On three of the several paths in entry_64.S that call
do_notify_resume() on the way back to user mode, we fail to properly
check again for newly-arrived work that requires another call to
do_notify_resume() before going to user mode.  These paths set the
mask to check only _TIF_NEED_RESCHED, but this is wrong.  The other
paths that lead to do_notify_resume() do this correctly already, and
entry_32.S does it correctly in all cases.

All paths back to user mode have to check all the _TIF_WORK_MASK
flags at the last possible stage, with interrupts disabled.
Otherwise, we miss any flags (TIF_SIGPENDING for example) that were
set any time after we entered do_notify_resume().  More work flags
can be set (or left set) synchronously inside do_notify_resume(), as
TIF_SIGPENDING can be, or asynchronously by interrupts or other CPUs
(which then send an asynchronous interrupt).

There are many different scenarios that could hit this bug, most of
them races.  The simplest one to demonstrate does not require any
race: when one signal has done handler setup at the check before
returning from a syscall, and there is another signal pending that
should be handled.  The second signal's handler should interrupt the
first signal handler before it actually starts (so the interrupted PC
is still at the handler's entry point).  Instead, it runs away until
the next kernel entry (next syscall, tick, etc).

This test behaves correctly on 32-bit kernels, and fails on 64-bit
(either 32-bit or 64-bit test binary).  With this fix, it works.

    #define _GNU_SOURCE
    #include <stdio.h>
    #include <signal.h>
    #include <string.h>
    #include <sys/ucontext.h>

    #ifndef REG_RIP
    #define REG_RIP REG_EIP
    #endif

    static sig_atomic_t hit1, hit2;

    static void
    handler (int sig, siginfo_t *info, void *ctx)
    {
      ucontext_t *uc = ctx;

      if ((void *) uc->uc_mcontext.gregs[REG_RIP] == &handler)
        {
          if (sig == SIGUSR1)
            hit1 = 1;
          else
            hit2 = 1;
        }

      printf ("%s at %#lx\n", strsignal (sig),
              uc->uc_mcontext.gregs[REG_RIP]);
    }

    int
    main (void)
    {
      struct sigaction sa;
      sigset_t set;

      sigemptyset (&sa.sa_mask);
      sa.sa_flags = SA_SIGINFO;
      sa.sa_sigaction = &handler;

      if (sigaction (SIGUSR1, &sa, NULL)
          || sigaction (SIGUSR2, &sa, NULL))
        return 2;

      sigemptyset (&set);
      sigaddset (&set, SIGUSR1);
      sigaddset (&set, SIGUSR2);
      if (sigprocmask (SIG_BLOCK, &set, NULL))
        return 3;

      printf ("main at %p, handler at %p\n", &main, &handler);

      raise (SIGUSR1);
      raise (SIGUSR2);

      if (sigprocmask (SIG_UNBLOCK, &set, NULL))
        return 4;

      if (hit1 + hit2 == 1)
        {
          puts ("PASS");
          return 0;
        }

      puts ("FAIL");
      return 1;
    }
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

We have two conflicting DMA-based quirks in there for the same set of
boxes (HP nx6325 and nx6125) and one of them actually breaks my box.

So remove the extra code.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: =?iso-8859-1?q?T=F6r=F6k_Edwin?= <edwintorok@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

In the course of the recent unification of the NMI watchdog an assignment
to timer_ack to switch off unnecesary POLL commands to the 8259A in the
case of a watchdog failure has been accidentally removed.  The statement
used to be limited to the 32-bit variation as since the rewrite of the
timer code it has been relevant for the 82489DX only.  This change brings
it back.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

There is no such entity as ISA IRQ2.  The ACPI spec does not make it
explicitly clear, but does not preclude it either -- all it says is ISA
legacy interrupts are identity mapped by default (subject to overrides),
but it does not state whether IRQ2 exists or not.  As a result if there is
no IRQ0 override, then IRQ2 is normally initialised as an ISA interrupt,
which implies an edge-triggered line, which is unmasked by default as this
is what we do for edge-triggered I/O APIC interrupts so as not to miss an
edge.

To the best of my knowledge it is useless, as IRQ2 has not been in use
since the PC/AT as back then it was taken by the 8259A cascade interrupt
to the slave, with the line position in the slot rerouted to newly-created
IRQ9.  No device could thus make use of this line with the pair of 8259A
chips.  Now in theory INTIN2 of the I/O APIC may be usable, but the
interrupt of the device wired to it would not be available in the PIC mode
at all, so I seriously doubt if anybody decided to reuse it for a regular
device.

However there are two common uses of INTIN2.  One is for IRQ0, with an
ACPI interrupt override (or its equivalent in the MP table).  But in this
case IRQ2 is gone entirely with INTIN0 left vacant.  The other one is for
an 8959A ExtINTA cascade.  In this case IRQ0 goes to INTIN0 and if ACPI is
used INTIN2 is assumed to be IRQ2 (there is no override and ACPI has no
way to report ExtINTA interrupts).  This is where a problem happens.

The problem is INTIN2 is configured as a native APIC interrupt, with a
vector assigned and the mask cleared.  And the line may indeed get active
and inject interrupts if the master 8959A has its timer interrupt enabled
(it might happen for other interrupts too, but they are normally masked in
the process of rerouting them to the I/O APIC).  There are two cases where
it will happen:

* When the I/O APIC NMI watchdog is enabled.  This is actually a misnomer
  as the watchdog pulses are delivered through the 8259A to the LINT0
  inputs of all the local APICs in the system.  The implication is the
  output of the master 8259A goes high and low repeatedly, signalling
  interrupts to INTIN2 which is enabled too!

  [The origin of the name is I think for a brief period during the
  development we had a capability in our code to configure the watchdog to
  use an I/O APIC input; that would be INTIN2 in this scenario.]

* When the native route of IRQ0 via INTIN0 fails for whatever reason -- as
  it happens with the system considered here.  In this scenario the timer
  pulse is delivered through the 8259A to LINT0 input of the local APIC of
  the bootstrap processor, quite similarly to how is done for the watchdog
  described above.  The result is, again, INTIN2 receives these pulses
  too.  Rafael's system used to escape this scenario, because an incorrect
  IRQ0 override would occupy INTIN2 and prevent it from being unmasked.

My conclusion is IRQ2 should be excluded from configuration in all the
cases and the current exception for ACPI systems should be lifted.  The
reason being the exception not only being useless, but harmful as well.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Unlike the 32-bit one, the 64-bit variation of the LVT0 setup code for
the "8259A Virtual Wire" through the local APIC timer configuration does
not fully configure the relevant irq_chip structure.  Instead it relies on
the preceding I/O APIC code to have set it up, which does not happen if
the I/O APIC variants have not been tried.

The patch includes corresponding changes to the 32-bit variation too
which make them both the same, barring a small syntactic difference
involving sequence of functions in the source.  That should work as an aid
with the upcoming merge.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

 IRQ0 is edge-triggered, but the "8259A Virtual Wire" through the local
APIC configuration in the 32-bit version uses the "fasteoi" handler
suitable for level-triggered APIC interrupt.  Rewrite code so that the
"edge" handler is used.  The 64-bit version uses different code and is
unaffected.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge dwarf2_32.h and dwarf2_64.h into dwarf2.h.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

In dwarf2_32.h, test for CONFIG_AS_CFI instead of
CONFIG_UNWIND_INFO. Turns out that searching for UNWIND_INFO
returns no match in any Kconfig or Makefile, so we're really
just throwing everything away regarding dwarf frames for i386.

The test that generates CONFIG_AS_CFI does not have anything
x86_64-specific, and right now, checking V=1 builds shows me
that the flags is there anyway, although unused.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

In dwarf_64.h header, use the "ignore" macro the way
i386 does.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The RING0_INT_FRAME macro defines a CFI_STARTPROC.
So we should really be using CFI_ENDPROC after it.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

i spent a fair amount of time chasing a 64-bit bootup crash that manifested
itself as bootup segfaults:

  S10network[1825]: segfault at 7f3e2b5d16b8 ip 00000031108748c9 sp 00007fffb9c14c70 error 4 in libc-2.7.so[3110800000+14d000]

eventually causing init to die and panic the system:

  Kernel panic - not syncing: Attempted to kill init!
  Pid: 1, comm: init Not tainted 2.6.26-rc9-tip #13878

after a maratonic bisection session, the bad commit turned out to be:

| b7675791859075418199c7af86a116ea34eaf5bd is first bad commit
| commit b7675791859075418199c7af86a116ea34eaf5bd
| Author: Jeremy Fitzhardinge <jeremy@goop.org>
| Date:   Wed Jun 25 00:19:00 2008 -0400
|
|     x86: remove open-coded save/load segment operations
|
|     This removes a pile of buggy open-coded implementations of savesegment
|     and loadsegment.

after some more bisection of this patch itself, it turns out that what
makes the difference are the savesegment() changes to __switch_to().

Taking a look at this portion of arch/x86/kernel/process_64.o revealed
this crutial difference:

| good:    99c:       8c e0                   mov    %fs,%eax
|          99e:       89 45 cc                mov    %eax,-0x34(%rbp)
|
| bad:     99c:       8c 65 cc                mov    %fs,-0x34(%rbp)

which is due to:

|                 unsigned fsindex;
| -               asm volatile("movl %%fs,%0" : "=r" (fsindex));
| +               savesegment(fs, fsindex);

savesegment() is implemented as:

 #define savesegment(seg, value)                                \
          asm("mov %%" #seg ",%0":"=rm" (value) : : "memory")

note the "m" modifier - it allows GCC to generate the segment move
into a memory operand as well.

But regarding segment operands there's a subtle detail in the x86
instruction set: the above 16-bit moves are zero-extend, but only
if it goes to a register.

If it goes to a memory operand, -0x34(%rbp) in the above case, there's
no zero-extend to 32-bit and the instruction will only save 16 bits
instead of the intended 32-bit.

The other 16 bits is random data - which can cause problems when that
value is used later on.

The solution is to only allow segment operands to go to registers.
This fix allows my test-system to boot up without crashing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Use the X86_FEATURE_SYSENTER32 to remove hard-coded CPU vendor check.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Add pseudo-feature bits to describe whether the CPU supports sysenter
and/or syscall from ia32-compat userspace.  This removes a hardcoded
test in vdso32-setup.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Yinghai Lu reported crashes on 64-bit x86:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
 IP: [<ffffffff80253b17>] hrtick_start_fair+0x89/0x173
 [...]

And with a long session of debugging and a lot of difficulty, tracked it down
to this commit:

 --------------->
 8fbbc4b4 is first bad commit
 commit 8fbbc4b4
 Author: Alok Kataria <akataria@vmware.com>
 Date:   Tue Jul 1 11:43:34 2008 -0700

     x86: merge tsc_init and clocksource code
 <--------------

The problem is that the TSC unification missed these Makefile rules
in arch/x86/kernel/Makefile:

  # Do not profile debug and lowlevel utilities
  CFLAGS_REMOVE_tsc_64.o = -pg
  CFLAGS_REMOVE_tsc_32.o = -pg
  ...
  CFLAGS_tsc_64.o         := $(nostackp)
  ...

which rules make sure that various instrumentation and debugging
facilities are disabled for code that might end up in a VDSO - such as
the TSC code.
Reported-and-bisected-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Conflicts:
Signed-off-by: Ingo Molnar <mingo@elte.hu>

when more than 4g memory is installed, don't map the big hole below 4g.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

save the SLIT, in case we are using fixmap to read it, and that fixmap
could be cleared by others.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

also let mem= to print out modified e820 map too
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Bernhard Walle <bwalle@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Gas 2.15 complains about 32-bit registers being used in lea.

  AS      arch/x86/lib/copy_user_64.o
/local/scratch-2/jeremy/hg/xen/paravirt/linux/arch/x86/lib/copy_user_64.S: Assembler messages:
/local/scratch-2/jeremy/hg/xen/paravirt/linux/arch/x86/lib/copy_user_64.S:188: Error: `(%edx,%ecx,8)' is not a valid 64 bit base/index expression
/local/scratch-2/jeremy/hg/xen/paravirt/linux/arch/x86/lib/copy_user_64.S:257: Error: `(%edx,%ecx,8)' is not a valid 64 bit base/index expression
  AS      arch/x86/lib/copy_user_nocache_64.o
/local/scratch-2/jeremy/hg/xen/paravirt/linux/arch/x86/lib/copy_user_nocache_64.S: Assembler messages:
/local/scratch-2/jeremy/hg/xen/paravirt/linux/arch/x86/lib/copy_user_nocache_64.S:107: Error: `(%edx,%ecx,8)' is not a valid 64 bit base/index expression
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

fix:

 arch/x86/pci/built-in.o: In function `pci_subsys_init':
 visws.c:(.init.text+0xfc5): undefined reference to `pci_direct_conf1'
Signed-off-by: Ingo Molnar <mingo@elte.hu>

fix:

 arch/x86/kernel/built-in.o: In function `visws_early_detect':
 : undefined reference to `mach_get_smp_config_quirk'
 arch/x86/kernel/built-in.o: In function `visws_early_detect':
 : undefined reference to `mach_find_smp_config_quirk'
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Integration generated a duplicate call to use_tsc_delay.
Particularly, the one that is done before we check for general
tsc usability seems wrong.
Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

fix:

arch/x86/kernel/visws_quirks.c: In function ‘visws_early_detect’:
arch/x86/kernel/visws_quirks.c:293: error: ‘no_broadcast’ undeclared (first use in this function)
arch/x86/kernel/visws_quirks.c:293: error: (Each undeclared identifier is reported only once
arch/x86/kernel/visws_quirks.c:293: error: for each function it appears in.)
make[1]: *** [arch/x86/kernel/visws_quirks.o] Error 1
make: *** [arch/x86/kernel/visws_quirks.o] Error 2
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Signed-off-by: Ingo Molnar <mingo@elte.hu>

Signed-off-by: Ingo Molnar <mingo@elte.hu>

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Robert Richter <robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Patch d49c4288 (tip/x86/mpparse) introduced some changes in calling
subsys_init calls if CONFIG_X86_NUMAQ option is set. This patch
updates subsystem initalization according to this changes.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Robert Richter <robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

remove leftover traces of various VISWS related Kconfig specials.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

remove leftover arch/x86/mach-visws/* files.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

merge traps_visws.c and apic_visws.c into visws_quirks.c.

(no code changed)
Signed-off-by: Ingo Molnar <mingo@elte.hu>

rename setup_visws.c to visws_quirks.c.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

skip IO-APIC setup on a VISWS if it's enabled.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

remove VISWS Kconfig complications, now that it's supported by the generic
architecture.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

this is the big move: flip over VISWS to generic arch support.

From this commit on CONFIG_X86_VISWS is just another (default-disabled)
option that turns on certain quirks - no other complications.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

copy arch/x86/mach-visws/setup_visws.c, apic_visws.c and traps_visws.c
files to arch/x86/kernel/, in preparation of the switchover to a
non-subarch setup for VISWS.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

add early quirk support to the generic architecture code.

this allows VISWS to be supported by the generic code and allows us
to remove the VISWS subarch.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

NR_IRQS: let VISWS be just a sub-case of the generic code.

This can create a somewhat larger irq_desc[] array if NR_CPUS is high
but that should not worry VisWS which has 4 CPUs at most.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

use the generic version of setup_arch.h - it's the same.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

move the SGIVW definitions from setup_arch.h into its own header file.

preparation for turning VISWS into a generic PC architecture.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

move the include/asm-x86/mach-visws/ VISWS specific hardware
details include files into include/asm-x86/visws, to be used from
generic code.

No code changed.
Signed-off-by: Ingo Molnar <mingo@elte.hu>