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  1. 01 6月, 2012 1 次提交
    • S
      ftrace: Synchronize variable setting with breakpoints · a192cd04
      由 Steven Rostedt 提交于 
      When the function tracer starts modifying the code via breakpoints
it sets a variable (modifying_ftrace_code) to inform the breakpoint
handler to call the ftrace int3 code.

But there's no synchronization between setting this code and the
handler, thus it is possible for the handler to be called on another
CPU before it sees the variable. This will cause a kernel crash as
the int3 handler will not know what to do with it.

I originally added smp_mb()'s to force the visibility of the variable
but H. Peter Anvin suggested that I just make it atomic.

[ Added comments as suggested by Peter Zijlstra ]
Suggested-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      a192cd04
  3. 22 5月, 2012 9 次提交
  5. 21 5月, 2012 1 次提交
  7. 19 5月, 2012 3 次提交
    • H
      x86, relocs: When printing an error, say relative or absolute · 24ab82bd
      由 H. Peter Anvin 提交于 
      When the relocs tool throws an error, let the error message say if it
is an absolute or relative symbol.  This should make it a lot more
clear what action the programmer needs to take and should help us find
the reason if additional symbol bugs show up.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org>
      24ab82bd
    • H
      x86, relocs: Workaround for binutils 2.22.52.0.1 section bug · a3e854d9
      由 H. Peter Anvin 提交于 
      GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from
section-relative to absolute if they are in a section of zero length.
This turns the symbols __init_begin and __init_end into absolute
symbols.  Let the relocs program know that those should be treated as
relative symbols.
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
      a3e854d9
    • H
      x86, realmode: 16-bit real-mode code support for relocs tool · 6520fe55
      由 H. Peter Anvin 提交于 
      A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.

In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.

16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.

The relocs tool is moved to arch/x86/tools/relocs.c, and added new
target archscripts that can be used to build scripts needed building
an architecture.  be compiled before building the arch/x86 tree.

[ hpa: accelerating this because it detects invalid absolute
  relocations, a serious bug in binutils 2.22.52.0.x which currently
  produces bad kernels. ]
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.comSigned-off-by: NJarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
      6520fe55
  9. 18 5月, 2012 10 次提交
  11. 17 5月, 2012 6 次提交
    • P
      sched: Remove stale power aware scheduling remnants and dysfunctional knobs · 8e7fbcbc
      由 Peter Zijlstra 提交于 
      It's been broken forever (i.e. it's not scheduling in a power
aware fashion), as reported by Suresh and others sending
patches, and nobody cares enough to fix it properly ...
so remove it to make space free for something better.

There's various problems with the code as it stands today, first
and foremost the user interface which is bound to topology
levels and has multiple values per level. This results in a
state explosion which the administrator or distro needs to
master and almost nobody does.

Furthermore large configuration state spaces aren't good, it
means the thing doesn't just work right because it's either
under so many impossibe to meet constraints, or even if
there's an achievable state workloads have to be aware of
it precisely and can never meet it for dynamic workloads.

So pushing this kind of decision to user-space was a bad idea
even with a single knob - it's exponentially worse with knobs
on every node of the topology.

There is a proposal to replace the user interface with a single
3 state knob:

 sched_balance_policy := { performance, power, auto }

where 'auto' would be the preferred default which looks at things
like Battery/AC mode and possible cpufreq state or whatever the hw
exposes to show us power use expectations - but there's been no
progress on it in the past many months.

Aside from that, the actual implementation of the various knobs
is known to be broken. There have been sporadic attempts at
fixing things but these always stop short of reaching a mergable
state.

Therefore this wholesale removal with the hopes of spurring
people who care to come forward once again and work on a
coherent replacement.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twinsSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8e7fbcbc
    • S
      ftrace/x86: Have x86 ftrace use the ftrace_modify_all_code() · e4f5d544
      由 Steven Rostedt 提交于 
      To remove duplicate code, have the ftrace arch_ftrace_update_code()
use the generic ftrace_modify_all_code(). This requires that the
default ftrace_replace_code() becomes a weak function so that an
arch may override it.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      e4f5d544
    • S
      x86, fpu: drop the fpu state during thread exit · 1dcc8d7b
      由 Suresh Siddha 提交于 
      There is no need to save any active fpu state to the task structure
memory if the task is dead. Just drop the state instead.

For example, this saved some 1770 xsave's during the system boot
of a two socket Xeon system.
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1336692811-30576-4-git-send-email-suresh.b.siddha@intel.com
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      1dcc8d7b
    • S
      x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state() · d75f1b39
      由 Suresh Siddha 提交于 
      Code paths like fork(), exit() and signal handling flush the fpu
state explicitly to the structures in memory.

BUG_ON() in __sanitize_i387_state() is checking that the fpu state
is not live any more. But for preempt kernels, task can be scheduled
out and in at any place and the preload_fpu logic during context switch
can make the fpu registers live again.

For example, consider a 64-bit Task which uses fpu frequently and as such
you will find its fpu_counter mostly non-zero. During its time slice, kernel
used fpu by doing kernel_fpu_begin/kernel_fpu_end(). After this, in the same
scheduling slice, task-A got a signal to handle. Then during the signal
setup path we got preempted when we are just before the sanitize_i387_state()
in arch/x86/kernel/xsave.c:save_i387_xstate(). And when we come back we
will have the fpu registers live that can hit the bug_on.

Similarly during core dump, other threads can context-switch in and out
(because of spurious wakeups while waiting for the coredump to finish in
 kernel/exit.c:exit_mm()) and the main thread dumping core can run into this
bug when it finds some other thread with its fpu registers live on some other cpu.

So remove the paranoid check for now, even though it caught a bug in the
multi-threaded core dump case (fixed in the previous patch).
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1336692811-30576-3-git-send-email-suresh.b.siddha@intel.com
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      d75f1b39
    • S
      fork: move the real prepare_to_copy() users to arch_dup_task_struct() · 55ccf3fe
      由 Suresh Siddha 提交于 
      Historical prepare_to_copy() is mostly a no-op, duplicated for majority of
the architectures and the rest following the x86 model of flushing the extended
register state like fpu there.

Remove it and use the arch_dup_task_struct() instead.
Suggested-by: NOleg Nesterov <oleg@redhat.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1336692811-30576-1-git-send-email-suresh.b.siddha@intel.comAcked-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      55ccf3fe
    • P
      x86: Don't continue booting if we can't load the specified initrd · ab7b64e9
      由 Peter Jones 提交于 
      If we've determined we can't do what the user asked, trying to do
something else isn't going to make the user's life better.

Without this the screen scrolls a bit and then you get a panic
anyway, and it's nice not to have so much scroll after the real
problem in bug reports.

Link: http://lkml.kernel.org/r/1337190206-12121-1-git-send-email-pjones@redhat.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>
      ab7b64e9
  13. 16 5月, 2012 4 次提交
  15. 15 5月, 2012 6 次提交