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  1. Jun 14, 2011
  3. Jun 11, 2011
  5. Jun 09, 2011
  7. Jun 08, 2011
    • Thomas Gleixner's avatar
      x86: cpu-hotplug: Prevent softirq wakeup on wrong CPU · fd8a7de1
      Thomas Gleixner authored 
      

After a newly plugged CPU sets the cpu_online bit it enables
interrupts and goes idle. The cpu which brought up the new cpu waits
for the cpu_online bit and when it observes it, it sets the cpu_active
bit for this cpu. The cpu_active bit is the relevant one for the
scheduler to consider the cpu as a viable target.

With forced threaded interrupt handlers which imply forced threaded
softirqs we observed the following race:

cpu 0                         cpu 1

bringup(cpu1);
                              set_cpu_online(smp_processor_id(), true);
		              local_irq_enable();
while (!cpu_online(cpu1));
                              timer_interrupt()
                                -> wake_up(softirq_thread_cpu1);
                                     -> enqueue_on(softirq_thread_cpu1, cpu0);

                                                                        ^^^^

cpu_notify(CPU_ONLINE, cpu1);
  -> sched_cpu_active(cpu1)
     -> set_cpu_active((cpu1, true);

When an interrupt happens before the cpu_active bit is set by the cpu
which brought up the newly onlined cpu, then the scheduler refuses to
enqueue the woken thread which is bound to that newly onlined cpu on
that newly onlined cpu due to the not yet set cpu_active bit and
selects a fallback runqueue. Not really an expected and desirable
behaviour.

So far this has only been observed with forced hard/softirq threading,
but in theory this could happen without forced threaded hard/softirqs
as well. It's probably unobservable as it would take a massive
interrupt storm on the newly onlined cpu which causes the softirq loop
to wake up the softirq thread and an even longer delay of the cpu
which waits for the cpu_online bit.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: stable@kernel.org # 2.6.39
      fd8a7de1
    • David Howells's avatar
      MN10300: Add missing _sdata declaration · 40182373
      David Howells authored 
      

_sdata needs to be declared in the linker script now as of commit
a2d063ac ("extable, core_kernel_data(): Make sure all archs define
_sdata")

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      40182373
    • David Howells's avatar
      MN10300: die_if_no_fixup() shouldn't use get_user() as it doesn't call set_fs() · db1c9dfa
      David Howells authored 
      

die_if_no_fixup() shouldn't use get_user() as it doesn't call set_fs() to
indicate that it wants to probe a kernel address.  Instead it should use
probe_kernel_read().

This fixes the problem of gdb seeing SIGILL rather than SIGTRAP when hitting
the KGDB special breakpoint upon SysRq+g being seen.  The problem was that
die_if_no_fixup() was failing to read the opcode of the instruction that caused
the exception, and thus not fixing up the exception.

This caused gdb to get a S04 response to the $? request in its remote protocol
rather than S05 - which would then cause it to continue with $C04 rather than
$c in an attempt to pass the signal onto the inferior process.  The kernel,
however, does not support $Cnn, and so objects by returning an E22 response,
indicating an error.  gdb does not expect this and prints:

	warning: Remote failure reply: E22

and then returns to the gdb command prompt unable to continue.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      db1c9dfa
    • David Howells's avatar
      MN10300: Fix one of the kernel debugger cacheflush variants · 2e65d1f6
      David Howells authored 
      

One of the kernel debugger cacheflush variants escaped proper testing.  Two of
the labels are wrong, being derived from the code that was copied to construct
the variant.

The first label results in the following assembler message:

    AS      arch/mn10300/mm/cache-dbg-flush-by-reg.o
  arch/mn10300/mm/cache-dbg-flush-by-reg.S: Assembler messages:
  arch/mn10300/mm/cache-dbg-flush-by-reg.S:123: Error: symbol `debugger_local_cache_flushinv_no_dcache' is already defined

And the second label results in the following linker message:

  arch/mn10300/mm/built-in.o:(.text+0x1d39): undefined reference to `mn10300_local_icache_inv_range_reg_end'
  arch/mn10300/mm/built-in.o:(.text+0x1d39): relocation truncated to fit: R_MN10300_PCREL16 against undefined symbol `mn10300_local_icache_inv_range_reg_end'

To test this file the following configuration pieces must be set:

	CONFIG_AM34=y
	CONFIG_MN10300_CACHE_WBACK=y
	CONFIG_MN10300_DEBUGGER_CACHE_FLUSH_BY_REG=y
	CONFIG_MN10300_CACHE_MANAGE_BY_REG=y
	CONFIG_AM34_HAS_CACHE_SNOOP=n

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      2e65d1f6
  9. Jun 07, 2011
  11. Jun 06, 2011
    • Joerg Roedel's avatar
      x86/amd-iommu: Use only per-device dma_ops · 27c2127a
      Joerg Roedel authored 
      

Unfortunatly there are systems where the AMD IOMMU does not
cover all devices. This breaks with the current driver as it
initializes the global dma_ops variable. This patch limits
the AMD IOMMU to the devices listed in the IVRS table fixing
DMA for devices not covered by the IOMMU.

Cc: stable@kernel.org
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
      27c2127a
    • Joerg Roedel's avatar
      x86/amd-iommu: Fix 3 possible endless loops · 0de66d5b
      Joerg Roedel authored 
      

The driver contains several loops counting on an u16 value
where the exit-condition is checked against variables that
can have values up to 0xffff. In this case the loops will
never exit. This patch fixed 3 such loops.

Cc: stable@kernel.org
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
      0de66d5b
    • Martin Schwidefsky's avatar
      [S390] fix kvm defines for 31 bit compile · 6c61cfe9
      Martin Schwidefsky authored 
      

KVM is not available for 31 bit but the KVM defines cause warnings:

arch/s390/include/asm/pgtable.h: In function 'ptep_test_and_clear_user_dirty':
arch/s390/include/asm/pgtable.h:817: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h:818: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h: In function 'ptep_test_and_clear_user_young':
arch/s390/include/asm/pgtable.h:837: warning: integer constant is too large for 'unsigned long' type
arch/s390/include/asm/pgtable.h:838: warning: integer constant is too large for 'unsigned long' type

Add 31 bit versions of the KVM defines to remove the warnings.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      6c61cfe9
    • Martin Schwidefsky's avatar
      [S390] use generic RCU page-table freeing code · 36409f63
      Martin Schwidefsky authored 
      

Replace the s390 specific rcu page-table freeing code with the
generic variant. This requires to duplicate the definition for the
struct mmu_table_batch as s390 does not use the generic tlb flush
code.

While we are at it remove the restriction that page table fragments
can not be reused after a single fragment has been freed with rcu
and split out allocation and freeing of page tables with pgstes.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      36409f63
    • Jan Glauber's avatar
      [S390] qdio: Split SBAL entry flags · 3ec90878
      Jan Glauber authored 
      

The qdio SBAL entry flag is made-up of four different values that are
independent of one another. Some of the bits are reserved by the
hardware and should not be changed by qdio. Currently all four values
are overwritten since the SBAL entry flag is defined as an u32.

Split the SBAL entry flag into four u8's as defined by the hardware
and don't touch the reserved bits.

Signed-off-by: default avatarJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      3ec90878
    • Christian Borntraeger's avatar
      [S390] kvm-s390: fix stfle facilities numbers >=64 · 9950f8be
      Christian Borntraeger authored 
      

Currently KVM masks out the known good facilities only for the first
double word, but passed the 2nd double word without filtering. This
breaks some code on newer systems:

[    0.593966] ------------[ cut here ]------------
[    0.594086] WARNING: at arch/s390/oprofile/hwsampler.c:696
[    0.594213] Modules linked in:
[    0.594321] Modules linked in:
[    0.594439] CPU: 0 Not tainted 3.0.0-rc1 #46
[    0.594564] Process swapper (pid: 1, task: 00000001effa8038, ksp: 00000001effafab8)
[    0.594735] Krnl PSW : 0704100180000000 00000000004ab89a (hwsampler_setup+0x75a/0x7b8)
[    0.594910]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
[    0.595120] Krnl GPRS: ffffffff00000000 00000000ffffffea ffffffffffffffea 00000000004a98f8
[    0.595351]            00000000004aa002 0000000000000001 000000000080e720 000000000088b9f8
[    0.595522]            000000000080d3e8 0000000000000000 0000000000000000 000000000080e464
[    0.595725]            0000000000000000 00000000005db198 00000000004ab3a2 00000001effafd98
[    0.595901] Krnl Code: 00000000004ab88c: c0e5000673ca        brasl   %r14,57a020
[    0.596071]            00000000004ab892: a7f4fc77            brc     15,4ab180
[    0.596276]            00000000004ab896: a7f40001            brc     15,4ab898
[    0.596454]           >00000000004ab89a: a7c8ffa1            lhi     %r12,-95
[    0.596657]            00000000004ab89e: a7f4fc71            brc     15,4ab180
[    0.596854]            00000000004ab8a2: a7f40001            brc     15,4ab8a4
[    0.597029]            00000000004ab8a6: a7f4ff22            brc     15,4ab6ea
[    0.597230]            00000000004ab8aa: c0200011009a        larl    %r2,6cb9de
[    0.597441] Call Trace:
[    0.597511] ([<00000000004ab3a2>] hwsampler_setup+0x262/0x7b8)
[    0.597676]  [<0000000000875812>] oprofile_arch_init+0x32/0xd0
[    0.597834]  [<0000000000875788>] oprofile_init+0x28/0x74
[    0.597991]  [<00000000001001be>] do_one_initcall+0x3a/0x170
[    0.598151]  [<000000000084fa22>] kernel_init+0x142/0x1ec
[    0.598314]  [<000000000057db16>] kernel_thread_starter+0x6/0xc
[    0.598468]  [<000000000057db10>] kernel_thread_starter+0x0/0xc
[    0.598606] Last Breaking-Event-Address:
[    0.598707]  [<00000000004ab896>] hwsampler_setup+0x756/0x7b8
[    0.598863] ---[ end trace ce3179037f4e3e5b ]---

So lets also mask the 2nd double word. Facilites 66,76,76,77 should be fine.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      9950f8be
    • Christian Borntraeger's avatar
      [S390] kvm-s390: Fix host crash on misbehaving guests · a578b37c
      Christian Borntraeger authored 
      

commit 9ff4cfb3 ([S390] kvm-390: Let
kernel exit SIE instruction on work) fixed a problem of commit
commit cd3b70f5 ([S390] virtualization
aware cpu measurement) but uncovered another one.

If a kvm guest accesses guest real memory that doesnt exist, the
page fault handler calls the sie hook, which then rewrites
the return psw from sie_inst to either sie_exit or sie_reenter.
On return, the page fault handler will then detect the wrong access
as a kernel fault causing a kernel oops in sie_reenter or sie_exit.

We have to add these two addresses to the exception  table to allow
graceful exits.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
      a578b37c
    • Marcelo Tosatti's avatar
      KVM: x86: use proper port value when checking io instruction permission · 221192bd
      Marcelo Tosatti authored 
      

Commit f6511935 moved the permission check for io instructions
to the ->check_perm callback. It failed to copy the port value from RDX
register for string and "in,out ax,dx" instructions.

Fix it by reading RDX register at decode stage when appropriate.

Fixes FC8.32 installation.

Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
      221192bd
  13. Jun 04, 2011
  15. Jun 03, 2011