile fail, as testing has shown"

* tag 'module_init-device_initcall-v4.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  MIPS: don't use module_init in non-modular cobalt/mtd.c file
  drivers/leds: don't use module_init in non-modular leds-cobalt-raq.c
  cris: don't use module_init for non-modular core eeprom.c code
  tty/metag_da: Avoid module_init/module_exit in non-modular code
  drivers/clk: don't use module_init in clk-nomadik.c which is non-modular
  xtensa: don't use module_init for non-modular core network.c code
  sh: don't use module_init in non-modular psw.c code
  mn10300: don't use module_init in non-modular flash.c code
  parisc64: don't use module_init for non-modular core perf code
  parisc: don't use module_init for non-modular core pdc_cons code
  cris: don't use module_init for non-modular core intmem.c code
  ia64: don't use module_init in non-modular sim/simscsi.c code
  ia64: don't use module_init for non-modular core kernel/mca.c code
  arm: don't use module_init in non-modular mach-vexpress/spc.c code
  powerpc: don't use module_init in non-modular 83xx suspend code
  powerpc: use device_initcall for registering rtc devices
  x86: don't use module_init in non-modular devicetree.c code
  x86: don't use module_init in non-modular intel_mid_vrtc.c

parisc: use for_each_sg()

2015-06-25T00:49:40+00:00

This replaces the plain loop over the sglist array with for_each_sg()
macro which consists of sg_next() function calls.  Since parisc doesn't
select ARCH_HAS_SG_CHAIN, it is not necessary to use for_each_sg() in
order to loop over each sg element.  But this can help find problems with
drivers that do not properly initialize their sg tables when
CONFIG_DEBUG_SG is enabled.

Signed-off-by: Akinobu Mita 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

parisc64: don't use module_init for non-modular core perf code

2015-06-16T18:12:30+00:00

The perf.c code depends on CONFIG_64BIT, so it is either built-in
or absent.  It will never be modular, so using module_init as an
alias for __initcall is rather misleading.

Fix this up now, so that we can relocate module_init from
init.h into module.h in the future.  If we don't do this, we'd
have to add module.h to obviously non-modular code, and that
would be a worse thing.  Aside from it not making sense, it also
causes a ~10% increase in CPP overhead due to module.h having a
large list of headers itself -- for example compare line counts:

 device_initcall() and 
	20238 arch/parisc/kernel/perf.i

 module_init() and 
	22194 arch/parisc/kernel/perf.i

Direct use of __initcall is discouraged, vs prioritized ones.
Use of device_initcall is consistent with what __initcall
maps onto, and hence does not change the init order, making the
impact of this change zero.   Should someone with real hardware
for boot testing want to change it later to arch_initcall or
something different, they can do that at a later date.

Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Paul Gortmaker