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  1. Jun 18, 2013
  3. Jun 15, 2013
    • Benjamin Herrenschmidt's avatar
      powerpc: Fix missing/delayed calls to irq_work · 230b3034
      Benjamin Herrenschmidt authored 
      

When replaying interrupts (as a result of the interrupt occurring
while soft-disabled), in the case of the decrementer, we are exclusively
testing for a pending timer target. However we also use decrementer
interrupts to trigger the new "irq_work", which in this case would
be missed.

This change the logic to force a replay in both cases of a timer
boundary reached and a decrementer interrupt having actually occurred
while disabled. The former test is still useful to catch cases where
a CPU having been hard-disabled for a long time completely misses the
interrupt due to a decrementer rollover.

CC: <stable@vger.kernel.org> [v3.4+]
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      230b3034
    • Paul Mackerras's avatar
      powerpc: Fix emulation of illegal instructions on PowerNV platform · bf593907
      Paul Mackerras authored 
      

Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr).  The emulation of unimplemented instructions is currently not
working on the PowerNV platform.  The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt.  This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt().  With this, old programs that use no-longer
implemented instructions such as dcba now work again.

CC: <stable@vger.kernel.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      bf593907
    • Michael Ellerman's avatar
      powerpc: Fix stack overflow crash in resume_kernel when ftracing · 0e37739b
      Michael Ellerman authored 
      

It's possible for us to crash when running with ftrace enabled, eg:

  Bad kernel stack pointer bffffd12 at c00000000000a454
  cpu 0x3: Vector: 300 (Data Access) at [c00000000ffe3d40]
      pc: c00000000000a454: resume_kernel+0x34/0x60
      lr: c00000000000335c: performance_monitor_common+0x15c/0x180
      sp: bffffd12
     msr: 8000000000001032
     dar: bffffd12
   dsisr: 42000000

If we look at current's stack (paca->__current->stack) we see it is
equal to c0000002ecab0000. Our stack is 16K, and comparing to
paca->kstack (c0000002ecab3e30) we can see that we have overflowed our
kernel stack. This leads to us writing over our struct thread_info, and
in this case we have corrupted thread_info->flags and set
_TIF_EMULATE_STACK_STORE.

Dumping the stack we see:

  3:mon> t c0000002ecab0000
  [c0000002ecab0000] c00000000002131c .performance_monitor_exception+0x5c/0x70
  [c0000002ecab0080] c00000000000335c performance_monitor_common+0x15c/0x180
  --- Exception: f01 (Performance Monitor) at c0000000000fb2ec .trace_hardirqs_off+0x1c/0x30
  [c0000002ecab0370] c00000000016fdb0 .trace_graph_entry+0xb0/0x280 (unreliable)
  [c0000002ecab0410] c00000000003d038 .prepare_ftrace_return+0x98/0x130
  [c0000002ecab04b0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
  [c0000002ecab0520] c0000000000d6b58 .idle_cpu+0x18/0x90
  [c0000002ecab05a0] c00000000000a934 .return_to_handler+0x0/0x34
  [c0000002ecab0620] c00000000001e660 .timer_interrupt+0x160/0x300
  [c0000002ecab06d0] c0000000000025dc decrementer_common+0x15c/0x180
  --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0
  [c0000002ecab09c0] c0000000000fe044 .trace_hardirqs_on+0x14/0x30 (unreliable)
  [c0000002ecab0fb0] c00000000016fe3c .trace_graph_entry+0x13c/0x280
  [c0000002ecab1050] c00000000003d038 .prepare_ftrace_return+0x98/0x130
  [c0000002ecab10f0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
  [c0000002ecab1160] c0000000000161f0 .__ppc64_runlatch_on+0x10/0x40
  [c0000002ecab11d0] c00000000000a934 .return_to_handler+0x0/0x34
  --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0

  ... and so on

__ppc64_runlatch_on() is called from RUNLATCH_ON in the exception entry
path. At that point the irq state is not consistent, ie. interrupts are
hard disabled (by the exception entry), but the paca soft-enabled flag
may be out of sync.

This leads to the local_irq_restore() in trace_graph_entry() actually
enabling interrupts, which we do not want. Because we have not yet
reprogrammed the decrementer we immediately take another decrementer
exception, and recurse.

The fix is twofold. Firstly make sure we call DISABLE_INTS before
calling RUNLATCH_ON. The badly named DISABLE_INTS actually reconciles
the irq state in the paca with the hardware, making it safe again to
call local_irq_save/restore().

Although that should be sufficient to fix the bug, we also mark the
runlatch routines as notrace. They are called very early in the
exception entry and we are asking for trouble tracing them. They are
also fairly uninteresting and tracing them just adds unnecessary
overhead.

[ This regression was introduced by fe1952fc
  "powerpc: Rework runlatch code" by myself --BenH
]

CC: <stable@vger.kernel.org> [v3.4+]
Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
      0e37739b
  5. Jun 13, 2013
  7. Jun 12, 2013
  9. Jun 11, 2013
  11. Jun 10, 2013
    • Matthew Garrett's avatar
      Modify UEFI anti-bricking code · f8b84043
      Matthew Garrett authored 
      

This patch reworks the UEFI anti-bricking code, including an effective
reversion of cc5a080c and 31ff2f20. It turns out that calling
QueryVariableInfo() from boot services results in some firmware
implementations jumping to physical addresses even after entering virtual
mode, so until we have 1:1 mappings for UEFI runtime space this isn't
going to work so well.

Reverting these gets us back to the situation where we'd refuse to create
variables on some systems because they classify deleted variables as "used"
until the firmware triggers a garbage collection run, which they won't do
until they reach a lower threshold. This results in it being impossible to
install a bootloader, which is unhelpful.

Feedback from Samsung indicates that the firmware doesn't need more than
5KB of storage space for its own purposes, so that seems like a reasonable
threshold. However, there's still no guarantee that a platform will attempt
garbage collection merely because it drops below this threshold. It seems
that this is often only triggered if an attempt to write generates a
genuine EFI_OUT_OF_RESOURCES error. We can force that by attempting to
create a variable larger than the remaining space. This should fail, but if
it somehow succeeds we can then immediately delete it.

I've tested this on the UEFI machines I have available, but I don't have
a Samsung and so can't verify that it avoids the bricking problem.

Signed-off-by: default avatarMatthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Lee, Chun-Y <jlee@suse.com> [ dummy variable cleanup ]
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
      f8b84043
    • Markos Chandras's avatar
      MIPS: ftrace: Add missing CONFIG_DYNAMIC_FTRACE · cb2f9938
      Markos Chandras authored 
      

arch_ftrace_update_code and ftrace_modify_all_code are only
available if CONFIG_DYNAMIC_FTRACE is selected.

Fixes the following build problem on MIPS randconfig:

arch/mips/kernel/ftrace.c: In function 'arch_ftrace_update_code':
arch/mips/kernel/ftrace.c:31:2: error: implicit declaration of function
'ftrace_modify_all_code' [-Werror=implicit-function-declaration]

Signed-off-by: default avatarMarkos Chandras <markos.chandras@imgtec.com>
Acked-by: default avatarSteven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5435/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
      cb2f9938
    • Markos Chandras's avatar
      MIPS: include: mmu_context.h: Replace VIRTUALIZATION with KVM · d414976d
      Markos Chandras authored 
      

The kvm_* symbols are only available if KVM is selected.

Fixes the following linking problem on a randconfig:

arch/mips/built-in.o: In function `local_flush_tlb_mm':
(.text+0x18a94): undefined reference to `kvm_local_flush_tlb_all'
arch/mips/built-in.o: In function `local_flush_tlb_range':
(.text+0x18d0c): undefined reference to `kvm_local_flush_tlb_all'
kernel/built-in.o: In function `__schedule':
core.c:(.sched.text+0x2a00): undefined reference to `kvm_local_flush_tlb_all'
mm/built-in.o: In function `use_mm':
(.text+0x30214): undefined reference to `kvm_local_flush_tlb_all'
fs/built-in.o: In function `flush_old_exec':
(.text+0xf0a0): undefined reference to `kvm_local_flush_tlb_all'
make: *** [vmlinux] Error 1

Signed-off-by: default avatarMarkos Chandras <markos.chandras@imgtec.com>
Acked-by: default avatarSteven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5437/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
      d414976d
    • Manuel Lauss's avatar
      MIPS: Alchemy: fix wait function · e63a24dd
      Manuel Lauss authored 
      

Only an interrupt can wake the core from 'wait', enable interrupts
locally before executing 'wait'.

[ralf@linux-mips.org: This leave the race between an interrupt that's
setting TIF_NEED_RESCHEd and entering the WAIT status. but at least it's
going to bring Alchemy back from the dead, so I'm going to apply this
patch.]

Signed-off-by: default avatarManuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/5408/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
      e63a24dd
    • Ben Hutchings's avatar
      s390/pci: Implement IRQ functions if !PCI · c46b54f7
      Ben Hutchings authored 
      

All architectures must implement IRQ functions.  Since various
dependencies on !S390 were removed, there are various drivers that can
be selected but will fail to link.  Provide a dummy implementation of
these functions for the !PCI case.

Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org # 3.9
Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      c46b54f7