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* hw_breakpoints: Fix percpu build failureFrederic Weisbecker2010-05-041-1/+1
| | | | | | | | | | | | | | | | | | | | Fix this build error: kernel/hw_breakpoint.c:58:1: error: pasting "__pcpu_scope_" and "*" does not give a valid preprocessing token It happens if CONFIG_DEBUG_FORCE_WEAK_PER_CPU, because we concatenate someting with the name and we have the "*" in the name. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> LKML-Reference: <20100503133942.GA5497@nowhere> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Get the number of available registers on boot dynamicallyFrederic Weisbecker2010-05-011-12/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The breakpoint generic layer assumes that archs always know in advance the static number of address registers available to host breakpoints through the HBP_NUM macro. However this is not true for every archs. For example Arm needs to get this information dynamically to handle the compatiblity between different versions. To solve this, this patch proposes to drop the static HBP_NUM macro and let the arch provide the number of available slots through a new hw_breakpoint_slots() function. For archs that have CONFIG_HAVE_MIXED_BREAKPOINTS_REGS selected, it will be called once as the number of registers fits for instruction and data breakpoints together. For the others it will be called first to get the number of instruction breakpoint registers and another time to get the data breakpoint registers, the targeted type is given as a parameter of hw_breakpoint_slots(). Reported-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Handle breakpoint weight in allocation constraintsFrederic Weisbecker2010-05-011-18/+45
| | | | | | | | | | | | | | | | | | | | | | | | | Depending on their nature and on what an arch supports, breakpoints may consume more than one address register. For example a simple absolute address match usually only requires one address register. But an address range match may consume two registers. Currently our slot allocation constraints, that tend to reflect the limited arch's resources, always consider that a breakpoint consumes one slot. Then provide a way for archs to tell us the weight of a breakpoint through a new hw_breakpoint_weight() helper. This weight will be computed against the generic allocation constraints instead of a constant value. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Separate constraint space for data and instruction breakpointsFrederic Weisbecker2010-05-011-27/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Change/Enforce some breakpoints policiesFrederic Weisbecker2010-05-011-2/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current policies of breakpoints in x86 and SH are the following: - task bound breakpoints can only break on userspace addresses - cpu wide breakpoints can only break on kernel addresses The former rule prevents ptrace breakpoints to be set to trigger on kernel addresses, which is good. But as a side effect, we can't breakpoint on kernel addresses for task bound breakpoints. The latter rule simply makes no sense, there is no reason why we can't set breakpoints on userspace while performing cpu bound profiles. We want the following new policies: - task bound breakpoint can set userspace address breakpoints, with no particular privilege required. - task bound breakpoints can set kernelspace address breakpoints but must be privileged to do that. - cpu bound breakpoints can do what they want as they are privileged already. To implement these new policies, this patch checks if we are dealing with a kernel address breakpoint, if so and if the exclude_kernel parameter is set, we tell the user that the breakpoint is invalid, which makes a good generic ptrace protection. If we don't have exclude_kernel, ensure the user has the right privileges as kernel breakpoints are quite sensitive (risk of trap recursion attacks and global performance impacts). [ Paul Mundt: keep addr space check for sh signal delivery and fix double function declaration] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* hw-breakpoints: Check disabled breakpoints againFrederic Weisbecker2010-05-011-11/+1
| | | | | | | | | | | | | | | | | | | | We stopped checking disabled breakpoints because we weren't allowing breakpoints on NULL addresses. And gdb tends to set NULL addresses on inactive breakpoints. But refusing NULL addresses was actually a regression that has been fixed now. There is no reason anymore to not validate inactive breakpoint settings. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Ingo Molnar <mingo@elte.hu>
* Merge branch 'perf/core' into perf/urgentIngo Molnar2010-03-041-5/+5
|\ | | | | | | | | | | Merge reason: Switch from pre-merge topical split to the post-merge urgent track Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * percpu: Add __percpu sparse annotations to hw_breakpointTejun Heo2010-02-271-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add __percpu sparse annotations to hw_breakpoint. These annotations are to make sparse consider percpu variables to be in a different address space and warn if accessed without going through percpu accessors. This patch doesn't affect normal builds. In kernel/hw_breakpoint.c, per_cpu(nr_task_bp_pinned, cpu)'s will trigger spurious noderef related warnings from sparse. Changing it to &per_cpu(nr_task_bp_pinned[0], cpu) will work around the problem but deemed to ugly by the maintainer. Leave it alone until better solution can be found. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: K.Prasad <prasad@linux.vnet.ibm.com> LKML-Reference: <4B7B4B7A.9050902@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* | hw-breakpoints: Remove stub unthrottle callbackFrederic Weisbecker2010-02-281-1/+0
|/ | | | | | | | | | | | | | | | | | | | | We support event unthrottling in breakpoint events. It means that if we have more than sysctl_perf_event_sample_rate/HZ, perf will throttle, ignoring subsequent events until the next tick. So if ptrace exceeds this max rate, it will omit events, which breaks the ptrace determinism that is supposed to report every triggered breakpoints. This is likely to happen if we set sysctl_perf_event_sample_rate to 1. This patch removes support for unthrottling in breakpoint events to break throttling and restore ptrace determinism. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: 2.6.33.x <stable@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Paul Mackerras <paulus@samba.org>
* perf: Make bp_len type to u64 generic across the archMahesh Salgaonkar2010-02-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | Change 'bp_len' type to __u64 to make it work across archs as the s390 architecture watch point length can be upto 2^64. reference: http://lkml.org/lkml/2010/1/25/212 This is an ABI change that is not backward compatible with the previous hardware breakpoint info layout integrated in this development cycle, a rebuilt of perf tools is necessary for versions based on 2.6.33-rc1 - 2.6.33-rc6 to work with a kernel based on this patch. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin <schwidefsky@de.ibm.com> LKML-Reference: <20100130045518.GA20776@in.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* perf, hw_breakpoint, kgdb: Do not take mutex for kernel debuggerJason Wessel2010-01-301-10/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: Jason Wessel <jason.wessel@windriver.com> Acked-by: Frederic 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: Ingo Molnar <mingo@elte.hu>
* hw_breakpoints: Release the bp slot if arch_validate_hwbkpt_settings() fails.Mahesh Salgaonkar2010-01-281-0/+4
| | | | | | | | | | | | | | | | | | | On a given architecture, when hardware breakpoint registration fails due to un-supported access type (read/write/execute), we lose the bp slot since register_perf_hw_breakpoint() does not release the bp slot on failure. Hence, any subsequent hardware breakpoint registration starts failing with 'no space left on device' error. This patch introduces error handling in register_perf_hw_breakpoint() function and releases bp slot on error. Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> LKML-Reference: <20100121125516.GA32521@in.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* Merge branch 'tracing-fixes-for-linus' of ↵Linus Torvalds2009-12-311-3/+7
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tracing: Fix sign fields in ftrace_define_fields_##call() tracing/syscalls: Fix typo in SYSCALL_DEFINE0 tracing/kprobe: Show sign of fields in trace_kprobe format files ksym_tracer: Remove trace_stat ksym_tracer: Fix race when incrementing count ksym_tracer: Fix to allow writing newline to ksym_trace_filter ksym_tracer: Fix to make the tracer work tracing: Kconfig spelling fixes and cleanups tracing: Fix setting tracer specific options Documentation: Update ftrace-design.txt Documentation: Update tracepoint-analysis.txt Documentation: Update mmiotrace.txt
| * ksym_tracer: Fix to make the tracer workLi Zefan2009-12-301-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ksym tracer doesn't work: # echo tasklist_lock:rw- > ksym_trace_filter -bash: echo: write error: No such device It's because we pass to perf_event_create_kernel_counter() a cpu number which is not present. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4B3AF19E.1010201@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | perf_event: Convert to raw_spinlockThomas Gleixner2009-12-141-2/+2
|/ | | | | | | | | Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Modify breakpoints without unregistering themFrederic Weisbecker2009-12-091-10/+32
| | | | | | | | | | | | | | | | | | | | | | | Currently, when ptrace needs to modify a breakpoint, like disabling it, changing its address, type or len, it calls modify_user_hw_breakpoint(). This latter will perform the heavy and racy task of unregistering the old breakpoint and registering a new one. This is racy as someone else might steal the reserved breakpoint slot under us, which is undesired as the breakpoint is only supposed to be modified, sometimes in the middle of a debugging workflow. We don't want our slot to be stolen in the middle. So instead of unregistering/registering the breakpoint, just disable it while we modify its breakpoint fields and re-enable it after if necessary. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Prasad <prasad@linux.vnet.ibm.com> LKML-Reference: <1260347148-5519-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* perf: hw_breakpoints: Fix percpu namespace clashStephen Rothwell2009-12-081-7/+7
| | | | | | | | | | | | | | | | | | | | | | | Today's linux-next build failed with: kernel/hw_breakpoint.c:86: error: 'task_bp_pinned' redeclared as different kind of symbol ... Caused by commit dd17c8f72993f9461e9c19250e3f155d6d99df22 ("percpu: remove per_cpu__ prefix") from the percpu tree interacting with commit 56053170ea2a2c0dc17420e9b94aa3ca51d80408 ("hw-breakpoints: Fix task-bound breakpoint slot allocation") from the tip tree. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <20091208182515.bb6dda4a.sfr@canb.auug.org.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Fix task-bound breakpoint slot allocationFrederic Weisbecker2009-12-071-29/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | Whatever the context nature of a breakpoint, we always perform the following constraint checks before allocating it a slot: - Check the number of pinned breakpoint bound the concerned cpus - Check the max number of task-bound breakpoints that are belonging to a task. - Add both and see if we have a reamining slot for the new breakpoint This is the right thing to do when we are about to register a cpu-only bound breakpoint. But not if we are dealing with a task bound breakpoint. What we want in this case is: - Check the number of pinned breakpoint bound the concerned cpus - Check the number of breakpoints that already belong to the task in which the breakpoint to register is bound to. - Add both This fixes a regression that makes the "firefox -g" command fail to register breakpoints once we deal with a secondary thread. Reported-by: Walt <w41ter@gmail.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com>
* hw-breakpoints: Use overflow handler instead of the event callbackFrederic Weisbecker2009-12-061-12/+5
| | | | | | | | | | | | | | | | struct perf_event::event callback was called when a breakpoint triggers. But this is a rather opaque callback, pretty tied-only to the breakpoint API and not really integrated into perf as it triggers even when we don't overflow. We prefer to use overflow_handler() as it fits into the perf events rules, being called only when we overflow. Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
* hw-breakpoints: Drop callback and task parameters from modify helperFrederic Weisbecker2009-12-061-4/+3
| | | | | | | | | Drop the callback and task parameters from modify_user_hw_breakpoint(). For now we have no user that need to modify a breakpoint to the point of changing its handler or its task context. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>
* hw-breakpoints: Use struct perf_event_attr to define kernel breakpointsFrederic Weisbecker2009-11-271-31/+4
| | | | | | | | | | | | | | | | | Kernel breakpoints are created using functions in which we pass breakpoint parameters as individual variables: address, length and type. Although it fits well for x86, this just does not scale across architectures that may support this api later as these may have more or different needs. Pass in a perf_event_attr structure instead because it is meant to evolve as much as possible into a generic hardware breakpoint parameter structure. Reported-by: K.Prasad <prasad@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1259294154-5197-2-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Use struct perf_event_attr to define user breakpointsFrederic Weisbecker2009-11-271-69/+18
| | | | | | | | | | | | | | | | | In-kernel user breakpoints are created using functions in which we pass breakpoint parameters as individual variables: address, length and type. Although it fits well for x86, this just does not scale across archictectures that may support this api later as these may have more or different needs. Pass in a perf_event_attr structure instead because it is meant to evolve as much as possible into a generic hardware breakpoint parameter structure. Reported-by: K.Prasad <prasad@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1259294154-5197-1-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* kernel/hw_breakpoint.c: Fix local/global shadowingAndrew Morton2009-11-261-6/+6
| | | | | | | | | | | | | | | | | | | | | | | If the new percpu tree is combined with the perf events tree the following new warning triggers: kernel/hw_breakpoint.c: In function 'toggle_bp_task_slot': kernel/hw_breakpoint.c:151: warning: 'task_bp_pinned' is used uninitialized in this function Because it's not valid anymore to define a local variable and a percpu variable (even if it's file scope local) with the same name. Rename the local variable to resolve this. Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <200911260701.nAQ71owx016356@imap1.linux-foundation.org> [ v2: added changelog ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Simplify error handling in breakpoint creation requestsFrederic Weisbecker2009-11-261-2/+2
| | | | | | | | | | | | | | | | This simplifies the error handling when we create a breakpoint. We don't need to check the NULL return value corner case anymore since we have improved perf_event_create_kernel_counter() to always return an error code in the failure case. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Prasad <prasad@linux.vnet.ibm.com> LKML-Reference: <1259210142-5714-3-git-send-regression-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Check the breakpoint params from perf toolsFrederic Weisbecker2009-11-231-1/+10
| | | | | | | | | | | | | | | | | | | | | | | Perf tools create perf events as disabled in the beginning. Breakpoints are then considered like ptrace temporary breakpoints, only meant to reserve a breakpoint slot until we get all the necessary informations from the user. In this case, we don't check the address that is breakpointed as it is NULL in the ptrace case. But perf tools don't have the same purpose, events are created disabled to wait for all events to be created before enabling all of them. We want to check the breakpoint parameters in this case. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Prasad <prasad@linux.vnet.ibm.com> LKML-Reference: <1258987355-8751-2-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoint: Attribute authorship of hw-breakpoint related filesK.Prasad2009-11-231-0/+4
| | | | | | | | | | | | Attribute authorship to developers of hw-breakpoint related files. Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20091123154713.GA5593@in.ibm.com> [ v2: moved it to latest -tip ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Remove x86 specific headers from core fileFrederic Weisbecker2009-11-221-6/+0
| | | | | | | | | | Remove asm/processor.h and asm/debugreg.h as these headers are not used anymore in the hw-breakpoints core file. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com> LKML-Reference: <1258863695-10464-3-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* hw-breakpoints: Fix broken hw-breakpoint sample moduleFrederic Weisbecker2009-11-101-1/+2
| | | | | | | | | The hw-breakpoint sample module has been broken during the hw-breakpoint internals refactoring. Propagate the changes to it. Reported-by: "K. Prasad" <prasad@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* hw-breakpoints: Arbitrate access to pmu following registers constraintsFrederic Weisbecker2009-11-081-6/+205
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Allow or refuse to build a counter using the breakpoints pmu following given constraints. We keep track of the pmu users by using three per cpu variables: - nr_cpu_bp_pinned stores the number of pinned cpu breakpoints counters in the given cpu - nr_bp_flexible stores the number of non-pinned breakpoints counters in the given cpu. - task_bp_pinned stores the number of pinned task breakpoints in a cpu The latter is not a simple counter but gathers the number of tasks that have n pinned breakpoints. Considering HBP_NUM the number of available breakpoint address registers: task_bp_pinned[0] is the number of tasks having 1 breakpoint task_bp_pinned[1] is the number of tasks having 2 breakpoints [...] task_bp_pinned[HBP_NUM - 1] is the number of tasks having the maximum number of registers (HBP_NUM). When a breakpoint counter is created and wants an access to the pmu, we evaluate the following constraints: == Non-pinned counter == - If attached to a single cpu, check: (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu) + max(per_cpu(task_bp_pinned, cpu)))) < HBP_NUM -> If there are already non-pinned counters in this cpu, it means there is already a free slot for them. Otherwise, we check that the maximum number of per task breakpoints (for this cpu) plus the number of per cpu breakpoint (for this cpu) doesn't cover every registers. - If attached to every cpus, check: (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *)) + max(per_cpu(task_bp_pinned, *)))) < HBP_NUM -> This is roughly the same, except we check the number of per cpu bp for every cpu and we keep the max one. Same for the per tasks breakpoints. == Pinned counter == - If attached to a single cpu, check: ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu) + max(per_cpu(task_bp_pinned, cpu))) < HBP_NUM -> Same checks as before. But now the nr_bp_flexible, if any, must keep one register at least (or flexible breakpoints will never be be fed). - If attached to every cpus, check: ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *)) + max(per_cpu(task_bp_pinned, *))) < HBP_NUM Changes in v2: - Counter -> event rename Changes in v5: - Fix unreleased non-pinned task-bound-only counters. We only released it in the first cpu. (Thanks to Paul Mackerras for reporting that) Changes in v6: - Currently, events scheduling are done in this order: cpu context pinned + cpu context non-pinned + task context pinned + task context non-pinned events. Then our current constraints are right theoretically but not in practice, because non-pinned counters may be scheduled before we can apply every possible pinned counters. So consider non-pinned counters as pinned for now. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jan Kiszka <jan.kiszka@web.de> Cc: Jiri Slaby <jirislaby@gmail.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Avi Kivity <avi@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Masami Hiramatsu <mhiramat@redhat.com> Cc: Paul Mundt <lethal@linux-sh.org>
* hw-breakpoints: Rewrite the hw-breakpoints layer on top of perf eventsFrederic Weisbecker2009-11-081-254/+170
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch rebase the implementation of the breakpoints API on top of perf events instances. Each breakpoints are now perf events that handle the register scheduling, thread/cpu attachment, etc.. The new layering is now made as follows: ptrace kgdb ftrace perf syscall \ | / / \ | / / / Core breakpoint API / / | / | / Breakpoints perf events | | Breakpoints PMU ---- Debug Register constraints handling (Part of core breakpoint API) | | Hardware debug registers Reasons of this rewrite: - Use the centralized/optimized pmu registers scheduling, implying an easier arch integration - More powerful register handling: perf attributes (pinned/flexible events, exclusive/non-exclusive, tunable period, etc...) Impact: - New perf ABI: the hardware breakpoints counters - Ptrace breakpoints setting remains tricky and still needs some per thread breakpoints references. Todo (in the order): - Support breakpoints perf counter events for perf tools (ie: implement perf_bpcounter_event()) - Support from perf tools Changes in v2: - Follow the perf "event " rename - The ptrace regression have been fixed (ptrace breakpoint perf events weren't released when a task ended) - Drop the struct hw_breakpoint and store generic fields in perf_event_attr. - Separate core and arch specific headers, drop asm-generic/hw_breakpoint.h and create linux/hw_breakpoint.h - Use new generic len/type for breakpoint - Handle off case: when breakpoints api is not supported by an arch Changes in v3: - Fix broken CONFIG_KVM, we need to propagate the breakpoint api changes to kvm when we exit the guest and restore the bp registers to the host. Changes in v4: - Drop the hw_breakpoint_restore() stub as it is only used by KVM - EXPORT_SYMBOL_GPL hw_breakpoint_restore() as KVM can be built as a module - Restore the breakpoints unconditionally on kvm guest exit: TIF_DEBUG_THREAD doesn't anymore cover every cases of running breakpoints and vcpu->arch.switch_db_regs might not always be set when the guest used debug registers. (Waiting for a reliable optimization) Changes in v5: - Split-up the asm-generic/hw-breakpoint.h moving to linux/hw_breakpoint.h into a separate patch - Optimize the breakpoints restoring while switching from kvm guest to host. We only want to restore the state if we have active breakpoints to the host, otherwise we don't care about messed-up address registers. - Add asm/hw_breakpoint.h to Kbuild - Fix bad breakpoint type in trace_selftest.c Changes in v6: - Fix wrong header inclusion in trace.h (triggered a build error with CONFIG_FTRACE_SELFTEST Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jan Kiszka <jan.kiszka@web.de> Cc: Jiri Slaby <jirislaby@gmail.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Avi Kivity <avi@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Masami Hiramatsu <mhiramat@redhat.com> Cc: Paul Mundt <lethal@linux-sh.org>
* hw-breakpoints: introducing generic hardware breakpoint handler interfacesK.Prasad2009-06-021-0/+378
This patch introduces the generic Hardware Breakpoint interfaces for both user and kernel space requests. This core Api handles the hardware breakpoints through new helpers. It handles the user-space breakpoints and kernel breakpoints in front of arch implementation. One can choose kernel wide breakpoints using the following helpers and passing them a generic struct hw_breakpoint: - register_kernel_hw_breakpoint() - unregister_kernel_hw_breakpoint() - modify_kernel_hw_breakpoint() On the other side, you can choose per task breakpoints. - register_user_hw_breakpoint() - unregister_user_hw_breakpoint() - modify_user_hw_breakpoint() [ fweisbec@gmail.com: fix conflict against perfcounter ] Original-patch-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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