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perf/x86/intel/pt: Split ToPA metadata and page layout

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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: Alexander 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexander Shishkin 2019-08-21 15:47:25 +03:00 committed by Ingo Molnar
parent 539f7c26b4
commit 38bb8d77d0
1 changed files with 60 additions and 33 deletions
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93
arch/x86/events/intel/pt.c
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@ -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);