Impact: fix possible race condition in ftrace function return tracer

This fixes a possible race condition if index incrementation
is not immediately flushed in memory.

Thanks for Andi Kleen and Steven Rostedt for pointing out this issue
and give me this solution.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: allow archs more flexibility on dynamic ftrace implementations

Dynamic ftrace has largly been developed on x86. Since x86 does not
have the same limitations as other architectures, the ftrace interaction
between the generic code and the architecture specific code was not
flexible enough to handle some of the issues that other architectures
have.

Most notably, module trampolines. Due to the limited branch distance
that archs make in calling kernel core code from modules, the module
load code must create a trampoline to jump to what will make the
larger jump into core kernel code.

The problem arises when this happens to a call to mcount. Ftrace checks
all code before modifying it and makes sure the current code is what
it expects. Right now, there is not enough information to handle modifying
module trampolines.

This patch changes the API between generic dynamic ftrace code and
the arch dependent code. There is now two functions for modifying code:

  ftrace_make_nop(mod, rec, addr) - convert the code at rec->ip into
       a nop, where the original text is calling addr. (mod is the
       module struct if called by module init)

  ftrace_make_caller(rec, addr) - convert the code rec->ip that should
       be a nop into a caller to addr.

The record "rec" now has a new field called "arch" where the architecture
can add any special attributes to each call site record.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Optimize a bit the function return tracer

This patch changes the calling convention of prepare_ftrace_return to
pass its arguments by register. This will optimize it a bit and
prepare it to support dynamic tracing.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: remove spinlocks and irq disabling in function return tracer.

I've tried to figure out all of the race condition that could happen
when the tracer pushes or pops a return address trace to/from the
current thread_info.

Theory:

_ One thread can only execute on one cpu at a time. So this code
  doesn't need to be SMP-safe. Just drop the spinlock.

_ The only race could happen between the current thread and an
  interrupt. If an interrupt is raised, it will increase the index of
  the return stack storage and then execute until the end of the
  tracing to finally free the index it used. We don't need to disable
  irqs.

This is theorical. In practice, I've tested it with a two-core SMP and
had no problem at all. Perhaps -tip testing could confirm it.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: name change of unlikely tracer and profiler

Ingo Molnar suggested changing the config from UNLIKELY_PROFILE
to BRANCH_PROFILING. I never did like the "unlikely" name so I
went one step farther, and renamed all the unlikely configurations
to a "BRANCH" variant.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix bootup crash

the branch tracer missed arch/x86/vdso/vclock_gettime.c from
disabling tracing, which caused such bootup crashes:

  [  201.840097] init[1]: segfault at 7fffed3fe7c0 ip 00007fffed3fea2e sp 000077

also clean up the ugly ifdefs in arch/x86/kernel/vsyscall_64.c by
creating DISABLE_UNLIKELY_PROFILE facility for code to turn off
instrumentation on a per file basis.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: new unlikely/likely profiler

Andrew Morton recently suggested having an in-kernel way to profile
likely and unlikely macros. This patch achieves that goal.

When configured, every(*) likely and unlikely macro gets a counter attached
to it. When the condition is hit, the hit and misses of that condition
are recorded. These numbers can later be retrieved by:

  /debugfs/tracing/profile_likely    - All likely markers
  /debugfs/tracing/profile_unlikely  - All unlikely markers.

# cat /debug/tracing/profile_unlikely | head
 correct incorrect  %        Function                  File              Line
 ------- ---------  -        --------                  ----              ----
    2167        0   0 do_arch_prctl                  process_64.c         832
       0        0   0 do_arch_prctl                  process_64.c         804
    2670        0   0 IS_ERR                         err.h                34
   71230     5693   7 __switch_to                    process_64.c         673
   76919        0   0 __switch_to                    process_64.c         639
   43184    33743  43 __switch_to                    process_64.c         624
   12740    64181  83 __switch_to                    process_64.c         594
   12740    64174  83 __switch_to                    process_64.c         590

# cat /debug/tracing/profile_unlikely | \
  awk '{ if ($3 > 25) print $0; }' |head -20
   44963    35259  43 __switch_to                    process_64.c         624
   12762    67454  84 __switch_to                    process_64.c         594
   12762    67447  84 __switch_to                    process_64.c         590
    1478      595  28 syscall_get_error              syscall.h            51
       0     2821 100 syscall_trace_leave            ptrace.c             1567
       0        1 100 native_smp_prepare_cpus        smpboot.c            1237
   86338   265881  75 calc_delta_fair                sched_fair.c         408
  210410   108540  34 calc_delta_mine                sched.c              1267
       0    54550 100 sched_info_queued              sched_stats.h        222
   51899    66435  56 pick_next_task_fair            sched_fair.c         1422
       6       10  62 yield_task_fair                sched_fair.c         982
    7325     2692  26 rt_policy                      sched.c              144
       0     1270 100 pre_schedule_rt                sched_rt.c           1261
    1268    48073  97 pick_next_task_rt              sched_rt.c           884
       0    45181 100 sched_info_dequeued            sched_stats.h        177
       0       15 100 sched_move_task                sched.c              8700
       0       15 100 sched_move_task                sched.c              8690
   53167    33217  38 schedule                       sched.c              4457
       0    80208 100 sched_info_switch              sched_stats.h        270
   30585    49631  61 context_switch                 sched.c              2619

# cat /debug/tracing/profile_likely | awk '{ if ($3 > 25) print $0; }'
   39900    36577  47 pick_next_task                 sched.c              4397
   20824    15233  42 switch_mm                      mmu_context_64.h     18
       0        7 100 __cancel_work_timer            workqueue.c          560
     617    66484  99 clocksource_adjust             timekeeping.c        456
       0   346340 100 audit_syscall_exit             auditsc.c            1570
      38   347350  99 audit_get_context              auditsc.c            732
       0   345244 100 audit_syscall_entry            auditsc.c            1541
      38     1017  96 audit_free                     auditsc.c            1446
       0     1090 100 audit_alloc                    auditsc.c            862
    2618     1090  29 audit_alloc                    auditsc.c            858
       0        6 100 move_masked_irq                migration.c          9
       1      198  99 probe_sched_wakeup             trace_sched_switch.c 58
       2        2  50 probe_wakeup                   trace_sched_wakeup.c 227
       0        2 100 probe_wakeup_sched_switch      trace_sched_wakeup.c 144
    4514     2090  31 __grab_cache_page              filemap.c            2149
   12882   228786  94 mapping_unevictable            pagemap.h            50
       4       11  73 __flush_cpu_slab               slub.c               1466
  627757   330451  34 slab_free                      slub.c               1731
    2959    61245  95 dentry_lru_del_init            dcache.c             153
     946     1217  56 load_elf_binary                binfmt_elf.c         904
     102       82  44 disk_put_part                  genhd.h              206
       1        1  50 dst_gc_task                    dst.c                82
       0       19 100 tcp_mss_split_point            tcp_output.c         1126

As you can see by the above, there's a bit of work to do in rethinking
the use of some unlikelys and likelys. Note: the unlikely case had 71 hits
that were more than 25%.

Note:  After submitting my first version of this patch, Andrew Morton
  showed me a version written by Daniel Walker, where I picked up
  the following ideas from:

  1)  Using __builtin_constant_p to avoid profiling fixed values.
  2)  Using __FILE__ instead of instruction pointers.
  3)  Using the preprocessor to stop all profiling of likely
       annotations from vsyscall_64.c.

Thanks to Andrew Morton, Arjan van de Ven, Theodore Tso and Ingo Molnar
for their feed back on this patch.

(*) Not ever unlikely is recorded, those that are used by vsyscalls
 (a few of them) had to have profiling disabled.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 arch/x86/kernel/ftrace.c: In function 'ftrace_return_to_handler':
 arch/x86/kernel/ftrace.c:112: error: implicit declaration of function 'cpu_clock'

cpu_clock() is implicitly included via a number of ways, but its real
location is sched.h. (Build failure is triggerable if enough other
kernel components are turned off.)
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 arch/x86/kernel/ftrace.c: Assembler messages:
 arch/x86/kernel/ftrace.c:140: Error: missing ')'
 arch/x86/kernel/ftrace.c:140: Error: junk `(%ebp))' after expression
 arch/x86/kernel/ftrace.c:141: Error: missing ')'
 arch/x86/kernel/ftrace.c:141: Error: junk `(%ebp))' after expression

the [parent_replaced] is used in an =rm fashion, so that constraint
is correct in isolation - but [parent_old] aliases register %0 and uses
it in an addressing mode that is only valid with registers - so change
the constraint from =rm to =r.

This fixes the build failure.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add infrastructure for function-return tracing

Add low level support for ftrace return tracing.

This plug-in stores return addresses on the thread_info structure of
the current task.

The index of the current return address is initialized when the task
is the first one (init) and when a process forks (the child). It is
not needed when a task does a sys_execve because after this syscall,
it still needs to return on the kernel functions it called.

Note that the code of return_to_handler has been suggested by Steven
Rostedt as almost all of the ideas of improvements in this V3.

For purpose of security, arch/x86/kernel/process_32.c is not traced
because __switch_to() changes the current task during its execution.
That could cause inconsistency in the stored return address of this
function even if I didn't have any crash after testing with tracing on
this function enabled.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Some functions that may be called from this handler require that
interrupts are disabled. Also, combining IRQF_DISABLED and
IRQF_SHARED does not reliably disable interrupts in a handler, so
remove IRQF_SHARED from the irq flags (this irq is not shared anyway).
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Cc: "Will Newton" <will.newton@gmail.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

In hpet_next_event() we check that the value we just wrote to
HPET_Tn_CMP(timer) has reached the chip. Currently, we're checking that
the value we wrote to HPET_Tn_CMP(timer) is in HPET_T0_CMP, which, if
timer is anything other than timer 0, is likely to fail.
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

It is possible to flood the console with call traces if the WARN_ON
condition is true because of the frequency with which this function is
called.
Signed-off-by: NMatt Fleming <mjf@gentoo.org>
Cc: mingo@elte.hu
Cc: venkatesh.pallipadi@intel.com
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

sched_clock() uses cycles_2_ns() needlessly - which is an irq-disabling
variant of __cycles_2_ns().

Most of the time sched_clock() is called with irqs disabled already.
The few places that call it with irqs enabled need to be updated.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit c7ffa6c2.

the assumptio of this change was that this would not break
any existing machine. Andrey Borzenkov reported troubles with
the ACPI reboot method: the system would hang on reboot, necessiating
a power cycle. Probably more systems are affected as well.

Also, there are patches queued up for v2.6.29 to disable virtualization
on emergency_restart() - which was the original motivation of
this change.
Reported-by: NAndrey Borzenkov <arvidjaar@mail.ru>
Bisected-by: NAndrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Acked-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Lazy flushing needs to take care of the unmap path too which is not yet
implemented and leads to stale IO/TLB entries. This is fixed by this
patch.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Impact: fix rare x2apic hang

On x86, x2apic mode accesses for sending IPI's don't have serializing
semantics. If the IPI receivner refers(in lock-free fashion) to some
memory setup by the sender, the need for smp_mb() before sending the
IPI becomes critical in x2apic mode.

Add the smp_mb() in native_flush_tlb_others() before sending the IPI.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: quick start and stop of function tracer

This patch adds a way to disable the function tracer quickly without
the need to run kstop_machine. It adds a new variable called
function_trace_stop which will stop the calls to functions from mcount
when set.  This is just an on/off switch and does not handle recursion
like preempt_disable().

It's main purpose is to help other tracers/debuggers start and stop tracing
fuctions without the need to call kstop_machine.

The config option HAVE_FUNCTION_TRACE_MCOUNT_TEST is added for archs
that implement the testing of the function_trace_stop in the mcount
arch dependent code. Otherwise, the test is done in the C code.

x86 is the only arch at the moment that supports this.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix boot hang on 32-bit systems with more than 224 IO-APIC pins

On some 32-bit systems with a lot of IO-APICs probe_nr_irqs() can
return a value larger than NR_IRQS. This will lead to probe_irq_on()
overrunning the irq_desc array.

I hit this when running net-next-2.6 (close to 2.6.28-rc3) on a
Supermicro dual Xeon system.  NR_IRQS is 224 but probe_nr_irqs() detects
5 IOAPICs and returns 240.  Here are the log messages:

Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x01] address[0xfec00000] gsi_base[0])
Tue Nov  4 16:53:47 2008 IOAPIC[0]: apic_id 1, version 32, address 0xfec00000, GSI 0-23
Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x02] address[0xfec81000] gsi_base[24])
Tue Nov  4 16:53:47 2008 IOAPIC[1]: apic_id 2, version 32, address 0xfec81000, GSI 24-47
Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x03] address[0xfec81400] gsi_base[48])
Tue Nov  4 16:53:47 2008 IOAPIC[2]: apic_id 3, version 32, address 0xfec81400, GSI 48-71
Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x04] address[0xfec82000] gsi_base[72])
Tue Nov  4 16:53:47 2008 IOAPIC[3]: apic_id 4, version 32, address 0xfec82000, GSI 72-95
Tue Nov  4 16:53:47 2008 ACPI: IOAPIC (id[0x05] address[0xfec82400] gsi_base[96])
Tue Nov  4 16:53:47 2008 IOAPIC[4]: apic_id 5, version 32, address 0xfec82400, GSI 96-119
Tue Nov  4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 high edge)
Tue Nov  4 16:53:47 2008 ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
Tue Nov  4 16:53:47 2008 Enabling APIC mode:  Flat.  Using 5 I/O APICs
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Acked-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix udelay when "notsc" boot parameter is passed

With notsc passed on commandline, tsc may not be used for
udelays, make sure that we do not use tsc_khz to calculate
the lpj value in such cases.
Reported-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: NAlok N Kataria <akataria@vmware.com>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This makes the late e820 resources use 'insert_resource_expand_to_fit()'
instead of doing a 'reserve_region_with_split()', and also avoids
marking them as IORESOURCE_BUSY.

This results in us being perfectly happy to use pre-existing PCI
resources even if they were marked as being in a reserved region, while
still avoiding any _new_ allocations in the reserved regions.  It also
makes for a simpler and more accurate resource tree.

Example resource allocation from Jonathan Corbet, who has firmware that
has an e820 reserved entry that covered a big range (e0000000-fed003ff),
and that had various PCI resources in it set up by firmware.

With old kernels, the reserved range would force us to re-allocate all
pre-existing PCI resources, and his reserved range would end up looking
like this:

	e0000000-fed003ff : reserved
	  fec00000-fec00fff : IOAPIC 0
	  fed00000-fed003ff : HPET 0

where only the pre-allocated special regions (IOAPIC and HPET) were kept
around.

With 2.6.28-rc2, which uses 'reserve_region_with_split()', Jonathan's
resource tree looked like this:

	e0000000-fe7fffff : reserved
	fe800000-fe8fffff : PCI Bus 0000:01
	 fe800000-fe8fffff : reserved
	fe900000-fe9d9aff : reserved
	fe9d9b00-fe9d9bff : 0000:00:1f.3
	 fe9d9b00-fe9d9bff : reserved
	fe9d9c00-fe9d9fff : 0000:00:1a.7
	 fe9d9c00-fe9d9fff : reserved
	fe9da000-fe9dafff : 0000:00:03.3
	 fe9da000-fe9dafff : reserved
	fe9db000-fe9dbfff : 0000:00:19.0
	 fe9db000-fe9dbfff : reserved
	fe9dc000-fe9dffff : 0000:00:1b.0
	 fe9dc000-fe9dffff : reserved
	fe9e0000-fe9fffff : 0000:00:19.0
	 fe9e0000-fe9fffff : reserved
	fea00000-fea7ffff : 0000:00:02.0
	 fea00000-fea7ffff : reserved
	fea80000-feafffff : 0000:00:02.1
	 fea80000-feafffff : reserved
	feb00000-febfffff : 0000:00:02.0
	 feb00000-febfffff : reserved
	fec00000-fed003ff : reserved
	 fec00000-fec00fff : IOAPIC 0
	 fed00000-fed003ff : HPET 0

and because the reserved entry had been split and moved into the
individual resources, and because it used the IORESOURCE_BUSY flag, the
drivers that actually wanted to _use_ those resources couldn't actually
attach to them:

	e1000e 0000:00:19.0: BAR 0: can't reserve mem region [0xfe9e0000-0xfe9fffff]
	HDA Intel 0000:00:1b.0: BAR 0: can't reserve mem region [0xfe9dc000-0xfe9dffff]

with this patch, the resource tree instead becomes

	e0000000-fed003ff : reserved
	  fe800000-fe8fffff : PCI Bus 0000:01
	  fe9d9b00-fe9d9bff : 0000:00:1f.3
	  fe9d9c00-fe9d9fff : 0000:00:1a.7
	    fe9d9c00-fe9d9fff : ehci_hcd
	  fe9da000-fe9dafff : 0000:00:03.3
	  fe9db000-fe9dbfff : 0000:00:19.0
	    fe9db000-fe9dbfff : e1000e
	  fe9dc000-fe9dffff : 0000:00:1b.0
	    fe9dc000-fe9dffff : ICH HD audio
	  fe9e0000-fe9fffff : 0000:00:19.0
	    fe9e0000-fe9fffff : e1000e
	  fea00000-fea7ffff : 0000:00:02.0
	  fea80000-feafffff : 0000:00:02.1
	  feb00000-febfffff : 0000:00:02.0
	  fec00000-fec00fff : IOAPIC 0
	  fed00000-fed003ff : HPET 0

ie the one reserved region now ends up surrounding all the PCI resources
that were allocated inside of it by firmware, and because it is not
marked BUSY, drivers have no problem attaching to the pre-allocated
resources.
Reported-and-tested-by: NJonathan Corbet <corbet@lwn.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Impact: cleanup

This patch cleans up the NMI safe code for dynamic ftrace as suggested
by Andrew Morton.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on certain UP configs

fix:

 arch/x86/kernel/cpu/common.c: In function 'cpu_init':
 arch/x86/kernel/cpu/common.c:1141: error: 'boot_cpu_id' undeclared (first use in this function)
 arch/x86/kernel/cpu/common.c:1141: error: (Each undeclared identifier is reported only once
 arch/x86/kernel/cpu/common.c:1141: error: for each function it appears in.)

Pull in asm/smp.h on UP, so that we get the definition of
boot_cpu_id.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 arch/x86/kernel/cpu/common.c: In function 'early_identify_cpu':
 arch/x86/kernel/cpu/common.c:553: error: 'struct cpuinfo_x86' has no member named 'cpu_index'

as cpu_index is only available on SMP.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix /proc/cpuinfo output on x86/Voyager

Ever since

| commit 92cb7612
| Author: Mike Travis <travis@sgi.com>
| Date:   Fri Oct 19 20:35:04 2007 +0200
|
|     x86: convert cpuinfo_x86 array to a per_cpu array

We've had an extra field in cpuinfo_x86 which is cpu_index.
Unfortunately, voyager has never initialised this, although the only
noticeable impact seems to be that /proc/cpuinfo shows all zeros for
the processor ids.

Anyway, fix this by initialising the boot CPU properly and setting the
index when the secondaries update.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: build fix on x86/Voyager

Given commits like this:

| Author: Suresh Siddha <suresh.b.siddha@intel.com>
| Date:   Tue Jul 29 10:29:19 2008 -0700
|
|     x86, xsave: enable xsave/xrstor on cpus with xsave support

Which deliberately expose boot cpu dependence to pieces of the system,
I think it's time to explicitly have a variable for it to prevent this
continual misassumption that the boot CPU is zero.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix x86/Voyager boot

CONFIG_SMP is used for features which work on *all* x86 boxes.
CONFIG_X86_SMP is used for standard PC like x86 boxes (for things like
multi core and apics)
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: add more debug info to /debugfs/tracing/dyn_ftrace_total_info

This patch adds dynamic ftrace NMI update statistics to the
/debugfs/tracing/dyn_ftrace_total_info stat file.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix crashes that can occur in NMI handlers, if their code is modified

Modifying code is something that needs special care. On SMP boxes,
if code that is being modified is also being executed on another CPU,
that CPU will have undefined results.

The dynamic ftrace uses kstop_machine to make the system act like a
uniprocessor system. But this does not address NMIs, that can still
run on other CPUs.

One approach to handle this is to make all code that are used by NMIs
not be traced. But NMIs can call notifiers that spread throughout the
kernel and this will be very hard to maintain, and the chance of missing
a function is very high.

The approach that this patch takes is to have the NMIs modify the code
if the modification is taking place. The way this works is that just
writing to code executing on another CPU is not harmful if what is
written is the same as what exists.

Two buffers are used: an IP buffer and a "code" buffer.

The steps that the patcher takes are:

 1) Put in the instruction pointer into the IP buffer
    and the new code into the "code" buffer.
 2) Set a flag that says we are modifying code
 3) Wait for any running NMIs to finish.
 4) Write the code
 5) clear the flag.
 6) Wait for any running NMIs to finish.

If an NMI is executed, it will also write the pending code.
Multiple writes are OK, because what is being written is the same.
Then the patcher must wait for all running NMIs to finish before
going to the next line that must be patched.

This is basically the RCU approach to code modification.

Thanks to Ingo Molnar for suggesting the idea, and to Arjan van de Ven
for his guidence on what is safe and what is not.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch changes the code to use IOMMU_CAP_NPCACHE as a shift and not
as a mask.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Impact: fewer sparse warnings, no functional changes

arch/x86/kernel/vsmp_64.c:87:14: warning: incorrect type in argument 1 (different address spaces)
arch/x86/kernel/vsmp_64.c:87:14:    expected void const volatile [noderef] <asn:2>*addr
arch/x86/kernel/vsmp_64.c:87:14:    got void *[assigned] address
arch/x86/kernel/vsmp_64.c:88:22: warning: incorrect type in argument 1 (different address spaces)
arch/x86/kernel/vsmp_64.c:88:22:    expected void const volatile [noderef] <asn:2>*addr
arch/x86/kernel/vsmp_64.c:88:22:    got void *
arch/x86/kernel/vsmp_64.c:100:23: warning: incorrect type in argument 2 (different address spaces)
arch/x86/kernel/vsmp_64.c:100:23:    expected void volatile [noderef] <asn:2>*addr
arch/x86/kernel/vsmp_64.c:100:23:    got void *
arch/x86/kernel/vsmp_64.c:101:23: warning: incorrect type in argument 1 (different address spaces)
arch/x86/kernel/vsmp_64.c:101:23:    expected void const volatile [noderef] <asn:2>*addr
arch/x86/kernel/vsmp_64.c:101:23:    got void *
arch/x86/mm/gup.c:235:6: warning: incorrect type in argument 1 (different base types)
arch/x86/mm/gup.c:235:6:    expected void const volatile [noderef] <asn:1>*<noident>
arch/x86/mm/gup.c:235:6:    got unsigned long [unsigned] [assigned] start
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix AMD Family 11h boot hangs / USB device problems

The AMD Fam11h CPUs have a K8 northbridge. This northbridge is different
from other family's because it lacks GART support (as I just learned).

But the kernel implicitly expects a GART if it finds an AMD northbridge.

Fix this by removing the Fam11h northbridge id from the scan list of K8
northbridges. This patch also changes the message in the GART driver
about missing K8 northbridges to tell that the GART is missing which is
the correct information in this case.
Reported-by: NJouni Malinen <jkmalinen@gmail.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: fix kdump crash on 32-bit sparsemem kernels

Since linux-2.6.27, kdump has failed on i386 sparsemem kernel.
1st-kernel gets a panic just before switching to 2nd-kernel.

The cause is that a kernel accesses invalid mem_section by
page_to_pfn(image->swap_page) at machine_kexec().
image->swap_page is allocated if kexec for hibernation, but
it is not allocated if kdump. So if kdump, a kernel should
not access the mem_section corresponding to image->swap_page.

The attached patch fixes this invalid access.
Signed-off-by: NKen'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Cc: kexec-ml <kexec@lists.infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Removed author's email address from MODULE_AUTHOR.
Signed-off-by: NPeter Oruba <peter.oruba@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Removed one author's email address from module init message.
Signed-off-by: NPeter Oruba <peter.oruba@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: avoid section mismatch warning, clean up

The dynamic ftrace determines which nop is safe to use at start up.
When it finds a safe nop for patching, it sets a pointer called ftrace_nop
to point to the code. All call sites are then patched to this nop.

Later, when tracing is turned on, this ftrace_nop variable is again used
to compare the location to make sure it is a nop before we update it to
an mcount call. If this fails just once, a warning is printed and ftrace
is disabled.

Rakib Mullick noted that the code that sets up the nop is a .init section
where as the nop itself is in the .text section. This is needed because
the nop is used later on after boot up. The problem is that the test of the
nop jumps back to the setup code and causes a "section mismatch" warning.

Rakib first recommended to convert the nop to .init.text, but as stated
above, this would fail since that text is used later.

The real solution is to extend Rabik's patch, and to make the ftrace_nop
into an array, and just save the code from the assembly to this array.

Now the section can stay as an init section, and we have a nop to use
later on.
Reported-by: NRakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: on SGI UV platforms, fix boot crash

UV initialization is currently called too late to call alloc_bootmem_pages().
The current sequence is:

 start_kernel()
   mem_init()
     free_all_bootmem()           <--- discard of bootmem
   rest_init()
     kernel_init()
       smp_prepare_cpus()
       native_smp_prepare_cpus()
         uv_system_init()         <--- uses alloc_bootmem_pages()

It should be calling kmalloc().
Signed-off-by: NCliff Wickman <cpw@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

On Thu, Oct 23, 2008 at 04:09:52PM -0700, Alexander Beregalov wrote:
> arch/x86/kernel/built-in.o: In function `iommu_setup':
> pci-dma.c:(.init.text+0x36ad): undefined reference to `forbid_dac'
> pci-dma.c:(.init.text+0x36cc): undefined reference to `forbid_dac'
> pci-dma.c:(.init.text+0x3711): undefined reference to `forbid_dac

This patch partially reverts a patch to add IOMMU support to ia64.  The
forbid_dac variable was incorrectly moved to quirks.c, which isn't built
when PCI is disabled.
Tested-by: N"Alexander Beregalov" <a.beregalov@gmail.com>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

This restores the old swiotlb alloc_coherent behavior (before the
alloc_coherent rewrite):

  http://lkml.org/lkml/2008/8/12/200

The old alloc_coherent avoids GFP_DMA allocation first and if the
allocated address is not fit for the device's coherent_dma_mask, then
dma_alloc_coherent does GFP_DMA allocation. If it fails,
alloc_coherent calls swiotlb_alloc_coherent (in short, we rarely used
swiotlb_alloc_coherent).

After the alloc_coherent rewrite, dma_alloc_coherent
(include/asm-x86/dma-mapping.h) directly calls swiotlb_alloc_coherent.
It means that we possibly can't handle a device having dma_masks >
24bit < 32bits since swiotlb_alloc_coherent doesn't have the above
GFP_DMA retry mechanism.

This patch fixes x86's swiotlb alloc_coherent to use the GFP_DMA retry
mechanism, which dma_generic_alloc_coherent() provides now
(pci-nommu.c and GART IOMMU driver also use
dma_generic_alloc_coherent).
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The entire file of ftrace.c in the arch code needs to be marked
as notrace. It is much cleaner to do this from the Makefile with
CFLAGS_REMOVE_ftrace.o.

[ powerpc already had this in its Makefile. ]
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>