1. 28 9月, 2013 1 次提交
  2. 14 8月, 2013 1 次提交
  3. 04 7月, 2013 1 次提交
    • P
      mm: soft-dirty bits for user memory changes tracking · 0f8975ec
      Pavel Emelyanov 提交于
      The soft-dirty is a bit on a PTE which helps to track which pages a task
      writes to.  In order to do this tracking one should
      
        1. Clear soft-dirty bits from PTEs ("echo 4 > /proc/PID/clear_refs)
        2. Wait some time.
        3. Read soft-dirty bits (55'th in /proc/PID/pagemap2 entries)
      
      To do this tracking, the writable bit is cleared from PTEs when the
      soft-dirty bit is.  Thus, after this, when the task tries to modify a
      page at some virtual address the #PF occurs and the kernel sets the
      soft-dirty bit on the respective PTE.
      
      Note, that although all the task's address space is marked as r/o after
      the soft-dirty bits clear, the #PF-s that occur after that are processed
      fast.  This is so, since the pages are still mapped to physical memory,
      and thus all the kernel does is finds this fact out and puts back
      writable, dirty and soft-dirty bits on the PTE.
      
      Another thing to note, is that when mremap moves PTEs they are marked
      with soft-dirty as well, since from the user perspective mremap modifies
      the virtual memory at mremap's new address.
      Signed-off-by: NPavel Emelyanov <xemul@parallels.com>
      Cc: Matt Mackall <mpm@selenic.com>
      Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
      Cc: Glauber Costa <glommer@parallels.com>
      Cc: Marcelo Tosatti <mtosatti@redhat.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0f8975ec
  4. 05 5月, 2013 1 次提交
    • K
      idle: Fix hlt/nohlt command-line handling in new generic idle · 485cf5da
      Kevin Hilman 提交于
      commit d1669912 (idle: Implement generic idle function) added a new
      generic idle along with support for hlt/nohlt command line options to
      override default idle loop behavior.  However, the command-line
      processing is never compiled.
      
      The command-line handling is wrapped by CONFIG_GENERIC_IDLE_POLL_SETUP
      and arches that use this feature select it in their Kconfigs.
      However, no Kconfig definition was created for this option, so it is
      never enabled, and therefore command-line override of the idle-loop
      behavior is broken after migrating to the generic idle loop.
      
      To fix, add a Kconfig definition for GENERIC_IDLE_POLL_SETUP.
      
      Tested on ARM (OMAP4/Panda) which enables the command-line overrides
      by default.
      Signed-off-by: NKevin Hilman <khilman@linaro.org>
      Reviewed-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Magnus Damm <magnus.damm@gmail.com>
      Cc: linux-arm-kernel@lists.infradead.org
      Cc: linaro-kernel@lists.linaro.org
      Link: http://lkml.kernel.org/r/1366849153-25564-1-git-send-email-khilman@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      485cf5da
  5. 17 4月, 2013 1 次提交
  6. 08 4月, 2013 1 次提交
  7. 15 3月, 2013 1 次提交
    • R
      CONFIG_SYMBOL_PREFIX: cleanup. · b92021b0
      Rusty Russell 提交于
      We have CONFIG_SYMBOL_PREFIX, which three archs define to the string
      "_".  But Al Viro broke this in "consolidate cond_syscall and
      SYSCALL_ALIAS declarations" (in linux-next), and he's not the first to
      do so.
      
      Using CONFIG_SYMBOL_PREFIX is awkward, since we usually just want to
      prefix it so something.  So various places define helpers which are
      defined to nothing if CONFIG_SYMBOL_PREFIX isn't set:
      
      1) include/asm-generic/unistd.h defines __SYMBOL_PREFIX.
      2) include/asm-generic/vmlinux.lds.h defines VMLINUX_SYMBOL(sym)
      3) include/linux/export.h defines MODULE_SYMBOL_PREFIX.
      4) include/linux/kernel.h defines SYMBOL_PREFIX (which differs from #7)
      5) kernel/modsign_certificate.S defines ASM_SYMBOL(sym)
      6) scripts/modpost.c defines MODULE_SYMBOL_PREFIX
      7) scripts/Makefile.lib defines SYMBOL_PREFIX on the commandline if
         CONFIG_SYMBOL_PREFIX is set, so that we have a non-string version
         for pasting.
      
      (arch/h8300/include/asm/linkage.h defines SYMBOL_NAME(), too).
      
      Let's solve this properly:
      1) No more generic prefix, just CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX.
      2) Make linux/export.h usable from asm.
      3) Define VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR().
      4) Make everyone use them.
      Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      Reviewed-by: NJames Hogan <james.hogan@imgtec.com>
      Tested-by: James Hogan <james.hogan@imgtec.com> (metag)
      b92021b0
  8. 13 3月, 2013 1 次提交
  9. 04 3月, 2013 1 次提交
  10. 03 3月, 2013 1 次提交
    • J
      Add HAVE_64BIT_ALIGNED_ACCESS · c19fa94a
      James Hogan 提交于
      On 64 bit architectures with no efficient unaligned access, padding and
      explicit alignment must be added in various places to prevent unaligned
      64bit accesses (such as taskstats and trace ring buffer).
      
      However this also needs to apply to 32 bit architectures with 64 bit
      accesses requiring alignment such as metag.
      
      This is solved by adding a new Kconfig symbol HAVE_64BIT_ALIGNED_ACCESS
      which defaults to 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS, and can be
      explicitly selected by METAG and any other relevant architectures. This
      can be used in various places to determine whether 64bit alignment is
      required.
      Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Eric Paris <eparis@redhat.com>
      Cc: Will Drewry <wad@chromium.org>
      c19fa94a
  11. 28 2月, 2013 1 次提交
  12. 14 2月, 2013 1 次提交
    • A
      burying unused conditionals · d64008a8
      Al Viro 提交于
      __ARCH_WANT_SYS_RT_SIGACTION,
      __ARCH_WANT_SYS_RT_SIGSUSPEND,
      __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND,
      __ARCH_WANT_COMPAT_SYS_SCHED_RR_GET_INTERVAL - not used anymore
      CONFIG_GENERIC_{SIGALTSTACK,COMPAT_RT_SIG{ACTION,QUEUEINFO,PENDING,PROCMASK}} -
      can be assumed always set.
      d64008a8
  13. 04 2月, 2013 7 次提交
  14. 22 1月, 2013 1 次提交
  15. 20 12月, 2012 2 次提交
  16. 18 12月, 2012 1 次提交
  17. 06 12月, 2012 1 次提交
    • D
      byteorder: allow arch to opt to use GCC intrinsics for byteswapping · cf66bb93
      David Woodhouse 提交于
      Since GCC 4.4, there have been __builtin_bswap32() and __builtin_bswap16()
      intrinsics. A __builtin_bswap16() came a little later (4.6 for PowerPC,
      48 for other platforms).
      
      By using these instead of the inline assembler that most architectures
      have in their __arch_swabXX() macros, we let the compiler see what's
      actually happening. The resulting code should be at least as good, and
      much *better* in the cases where it can be combined with a nearby load
      or store, using a load-and-byteswap or store-and-byteswap instruction
      (e.g. lwbrx/stwbrx on PowerPC, movbe on Atom).
      
      When GCC is sufficiently recent *and* the architecture opts in to using
      the intrinsics by setting CONFIG_ARCH_USE_BUILTIN_BSWAP, they will be
      used in preference to the __arch_swabXX() macros. An architecture which
      does not set ARCH_USE_BUILTIN_BSWAP will continue to use its own
      hand-crafted macros.
      Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
      Acked-by: NH. Peter Anvin <hpa@linux.intel.com>
      cf66bb93
  18. 01 12月, 2012 1 次提交
    • F
      context_tracking: New context tracking susbsystem · 91d1aa43
      Frederic Weisbecker 提交于
      Create a new subsystem that probes on kernel boundaries
      to keep track of the transitions between level contexts
      with two basic initial contexts: user or kernel.
      
      This is an abstraction of some RCU code that use such tracking
      to implement its userspace extended quiescent state.
      
      We need to pull this up from RCU into this new level of indirection
      because this tracking is also going to be used to implement an "on
      demand" generic virtual cputime accounting. A necessary step to
      shutdown the tick while still accounting the cputime.
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Li Zhong <zhong@linux.vnet.ibm.com>
      Cc: Gilad Ben-Yossef <gilad@benyossef.com>
      Reviewed-by: NSteven Rostedt <rostedt@goodmis.org>
      [ paulmck: fix whitespace error and email address. ]
      Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      91d1aa43
  19. 29 11月, 2012 1 次提交
    • A
      generic sys_fork / sys_vfork / sys_clone · d2125043
      Al Viro 提交于
      ... and get rid of idiotic struct pt_regs * in asm-generic/syscalls.h
      prototypes of the same, while we are at it.  Eventually we want those
      in linux/syscalls.h, of course, but that'll have to wait a bit.
      
      Note that there are *three* variants of sys_clone() order of arguments.
      Braindamage galore...
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      d2125043
  20. 13 10月, 2012 1 次提交
    • A
      infrastructure for saner ret_from_kernel_thread semantics · a74fb73c
      Al Viro 提交于
      * allow kernel_execve() leave the actual return to userland to
      caller (selected by CONFIG_GENERIC_KERNEL_EXECVE).  Callers
      updated accordingly.
      * architecture that does select GENERIC_KERNEL_EXECVE in its
      Kconfig should have its ret_from_kernel_thread() do this:
      	call schedule_tail
      	call the callback left for it by copy_thread(); if it ever
      returns, that's because it has just done successful kernel_execve()
      	jump to return from syscall
      IOW, its only difference from ret_from_fork() is that it does call the
      callback.
      * such an architecture should also get rid of ret_from_kernel_execve()
      and __ARCH_WANT_KERNEL_EXECVE
      
      This is the last part of infrastructure patches in that area - from
      that point on work on different architectures can live independently.
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      a74fb73c
  21. 09 10月, 2012 1 次提交
    • G
      thp, x86: introduce HAVE_ARCH_TRANSPARENT_HUGEPAGE · 15626062
      Gerald Schaefer 提交于
      Cleanup patch in preparation for transparent hugepage support on s390.
      Adding new architectures to the TRANSPARENT_HUGEPAGE config option can
      make the "depends" line rather ugly, like "depends on (X86 || (S390 &&
      64BIT)) && MMU".
      
      This patch adds a HAVE_ARCH_TRANSPARENT_HUGEPAGE instead.  x86 already has
      MMU "def_bool y", so the MMU check is superfluous there and
      HAVE_ARCH_TRANSPARENT_HUGEPAGE can be selected in arch/x86/Kconfig.
      Signed-off-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: Andi Kleen <ak@linux.intel.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Hillf Danton <dhillf@gmail.com>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      15626062
  22. 01 10月, 2012 1 次提交
    • A
      preparation for generic kernel_thread() · 2aa3a7f8
      Al Viro 提交于
      Let architectures select GENERIC_KERNEL_THREAD and have their copy_thread()
      treat NULL regs as "it came from kernel_thread(), sp argument contains
      the function new thread will be calling and stack_size - the argument for
      that function".  Switching the architectures begins shortly...
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      2aa3a7f8
  23. 28 9月, 2012 1 次提交
    • D
      Make most arch asm/module.h files use asm-generic/module.h · 786d35d4
      David Howells 提交于
      Use the mapping of Elf_[SPE]hdr, Elf_Addr, Elf_Sym, Elf_Dyn, Elf_Rel/Rela,
      ELF_R_TYPE() and ELF_R_SYM() to either the 32-bit version or the 64-bit version
      into asm-generic/module.h for all arches bar MIPS.
      
      Also, use the generic definition mod_arch_specific where possible.
      
      To this end, I've defined three new config bools:
      
       (*) HAVE_MOD_ARCH_SPECIFIC
      
           Arches define this if they don't want to use the empty generic
           mod_arch_specific struct.
      
       (*) MODULES_USE_ELF_RELA
      
           Arches define this if their modules can contain RELA records.  This causes
           the Elf_Rela mapping to be emitted and allows apply_relocate_add() to be
           defined by the arch rather than have the core emit an error message.
      
       (*) MODULES_USE_ELF_REL
      
           Arches define this if their modules can contain REL records.  This causes
           the Elf_Rel mapping to be emitted and allows apply_relocate() to be
           defined by the arch rather than have the core emit an error message.
      
      Note that it is possible to allow both REL and RELA records: m68k and mips are
      two arches that do this.
      
      With this, some arch asm/module.h files can be deleted entirely and replaced
      with a generic-y marker in the arch Kbuild file.
      
      Additionally, I have removed the bits from m32r and score that handle the
      unsupported type of relocation record as that's now handled centrally.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Acked-by: NSam Ravnborg <sam@ravnborg.org>
      Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      786d35d4
  24. 26 9月, 2012 1 次提交
    • F
      rcu: Settle config for userspace extended quiescent state · 2b1d5024
      Frederic Weisbecker 提交于
      Create a new config option under the RCU menu that put
      CPUs under RCU extended quiescent state (as in dynticks
      idle mode) when they run in userspace. This require
      some contribution from architectures to hook into kernel
      and userspace boundaries.
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Alessio Igor Bogani <abogani@kernel.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Avi Kivity <avi@redhat.com>
      Cc: Chris Metcalf <cmetcalf@tilera.com>
      Cc: Christoph Lameter <cl@linux.com>
      Cc: Geoff Levand <geoff@infradead.org>
      Cc: Gilad Ben Yossef <gilad@benyossef.com>
      Cc: Hakan Akkan <hakanakkan@gmail.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Josh Triplett <josh@joshtriplett.org>
      Cc: Kevin Hilman <khilman@ti.com>
      Cc: Max Krasnyansky <maxk@qualcomm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Stephen Hemminger <shemminger@vyatta.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
      2b1d5024
  25. 25 9月, 2012 1 次提交
    • F
      cputime: Make finegrained irqtime accounting generally available · fdf9c356
      Frederic Weisbecker 提交于
      There is no known reason for this option to be unavailable on other
      archs than x86. They just need to call enable_sched_clock_irqtime()
      if they have a sufficiently finegrained clock to make it working.
      
      Move it to the general option and let the user choose between
      it and pure tick based or virtual cputime accounting.
      
      Note that virtual cputime accounting already performs a finegrained
      irqtime accounting. CONFIG_IRQ_TIME_ACCOUNTING is a kind of middle ground
      between tick and virtual based accounting. So CONFIG_IRQ_TIME_ACCOUNTING
      and CONFIG_VIRT_CPU_ACCOUNTING are mutually exclusive choices.
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      fdf9c356
  26. 17 8月, 2012 1 次提交
    • F
      cputime: Generalize CONFIG_VIRT_CPU_ACCOUNTING · b952741c
      Frederic Weisbecker 提交于
      S390, ia64 and powerpc all define their own version
      of CONFIG_VIRT_CPU_ACCOUNTING. Generalize the config
      and its description to a single place to avoid
      duplication.
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      b952741c
  27. 10 8月, 2012 2 次提交
    • J
      perf: Add ability to attach user stack dump to sample · c5ebcedb
      Jiri Olsa 提交于
      Introducing PERF_SAMPLE_STACK_USER sample type bit to trigger the dump
      of the user level stack on sample. The size of the dump is specified by
      sample_stack_user value.
      
      Being able to dump parts of the user stack, starting from the stack
      pointer, will be useful to make a post mortem dwarf CFI based stack
      unwinding.
      
      Added HAVE_PERF_USER_STACK_DUMP config option to determine if the
      architecture provides user stack dump on perf event samples.  This needs
      access to the user stack pointer which is not unified across
      architectures. Enabling this for x86 architecture.
      Signed-off-by: NJiri Olsa <jolsa@redhat.com>
      Original-patch-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: "Frank Ch. Eigler" <fche@redhat.com>
      Cc: Arun Sharma <asharma@fb.com>
      Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
      Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
      Cc: Cyrill Gorcunov <gorcunov@openvz.org>
      Cc: Frank Ch. Eigler <fche@redhat.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Robert Richter <robert.richter@amd.com>
      Cc: Stephane Eranian <eranian@google.com>
      Cc: Tom Zanussi <tzanussi@gmail.com>
      Cc: Ulrich Drepper <drepper@gmail.com>
      Link: http://lkml.kernel.org/r/1344345647-11536-6-git-send-email-jolsa@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      c5ebcedb
    • J
      perf: Unified API to record selective sets of arch registers · c5e63197
      Jiri Olsa 提交于
      This brings a new API to help the selective dump of registers on event
      sampling, and its implementation for x86 arch.
      
      Added HAVE_PERF_REGS config option to determine if the architecture
      provides perf registers ABI.
      
      The information about desired registers will be passed in u64 mask.
      It's up to the architecture to map the registers into the mask bits.
      
      For the x86 arch implementation, both 32 and 64 bit registers bits are
      defined within single enum to ensure 64 bit system can provide register
      dump for compat task if needed in the future.
      Original-patch-by: NFrederic Weisbecker <fweisbec@gmail.com>
      [ Added missing linux/errno.h include ]
      Signed-off-by: NJiri Olsa <jolsa@redhat.com>
      Cc: "Frank Ch. Eigler" <fche@redhat.com>
      Cc: Arun Sharma <asharma@fb.com>
      Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
      Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
      Cc: Cyrill Gorcunov <gorcunov@openvz.org>
      Cc: Frank Ch. Eigler <fche@redhat.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Robert Richter <robert.richter@amd.com>
      Cc: Stephane Eranian <eranian@google.com>
      Cc: Tom Zanussi <tzanussi@gmail.com>
      Cc: Ulrich Drepper <drepper@gmail.com>
      Link: http://lkml.kernel.org/r/1344345647-11536-2-git-send-email-jolsa@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      c5e63197
  28. 31 7月, 2012 1 次提交
  29. 21 5月, 2012 1 次提交
  30. 08 5月, 2012 2 次提交
  31. 07 5月, 2012 1 次提交
    • S
      tracing: Provide trace events interface for uprobes · f3f096cf
      Srikar Dronamraju 提交于
      Implements trace_event support for uprobes. In its current form
      it can be used to put probes at a specified offset in a file and
      dump the required registers when the code flow reaches the
      probed address.
      
      The following example shows how to dump the instruction pointer
      and %ax a register at the probed text address.  Here we are
      trying to probe zfree in /bin/zsh:
      
       # cd /sys/kernel/debug/tracing/
       # cat /proc/`pgrep  zsh`/maps | grep /bin/zsh | grep r-xp
       00400000-0048a000 r-xp 00000000 08:03 130904 /bin/zsh
       # objdump -T /bin/zsh | grep -w zfree
       0000000000446420 g    DF .text  0000000000000012  Base
       zfree # echo 'p /bin/zsh:0x46420 %ip %ax' > uprobe_events
       # cat uprobe_events
       p:uprobes/p_zsh_0x46420 /bin/zsh:0x0000000000046420
       # echo 1 > events/uprobes/enable
       # sleep 20
       # echo 0 > events/uprobes/enable
       # cat trace
       # tracer: nop
       #
       #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
       #              | |       |          |         |
                    zsh-24842 [006] 258544.995456: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
                    zsh-24842 [007] 258545.000270: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
                    zsh-24842 [002] 258545.043929: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
                    zsh-24842 [004] 258547.046129: p_zsh_0x46420: (0x446420) arg1=446421 arg2=79
      Signed-off-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
      Acked-by: NSteven Rostedt <rostedt@goodmis.org>
      Acked-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
      Cc: Jim Keniston <jkenisto@linux.vnet.ibm.com>
      Cc: Linux-mm <linux-mm@kvack.org>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Andi Kleen <andi@firstfloor.org>
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
      Cc: Anton Arapov <anton@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Link: http://lkml.kernel.org/r/20120411103043.GB29437@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f3f096cf