user/sven/linux.git/kernel/debug/debug_core.c, branch v3.1.1

atomic: use

2011-07-26T23:49:47Z

This allows us to move duplicated code in (atomic_inc_not_zero() for now) to Signed-off-by: Arun Sharma Reviewed-by: Eric Dumazet Cc: Ingo Molnar Cc: David Miller Cc: Eric Dumazet Acked-by: Mike Frysinger Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Fix common misspellings

2011-03-31T14:26:23Z

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi

debug_core,x86,blackfin: Clean up hw debug disable API

2010-10-29T18:14:41Z

The kgdb_disable_hw_debug() was an architecture specific function for disabling all hardware breakpoints on a per cpu basis when entering the debug core. This patch will remove the weak function kdbg_disable_hw_debug() and change it into a call back which lives with the rest of hw breakpoint call backs in struct kgdb_arch. Signed-off-by: Dongdong Deng Signed-off-by: Jason Wessel

kdb,debug_core: adjust master cpu switch logic against new debug_core locking

2010-10-22T20:34:13Z

The kdb shell needs to enforce switching back to the original CPU that took the exception before restoring normal kernel execution. Resuming from a different CPU than what took the original exception will cause problems with spin locks that are freed from the a different processor than had taken the lock. The special logic in dbg_cpu_switch() can go away entirely with because the state of what cpus want to be masters or slaves will remain unchanged between entry and exit of the debug_core exception context. Signed-off-by: Jason Wessel

debug_core: refactor locking for master/slave cpus

2010-10-22T20:34:13Z

For quite some time there have been problems with memory barriers and various races with NMI on multi processor systems using the kernel debugger. The algorithm for entering the kernel debug core and resuming kernel execution was racy and had several known edge case problems with attempting to debug something on a heavily loaded system using breakpoints that are hit repeatedly and quickly. The prior "locking" design entry worked as follows: * The atomic counter kgdb_active was used with atomic exchange in order to elect a master cpu out of all the cpus that may have taken a debug exception. * The master cpu increments all elements of passive_cpu_wait[]. * The master cpu issues the round up cpus message. * Each "slave cpu" that enters the debug core increments its own element in cpu_in_kgdb[]. * Each "slave cpu" spins on passive_cpu_wait[] until it becomes 0. * The master cpu debugs the system. The new scheme removes the two arrays of atomic counters and replaces them with 2 single counters. One counter is used to count the number of cpus waiting to become a master cpu (because one or more hit an exception). The second counter is use to indicate how many cpus have entered as slave cpus. The new entry logic works as follows: * One or more cpus enters via kgdb_handle_exception() and increments the masters_in_kgdb. Each cpu attempts to get the spin lock called dbg_master_lock. * The master cpu sets kgdb_active to the current cpu. * The master cpu takes the spinlock dbg_slave_lock. * The master cpu asks to round up all the other cpus. * Each slave cpu that is not already in kgdb_handle_exception() will enter and increment slaves_in_kgdb. Each slave will now spin try_locking on dbg_slave_lock. * The master cpu waits for the sum of masters_in_kgdb and slaves_in_kgdb to be equal to the sum of the online cpus. * The master cpu debugs the system. In the new design the kgdb_active can only be changed while holding dbg_master_lock. Stress testing has not turned up any further entry/exit races that existed in the prior locking design. The prior locking design suffered from atomic variables not being truly atomic (in the capacity as used by kgdb) along with memory barrier races. Signed-off-by: Jason Wessel Acked-by: Dongdong Deng

debug_core: disable hw_breakpoints on all cores in kgdb_cpu_enter()

2010-10-22T20:34:12Z

The slave cpus do not have the hw breakpoints disabled upon entry to the debug_core and as a result could cause unrecoverable recursive faults on badly placed breakpoints, or get out of sync with the arch specific hw breakpoint operations. This patch addresses the problem by invoking kgdb_disable_hw_debug() earlier in kgdb_enter_cpu for each cpu that enters the debug core. The hw breakpoint dis/enable flow should be: master_debug_cpu slave_debug_cpu \ / kgdb_cpu_enter | kgdb_disable_hw_debug --> uninstall pre-enabled hw_breakpoint | do add/rm dis/enable operates to hw_breakpoints on master_debug_cpu.. | correct_hw_break --> correct/install the enabled hw_breakpoint | leave_kgdb Signed-off-by: Dongdong Deng Signed-off-by: Jason Wessel

debug_core: stop rcu warnings on kernel resume

2010-10-22T20:34:10Z

When returning from the kernel debugger reset the rcu jiffies_stall value to prevent the rcu stall detector from sending NMI events which invoke a stack dump for each cpu in the system. Signed-off-by: Jason Wessel

debug_core: move all watch dog syncs to a single function

2010-10-22T20:34:10Z

Move the various clock and watch dog syncs to a single function in advance of adding another sync for the rcu stall detector. Signed-off-by: Jason Wessel

Input: sysrq - drop tty argument from sysrq ops handlers

2010-08-20T05:07:06Z

Noone is using tty argument so let's get rid of it. Acked-by: Alan Cox Acked-by: Jason Wessel Acked-by: Greg Kroah-Hartman Signed-off-by: Dmitry Torokhov

Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb

2010-08-05T22:59:48Z

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb: debug_core,kdb: fix crash when arch does not have single step kgdb,x86: use macro HBP_NUM to replace magic number 4 kgdb,mips: remove unused kgdb_cpu_doing_single_step operations mm,kdb,kgdb: Add a debug reference for the kdb kmap usage KGDB: Remove set but unused newPC ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump ftrace,kdb: Extend kdb to be able to dump the ftrace buffer kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE arm,kgdb: Add ability to trap into debugger on notify_die gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set() gdbstub: Implement gdbserial 'p' and 'P' packets kgdb,arm: Individual register get/set for arm kgdb,mips: Individual register get/set for mips kgdb,x86: Individual register get/set for x86 kgdb,kdb: individual register set and and get API gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol kgdb: remove custom hex_to_bin()implementation