227 lines
6.5 KiB
C
227 lines
6.5 KiB
C
/*
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* Debug Store (DS) support
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*
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* This provides a low-level interface to the hardware's Debug Store
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* feature that is used for branch trace store (BTS) and
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* precise-event based sampling (PEBS).
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*
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* It manages:
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* - per-thread and per-cpu allocation of BTS and PEBS
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* - buffer overflow handling (to be done)
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* - buffer access
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*
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* It assumes:
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* - get_task_struct on all traced tasks
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* - current is allowed to trace tasks
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*
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*
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* Copyright (C) 2007-2008 Intel Corporation.
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* Markus Metzger <markus.t.metzger@intel.com>, 2007-2008
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*/
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#ifndef _ASM_X86_DS_H
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#define _ASM_X86_DS_H
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#ifdef CONFIG_X86_DS
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struct task_struct;
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struct ds_tracer;
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struct bts_tracer;
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struct pebs_tracer;
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typedef void (*bts_ovfl_callback_t)(struct bts_tracer *);
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typedef void (*pebs_ovfl_callback_t)(struct pebs_tracer *);
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/*
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* Request BTS or PEBS
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*
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* Due to alignement constraints, the actual buffer may be slightly
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* smaller than the requested or provided buffer.
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*
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* Returns a pointer to a tracer structure on success, or
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* ERR_PTR(errcode) on failure.
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*
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* The interrupt threshold is independent from the overflow callback
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* to allow users to use their own overflow interrupt handling mechanism.
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*
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* task: the task to request recording for;
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* NULL for per-cpu recording on the current cpu
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* base: the base pointer for the (non-pageable) buffer;
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* size: the size of the provided buffer in bytes
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* ovfl: pointer to a function to be called on buffer overflow;
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* NULL if cyclic buffer requested
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* th: the interrupt threshold in records from the end of the buffer;
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* -1 if no interrupt threshold is requested.
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*/
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extern struct bts_tracer *ds_request_bts(struct task_struct *task,
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void *base, size_t size,
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bts_ovfl_callback_t ovfl, size_t th);
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extern struct pebs_tracer *ds_request_pebs(struct task_struct *task,
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void *base, size_t size,
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pebs_ovfl_callback_t ovfl,
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size_t th);
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/*
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* Release BTS or PEBS resources
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*
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* Returns 0 on success; -Eerrno otherwise
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*
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* tracer: the tracer handle returned from ds_request_~()
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*/
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extern int ds_release_bts(struct bts_tracer *tracer);
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extern int ds_release_pebs(struct pebs_tracer *tracer);
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/*
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* Get the (array) index of the write pointer.
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* (assuming an array of BTS/PEBS records)
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* pos (out): will hold the result
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*/
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extern int ds_get_bts_index(struct bts_tracer *tracer, size_t *pos);
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extern int ds_get_pebs_index(struct pebs_tracer *tracer, size_t *pos);
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/*
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* Get the (array) index one record beyond the end of the array.
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* (assuming an array of BTS/PEBS records)
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* pos (out): will hold the result
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*/
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extern int ds_get_bts_end(struct bts_tracer *tracer, size_t *pos);
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extern int ds_get_pebs_end(struct pebs_tracer *tracer, size_t *pos);
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/*
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* Provide a pointer to the BTS/PEBS record at parameter index.
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* (assuming an array of BTS/PEBS records)
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*
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* The pointer points directly into the buffer. The user is
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* responsible for copying the record.
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*
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* Returns the size of a single record on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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* index: the index of the requested record
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* record (out): pointer to the requested record
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*/
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extern int ds_access_bts(struct bts_tracer *tracer,
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size_t index, const void **record);
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extern int ds_access_pebs(struct pebs_tracer *tracer,
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size_t index, const void **record);
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/*
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* Write one or more BTS/PEBS records at the write pointer index and
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* advance the write pointer.
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*
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* If size is not a multiple of the record size, trailing bytes are
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* zeroed out.
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*
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* May result in one or more overflow notifications.
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*
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* If called during overflow handling, that is, with index >=
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* interrupt threshold, the write will wrap around.
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*
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* An overflow notification is given if and when the interrupt
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* threshold is reached during or after the write.
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*
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* Returns the number of bytes written or -Eerrno.
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*
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* tracer: the tracer handle returned from ds_request_~()
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* buffer: the buffer to write
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* size: the size of the buffer
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*/
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extern int ds_write_bts(struct bts_tracer *tracer,
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const void *buffer, size_t size);
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extern int ds_write_pebs(struct pebs_tracer *tracer,
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const void *buffer, size_t size);
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/*
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* Reset the write pointer of the BTS/PEBS buffer.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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*/
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extern int ds_reset_bts(struct bts_tracer *tracer);
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extern int ds_reset_pebs(struct pebs_tracer *tracer);
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/*
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* Clear the BTS/PEBS buffer and reset the write pointer.
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* The entire buffer will be zeroed out.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_~()
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*/
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extern int ds_clear_bts(struct bts_tracer *tracer);
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extern int ds_clear_pebs(struct pebs_tracer *tracer);
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/*
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* Provide the PEBS counter reset value.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_pebs()
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* value (out): the counter reset value
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*/
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extern int ds_get_pebs_reset(struct pebs_tracer *tracer, u64 *value);
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/*
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* Set the PEBS counter reset value.
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*
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* Returns 0 on success; -Eerrno on error
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*
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* tracer: the tracer handle returned from ds_request_pebs()
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* value: the new counter reset value
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*/
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extern int ds_set_pebs_reset(struct pebs_tracer *tracer, u64 value);
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/*
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* Initialization
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*/
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struct cpuinfo_x86;
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extern void __cpuinit ds_init_intel(struct cpuinfo_x86 *);
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/*
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* The DS context - part of struct thread_struct.
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*/
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#define MAX_SIZEOF_DS (12 * 8)
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struct ds_context {
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/* pointer to the DS configuration; goes into MSR_IA32_DS_AREA */
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unsigned char ds[MAX_SIZEOF_DS];
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/* the owner of the BTS and PEBS configuration, respectively */
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struct ds_tracer *owner[2];
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/* use count */
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unsigned long count;
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/* a pointer to the context location inside the thread_struct
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* or the per_cpu context array */
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struct ds_context **this;
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/* a pointer to the task owning this context, or NULL, if the
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* context is owned by a cpu */
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struct task_struct *task;
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};
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/* called by exit_thread() to free leftover contexts */
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extern void ds_free(struct ds_context *context);
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#else /* CONFIG_X86_DS */
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struct cpuinfo_x86;
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static inline void __cpuinit ds_init_intel(struct cpuinfo_x86 *ignored) {}
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#endif /* CONFIG_X86_DS */
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#endif /* _ASM_X86_DS_H */
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