Commit 38bb8d77 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Ingo Molnar
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perf/x86/intel/pt: Split ToPA metadata and page layout 



PT uses page sized ToPA tables, where the ToPA table resides at the bottom
and its driver-specific metadata taking up a few words at the top of the
page. The split is currently calculated manually and needs to be redone
every time a field is added to or removed from the metadata structure.
Also, the 32-bit version can be made smaller.

By splitting the table and metadata into separate structures, we are making
the compiler figure out the division of the page.

Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20190821124727.73310-5-alexander.shishkin@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 539f7c26

arch/x86/events/intel/pt.c

+60 −33
Original line number Diff line number Diff line
@@ -545,16 +545,8 @@ static void pt_config_buffer(void *buf, unsigned int topa_idx, 
	wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg);

}



/*

 * Keep ToPA table-related metadata on the same page as the actual table,

 * taking up a few words from the top

 */



#define TENTS_PER_PAGE (((PAGE_SIZE - 40) / sizeof(struct topa_entry)) - 1)



/**

 * struct topa - page-sized ToPA table with metadata at the top

 * @table:	actual ToPA table entries, as understood by PT hardware

 * struct topa - ToPA metadata

 * @list:	linkage to struct pt_buffer's list of tables

 * @phys:	physical address of this page

 * @offset:	offset of the first entry in this table in the buffer
@@ -562,7 +554,6 @@ static void pt_config_buffer(void *buf, unsigned int topa_idx, 
 * @last:	index of the last initialized entry in this table

 */

struct topa {

	struct topa_entry	table[TENTS_PER_PAGE];

	struct list_head	list;

	u64			phys;

	u64			offset;
@@ -570,8 +561,39 @@ struct topa { 
	int			last;

};



/*

 * Keep ToPA table-related metadata on the same page as the actual table,

 * taking up a few words from the top

 */



#define TENTS_PER_PAGE	\

	((PAGE_SIZE - sizeof(struct topa)) / sizeof(struct topa_entry))



/**

 * struct topa_page - page-sized ToPA table with metadata at the top

 * @table:	actual ToPA table entries, as understood by PT hardware

 * @topa:	metadata

 */

struct topa_page {

	struct topa_entry	table[TENTS_PER_PAGE];

	struct topa		topa;

};



static inline struct topa_page *topa_to_page(struct topa *topa)

{

	return container_of(topa, struct topa_page, topa);

}



static inline struct topa_page *topa_entry_to_page(struct topa_entry *te)

{

	return (struct topa_page *)((unsigned long)te & PAGE_MASK);

}



/* make -1 stand for the last table entry */

#define TOPA_ENTRY(t, i) ((i) == -1 ? &(t)->table[(t)->last] : &(t)->table[(i)])

#define TOPA_ENTRY(t, i)				\

	((i) == -1					\

		? &topa_to_page(t)->table[(t)->last]	\

		: &topa_to_page(t)->table[(i)])

#define TOPA_ENTRY_SIZE(t, i) (sizes(TOPA_ENTRY((t), (i))->size))



/**
@@ -584,27 +606,27 @@ struct topa { 
static struct topa *topa_alloc(int cpu, gfp_t gfp)

{

	int node = cpu_to_node(cpu);

	struct topa *topa;

	struct topa_page *tp;

	struct page *p;



	p = alloc_pages_node(node, gfp | __GFP_ZERO, 0);

	if (!p)

		return NULL;



	topa = page_address(p);

	topa->last = 0;

	topa->phys = page_to_phys(p);

	tp = page_address(p);

	tp->topa.last = 0;

	tp->topa.phys = page_to_phys(p);



	/*

	 * In case of singe-entry ToPA, always put the self-referencing END

	 * link as the 2nd entry in the table

	 */

	if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) {

		TOPA_ENTRY(topa, 1)->base = topa->phys >> TOPA_SHIFT;

		TOPA_ENTRY(topa, 1)->end = 1;

		TOPA_ENTRY(&tp->topa, 1)->base = tp->topa.phys;

		TOPA_ENTRY(&tp->topa, 1)->end = 1;

	}



	return topa;

	return &tp->topa;

}



/**
@@ -714,22 +736,23 @@ static void pt_topa_dump(struct pt_buffer *buf) 
	struct topa *topa;



	list_for_each_entry(topa, &buf->tables, list) {

		struct topa_page *tp = topa_to_page(topa);

		int i;



		pr_debug("# table @%p (%016Lx), off %llx size %zx\n", topa->table,

		pr_debug("# table @%p (%016Lx), off %llx size %zx\n", tp->table,

			 topa->phys, topa->offset, topa->size);

		for (i = 0; i < TENTS_PER_PAGE; i++) {

			pr_debug("# entry @%p (%lx sz %u %c%c%c) raw=%16llx\n",

				 &topa->table[i],

				 (unsigned long)topa->table[i].base << TOPA_SHIFT,

				 sizes(topa->table[i].size),

				 topa->table[i].end ?  'E' : ' ',

				 topa->table[i].intr ? 'I' : ' ',

				 topa->table[i].stop ? 'S' : ' ',

				 *(u64 *)&topa->table[i]);

				 &tp->table[i],

				 (unsigned long)tp->table[i].base << TOPA_SHIFT,

				 sizes(tp->table[i].size),

				 tp->table[i].end ?  'E' : ' ',

				 tp->table[i].intr ? 'I' : ' ',

				 tp->table[i].stop ? 'S' : ' ',

				 *(u64 *)&tp->table[i]);

			if ((intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) &&

			     topa->table[i].stop) ||

			    topa->table[i].end)

			     tp->table[i].stop) ||

			    tp->table[i].end)

				break;

		}

	}
@@ -792,7 +815,7 @@ static void pt_update_head(struct pt *pt) 
 */

static void *pt_buffer_region(struct pt_buffer *buf)

{

	return phys_to_virt(buf->cur->table[buf->cur_idx].base << TOPA_SHIFT);

	return phys_to_virt(TOPA_ENTRY(buf->cur, buf->cur_idx)->base << TOPA_SHIFT);

}



/**
@@ -869,9 +892,11 @@ static void pt_handle_status(struct pt *pt) 
static void pt_read_offset(struct pt_buffer *buf)

{

	u64 offset, base_topa;

	struct topa_page *tp;



	rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, base_topa);

	buf->cur = phys_to_virt(base_topa);

	tp = phys_to_virt(base_topa);

	buf->cur = &tp->topa;



	rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, offset);

	/* offset within current output region */
@@ -1021,6 +1046,7 @@ static void pt_buffer_setup_topa_index(struct pt_buffer *buf) 
 */

static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head)

{

	struct topa_page *cur_tp;

	int pg;



	if (buf->snapshot)
@@ -1029,7 +1055,8 @@ static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head) 
	pg = (head >> PAGE_SHIFT) & (buf->nr_pages - 1);

	pg = pt_topa_next_entry(buf, pg);



	buf->cur = (struct topa *)((unsigned long)buf->topa_index[pg] & PAGE_MASK);

	cur_tp = topa_entry_to_page(buf->topa_index[pg]);

	buf->cur = &cur_tp->topa;

	buf->cur_idx = buf->topa_index[pg] - TOPA_ENTRY(buf->cur, 0);

	buf->output_off = head & (pt_buffer_region_size(buf) - 1);
@@ -1294,7 +1321,7 @@ void intel_pt_interrupt(void) 
			return;

		}



		pt_config_buffer(buf->cur->table, buf->cur_idx,

		pt_config_buffer(topa_to_page(buf->cur)->table, buf->cur_idx,

				 buf->output_off);

		pt_config(event);

	}
@@ -1359,7 +1386,7 @@ static void pt_event_start(struct perf_event *event, int mode) 
	WRITE_ONCE(pt->handle_nmi, 1);

	hwc->state = 0;



	pt_config_buffer(buf->cur->table, buf->cur_idx,

	pt_config_buffer(topa_to_page(buf->cur)->table, buf->cur_idx,

			 buf->output_off);

	pt_config(event);

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