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  1. 08 2月, 2009 3 次提交
    • S
      ftrace: change function graph tracer to use new in_nmi · 9a5fd902
      由 Steven Rostedt 提交于 
      The function graph tracer piggy backed onto the dynamic ftracer
to use the in_nmi custom code for dynamic tracing. The problem
was (as Andrew Morton pointed out) it really only wanted to bail
out if the context of the current CPU was in NMI context. But the
dynamic ftrace in_nmi custom code was true if _any_ CPU happened
to be in NMI context.

Now that we have a generic in_nmi interface, this patch changes
the function graph code to use it instead of the dynamic ftarce
custom code.
Reported-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      9a5fd902
    • S
      ftrace, x86: rename in_nmi variable · 4e6ea144
      由 Steven Rostedt 提交于 
      Impact: clean up

The in_nmi variable in x86 arch ftrace.c is a misnomer.
Andrew Morton pointed out that the in_nmi variable is incremented
by all CPUS. It can be set when another CPU is running an NMI.

Since this is actually intentional, the fix is to rename it to
what it really is: "nmi_running"
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      4e6ea144
    • S
      ring-buffer: add NMI protection for spinlocks · 78d904b4
      由 Steven Rostedt 提交于 
      Impact: prevent deadlock in NMI

The ring buffers are not yet totally lockless with writing to
the buffer. When a writer crosses a page, it grabs a per cpu spinlock
to protect against a reader. The spinlocks taken by a writer are not
to protect against other writers, since a writer can only write to
its own per cpu buffer. The spinlocks protect against readers that
can touch any cpu buffer. The writers are made to be reentrant
with the spinlocks disabling interrupts.

The problem arises when an NMI writes to the buffer, and that write
crosses a page boundary. If it grabs a spinlock, it can be racing
with another writer (since disabling interrupts does not protect
against NMIs) or with a reader on the same CPU. Luckily, most of the
users are not reentrant and protects against this issue. But if a
user of the ring buffer becomes reentrant (which is what the ring
buffers do allow), if the NMI also writes to the ring buffer then
we risk the chance of a deadlock.

This patch moves the ftrace_nmi_enter called by nmi_enter() to the
ring buffer code. It replaces the current ftrace_nmi_enter that is
used by arch specific code to arch_ftrace_nmi_enter and updates
the Kconfig to handle it.

When an NMI is called, it will set a per cpu variable in the ring buffer
code and will clear it when the NMI exits. If a write to the ring buffer
crosses page boundaries inside an NMI, a trylock is used on the spin
lock instead. If the spinlock fails to be acquired, then the entry
is discarded.

This bug appeared in the ftrace work in the RT tree, where event tracing
is reentrant. This workaround solved the deadlocks that appeared there.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
      78d904b4
  3. 31 1月, 2009 9 次提交
  5. 30 1月, 2009 2 次提交
  7. 29 1月, 2009 1 次提交
  9. 28 1月, 2009 1 次提交
  11. 27 1月, 2009 3 次提交
  13. 26 1月, 2009 3 次提交
    • R
      x86: fix section mismatch warning · 659d2618
      由 Rakib Mullick 提交于 
      Here function vmi_activate calls a init function activate_vmi , which
causes the following section mismatch warnings:

  LD      arch/x86/kernel/built-in.o
WARNING: arch/x86/kernel/built-in.o(.text+0x13ba9): Section mismatch
in reference from the function vmi_activate() to the function
.init.text:vmi_time_init()
The function vmi_activate() references
the function __init vmi_time_init().
This is often because vmi_activate lacks a __init
annotation or the annotation of vmi_time_init is wrong.

WARNING: arch/x86/kernel/built-in.o(.text+0x13bd1): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_bsp_init()
The function vmi_activate() references
the function __devinit vmi_time_bsp_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_bsp_init is wrong.

WARNING: arch/x86/kernel/built-in.o(.text+0x13bdb): Section mismatch
in reference from the function vmi_activate() to the function
.devinit.text:vmi_time_ap_init()
The function vmi_activate() references
the function __devinit vmi_time_ap_init().
This is often because vmi_activate lacks a __devinit
annotation or the annotation of vmi_time_ap_init is wrong.

Fix it by marking vmi_activate() as __init too.
Signed-off-by: NRakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      659d2618
    • I
      x86: unmask CPUID levels on Intel CPUs, fix · 99fb4d34
      由 Ingo Molnar 提交于 
      Impact: fix boot hang on pre-model-15 Intel CPUs

rdmsrl_safe() does not work in very early bootup code yet, because we
dont have the pagefault handler installed yet so exception section
does not get parsed. rdmsr_safe() will just crash and hang the bootup.

So limit the MSR_IA32_MISC_ENABLE MSR read to those CPU types that
support it.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      99fb4d34
    • E
      x86: work around PAGE_KERNEL_WC not getting WC in iomap_atomic_prot_pfn. · ef5fa0ab
      由 Eric Anholt 提交于 
      In the absence of PAT, PAGE_KERNEL_WC ends up mapping to a memory type that
gets UC behavior even in the presence of a WC MTRR covering the area in
question.  By swapping to PAGE_KERNEL_UC_MINUS, we can get the actual
behavior the caller wanted (WC if you can manage it, UC otherwise).

This recovers the 40% performance improvement of using WC in the DRM
to upload vertex data.
Signed-off-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
      ef5fa0ab
  15. 25 1月, 2009 1 次提交
    • I
      x86: use standard PIT frequency · e1b4d114
      由 Ingo Molnar 提交于 
      the RDC and ELAN platforms use slighly different PIT clocks, resulting in
a timex.h hack that changes PIT_TICK_RATE during build time. But if a
tester enables any of these platform support .config options, the PIT
will be miscalibrated on standard PC platforms.

So use one frequency - in a subsequent patch we'll add a quirk to allow
x86 platforms to define different PIT frequencies.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e1b4d114
  17. 24 1月, 2009 1 次提交
    • P
      x86, mm: fix pte_free() · 42ef73fe
      由 Peter Zijlstra 提交于 
      On -rt we were seeing spurious bad page states like:

Bad page state in process 'firefox'
page:c1bc2380 flags:0x40000000 mapping:c1bc2390 mapcount:0 count:0
Trying to fix it up, but a reboot is needed
Backtrace:
Pid: 503, comm: firefox Not tainted 2.6.26.8-rt13 #3
[<c043d0f3>] ? printk+0x14/0x19
[<c0272d4e>] bad_page+0x4e/0x79
[<c0273831>] free_hot_cold_page+0x5b/0x1d3
[<c02739f6>] free_hot_page+0xf/0x11
[<c0273a18>] __free_pages+0x20/0x2b
[<c027d170>] __pte_alloc+0x87/0x91
[<c027d25e>] handle_mm_fault+0xe4/0x733
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c043f680>] ? rt_mutex_down_read_trylock+0x57/0x63
[<c0218875>] do_page_fault+0x36f/0x88a

This is the case where a concurrent fault already installed the PTE and
we get to free the newly allocated one.

This is due to pgtable_page_ctor() doing the spin_lock_init(&page->ptl)
which is overlaid with the {private, mapping} struct.

union {
    struct {
        unsigned long private;
        struct address_space *mapping;
    };
    spinlock_t ptl;
    struct kmem_cache *slab;
    struct page *first_page;
};

Normally the spinlock is small enough to not stomp on page->mapping, but
PREEMPT_RT=y has huge 'spin'locks.

But lockdep kernels should also be able to trigger this splat, as the
lock tracking code grows the spinlock to cover page->mapping.

The obvious fix is calling pgtable_page_dtor() like the regular pte free
path __pte_free_tlb() does.

It seems all architectures except x86 and nm10300 already do this, and
nm10300 doesn't seem to use pgtable_page_ctor(), which suggests it
doesn't do SMP or simply doesnt do MMU at all or something.
Signed-off-by: NPeter Zijlstra <a.p.zijlsta@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
      42ef73fe
  19. 22 1月, 2009 5 次提交
  21. 21 1月, 2009 4 次提交
    • T
      x86: mtrr fix debug boot parameter · 731f1872
      由 Thomas Renninger 提交于 
      while looking at:

  http://bugzilla.kernel.org/show_bug.cgi?id=11541

I realized that the mtrr.show param cannot work, because
the code is processed much too early.

This patch:
 - Declares mtrr.show as early_param
 - Stays consistent with the previous param (which I doubt
   that it ever worked), so mtrr.show=1 would still work
 - Declares mtrr_show as initdata
Signed-off-by: NThomas Renninger <trenn@suse.de>
Acked-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      731f1872
    • S
      x86: fix page attribute corruption with cpa() · a1e46212
      由 Suresh Siddha 提交于 
      Impact: fix sporadic slowdowns and warning messages

This patch fixes a performance issue reported by Linus on his
Nehalem system. While Linus reverted the PAT patch (commit
58dab916) which exposed the issue,
existing cpa() code can potentially still cause wrong(page attribute
corruption) behavior.

This patch also fixes the "WARNING: at arch/x86/mm/pageattr.c:560" that
various people reported.

In 64bit kernel, kernel identity mapping might have holes depending
on the available memory and how e820 reports the address range
covering the RAM, ACPI, PCI reserved regions. If there is a 2MB/1GB hole
in the address range that is not listed by e820 entries, kernel identity
mapping will have a corresponding hole in its 1-1 identity mapping.

If cpa() happens on the kernel identity mapping which falls into these holes,
existing code fails like this:

	__change_page_attr_set_clr()
		__change_page_attr()
			returns 0 because of if (!kpte). But doesn't
			set cpa->numpages and cpa->pfn.
		cpa_process_alias()
			uses uninitialized cpa->pfn (random value)
			which can potentially lead to changing the page
			attribute of kernel text/data, kernel identity
			mapping of RAM pages etc. oops!

This bug was easily exposed by another PAT patch which was doing
cpa() more often on kernel identity mapping holes (physical range between
max_low_pfn_mapped and 4GB), where in here it was setting the
cache disable attribute(PCD) for kernel identity mappings aswell.

Fix cpa() to handle the kernel identity mapping holes. Retain
the WARN() for cpa() calls to other not present address ranges
(kernel-text/data, ioremap() addresses)
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      a1e46212
    • I
      Revert "x86: signal: change type of paramter for sys_rt_sigreturn()" · 552b8aa4
      由 Ingo Molnar 提交于 
      This reverts commit 4217458d.

Justin Madru bisected this commit, it was causing weird Firefox
crashes.

The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.

So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.

Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505Reported-and-bisected-by: NJustin Madru <jdm64@gawab.com>
Tested-by: NJustin Madru <jdm64@gawab.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      552b8aa4
    • A
      x86: use early clobbers in usercopy*.c · e0a96129
      由 Andi Kleen 提交于 
      Impact: fix rare (but currently harmless) miscompile with certain configs and gcc versions

Hugh Dickins noticed that strncpy_from_user() was miscompiled
in some circumstances with gcc 4.3.

Thanks to Hugh's excellent analysis it was easy to track down.

Hugh writes:

> Try building an x86_64 defconfig 2.6.29-rc1 kernel tree,
> except not quite defconfig, switch CONFIG_PREEMPT_NONE=y
> and CONFIG_PREEMPT_VOLUNTARY off (because it expands a
> might_fault() there, which hides the issue): using a
> gcc 4.3.2 (I've checked both openSUSE 11.1 and Fedora 10).
>
> It generates the following:
>
> 0000000000000000 <__strncpy_from_user>:
>    0:   48 89 d1                mov    %rdx,%rcx
>    3:   48 85 c9                test   %rcx,%rcx
>    6:   74 0e                   je     16 <__strncpy_from_user+0x16>
>    8:   ac                      lods   %ds:(%rsi),%al
>    9:   aa                      stos   %al,%es:(%rdi)
>    a:   84 c0                   test   %al,%al
>    c:   74 05                   je     13 <__strncpy_from_user+0x13>
>    e:   48 ff c9                dec    %rcx
>   11:   75 f5                   jne    8 <__strncpy_from_user+0x8>
>   13:   48 29 c9                sub    %rcx,%rcx
>   16:   48 89 c8                mov    %rcx,%rax
>   19:   c3                      retq
>
> Observe that "sub %rcx,%rcx; mov %rcx,%rax", whereas gcc 4.2.1
> (and many other configs) say "sub %rcx,%rdx; mov %rdx,%rax".
> Isn't it returning 0 when it ought to be returning strlen?

The asm constraints for the strncpy_from_user() result were missing an
early clobber, which tells gcc that the last output arguments
are written before all input arguments are read.

Also add more early clobbers in the rest of the file and fix 32-bit
usercopy.c in the same way.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
[ since this API is rarely used and no in-kernel user relies on a 'len'
  return value (they only rely on negative return values) this miscompile
  was never noticed in the field. But it's worth fixing it nevertheless. ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e0a96129
  23. 20 1月, 2009 5 次提交
  25. 19 1月, 2009 2 次提交
    • L
      x86: fix section mismatch warnings in kernel/setup_percpu.c · c7f8562a
      由 Leonardo Potenza 提交于 
      The function setup_cpu_local_masks() has been marked __init, in
order to remove the following section mismatch messages:

WARNING: vmlinux.o(.text+0x3c2c7): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2d3): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2df): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.

WARNING: vmlinux.o(.text+0x3c2eb): Section mismatch in reference from the function setup_cpu_local_masks() to the function .init.text:alloc_bootmem_cpumask_var()
The function setup_cpu_local_masks() references
the function __init alloc_bootmem_cpumask_var().
This is often because setup_cpu_local_masks lacks a __init
annotation or the annotation of alloc_bootmem_cpumask_var is wrong.
Signed-off-by: NLeonardo Potenza <lpotenza@inwind.it>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c7f8562a
    • M
      x86: put trigger in to detect mismatched apic versions · b2b815d8
      由 Mike Travis 提交于 
      Impact: add debug warning

Fire off one message if two apic's discovered with different
apic versions. (this code is only called during CPU init)

The goal of this is to pave the way of the removal of the apic_version[]
array. We dont expect any apic version incompatibilities in the x86
landscape of systems [if so we dont handle them very well and probably
never will handle deep apic version assymetries well], but it's prudent
to have a debug check for one kernel cycle nevertheless.
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b2b815d8