1. 02 Feb, 2010 4 commits
  2. 01 Feb, 2010 30 commits
  3. 31 Jan, 2010 3 commits
  4. 30 Jan, 2010 2 commits
    • Jason Wessel's avatar
      perf, hw_breakpoint, kgdb: Do not take mutex for kernel debugger · 5352ae63
      Jason Wessel authored
      This patch fixes the regression in functionality where the
      kernel debugger and the perf API do not nicely share hw
      breakpoint reservations.
      
      The kernel debugger cannot use any mutex_lock() calls because it
      can start the kernel running from an invalid context.
      
      A mutex free version of the reservation API needed to get
      created for the kernel debugger to safely update hw breakpoint
      reservations.
      
      The possibility for a breakpoint reservation to be concurrently
      processed at the time that kgdb interrupts the system is
      improbable. Should this corner case occur the end user is
      warned, and the kernel debugger will prohibit updating the
      hardware breakpoint reservations.
      
      Any time the kernel debugger reserves a hardware breakpoint it
      will be a system wide reservation.
      Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
      Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Cc: kgdb-bugreport@lists.sourceforge.net
      Cc: K.Prasad <prasad@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Alan Stern <stern@rowland.harvard.edu>
      Cc: torvalds@linux-foundation.org
      LKML-Reference: <1264719883-7285-3-git-send-email-jason.wessel@windriver.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      5352ae63
    • Jason Wessel's avatar
      x86, hw_breakpoints, kgdb: Fix kgdb to use hw_breakpoint API · cc096749
      Jason Wessel authored
      In the 2.6.33 kernel, the hw_breakpoint API is now used for the
      performance event counters.  The hw_breakpoint_handler() now
      consumes the hw breakpoints that were previously set by kgdb
      arch specific code.  In order for kgdb to work in conjunction
      with this core API change, kgdb must use some of the low level
      functions of the hw_breakpoint API to install, uninstall, and
      deal with hw breakpoint reservations.
      
      The kgdb core required a change to call kgdb_disable_hw_debug
      anytime a slave cpu enters kgdb_wait() in order to keep all the
      hw breakpoints in sync as well as to prevent hitting a hw
      breakpoint while kgdb is active.
      
      During the architecture specific initialization of kgdb, it will
      pre-allocate 4 disabled (struct perf event **) structures.  Kgdb
      will use these to manage the capabilities for the 4 hw
      breakpoint registers, per cpu.  Right now the hw_breakpoint API
      does not have a way to ask how many breakpoints are available,
      on each CPU so it is possible that the install of a breakpoint
      might fail when kgdb restores the system to the run state.  The
      intent of this patch is to first get the basic functionality of
      hw breakpoints working and leave it to the person debugging the
      kernel to understand what hw breakpoints are in use and what
      restrictions have been imposed as a result.  Breakpoint
      constraints will be dealt with in a future patch.
      
      While atomic, the x86 specific kgdb code will call
      arch_uninstall_hw_breakpoint() and arch_install_hw_breakpoint()
      to manage the cpu specific hw breakpoints.
      
      The net result of these changes allow kgdb to use the same pool
      of hw_breakpoints that are used by the perf event API, but
      neither knows about future reservations for the available hw
      breakpoint slots.
      Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
      Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Cc: kgdb-bugreport@lists.sourceforge.net
      Cc: K.Prasad <prasad@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Alan Stern <stern@rowland.harvard.edu>
      Cc: torvalds@linux-foundation.org
      LKML-Reference: <1264719883-7285-2-git-send-email-jason.wessel@windriver.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      cc096749
  5. 29 Jan, 2010 1 commit