linux-toradex.git/arch/s390, branch v3.4.1

s390/pfault: fix task state race

2012-06-01T07:18:15+00:00

commit d5e50a51ccbda36b379aba9d1131a852eb908dda upstream.

When setting the current task state to TASK_UNINTERRUPTIBLE this can
race with a different cpu. The other cpu could set the task state after
it inspected it (while it was still TASK_RUNNING) to TASK_RUNNING which
would change the state from TASK_UNINTERRUPTIBLE to TASK_RUNNING again.

This race was always present in the pfault interrupt code but didn't
cause anything harmful before commit f2db2e6c "[S390] pfault: cpu hotplug
vs missing completion interrupts" which relied on the fact that after
setting the task state to TASK_UNINTERRUPTIBLE the task would really
sleep.
Since this is not necessarily the case the result may be a list corruption
of the pfault_list or, as observed, a use-after-free bug while trying to
access the task_struct of a task which terminated itself already.

To fix this, we need to get a reference of the affected task when receiving
the initial pfault interrupt and add special handling if we receive yet
another initial pfault interrupt when the task is already enqueued in the
pfault list.

Signed-off-by: Heiko Carstens 
Reviewed-by: Martin Schwidefsky 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

[S390] Fix compile error in swab.h

2012-04-11T12:28:26+00:00

The inline assembly in__arch_swab16p causes compile errors of the form:

*error*: *invalid* '*asm*': operand number missing after %-*letter*

The assembly uses the %O/%R notation but the first operand misses
the operand number, it needs to be "%O1" instead of "%O".

Reported-by: Gil Peleg 
Signed-off-by: Martin Schwidefsky

[S390] Fix stfle() lowcore protection problem

2012-04-11T12:28:26+00:00

The stfle() function writes into lowcore memory when stfl_fac_list
is initialized with "S390_lowcore.stfl_fac_list = 0". For older
compilers this triggers a lowcore exception. With newer compilers
and "-OXX" compile option the bug does not show up because
the "S390_lowcore.stfl_fac_list" initialization is removed by the
compiler. The reason for thatis the incorrect "=m"
(S390_lowcore.stfl_fac_list) constraint in the stfl inline assembly.

The following shows the disassembly of the stfle() optimized code
that is inlined in the lgr_info_get() function:

000000000011325c :
  11325c:       eb 9f f0 60 00 24       stmg    %r9,%r15,96(%r15)
  113262:       c0 d0 00 29 0e 47       larl    %r13,634ef0 
  113268:       a7 f1 3f c0             tml     %r15,16320
  11326c:       b9 04 00 ef             lgr     %r14,%r15
  113270:       a7 84 00 01             je      113272 
  113274:       a7 fb ff c0             aghi    %r15,-64
  113278:       b9 04 00 c2             lgr     %r12,%r2
  11327c:       a7 29 00 01             lghi    %r2,1
  113280:       e3 e0 f0 98 00 24       stg     %r14,152(%r15)
  113286:       d7 97 c0 00 c0 00       xc      0(152,%r12),0(%r12)
  11328c:       c0 e5 00 28 db 4c       brasl   %r14,62e924 
  113292:       b2 b1 00 00             stfl    0

To fix the problem we now clear the S390_lowcore.stfl_fac_list at
startup in "head.S" for all machine types before lowcore protection
is enabled.

In addition to that the "=m" constraint is replaced by "+m".

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

[S390] cpum_cf: get rid of compile warnings

2012-04-11T12:28:25+00:00

Fix these:

arch/s390/kernel/perf_cpum_cf.c:180:3: warning: format '%lx'
   expects argument of type 'long unsigned int',
   but argument 2 has type 'int' [-Wformat]
arch/s390/kernel/perf_cpum_cf.c: In function 'cpumf_pmu_disable':
arch/s390/kernel/perf_cpum_cf.c:205:3: warning: format '%lx'
   expects argument of type 'long unsigned int',
   but argument 2 has type 'int' [-Wformat]

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

[S390] irq: simple coding style change

2012-04-11T12:28:25+00:00

Use braces for if/else/list_for_each_entry bodies if the body consists
of more than a single line. Otherwise I get confused and check if there
is something broken whenever I see these code snippets.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

[S390] update default configuration

2012-04-11T12:28:25+00:00

Add TASKSTATS options, enable CRASH_DUMP, and regenerate defconfig
file with "make savedefconfig".

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

[S390] fix tlb flushing for page table pages

2012-04-11T12:28:24+00:00

Git commit 36409f6353fc2d7b6516e631415f938eadd92ffa "use generic RCU
page-table freeing code" introduced a tlb flushing bug. Partially revert
the above git commit and go back to s390 specific page table flush code.

For s390 the TLB can contain three types of entries, "normal" TLB
page-table entries, TLB combined region-and-segment-table (CRST) entries
and real-space entries. Linux does not use real-space entries which
leaves normal TLB entries and CRST entries. The CRST entries are
intermediate steps in the page-table translation called translation paths.
For example a 4K page access in a three-level page table setup will
create two CRST TLB entries and one page-table TLB entry. The advantage
of that approach is that a page access next to the previous one can reuse
the CRST entries and needs just a single read from memory to create the
page-table TLB entry. The disadvantage is that the TLB flushing rules are
more complicated, before any page-table may be freed the TLB needs to be
flushed.

In short: the generic RCU page-table freeing code is incorrect for the
CRST entries, in particular the check for mm_users < 2 is troublesome.

This is applicable to 3.0+ kernels.

Cc: 
Signed-off-by: Martin Schwidefsky

[S390] kernel: Use local_irq_save() for memcpy_real()

2012-04-11T12:28:24+00:00

Currently in the memcpy_real() function interrupts are disabled with
__arch_local_irq_stnsm(). In order to notify lockdep that interrupts
are disabled, with this patch local_irq_save() is used instead. The
function __arch_local_irq_stnsm() is still used for switching to
real mode.

Reviewed-by: Heiko Carstens 
Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

[S390] Fix build errors (fallout from system.h disintegration)

2012-03-30T07:41:12+00:00

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-30T01:12:23+00:00

Pull x32 support for x86-64 from Ingo Molnar:
 "This tree introduces the X32 binary format and execution mode for x86:
  32-bit data space binaries using 64-bit instructions and 64-bit kernel
  syscalls.

  This allows applications whose working set fits into a 32 bits address
  space to make use of 64-bit instructions while using a 32-bit address
  space with shorter pointers, more compressed data structures, etc."

Fix up trivial context conflicts in arch/x86/{Kconfig,vdso/vma.c}

* 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
  x32: Fix alignment fail in struct compat_siginfo
  x32: Fix stupid ia32/x32 inversion in the siginfo format
  x32: Add ptrace for x32
  x32: Switch to a 64-bit clock_t
  x32: Provide separate is_ia32_task() and is_x32_task() predicates
  x86, mtrr: Use explicit sizing and padding for the 64-bit ioctls
  x86/x32: Fix the binutils auto-detect
  x32: Warn and disable rather than error if binutils too old
  x32: Only clear TIF_X32 flag once
  x32: Make sure TS_COMPAT is cleared for x32 tasks
  fs: Remove missed ->fds_bits from cessation use of fd_set structs internally
  fs: Fix close_on_exec pointer in alloc_fdtable
  x32: Drop non-__vdso weak symbols from the x32 VDSO
  x32: Fix coding style violations in the x32 VDSO code
  x32: Add x32 VDSO support
  x32: Allow x32 to be configured
  x32: If configured, add x32 system calls to system call tables
  x32: Handle process creation
  x32: Signal-related system calls
  x86: Add #ifdef CONFIG_COMPAT to 
  ...