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2013-02-13workqueue: reimplement is_chained_work() using current_wq_worker()Tejun Heo
is_chained_work() was added before current_wq_worker() and implemented its own ham-fisted way of finding out whether %current is a workqueue worker - it iterates through all possible workers. Drop the custom implementation and reimplement using current_wq_worker(). Signed-off-by: Tejun Heo <tj@kernel.org>
2013-02-13workqueue: fix is_chained_work() regressionTejun Heo
c9e7cf273f ("workqueue: move busy_hash from global_cwq to worker_pool") incorrectly converted is_chained_work() to use get_gcwq() inside for_each_gcwq_cpu() while removing get_gcwq(). As cwq might not exist for all possible workqueue CPUs, @cwq can be NULL and the following cwq deferences can lead to oops. Fix it by using for_each_cwq_cpu() instead, which is the better one to use anyway as we only need to check pools that the wq is associated with. Signed-off-by: Tejun Heo <tj@kernel.org>
2013-02-12tracing/syscalls: Allow archs to ignore tracing compat syscallsSteven Rostedt
The tracing of ia32 compat system calls has been a bit of a pain as they use different system call numbers than the 64bit equivalents. I wrote a simple 'lls' program that lists files. I compiled it as a i686 ELF binary and ran it under a x86_64 box. This is the result: echo 0 > /debug/tracing/tracing_on echo 1 > /debug/tracing/events/syscalls/enable echo 1 > /debug/tracing/tracing_on ; ./lls ; echo 0 > /debug/tracing/tracing_on grep lls /debug/tracing/trace [.. skipping calls before TS_COMPAT is set ...] lls-1127 [005] d... 936.409188: sys_recvfrom(fd: 0, ubuf: 4d560fc4, size: 0, flags: 8048034, addr: 8, addr_len: f7700420) lls-1127 [005] d... 936.409190: sys_recvfrom -> 0x8a77000 lls-1127 [005] d... 936.409211: sys_lgetxattr(pathname: 0, name: 1000, value: 3, size: 22) lls-1127 [005] d... 936.409215: sys_lgetxattr -> 0xf76ff000 lls-1127 [005] d... 936.409223: sys_dup2(oldfd: 4d55ae9b, newfd: 4) lls-1127 [005] d... 936.409228: sys_dup2 -> 0xfffffffffffffffe lls-1127 [005] d... 936.409236: sys_newfstat(fd: 4d55b085, statbuf: 80000) lls-1127 [005] d... 936.409242: sys_newfstat -> 0x3 lls-1127 [005] d... 936.409243: sys_removexattr(pathname: 3, name: ffcd0060) lls-1127 [005] d... 936.409244: sys_removexattr -> 0x0 lls-1127 [005] d... 936.409245: sys_lgetxattr(pathname: 0, name: 19614, value: 1, size: 2) lls-1127 [005] d... 936.409248: sys_lgetxattr -> 0xf76e5000 lls-1127 [005] d... 936.409248: sys_newlstat(filename: 3, statbuf: 19614) lls-1127 [005] d... 936.409249: sys_newlstat -> 0x0 lls-1127 [005] d... 936.409262: sys_newfstat(fd: f76fb588, statbuf: 80000) lls-1127 [005] d... 936.409279: sys_newfstat -> 0x3 lls-1127 [005] d... 936.409279: sys_close(fd: 3) lls-1127 [005] d... 936.421550: sys_close -> 0x200 lls-1127 [005] d... 936.421558: sys_removexattr(pathname: 3, name: ffcd00d0) lls-1127 [005] d... 936.421560: sys_removexattr -> 0x0 lls-1127 [005] d... 936.421569: sys_lgetxattr(pathname: 4d564000, name: 1b1abc, value: 5, size: 802) lls-1127 [005] d... 936.421574: sys_lgetxattr -> 0x4d564000 lls-1127 [005] d... 936.421575: sys_capget(header: 4d70f000, dataptr: 1000) lls-1127 [005] d... 936.421580: sys_capget -> 0x0 lls-1127 [005] d... 936.421580: sys_lgetxattr(pathname: 4d710000, name: 3000, value: 3, size: 812) lls-1127 [005] d... 936.421589: sys_lgetxattr -> 0x4d710000 lls-1127 [005] d... 936.426130: sys_lgetxattr(pathname: 4d713000, name: 2abc, value: 3, size: 32) lls-1127 [005] d... 936.426141: sys_lgetxattr -> 0x4d713000 lls-1127 [005] d... 936.426145: sys_newlstat(filename: 3, statbuf: f76ff3f0) lls-1127 [005] d... 936.426146: sys_newlstat -> 0x0 lls-1127 [005] d... 936.431748: sys_lgetxattr(pathname: 0, name: 1000, value: 3, size: 22) Obviously I'm not calling newfstat with a fd of 4d55b085. The calls are obviously incorrect, and confusing. Other efforts have been made to fix this: https://lkml.org/lkml/2012/3/26/367 But the real solution is to rewrite the syscall internals and come up with a fixed solution. One that doesn't require all the kluge that the current solution has. Thus for now, instead of outputting incorrect data, simply ignore them. With this patch the changes now have: #> grep lls /debug/tracing/trace #> Compat system calls simply are not traced. If users need compat syscalls, then they should just use the raw syscall tracepoints. For an architecture to make their compat syscalls ignored, it must define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS (done in asm/ftrace.h) and also define an arch_trace_is_compat_syscall() function that will return true if the current task should ignore tracing the syscall. I want to stress that this change does not affect actual syscalls in any way, shape or form. It is only used within the tracing system and doesn't interfere with the syscall logic at all. The changes are consolidated nicely into trace_syscalls.c and asm/ftrace.h. I had to make one small modification to asm/thread_info.h and that was to remove the include of asm/ftrace.h. As asm/ftrace.h required the current_thread_info() it was causing include hell. That include was added back in 2008 when the function graph tracer was added: commit caf4b323 "tracing, x86: add low level support for ftrace return tracing" It does not need to be included there. Link: http://lkml.kernel.org/r/1360703939.21867.99.camel@gandalf.local.home Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2013-02-12kernel/pid.c: reenable interrupts when alloc_pid() fails because init has exitedEric W. Biederman
We're forgetting to reenable local interrupts on an error path. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Reported-by: Josh Boyer <jwboyer@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-12Merge branch 'timers/for-arm' into timers/coreThomas Gleixner
2013-02-12clockevents: Fix generic broadcast for FEAT_C3STOPMark Rutland
Commit 12ad100046: "clockevents: Add generic timer broadcast function" made tick_device_uses_broadcast set up the generic broadcast function for dummy devices (where !tick_device_is_functional(dev)), but neglected to set up the broadcast function for devices that stop in low power states (with the CLOCK_EVT_FEAT_C3STOP flag). When these devices enter low power states they will not have the generic broadcast function assigned, and will bring down the system when an attempt is made to broadcast to them. This patch ensures that the broadcast function is also assigned for devices which require broadcast in low power states. Reported-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Stephen Warren <swarren@nvidia.com> Cc: linux-arm-kernel@lists.infradead.org Cc: nico@linaro.org Cc: Marc.Zyngier@arm.com Cc: Will.Deacon@arm.com Cc: santosh.shilimkar@ti.com Cc: john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-02-09Merge tag 'v3.8-rc6' into next/cleanupOlof Johansson
Linux 3.8-rc6
2013-02-09suspend: enable freeze timeout configuration through sysLi Fei
At present, the value of timeout for freezing is 20s, which is meaningless in case that one thread is frozen with mutex locked and another thread is trying to lock the mutex, as this time of freezing will fail unavoidably. And if there is no new wakeup event registered, the system will waste at most 20s for such meaningless trying of freezing. With this patch, the value of timeout can be configured to smaller value, so such meaningless trying of freezing will be aborted in earlier time, and later freezing can be also triggered in earlier time. And more power will be saved. In normal case on mobile phone, it costs real little time to freeze processes. On some platform, it only costs about 20ms to freeze user space processes and 10ms to freeze kernel freezable threads. Signed-off-by: Liu Chuansheng <chuansheng.liu@intel.com> Signed-off-by: Li Fei <fei.li@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-09PM: Introduce suspend state PM_SUSPEND_FREEZEZhang Rui
PM_SUSPEND_FREEZE state is a general state that does not need any platform specific support, it equals frozen processes + suspended devices + idle processors. Compared with PM_SUSPEND_MEMORY, PM_SUSPEND_FREEZE saves less power because the system is still in a running state. PM_SUSPEND_FREEZE has less resume latency because it does not touch BIOS, and the processors are in idle state. Compared with RTPM/idle, PM_SUSPEND_FREEZE saves more power as 1. the processor has longer sleep time because processes are frozen. The deeper c-state the processor supports, more power saving we can get. 2. PM_SUSPEND_FREEZE uses system suspend code path, thus we can get more power saving from the devices that does not have good RTPM support. This state is useful for 1) platforms that do not have STR, or have a broken STR. 2) platforms that have an extremely low power idle state, which can be used to replace STR. The following describes how PM_SUSPEND_FREEZE state works. 1. echo freeze > /sys/power/state 2. the processes are frozen. 3. all the devices are suspended. 4. all the processors are blocked by a wait queue 5. all the processors idles and enters (Deep) c-state. 6. an interrupt fires. 7. a processor is woken up and handles the irq. 8. if it is a general event, a) the irq handler runs and quites. b) goto step 4. 9. if it is a real wake event, say, power button pressing, keyboard touch, mouse moving, a) the irq handler runs and activate the wakeup source b) wakeup_source_activate() notifies the wait queue. c) system starts resuming from PM_SUSPEND_FREEZE 10. all the devices are resumed. 11. all the processes are unfrozen. 12. system is back to working. Known Issue: The wakeup of this new PM_SUSPEND_FREEZE state may behave differently from the previous suspend state. Take ACPI platform for example, there are some GPEs that only enabled when the system is in sleep state, to wake the system backk from S3/S4. But we are not touching these GPEs during transition to PM_SUSPEND_FREEZE. This means we may lose some wake event. But on the other hand, as we do not disable all the Interrupts during PM_SUSPEND_FREEZE, we may get some extra "wakeup" Interrupts, that are not available for S3/S4. The patches has been tested on an old Sony laptop, and here are the results: Average Power: 1. RPTM/idle for half an hour: 14.8W, 12.6W, 14.1W, 12.5W, 14.4W, 13.2W, 12.9W 2. Freeze for half an hour: 11W, 10.4W, 9.4W, 11.3W 10.5W 3. RTPM/idle for three hours: 11.6W 4. Freeze for three hours: 10W 5. Suspend to Memory: 0.5~0.9W Average Resume Latency: 1. RTPM/idle with a black screen: (From pressing keyboard to screen back) Less than 0.2s 2. Freeze: (From pressing power button to screen back) 2.50s 3. Suspend to Memory: (From pressing power button to screen back) 4.33s >From the results, we can see that all the platforms should benefit from this patch, even if it does not have Low Power S0. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-09kprobes: fix wait_for_kprobe_optimizer()Tejun Heo
wait_for_kprobe_optimizer() seems largely broken. It uses optimizer_comp which is never re-initialized, so wait_for_kprobe_optimizer() will never wait for anything once kprobe_optimizer() finishes all pending jobs for the first time. Also, aside from completion, delayed_work_pending() is %false once kprobe_optimizer() starts execution and wait_for_kprobe_optimizer() won't wait for it. Reimplement it so that it flushes optimizing_work until [un]optimizing_lists are empty. Note that this also makes optimizing_work execute immediately if someone's waiting for it, which is the nicer behavior. Only compile tested. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: "David S. Miller" <davem@davemloft.net>
2013-02-08time, Fix setting of hardware clock in NTP codePrarit Bhargava
At init time, if the system time is "warped" forward in warp_clock() it will differ from the hardware clock by sys_tz.tz_minuteswest. This time difference is not taken into account when ntp updates the hardware clock, and this causes the system time to jump forward by this offset every reboot. The kernel must take this offset into account when writing the system time to the hardware clock in the ntp code. This patch adds persistent_clock_is_local which indicates that an offset has been applied in warp_clock() and accounts for the "warp" before writing the hardware clock. x86 does not have this problem as rtc writes are software limited to a +/-15 minute window relative to the current rtc time. Other arches, such as powerpc, however do a full synchronization of the system time to the rtc and will see this problem. [v2]: generated against tip/timers/core Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2013-02-08Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
Synchronize with 'net' in order to sort out some l2tp, wireless, and ipv6 GRE fixes that will be built on top of in 'net-next'. Signed-off-by: David S. Miller <davem@davemloft.net>
2013-02-08uprobes/perf: Avoid uprobe_apply() whenever possibleOleg Nesterov
uprobe_perf_open/close call the costly uprobe_apply() every time, we can avoid it if: - "nr_systemwide != 0" is not changed. - There is another process/thread with the same ->mm. - copy_proccess() does inherit_event(). dup_mmap() preserves the inserted breakpoints. - event->attr.enable_on_exec == T, we can rely on uprobe_mmap() called by exec/mmap paths. - tp_target is exiting. Only _close() checks PF_EXITING, I don't think TRACE_REG_PERF_OPEN can hit the dying task too often. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes/perf: Teach trace_uprobe/perf code to use UPROBE_HANDLER_REMOVEOleg Nesterov
Change uprobe_trace_func() and uprobe_perf_func() to return "int". Change uprobe_dispatcher() to return "trace_ret | perf_ret" although this is not needed, currently TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive. The only functional change is that uprobe_perf_func() checks the filtering too and returns UPROBE_HANDLER_REMOVE if nobody wants to trace current. Testing: # perf probe -x /lib/libc.so.6 syscall # perf record -e probe_libc:syscall -i perl -e 'fork; syscall -1 for 1..10; wait' # perf report --show-total-period 100.00% 10 perl libc-2.8.so [.] syscall Before this patch: # cat /sys/kernel/debug/tracing/uprobe_profile /lib/libc.so.6 syscall 20 A child process doesn't have a counter, but still it hits this breakoint "copied" by dup_mmap(). After the patch: # cat /sys/kernel/debug/tracing/uprobe_profile /lib/libc.so.6 syscall 11 The child process hits this int3 only once and does unapply_uprobe(). Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes/perf: Teach trace_uprobe/perf code to pre-filterOleg Nesterov
Finally implement uprobe_perf_filter() which checks ->nr_systemwide or ->perf_events to figure out whether we need to insert the breakpoint. uprobe_perf_open/close are changed to do uprobe_apply(true/false) when the new perf event comes or goes away. Note that currently this is very suboptimal: - uprobe_register() called by TRACE_REG_PERF_REGISTER becomes a heavy nop, consumer->filter() always returns F at this stage. As it was already discussed we need uprobe_register_only() to avoid the costly register_for_each_vma() when possible. - uprobe_apply() is oftenly overkill. Unless "nr_systemwide != 0" changes we need uprobe_apply_mm(), unapply_uprobe() is almost what we need. - uprobe_apply() can be simply avoided sometimes, see the next changes. Testing: # perf probe -x /lib/libc.so.6 syscall # perl -e 'syscall -1 while 1' & [1] 530 # perf record -e probe_libc:syscall perl -e 'syscall -1 for 1..10; sleep 1' # perf report --show-total-period 100.00% 10 perl libc-2.8.so [.] syscall Before this patch: # cat /sys/kernel/debug/tracing/uprobe_profile /lib/libc.so.6 syscall 79291 A huge ->nrhit == 79291 reflects the fact that the background process 530 constantly hits this breakpoint too, even if doesn't contribute to the output. After the patch: # cat /sys/kernel/debug/tracing/uprobe_profile /lib/libc.so.6 syscall 10 This shows that only the target process was punished by int3. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes/perf: Teach trace_uprobe/perf code to track the active perf_event'sOleg Nesterov
Introduce "struct trace_uprobe_filter" which records the "active" perf_event's attached to ftrace_event_call. For the start we simply use list_head, we can optimize this later if needed. For example, we do not really need to record an event with ->parent != NULL, we can rely on parent->child_list. And we can certainly do some optimizations for the case when 2 events have the same ->tp_target or tp_target->mm. Change trace_uprobe_register() to process TRACE_REG_PERF_OPEN/CLOSE and add/del this perf_event to the list. We can probably avoid any locking, but lets start with the "obvioulsy correct" trace_uprobe_filter->rwlock which protects everything. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes: Introduce uprobe_apply()Oleg Nesterov
Currently it is not possible to change the filtering constraints after uprobe_register(), so a consumer can not, say, start to trace a task/mm which was previously filtered out, or remove the no longer needed bp's. Introduce uprobe_apply() which simply does register_for_each_vma() again to consult uprobe_consumer->filter() and install/remove the breakpoints. The only complication is that register_for_each_vma() can no longer assume that uprobe->consumers should be consulter if is_register == T, so we change it to accept "struct uprobe_consumer *new" instead. Unlike uprobe_register(), uprobe_apply(true) doesn't do "unregister" if register_for_each_vma() fails, it is up to caller to handle the error. Note: we probably need to cleanup the current interface, it is strange that uprobe_apply/unregister need inode/offset. We should either change uprobe_register() to return "struct uprobe *", or add a private ->uprobe member in uprobe_consumer. And in the long term uprobe_apply() should take a single argument, uprobe or consumer, even "bool add" should go away. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08perf: Introduce hw_perf_event->tp_target and ->tp_listOleg Nesterov
sys_perf_event_open()->perf_init_event(event) is called before find_get_context(event), this means that event->ctx == NULL when class->reg(TRACE_REG_PERF_REGISTER/OPEN) is called and thus it can't know if this event is per-task or system-wide. This patch adds hw_perf_event->tp_target for PERF_TYPE_TRACEPOINT, this is analogous to PERF_TYPE_BREAKPOINT/bp_target we already have. The patch also moves ->bp_target up so that it can overlap with the new member, this can help the compiler to generate the better code. trace_uprobe_register() will use it for prefiltering to avoid the unnecessary breakpoints in mm's we do not want to trace. ->tp_target doesn't have its own reference, but we can rely on the fact that either sys_perf_event_open() holds a reference, or it is equal to event->ctx->task. So this pointer is always valid until free_event(). Also add the "struct list_head tp_list" into this union. It is not strictly necessary, but it can simplify the next changes and we can add it for free. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes/perf: Always increment trace_uprobe->nhitOleg Nesterov
Move tu->nhit++ from uprobe_trace_func() to uprobe_dispatcher(). ->nhit counts how many time we hit the breakpoint inserted by this uprobe, we do not want to loose this info if uprobe was enabled by sys_perf_event_open(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes/tracing: Kill uprobe_trace_consumer, embed uprobe_consumer into ↵Oleg Nesterov
trace_uprobe trace_uprobe->consumer and "struct uprobe_trace_consumer" add the unnecessary indirection and complicate the code for no reason. This patch simply embeds uprobe_consumer into "struct trace_uprobe", all other changes only fix the compilation errors. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes/tracing: Introduce is_trace_uprobe_enabled()Oleg Nesterov
probe_event_enable/disable() check tu->consumer != NULL to avoid the wrong uprobe_register/unregister(). We are going to kill this pointer and "struct uprobe_trace_consumer", so we add the new helper, is_trace_uprobe_enabled(), which can rely on TP_FLAG_TRACE/TP_FLAG_PROFILE instead. Note: the current logic doesn't look optimal, it is not clear why TP_FLAG_TRACE/TP_FLAG_PROFILE are mutually exclusive, we will probably change this later. Also kill the unused TP_FLAG_UPROBE. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes/tracing: Ensure inode != NULL in create_trace_uprobe()Oleg Nesterov
probe_event_enable/disable() check tu->inode != NULL at the start. This is ugly, if igrab() can fail create_trace_uprobe() should not succeed and "postpone" the failure. And S_ISREG(inode->i_mode) check added by d24d7dbf is not safe. Note: alloc_uprobe() should probably check igrab() != NULL as well. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes/tracing: Fully initialize uprobe_trace_consumer before uprobe_register()Oleg Nesterov
probe_event_enable() does uprobe_register() and only after that sets utc->tu and tu->consumer/flags. This can race with uprobe_dispatcher() which can miss these assignments or see them out of order. Nothing really bad can happen, but this doesn't look clean/safe. And this does not allow to use uprobe_consumer->filter() we are going to add, it is called by uprobe_register() and it needs utc->tu. Change this code to initialize everything before uprobe_register(), and reset tu->consumer/flags if it fails. We can't race with event_disable(), the caller holds event_mutex, and if we could the code would be wrong anyway. In fact I think uprobe_trace_consumer should die, it buys nothing but complicates the code. We can simply add uprobe_consumer into trace_uprobe. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes/tracing: Fix dentry/mount leak in create_trace_uprobe()Oleg Nesterov
create_trace_uprobe() does kern_path() to find ->d_inode, but forgets to do path_put(). We can do this right after igrab(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Add exports for module useJosh Stone
The original pull message for uprobes (commit 654443e2) noted: This tree includes uprobes support in 'perf probe' - but SystemTap (and other tools) can take advantage of user probe points as well. In order to actually be usable in module-based tools like SystemTap, the interface needs to be exported. This patch first adds the obvious exports for uprobe_register and uprobe_unregister. Then it also adds one for task_user_regset_view, which is necessary to get the correct state of userspace registers. Signed-off-by: Josh Stone <jistone@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08uprobes: Kill the bogus IS_ERR_VALUE(xol_vaddr) checkOleg Nesterov
utask->xol_vaddr is either zero or valid, remove the bogus IS_ERR_VALUE() check in xol_free_insn_slot(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Do not allocate current->utask unnecessaryOleg Nesterov
handle_swbp() does get_utask() before can_skip_sstep() for no reason, we do not need ->utask if can_skip_sstep() succeeds. Move get_utask() to pre_ssout() who actually starts to use it. Move the initialization of utask->active_uprobe/state as well. This way the whole initialization is consolidated in pre_ssout(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com>
2013-02-08uprobes: Fix utask->xol_vaddr leak in pre_ssout()Oleg Nesterov
pre_ssout() should do xol_free_insn_slot() if arch_uprobe_pre_xol() fails, otherwise nobody will free the allocated slot. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Do not play with utask in xol_get_insn_slot()Oleg Nesterov
pre_ssout()->xol_get_insn_slot() path is confusing and buggy. This patch cleanups the code, the next one fixes the bug. Change xol_get_insn_slot() to only allocate the slot and do nothing more, move the initialization of utask->xol_vaddr/vaddr into pre_ssout(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Turn add_utask() into get_utask()Oleg Nesterov
Rename add_utask() into get_utask() and change it to allocate on demand to simplify the caller. Like get_xol_area() it will have more users. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Fold xol_alloc_area() into get_xol_area()Oleg Nesterov
Currently only xol_get_insn_slot() does get_xol_area() + xol_alloc_area(), but this will have more users and we do not want to copy-and-paste this code. This patch simply moves xol_alloc_area() into get_xol_area() to simplify the current and future code. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Move alloc_page() from xol_add_vma() to xol_alloc_area()Oleg Nesterov
Move alloc_page() from xol_add_vma() to xol_alloc_area() to cleanup the code. This separates the memory allocations and consolidates the -EALREADY cleanups and the error handling. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Change handle_swbp() to expose bp_vaddr to handler_chain()Oleg Nesterov
Change handle_swbp() to set regs->ip = bp_vaddr in advance, this is what consumer->handler() needs but uprobe_get_swbp_addr() is not exported. This also simplifies the code and makes it more consistent across the supported architectures. handle_swbp() becomes the only caller of uprobe_get_swbp_addr(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
2013-02-08uprobes: Teach handler_chain() to filter out the probed taskOleg Nesterov
Currrently the are 2 problems with pre-filtering: 1. It is not possible to add/remove a task (mm) after uprobe_register() 2. A forked child inherits all breakpoints and uprobe_consumer can not control this. This patch does the first step to improve the filtering. handler_chain() removes the breakpoints installed by this uprobe from current->mm if all handlers return UPROBE_HANDLER_REMOVE. Note that handler_chain() relies on ->register_rwsem to avoid the race with uprobe_register/unregister which can add/del a consumer, or even remove and then insert the new uprobe at the same address. Perhaps we will add uprobe_apply_mm(uprobe, mm, is_register) and teach copy_mm() to do filter(UPROBE_FILTER_FORK), but I think this change makes sense anyway. Note: instead of checking the retcode from uc->handler, we could add uc->filter(UPROBE_FILTER_BPHIT). But I think this is not optimal to call 2 hooks in a row. This buys nothing, and if handler/filter do something nontrivial they will probably do the same work twice. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Reintroduce uprobe_consumer->filter()Oleg Nesterov
Finally add uprobe_consumer->filter() and change consumer_filter() to actually call this method. Note that ->filter() accepts mm_struct, not task_struct. Because: 1. We do not have for_each_mm_user(mm, task). 2. Even if we implement for_each_mm_user(), ->filter() can use it itself. 3. It is not clear who will actually need this interface to do the "nontrivial" filtering. Another argument is "enum uprobe_filter_ctx", consumer->filter() can use it to figure out why/where it was called. For example, perhaps we can add UPROBE_FILTER_PRE_REGISTER used by build_map_info() to quickly "nack" the unwanted mm's. In this case consumer should know that it is called under ->i_mmap_mutex. See the previous discussion at http://marc.info/?t=135214229700002 Perhaps we should pass more arguments, vma/vaddr? Note: this patch obviously can't help to filter out the child created by fork(), this will be addressed later. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Rationalize the usage of filter_chain()Oleg Nesterov
filter_chain() was added into install_breakpoint/remove_breakpoint to simplify the initial changes but this is sub-optimal. This patch shifts the callsite to the callers, register_for_each_vma() and uprobe_mmap(). This way: - It will be easier to add the new arguments. This is the main reason, we can do more optimizations later. - register_for_each_vma(is_register => true) can be optimized, we only need to consult the new consumer. The previous consumers were already asked when they called uprobe_register(). This patch also moves the MMF_HAS_UPROBES check from remove_breakpoint(), this allows to avoid the potentionally costly filter_chain(). Note that register_for_each_vma(is_register => false) doesn't really need to take ->consumer_rwsem, but I don't think it makes sense to optimize this and introduce filter_chain_lockless(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill uprobes_mutex[], separate alloc_uprobe() and __uprobe_register()Oleg Nesterov
uprobe_register() and uprobe_unregister() are the only users of mutex_lock(uprobes_hash(inode)), and the only reason why we can't simply remove it is that we need to ensure that delete_uprobe() is not possible after alloc_uprobe() and before consumer_add(). IOW, we need to ensure that when we take uprobe->register_rwsem this uprobe is still valid and we didn't race with _unregister() which called delete_uprobe() in between. With this patch uprobe_register() simply checks uprobe_is_active() and retries if it hits this very unlikely race. uprobes_mutex[] is no longer needed and can be removed. There is another reason for this change, prepare_uprobe() should be folded into alloc_uprobe() and we do not want to hold the extra locks around read_mapping_page/etc. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Introduce uprobe_is_active()Oleg Nesterov
The lifetime of uprobe->rb_node and uprobe->inode is not refcounted, delete_uprobe() is called when we detect that uprobe has no consumers, and it would be deadly wrong to do this twice. Change delete_uprobe() to WARN() if it was already called. We use RB_CLEAR_NODE() to mark uprobe "inactive", then RB_EMPTY_NODE() can be used to detect this case. RB_EMPTY_NODE() is not used directly, we add the trivial helper for the next change. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill uprobe_events, use RB_EMPTY_ROOT() insteadOleg Nesterov
uprobe_events counts the number of uprobes in uprobes_tree but it is used as a boolean. We can use RB_EMPTY_ROOT() instead. Probably no_uprobe_events() added by this patch can have more callers, say, mmf_recalc_uprobes(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Anton Arapov <anton@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill uprobe->copy_mutexOleg Nesterov
Now that ->register_rwsem is safe under ->mmap_sem we can kill ->copy_mutex and abuse down_write(&uprobe->consumer_rwsem). This makes prepare_uprobe() even more ugly, but we should kill it anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill UPROBE_RUN_HANDLER flagOleg Nesterov
Simply remove UPROBE_RUN_HANDLER and the corresponding code. It can only help if uprobe has a single consumer, and in fact it is no longer needed after handler_chain() was changed to use ->register_rwsem, we simply can not race with uprobe_register(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Change filter_chain() to iterate ->consumers listOleg Nesterov
Now that it safe to use ->consumer_rwsem under ->mmap_sem we can almost finish the implementation of filter_chain(). It still lacks the actual uc->filter(...) call but othewrwise it is ready, just it pretends that ->filter() always returns true. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Introduce uprobe->register_rwsemOleg Nesterov
Introduce uprobe->register_rwsem. It is taken for writing around __uprobe_register/unregister. Change handler_chain() to use this sem rather than consumer_rwsem. The main reason for this change is that we have the nasty problem with mmap_sem/consumer_rwsem dependency. filter_chain() needs to protect uprobe->consumers like handler_chain(), but they can not use the same lock. filter_chain() can be called under ->mmap_sem (currently this is always true), but we want to allow ->handler() to play with the probed task's memory, and this needs ->mmap_sem. Alternatively we could use srcu, but synchronize_srcu() is very slow and ->register_rwsem allows us to do more. In particular, we can teach handler_chain() to do remove_breakpoint() if this bp is "nacked" by all consumers, we know that we can't race with the new consumer which does uprobe_register(). See also the next patches. uprobes_mutex[] is almost ready to die. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: _register() should always do register_for_each_vma(true)Oleg Nesterov
To support the filtering uprobe_register() should do register_for_each_vma(true) every time the new consumer comes, we need to install the previously nacked breakpoints. Note: - uprobes_mutex[] should die, what it actually protects is alloc_uprobe(). - UPROBE_RUN_HANDLER should die too, obviously it can't work unless uprobe has a single consumer. The consumer should serialize with _register/_unregister itself. Or this flag should live in uprobe_consumer->state. - Perhaps we can do some optimizations later. For example, if filter_chain() never returns false uprobe can record this fact and avoid the unnecessary register_for_each_vma(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: _unregister() should always do register_for_each_vma(false)Oleg Nesterov
uprobe_unregister() removes the breakpoints only if the last consumer goes away. To support the filtering it should do this every time, we want to remove the breakpoints which nobody else want to keep. Note: given that filter_chain() is not actually implemented, this patch itself doesn't change the behaviour yet, register_for_each_vma(false) is a heavy "nop" unless there are no more consumers. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Introduce filter_chain()Oleg Nesterov
Add the new helper filter_chain(). Currently it is only placeholder, the comment explains what is should do. We will change it later to consult every consumer to decide whether we need to install the swbp. Until then it works as if any consumer returns true, this matches the current behavior. Change install_breakpoint() to call filter_chain() instead of checking uprobe->consumers != NULL. We obviously need this, and this equally closes the race with _unregister(). Change remove_breakpoint() to call this helper too. Currently this is pointless because remove_breakpoint() is only called when the last consumer goes away, but we will change this. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill uprobe_consumer->filter()Oleg Nesterov
uprobe_consumer->filter() is pointless in its current form, kill it. We will add it back, but with the different signature/semantics. Perhaps we will even re-introduce the callsite in handler_chain(), but not to just skip uc->handler(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Kill the pointless inode/uc checks in register/unregisterOleg Nesterov
register/unregister verifies that inode/uc != NULL. For what? This really looks like "hide the potential problem", the caller should pass the valid data. register() also checks uc->next == NULL, probably to prevent the double-register but the caller can do other stupid/wrong things. If we do this check, then we should document that uc->next should be cleared before register() and add BUG_ON(). Also add the small comment about the i_size_read() check. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08uprobes: Move __set_bit(UPROBE_SKIP_SSTEP) into alloc_uprobe()Oleg Nesterov
Cosmetic. __set_bit(UPROBE_SKIP_SSTEP) is the part of initialization, it is not clear why it is set in insert_uprobe(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08Revert "Revert "console: implement lockdep support for console_lock""Dave Airlie
This reverts commit ff0d05bf73620eb7dc8aee7423e992ef87870bdf. Now that we have all the locking fixes in place, we can revert the revert. This re-enables lockdep tracking for the console lock, daee779718a319ff9f83e1ba3339334ac650bb22. Signed-off-by: Dave Airlie <airlied@redhat.com>