/* * Debug Store (DS) support * * This provides a low-level interface to the hardware's Debug Store * feature that is used for branch trace store (BTS) and * precise-event based sampling (PEBS). * * It manages: * - per-thread and per-cpu allocation of BTS and PEBS * - buffer memory allocation (optional) * - buffer overflow handling * - buffer access * * It assumes: * - get_task_struct on all parameter tasks * - current is allowed to trace parameter tasks * * * Copyright (C) 2007-2008 Intel Corporation. * Markus Metzger , 2007-2008 */ #ifndef ASM_X86__DS_H #define ASM_X86__DS_H #ifdef CONFIG_X86_DS #include #include struct task_struct; /* * Request BTS or PEBS * * Due to alignement constraints, the actual buffer may be slightly * smaller than the requested or provided buffer. * * Returns 0 on success; -Eerrno otherwise * * task: the task to request recording for; * NULL for per-cpu recording on the current cpu * base: the base pointer for the (non-pageable) buffer; * NULL if buffer allocation requested * size: the size of the requested or provided buffer * ovfl: pointer to a function to be called on buffer overflow; * NULL if cyclic buffer requested */ typedef void (*ds_ovfl_callback_t)(struct task_struct *); extern int ds_request_bts(struct task_struct *task, void *base, size_t size, ds_ovfl_callback_t ovfl); extern int ds_request_pebs(struct task_struct *task, void *base, size_t size, ds_ovfl_callback_t ovfl); /* * Release BTS or PEBS resources * * Frees buffers allocated on ds_request. * * Returns 0 on success; -Eerrno otherwise * * task: the task to release resources for; * NULL to release resources for the current cpu */ extern int ds_release_bts(struct task_struct *task); extern int ds_release_pebs(struct task_struct *task); /* * Return the (array) index of the write pointer. * (assuming an array of BTS/PEBS records) * * Returns -Eerrno on error * * task: the task to access; * NULL to access the current cpu * pos (out): if not NULL, will hold the result */ extern int ds_get_bts_index(struct task_struct *task, size_t *pos); extern int ds_get_pebs_index(struct task_struct *task, size_t *pos); /* * Return the (array) index one record beyond the end of the array. * (assuming an array of BTS/PEBS records) * * Returns -Eerrno on error * * task: the task to access; * NULL to access the current cpu * pos (out): if not NULL, will hold the result */ extern int ds_get_bts_end(struct task_struct *task, size_t *pos); extern int ds_get_pebs_end(struct task_struct *task, size_t *pos); /* * 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 * * task: the task to access; * NULL to access the current cpu * index: the index of the requested record * record (out): pointer to the requested record */ extern int ds_access_bts(struct task_struct *task, size_t index, const void **record); extern int ds_access_pebs(struct task_struct *task, size_t index, const void **record); /* * 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. * * 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. * * task: the task to access; * NULL to access the current cpu * buffer: the buffer to write * size: the size of the buffer */ extern int ds_write_bts(struct task_struct *task, const void *buffer, size_t size); extern int ds_write_pebs(struct task_struct *task, const void *buffer, size_t size); /* * Same as ds_write_bts/pebs, but omit ownership checks. * * This is needed to have some other task than the owner of the * BTS/PEBS buffer or the parameter task itself write into the * respective buffer. */ extern int ds_unchecked_write_bts(struct task_struct *task, const void *buffer, size_t size); extern int ds_unchecked_write_pebs(struct task_struct *task, const void *buffer, size_t size); /* * Reset the write pointer of the BTS/PEBS buffer. * * Returns 0 on success; -Eerrno on error * * task: the task to access; * NULL to access the current cpu */ extern int ds_reset_bts(struct task_struct *task); extern int ds_reset_pebs(struct task_struct *task); /* * Clear the BTS/PEBS buffer and reset the write pointer. * The entire buffer will be zeroed out. * * Returns 0 on success; -Eerrno on error * * task: the task to access; * NULL to access the current cpu */ extern int ds_clear_bts(struct task_struct *task); extern int ds_clear_pebs(struct task_struct *task); /* * Provide the PEBS counter reset value. * * Returns 0 on success; -Eerrno on error * * task: the task to access; * NULL to access the current cpu * value (out): the counter reset value */ extern int ds_get_pebs_reset(struct task_struct *task, u64 *value); /* * Set the PEBS counter reset value. * * Returns 0 on success; -Eerrno on error * * task: the task to access; * NULL to access the current cpu * value: the new counter reset value */ extern int ds_set_pebs_reset(struct task_struct *task, u64 value); /* * Initialization */ struct cpuinfo_x86; extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *); /* * The DS context - part of struct thread_struct. */ struct ds_context { /* pointer to the DS configuration; goes into MSR_IA32_DS_AREA */ unsigned char *ds; /* the owner of the BTS and PEBS configuration, respectively */ struct task_struct *owner[2]; /* buffer overflow notification function for BTS and PEBS */ ds_ovfl_callback_t callback[2]; /* the original buffer address */ void *buffer[2]; /* the number of allocated pages for on-request allocated buffers */ unsigned int pages[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); #else /* CONFIG_X86_DS */ #define ds_init_intel(config) do {} while (0) #endif /* CONFIG_X86_DS */ #endif /* ASM_X86__DS_H */