24f1e32c60
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
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/
Core breakpoint API /
/
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Breakpoints perf events
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Breakpoints PMU ---- Debug Register constraints handling
(Part of core breakpoint API)
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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>
132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
#ifndef _LINUX_HW_BREAKPOINT_H
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#define _LINUX_HW_BREAKPOINT_H
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#include <linux/perf_event.h>
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enum {
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HW_BREAKPOINT_LEN_1 = 1,
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HW_BREAKPOINT_LEN_2 = 2,
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HW_BREAKPOINT_LEN_4 = 4,
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HW_BREAKPOINT_LEN_8 = 8,
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};
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enum {
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HW_BREAKPOINT_R = 1,
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HW_BREAKPOINT_W = 2,
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HW_BREAKPOINT_X = 4,
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};
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static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
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{
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return &bp->hw.info;
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}
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static inline unsigned long hw_breakpoint_addr(struct perf_event *bp)
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{
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return bp->attr.bp_addr;
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}
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static inline int hw_breakpoint_type(struct perf_event *bp)
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{
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return bp->attr.bp_type;
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}
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static inline int hw_breakpoint_len(struct perf_event *bp)
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{
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return bp->attr.bp_len;
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}
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#ifdef CONFIG_HAVE_HW_BREAKPOINT
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extern struct perf_event *
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register_user_hw_breakpoint(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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struct task_struct *tsk,
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bool active);
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/* FIXME: only change from the attr, and don't unregister */
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extern struct perf_event *
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modify_user_hw_breakpoint(struct perf_event *bp,
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unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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struct task_struct *tsk,
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bool active);
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/*
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* Kernel breakpoints are not associated with any particular thread.
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*/
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extern struct perf_event *
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register_wide_hw_breakpoint_cpu(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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int cpu,
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bool active);
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extern struct perf_event **
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register_wide_hw_breakpoint(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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bool active);
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extern int register_perf_hw_breakpoint(struct perf_event *bp);
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extern int __register_perf_hw_breakpoint(struct perf_event *bp);
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extern void unregister_hw_breakpoint(struct perf_event *bp);
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extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);
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extern int reserve_bp_slot(struct perf_event *bp);
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extern void release_bp_slot(struct perf_event *bp);
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extern void flush_ptrace_hw_breakpoint(struct task_struct *tsk);
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#else /* !CONFIG_HAVE_HW_BREAKPOINT */
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static inline struct perf_event *
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register_user_hw_breakpoint(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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struct task_struct *tsk,
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bool active) { return NULL; }
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static inline struct perf_event *
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modify_user_hw_breakpoint(struct perf_event *bp,
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unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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struct task_struct *tsk,
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bool active) { return NULL; }
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static inline struct perf_event *
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register_wide_hw_breakpoint_cpu(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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int cpu,
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bool active) { return NULL; }
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static inline struct perf_event **
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register_wide_hw_breakpoint(unsigned long addr,
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int len,
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int type,
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perf_callback_t triggered,
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bool active) { return NULL; }
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static inline int
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register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
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static inline int
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__register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
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static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
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static inline void
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unregister_wide_hw_breakpoint(struct perf_event **cpu_events) { }
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static inline int
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reserve_bp_slot(struct perf_event *bp) {return -ENOSYS; }
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static inline void release_bp_slot(struct perf_event *bp) { }
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static inline void flush_ptrace_hw_breakpoint(struct task_struct *tsk) { }
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#endif /* CONFIG_HAVE_HW_BREAKPOINT */
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#endif /* _LINUX_HW_BREAKPOINT_H */
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