* precise-event based sampling (PEBS).
*
* It manages:
- * - per-thread and per-cpu allocation of BTS and PEBS
+ * - DS and BTS hardware configuration
* - buffer overflow handling (to be done)
* - buffer access
*
- * It assumes:
- * - get_task_struct on all traced tasks
- * - current is allowed to trace tasks
+ * It does not do:
+ * - security checking (is the caller allowed to trace the task)
+ * - buffer allocation (memory accounting)
*
*
- * Copyright (C) 2007-2008 Intel Corporation.
- * Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
+ * Copyright (C) 2007-2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@intel.com>, 2007-2009
*/
#ifndef _ASM_X86_DS_H
#ifdef CONFIG_X86_DS
struct task_struct;
+struct ds_context;
struct ds_tracer;
struct bts_tracer;
struct pebs_tracer;
typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
+
+/*
+ * A list of features plus corresponding macros to talk about them in
+ * the ds_request function's flags parameter.
+ *
+ * We use the enum to index an array of corresponding control bits;
+ * we use the macro to index a flags bit-vector.
+ */
+enum ds_feature {
+ dsf_bts = 0,
+ dsf_bts_kernel,
+#define BTS_KERNEL (1 << dsf_bts_kernel)
+ /* trace kernel-mode branches */
+
+ dsf_bts_user,
+#define BTS_USER (1 << dsf_bts_user)
+ /* trace user-mode branches */
+
+ dsf_bts_overflow,
+ dsf_bts_max,
+ dsf_pebs = dsf_bts_max,
+
+ dsf_pebs_max,
+ dsf_ctl_max = dsf_pebs_max,
+ dsf_bts_timestamps = dsf_ctl_max,
+#define BTS_TIMESTAMPS (1 << dsf_bts_timestamps)
+ /* add timestamps into BTS trace */
+
+#define BTS_USER_FLAGS (BTS_KERNEL | BTS_USER | BTS_TIMESTAMPS)
+};
+
+
/*
* Request BTS or PEBS
*
* The interrupt threshold is independent from the overflow callback
* to allow users to use their own overflow interrupt handling mechanism.
*
- * task: the task to request recording for;
- * NULL for per-cpu recording on the current cpu
+ * The function might sleep.
+ *
+ * task: the task to request recording for
+ * cpu: the cpu to request recording for
* base: the base pointer for the (non-pageable) buffer;
* size: the size of the provided buffer in bytes
* ovfl: pointer to a function to be called on buffer overflow;
* NULL if cyclic buffer requested
* th: the interrupt threshold in records from the end of the buffer;
* -1 if no interrupt threshold is requested.
+ * flags: a bit-mask of the above flags
*/
-extern struct bts_tracer *ds_request_bts(struct task_struct *task,
- void *base, size_t size,
- bts_ovfl_callback_t ovfl, size_t th);
-extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
- void *base, size_t size,
- pebs_ovfl_callback_t ovfl,
- size_t th);
+extern struct bts_tracer *ds_request_bts_task(struct task_struct *task,
+ void *base, size_t size,
+ bts_ovfl_callback_t ovfl,
+ size_t th, unsigned int flags);
+extern struct bts_tracer *ds_request_bts_cpu(int cpu, void *base, size_t size,
+ bts_ovfl_callback_t ovfl,
+ size_t th, unsigned int flags);
+extern struct pebs_tracer *ds_request_pebs_task(struct task_struct *task,
+ void *base, size_t size,
+ pebs_ovfl_callback_t ovfl,
+ size_t th, unsigned int flags);
+extern struct pebs_tracer *ds_request_pebs_cpu(int cpu,
+ void *base, size_t size,
+ pebs_ovfl_callback_t ovfl,
+ size_t th, unsigned int flags);
/*
* Release BTS or PEBS resources
+ * Suspend and resume BTS or PEBS tracing
*
- * Returns 0 on success; -Eerrno otherwise
+ * Must be called with irq's enabled.
*
* tracer: the tracer handle returned from ds_request_~()
*/
-extern int ds_release_bts(struct bts_tracer *tracer);
-extern int ds_release_pebs(struct pebs_tracer *tracer);
+extern void ds_release_bts(struct bts_tracer *tracer);
+extern void ds_suspend_bts(struct bts_tracer *tracer);
+extern void ds_resume_bts(struct bts_tracer *tracer);
+extern void ds_release_pebs(struct pebs_tracer *tracer);
+extern void ds_suspend_pebs(struct pebs_tracer *tracer);
+extern void ds_resume_pebs(struct pebs_tracer *tracer);
/*
- * Get the (array) index of the write pointer.
- * (assuming an array of BTS/PEBS records)
+ * Release BTS or PEBS resources
+ * Suspend and resume BTS or PEBS tracing
*
- * Returns 0 on success; -Eerrno on error
+ * Cpu tracers must call this on the traced cpu.
+ * Task tracers must call ds_release_~_noirq() for themselves.
+ *
+ * May be called with irq's disabled.
+ *
+ * Returns 0 if successful;
+ * -EPERM if the cpu tracer does not trace the current cpu.
+ * -EPERM if the task tracer does not trace itself.
*
* tracer: the tracer handle returned from ds_request_~()
- * pos (out): will hold the result
*/
-extern int ds_get_bts_index(struct bts_tracer *tracer, size_t *pos);
-extern int ds_get_pebs_index(struct pebs_tracer *tracer, size_t *pos);
+extern int ds_release_bts_noirq(struct bts_tracer *tracer);
+extern int ds_suspend_bts_noirq(struct bts_tracer *tracer);
+extern int ds_resume_bts_noirq(struct bts_tracer *tracer);
+extern int ds_release_pebs_noirq(struct pebs_tracer *tracer);
+extern int ds_suspend_pebs_noirq(struct pebs_tracer *tracer);
+extern int ds_resume_pebs_noirq(struct pebs_tracer *tracer);
+
/*
- * Get the (array) index one record beyond the end of the array.
- * (assuming an array of BTS/PEBS records)
- *
- * Returns 0 on success; -Eerrno on error
+ * The raw DS buffer state as it is used for BTS and PEBS recording.
*
- * tracer: the tracer handle returned from ds_request_~()
- * pos (out): will hold the result
+ * This is the low-level, arch-dependent interface for working
+ * directly on the raw trace data.
*/
-extern int ds_get_bts_end(struct bts_tracer *tracer, size_t *pos);
-extern int ds_get_pebs_end(struct pebs_tracer *tracer, size_t *pos);
+struct ds_trace {
+ /* the number of bts/pebs records */
+ size_t n;
+ /* the size of a bts/pebs record in bytes */
+ size_t size;
+ /* pointers into the raw buffer:
+ - to the first entry */
+ void *begin;
+ /* - one beyond the last entry */
+ void *end;
+ /* - one beyond the newest entry */
+ void *top;
+ /* - the interrupt threshold */
+ void *ith;
+ /* flags given on ds_request() */
+ unsigned int flags;
+};
/*
- * Provide a pointer to the BTS/PEBS record at parameter index.
- * (assuming an array of BTS/PEBS records)
- *
- * The pointer points directly into the buffer. The user is
- * responsible for copying the record.
- *
- * Returns the size of a single record on success; -Eerrno on error
- *
- * tracer: the tracer handle returned from ds_request_~()
- * index: the index of the requested record
- * record (out): pointer to the requested record
+ * An arch-independent view on branch trace data.
*/
-extern int ds_access_bts(struct bts_tracer *tracer,
- size_t index, const void **record);
-extern int ds_access_pebs(struct pebs_tracer *tracer,
- size_t index, const void **record);
+enum bts_qualifier {
+ bts_invalid,
+#define BTS_INVALID bts_invalid
+
+ bts_branch,
+#define BTS_BRANCH bts_branch
+
+ bts_task_arrives,
+#define BTS_TASK_ARRIVES bts_task_arrives
+
+ bts_task_departs,
+#define BTS_TASK_DEPARTS bts_task_departs
+
+ bts_qual_bit_size = 4,
+ bts_qual_max = (1 << bts_qual_bit_size),
+};
+
+struct bts_struct {
+ __u64 qualifier;
+ union {
+ /* BTS_BRANCH */
+ struct {
+ __u64 from;
+ __u64 to;
+ } lbr;
+ /* BTS_TASK_ARRIVES or BTS_TASK_DEPARTS */
+ struct {
+ __u64 clock;
+ pid_t pid;
+ } event;
+ } variant;
+};
+
/*
- * Write one or more BTS/PEBS records at the write pointer index and
- * advance the write pointer.
- *
- * If size is not a multiple of the record size, trailing bytes are
- * zeroed out.
- *
- * May result in one or more overflow notifications.
- *
- * If called during overflow handling, that is, with index >=
- * interrupt threshold, the write will wrap around.
+ * The BTS state.
*
- * An overflow notification is given if and when the interrupt
- * threshold is reached during or after the write.
- *
- * Returns the number of bytes written or -Eerrno.
- *
- * tracer: the tracer handle returned from ds_request_~()
- * buffer: the buffer to write
- * size: the size of the buffer
+ * This gives access to the raw DS state and adds functions to provide
+ * an arch-independent view of the BTS data.
*/
-extern int ds_write_bts(struct bts_tracer *tracer,
- const void *buffer, size_t size);
-extern int ds_write_pebs(struct pebs_tracer *tracer,
- const void *buffer, size_t size);
+struct bts_trace {
+ struct ds_trace ds;
+
+ int (*read)(struct bts_tracer *tracer, const void *at,
+ struct bts_struct *out);
+ int (*write)(struct bts_tracer *tracer, const struct bts_struct *in);
+};
+
/*
- * Reset the write pointer of the BTS/PEBS buffer.
- *
- * Returns 0 on success; -Eerrno on error
+ * The PEBS state.
*
- * tracer: the tracer handle returned from ds_request_~()
+ * This gives access to the raw DS state and the PEBS-specific counter
+ * reset value.
*/
-extern int ds_reset_bts(struct bts_tracer *tracer);
-extern int ds_reset_pebs(struct pebs_tracer *tracer);
+struct pebs_trace {
+ struct ds_trace ds;
+
+ /* the number of valid counters in the below array */
+ unsigned int counters;
+
+#define MAX_PEBS_COUNTERS 4
+ /* the counter reset value */
+ unsigned long long counter_reset[MAX_PEBS_COUNTERS];
+};
+
/*
- * Clear the BTS/PEBS buffer and reset the write pointer.
- * The entire buffer will be zeroed out.
+ * Read the BTS or PEBS trace.
*
- * Returns 0 on success; -Eerrno on error
+ * Returns a view on the trace collected for the parameter tracer.
+ *
+ * The view remains valid as long as the traced task is not running or
+ * the tracer is suspended.
+ * Writes into the trace buffer are not reflected.
*
* tracer: the tracer handle returned from ds_request_~()
*/
-extern int ds_clear_bts(struct bts_tracer *tracer);
-extern int ds_clear_pebs(struct pebs_tracer *tracer);
+extern const struct bts_trace *ds_read_bts(struct bts_tracer *tracer);
+extern const struct pebs_trace *ds_read_pebs(struct pebs_tracer *tracer);
+
/*
- * Provide the PEBS counter reset value.
+ * Reset the write pointer of the BTS/PEBS buffer.
*
* Returns 0 on success; -Eerrno on error
*
- * tracer: the tracer handle returned from ds_request_pebs()
- * value (out): the counter reset value
+ * tracer: the tracer handle returned from ds_request_~()
*/
-extern int ds_get_pebs_reset(struct pebs_tracer *tracer, u64 *value);
+extern int ds_reset_bts(struct bts_tracer *tracer);
+extern int ds_reset_pebs(struct pebs_tracer *tracer);
/*
* Set the PEBS counter reset value.
* Returns 0 on success; -Eerrno on error
*
* tracer: the tracer handle returned from ds_request_pebs()
+ * counter: the index of the counter
* value: the new counter reset value
*/
-extern int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value);
+extern int ds_set_pebs_reset(struct pebs_tracer *tracer,
+ unsigned int counter, u64 value);
/*
* Initialization
struct cpuinfo_x86;
extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
-
-
/*
- * The DS context - part of struct thread_struct.
+ * Context switch work
*/
-#define MAX_SIZEOF_DS (12 * 8)
-
-struct ds_context {
- /* pointer to the DS configuration; goes into MSR_IA32_DS_AREA */
- unsigned char ds[MAX_SIZEOF_DS];
- /* the owner of the BTS and PEBS configuration, respectively */
- struct ds_tracer *owner[2];
- /* use count */
- unsigned long count;
- /* a pointer to the context location inside the thread_struct
- * or the per_cpu context array */
- struct ds_context **this;
- /* a pointer to the task owning this context, or NULL, if the
- * context is owned by a cpu */
- struct task_struct *task;
-};
-
-/* called by exit_thread() to free leftover contexts */
-extern void ds_free(struct ds_context *context);
+extern void ds_switch_to(struct task_struct *prev, struct task_struct *next);
#else /* CONFIG_X86_DS */
struct cpuinfo_x86;
static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
+static inline void ds_switch_to(struct task_struct *prev,
+ struct task_struct *next) {}
#endif /* CONFIG_X86_DS */
#endif /* _ASM_X86_DS_H */
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