238 lines
6.7 KiB
C
238 lines
6.7 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 memory allocation (optional)
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* - buffer overflow handling
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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 parameter tasks
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* - current is allowed to trace parameter 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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#ifdef CONFIG_X86_DS
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#include <linux/types.h>
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#include <linux/init.h>
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struct task_struct;
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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 0 on success; -Eerrno otherwise
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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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* NULL if buffer allocation requested
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* size: the size of the requested or provided buffer
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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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*/
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typedef void (*ds_ovfl_callback_t)(struct task_struct *);
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extern int ds_request_bts(struct task_struct *task, void *base, size_t size,
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ds_ovfl_callback_t ovfl);
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extern int ds_request_pebs(struct task_struct *task, void *base, size_t size,
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ds_ovfl_callback_t ovfl);
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/*
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* Release BTS or PEBS resources
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*
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* Frees buffers allocated on ds_request.
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*
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* Returns 0 on success; -Eerrno otherwise
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*
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* task: the task to release resources for;
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* NULL to release resources for the current cpu
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*/
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extern int ds_release_bts(struct task_struct *task);
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extern int ds_release_pebs(struct task_struct *task);
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/*
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* Return 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 -Eerrno on error
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*
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* task: the task to access;
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* NULL to access the current cpu
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* pos (out): if not NULL, will hold the result
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*/
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extern int ds_get_bts_index(struct task_struct *task, size_t *pos);
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extern int ds_get_pebs_index(struct task_struct *task, size_t *pos);
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/*
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* Return 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 -Eerrno on error
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*
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* task: the task to access;
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* NULL to access the current cpu
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* pos (out): if not NULL, will hold the result
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*/
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extern int ds_get_bts_end(struct task_struct *task, size_t *pos);
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extern int ds_get_pebs_end(struct task_struct *task, 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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* task: the task to access;
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* NULL to access the current cpu
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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 task_struct *task,
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size_t index, const void **record);
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extern int ds_access_pebs(struct task_struct *task,
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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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* task: the task to access;
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* NULL to access the current cpu
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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 task_struct *task,
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const void *buffer, size_t size);
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extern int ds_write_pebs(struct task_struct *task,
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const void *buffer, size_t size);
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/*
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* Same as ds_write_bts/pebs, but omit ownership checks.
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*
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* This is needed to have some other task than the owner of the
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* BTS/PEBS buffer or the parameter task itself write into the
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* respective buffer.
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*/
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extern int ds_unchecked_write_bts(struct task_struct *task,
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const void *buffer, size_t size);
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extern int ds_unchecked_write_pebs(struct task_struct *task,
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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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* task: the task to access;
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* NULL to access the current cpu
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*/
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extern int ds_reset_bts(struct task_struct *task);
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extern int ds_reset_pebs(struct task_struct *task);
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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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* task: the task to access;
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* NULL to access the current cpu
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*/
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extern int ds_clear_bts(struct task_struct *task);
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extern int ds_clear_pebs(struct task_struct *task);
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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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* task: the task to access;
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* NULL to access the current cpu
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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 task_struct *task, 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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* task: the task to access;
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* NULL to access the current cpu
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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 task_struct *task, 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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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;
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/* the owner of the BTS and PEBS configuration, respectively */
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struct task_struct *owner[2];
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/* buffer overflow notification function for BTS and PEBS */
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ds_ovfl_callback_t callback[2];
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/* the original buffer address */
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void *buffer[2];
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/* the number of allocated pages for on-request allocated buffers */
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unsigned int pages[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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#define ds_init_intel(config) do {} while (0)
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#endif /* CONFIG_X86_DS */
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#endif /* ASM_X86__DS_H */
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