linux.git/arch/Kconfig, branch v2.6.37

jump label: Add work around to i386 gcc asm goto bug

2010-10-29T18:45:29+00:00

On i386 (not x86_64) early implementations of gcc would have a bug
with asm goto causing it to produce code like the following:

(This was noticed by Peter Zijlstra)

   56 pushl 0
   67 nopl         jmp 0x6f
      popl
      jmp 0x8c

   6f              mov
                   test
                   je 0x8c

   8c mov
      call *(%esp)

The jump added in the asm goto skipped over the popl that matched
the pushl 0, which lead up to a quick crash of the system when
the jump was enabled. The nopl is defined in the asm goto () statement
and when tracepoints are enabled, the nop changes to a jump to the label
that was specified by the asm goto. asm goto is suppose to tell gcc that
the code in the asm might jump to an external label. Here gcc obviously
fails to make that work.

The bug report for gcc is here:

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46226

The bug only appears on x86 when not compiled with
-maccumulate-outgoing-args. This option is always set on x86_64 and it
is also the work around for a function graph tracer i386 bug.
(See commit: 746357d6a526d6da9d89a2ec645b28406e959c2e)
This explains why the bug only showed up on i386 when function graph
tracer was not enabled.

This patch now adds a CONFIG_JUMP_LABEL option that is default
off instead of using jump labels by default. When jump labels are
enabled, the -maccumulate-outgoing-args will be used (causing a
slightly larger kernel image on i386). This option will exist
until we have a way to detect if the gcc compiler in use is safe
to use on all configurations without the work around.

Note, there exists such a test, but for now we will keep the enabling
of jump label as a manual option.

Archs that know the compiler is safe with asm goto, may choose to
select JUMP_LABEL and enable it by default.

Reported-by: Ingo Molnar 
Cause-discovered-by: Peter Zijlstra 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Jason Baron 
Cc: H. Peter Anvin 
Cc: David Daney 
Cc: Mathieu Desnoyers 
Cc: Masami Hiramatsu 
Cc: David Miller 
Cc: Richard Henderson 
LKML-Reference: <1288028746.3673.11.camel@laptop>
Signed-off-by: Steven Rostedt

Merge branch 'tip/perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core

2010-09-24T07:12:05+00:00

jump label: Base patch for jump label

2010-09-22T20:29:41+00:00

base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
assembly gcc mechanism, we can now branch to labels from an 'asm goto'
statment. This allows us to create a 'no-op' fastpath, which can subsequently
be patched with a jump to the slowpath code. This is useful for code which
might be rarely used, but which we'd like to be able to call, if needed.
Tracepoints are the current usecase that these are being implemented for.

Acked-by: David S. Miller 
Signed-off-by: Jason Baron 
LKML-Reference: 

[ cleaned up some formating ]

Signed-off-by: Steven Rostedt

kprobes: Fix Kconfig dependency

2010-09-13T18:41:31+00:00

Fix Kconfig dependency among Kprobes, optprobe and kallsyms.

Kprobes uses kallsyms_lookup for finding target function and
checking instruction boundary, thus CONFIG_KPROBES should select
CONFIG_KALLSYMS.

Optprobe is an optional feature which is supported on x86 arch,
and it also uses kallsyms_lookup for checking instructions in
the target function. Since KALLSYMS_ALL just adds symbols of
kernel variables, it doesn't need to select KALLSYMS_ALL.

Signed-off-by: Masami Hiramatsu 
Acked-by: Randy Dunlap ,
Cc: Ananth N Mavinakayanahalli 
Cc: Felipe Contreras 
Cc: Randy Dunlap 
Cc: Ananth N Mavinakayanahalli 
Cc: Anil S Keshavamurthy 
Cc: David S. Miller 
Cc: akpm 
LKML-Reference: <20100913102541.20260.85700.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar

Merge branch 'perf/nmi' into perf/core

2010-08-05T06:45:05+00:00

Conflicts:
	kernel/Makefile

Merge reason: Add the now complete topic, fix the conflict.

Signed-off-by: Ingo Molnar

lockup_detector: Introduce CONFIG_HARDLOCKUP_DETECTOR

2010-05-15T23:57:42+00:00

This new config is deemed to simplify even more the lockup detector
dependencies and can make it easier to bring a smooth sorting
between archs that support the new generic lockup detector and those
that still have their own, especially for those that are in the
middle of this migration.

Instead of checking whether we have CONFIG_LOCKUP_DETECTOR +
CONFIG_PERF_EVENTS_NMI each time an arch wants to know if it needs
to build its own lockup detector, take a shortcut with this new
config. It is enabled only if the hardlockup detection part of
the whole lockup detector is on.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Don Zickus 
Cc: Cyrill Gorcunov

lockup_detector: Adapt CONFIG_PERF_EVENT_NMI to other archs

2010-05-15T23:57:36+00:00

CONFIG_PERF_EVENT_NMI is something that need to be enabled from the
arch. This is fine on x86 as PERF_EVENTS is builtin but if other
archs select it, they will need to handle the PERF_EVENTS dependency.

Instead, handle the dependency in the generic layer:

- archs need to tell what they support through HAVE_PERF_EVENTS_NMI
- Enable magically PERF_EVENTS_NMI if we have PERF_EVENTS and
  HAVE_PERF_EVENTS_NMI.

Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Don Zickus 
Cc: Cyrill Gorcunov

hw-breakpoints: Separate constraint space for data and instruction breakpoints

2010-05-01T02:32:11+00:00

There are two outstanding fashions for archs to implement hardware
breakpoints.

The first is to separate breakpoint address pattern definition
space between data and instruction breakpoints. We then have
typically distinct instruction address breakpoint registers
and data address breakpoint registers, delivered with
separate control registers for data and instruction breakpoints
as well. This is the case of PowerPc and ARM for example.

The second consists in having merged breakpoint address space
definition between data and instruction breakpoint. Address
registers can host either instruction or data address and
the access mode for the breakpoint is defined in a control
register. This is the case of x86 and Super H.

This patch adds a new CONFIG_HAVE_MIXED_BREAKPOINTS_REGS config
that archs can select if they belong to the second case. Those
will have their slot allocation merged for instructions and
data breakpoints.

The others will have a separate slot tracking between data and
instruction breakpoints.

Signed-off-by: Frederic Weisbecker 
Acked-by: Paul Mundt 
Cc: Will Deacon 
Cc: Mahesh Salgaonkar 
Cc: K. Prasad 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Ingo Molnar

kprobes: Hide CONFIG_OPTPROBES and set if arch supports optimized kprobes

2010-03-16T10:07:23+00:00

Hide CONFIG_OPTPROBES and set if the arch supports optimized
kprobes (IOW, HAVE_OPTPROBES=y), since this option doesn't
change the major behavior of kprobes, and workarounds for minor
changes are documented.

Signed-off-by: Masami Hiramatsu 
Cc: systemtap 
Cc: DLE 
Cc: Dieter Ries 
Cc: Ananth N Mavinakayanahalli 
Cc: OGAWA Hirofumi 
Cc: Peter Zijlstra 
Cc: Mike Galbraith 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Cc: Frederic Weisbecker 
LKML-Reference: <20100315170054.31593.3153.stgit@localhost6.localdomain6>
Signed-off-by: Ingo Molnar

Merge branch 'perf-probes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2010-03-05T18:50:22+00:00

* 'perf-probes-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Issue at least one memory barrier in stop_machine_text_poke()
  perf probe: Correct probe syntax on command line help
  perf probe: Add lazy line matching support
  perf probe: Show more lines after last line
  perf probe: Check function address range strictly in line finder
  perf probe: Use libdw callback routines
  perf probe: Use elfutils-libdw for analyzing debuginfo
  perf probe: Rename probe finder functions
  perf probe: Fix bugs in line range finder
  perf probe: Update perf probe document
  perf probe: Do not show --line option without dwarf support
  kprobes: Add documents of jump optimization
  kprobes/x86: Support kprobes jump optimization on x86
  x86: Add text_poke_smp for SMP cross modifying code
  kprobes/x86: Cleanup save/restore registers
  kprobes/x86: Boost probes when reentering
  kprobes: Jump optimization sysctl interface
  kprobes: Introduce kprobes jump optimization
  kprobes: Introduce generic insn_slot framework
  kprobes/x86: Cleanup RELATIVEJUMP_INSTRUCTION to RELATIVEJUMP_OPCODE