5352ae638e
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>
127 lines
3.6 KiB
C
127 lines
3.6 KiB
C
#ifndef _LINUX_HW_BREAKPOINT_H
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#define _LINUX_HW_BREAKPOINT_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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#ifdef __KERNEL__
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#include <linux/perf_event.h>
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#ifdef CONFIG_HAVE_HW_BREAKPOINT
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static inline void hw_breakpoint_init(struct perf_event_attr *attr)
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{
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memset(attr, 0, sizeof(*attr));
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attr->type = PERF_TYPE_BREAKPOINT;
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attr->size = sizeof(*attr);
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/*
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* As it's for in-kernel or ptrace use, we want it to be pinned
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* and to call its callback every hits.
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*/
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attr->pinned = 1;
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attr->sample_period = 1;
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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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extern struct perf_event *
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register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk);
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/* FIXME: only change from the attr, and don't unregister */
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extern int
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modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr);
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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(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered,
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int cpu);
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extern struct perf_event **
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register_wide_hw_breakpoint(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered);
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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 dbg_reserve_bp_slot(struct perf_event *bp);
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extern int dbg_release_bp_slot(struct perf_event *bp);
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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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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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#else /* !CONFIG_HAVE_HW_BREAKPOINT */
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static inline struct perf_event *
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register_user_hw_breakpoint(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered,
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struct task_struct *tsk) { return NULL; }
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static inline int
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modify_user_hw_breakpoint(struct perf_event *bp,
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struct perf_event_attr *attr) { return -ENOSYS; }
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static inline struct perf_event *
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register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered,
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int cpu) { return NULL; }
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static inline struct perf_event **
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register_wide_hw_breakpoint(struct perf_event_attr *attr,
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perf_overflow_handler_t triggered) { 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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static inline struct arch_hw_breakpoint *counter_arch_bp(struct perf_event *bp)
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{
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return NULL;
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}
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#endif /* CONFIG_HAVE_HW_BREAKPOINT */
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#endif /* __KERNEL__ */
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#endif /* _LINUX_HW_BREAKPOINT_H */
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