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  1. 25 2月, 2010 1 次提交
    • S
      ftrace: Remove memory barriers from NMI code when not needed · 0c54dd34
      由 Steven Rostedt 提交于 
      The code in stop_machine that modifies the kernel text has a bit
of logic to handle the case of NMIs. stop_machine does not prevent
NMIs from executing, and if an NMI were to trigger on another CPU
as the modifying CPU is changing the NMI text, a GPF could result.

To prevent the GPF, the NMI calls ftrace_nmi_enter() which may
modify the code first, then any other NMIs will just change the
text to the same content which will do no harm. The code that
stop_machine called must wait for NMIs to finish while it changes
each location in the kernel. That code may also change the text
to what the NMI changed it to. The key is that the text will never
change content while another CPU is executing it.

To make the above work, the call to ftrace_nmi_enter() must also
do a smp_mb() as well as atomic_inc().  But for applications like
perf that require a high number of NMIs for profiling, this can have
a dramatic effect on the system. Not only is it doing a full memory
barrier on both nmi_enter() as well as nmi_exit() it is also
modifying a global variable with an atomic operation. This kills
performance on large SMP machines.

Since the memory barriers are only needed when ftrace is in the
process of modifying the text (which is seldom), this patch
adds a "modifying_code" variable that gets set before stop machine
is executed and cleared afterwards.

The NMIs will check this variable and store it in a per CPU
"save_modifying_code" variable that it will use to check if it
needs to do the memory barriers and atomic dec on NMI exit.
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      0c54dd34
  3. 06 1月, 2010 1 次提交
  5. 05 1月, 2010 2 次提交
  7. 04 1月, 2010 5 次提交
  9. 31 12月, 2009 3 次提交
  11. 29 12月, 2009 2 次提交
    • M
      x86: SGI UV: Fix writes to led registers on remote uv hubs · 39d30770
      由 Mike Travis 提交于 
      The wrong address was being used to write the SCIR led regs on
remote hubs.  Also, there was an inconsistency between how BIOS
and the kernel indexed these regs.  Standardize on using the
lower 6 bits of the APIC ID as the index.

This patch fixes the problem of writing to an errant address to
a cpu # >= 64.
Signed-off-by: NMike Travis <travis@sgi.com>
Reviewed-by: NJack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@kernel.org
LKML-Reference: <4B3922F9.3060905@sgi.com>
[ v2: fix a number of annoying checkpatch artifacts and whitespace noise ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      39d30770
    • P
      sh: Only provide a PCLK definition for legacy CPG CPUs. · 8152a74b
      由 Paul Mundt 提交于 
      As CPUs are migrated over to more fully-featured clock frameworks of
their own and off of the legacy CPG code, they no longer have any real
need for defining the PCLK value. The PCLK define in itself is already
fairly misleading, as many boards get their input clocks from different
sources, making this value fairly arbitrary anyways.

Outside of the legacy CPG clock framework, the only place where this
value is used is for deriving CLOCK_TICK_RATE, which we set back to the
legacy PIT value that it was before the PCLK definitions were added in
the first place.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
      8152a74b
  13. 28 12月, 2009 2 次提交
    • P
      x86, kmemcheck: Use KERN_WARNING for error reporting · c0ca9da4
      由 Pekka Enberg 提交于 
      As suggested by Vegard Nossum, use KERN_WARNING for error
reporting to make sure kmemcheck reports end up in syslog.
Suggested-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1261990935.4641.7.camel@penberg-laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c0ca9da4
    • P
      x86: Use KERN_DEFAULT log-level in __show_regs() · d015a092
      由 Pekka Enberg 提交于 
      Andrew Morton reported a strange looking kmemcheck warning:

  WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff88004fba6c20)
  0000000000000000310000000000000000000000000000002413000000c9ffff
   u u u u u u u u u u u u u u u u i i i i i i i i u u u u u u u u

   [<ffffffff810af3aa>] kmemleak_scan+0x25a/0x540
   [<ffffffff810afbcb>] kmemleak_scan_thread+0x5b/0xe0
   [<ffffffff8104d0fe>] kthread+0x9e/0xb0
   [<ffffffff81003074>] kernel_thread_helper+0x4/0x10
   [<ffffffffffffffff>] 0xffffffffffffffff

The above printout is missing register dump completely. The
problem here is that the output comes from syslog which doesn't
show KERN_INFO log-level messages. We didn't see this before
because both of us were testing on 32-bit kernels which use the
_default_ log-level.

Fix that up by explicitly using KERN_DEFAULT log-level for
__show_regs() printks.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1261988819.4641.2.camel@penberg-laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      d015a092
  15. 27 12月, 2009 5 次提交
  17. 26 12月, 2009 1 次提交
    • H
      x86, compress: Force i386 instructions for the decompressor · 17a2a9b5
      由 H. Peter Anvin 提交于 
      Recently, some distros have started shipping versions of gcc which
default to -march=i686.  This breaks building kernels for pre-i686
machines, even if they have been selected in Kconfig, due to the
generation of CMOV instructions.

There isn't enough benefit to try to preserve the generation of these
instructions even when selected, so simply force -march=i386 for the
decompressor when building a 32-bit kernel.
Reported-and-tested-by: NChris Rankin <rankincj@yahoo.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
LKML-Reference: <219280.97558.qm@web52907.mail.re2.yahoo.com>
      17a2a9b5
  19. 25 12月, 2009 1 次提交
  21. 24 12月, 2009 10 次提交
  23. 23 12月, 2009 2 次提交
  25. 22 12月, 2009 5 次提交