- 根目录:
- arch
- x86
- kernel
- cpu
- perf_event_intel_pt.c
/*
* Intel(R) Processor Trace PMU driver for perf
* Copyright (c) 2013-2014, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* Intel PT is specified in the Intel Architecture Instruction Set Extensions
* Programming Reference:
* http://software.intel.com/en-us/intel-isa-extensions
*/
#undef DEBUG
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <asm/perf_event.h>
#include <asm/insn.h>
#include <asm/io.h>
#include "perf_event.h"
#include "intel_pt.h"
static DEFINE_PER_CPU(struct pt, pt_ctx);
static struct pt_pmu pt_pmu;
enum cpuid_regs {
CR_EAX = 0,
CR_ECX,
CR_EDX,
CR_EBX
};
/*
* Capabilities of Intel PT hardware, such as number of address bits or
* supported output schemes, are cached and exported to userspace as "caps"
* attribute group of pt pmu device
* (/sys/bus/event_source/devices/intel_pt/caps/) so that userspace can store
* relevant bits together with intel_pt traces.
*
* These are necessary for both trace decoding (payloads_lip, contains address
* width encoded in IP-related packets), and event configuration (bitmasks with
* permitted values for certain bit fields).
*/
#define PT_CAP(_n, _l, _r, _m) \
[PT_CAP_ ## _n] = { .name = __stringify(_n), .leaf = _l, \
.reg = _r, .mask = _m }
static struct pt_cap_desc {
const char *name;
u32 leaf;
u8 reg;
u32 mask;
} pt_caps[] = {
PT_CAP(max_subleaf, 0, CR_EAX, 0xffffffff),
PT_CAP(cr3_filtering, 0, CR_EBX, BIT(0)),
PT_CAP(psb_cyc, 0, CR_EBX, BIT(1)),
PT_CAP(mtc, 0, CR_EBX, BIT(3)),
PT_CAP(topa_output, 0, CR_ECX, BIT(0)),
PT_CAP(topa_multiple_entries, 0, CR_ECX, BIT(1)),
PT_CAP(single_range_output, 0, CR_ECX, BIT(2)),
PT_CAP(payloads_lip, 0, CR_ECX, BIT(31)),
PT_CAP(mtc_periods, 1, CR_EAX, 0xffff0000),
PT_CAP(cycle_thresholds, 1, CR_EBX, 0xffff),
PT_CAP(psb_periods, 1, CR_EBX, 0xffff0000),
};
static u32 pt_cap_get(enum pt_capabilities cap)
{
struct pt_cap_desc *cd = &pt_caps[cap];
u32 c = pt_pmu.caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
unsigned int shift = __ffs(cd->mask);
return (c & cd->mask) >> shift;
}
static ssize_t pt_cap_show(struct device *cdev,
struct device_attribute *attr,
char *buf)
{
struct dev_ext_attribute *ea =
container_of(attr, struct dev_ext_attribute, attr);
enum pt_capabilities cap = (long)ea->var;
return snprintf(buf, PAGE_SIZE, "%x\n", pt_cap_get(cap));
}
static struct attribute_group pt_cap_group = {
.name = "caps",
};
PMU_FORMAT_ATTR(cyc, "config:1" );
PMU_FORMAT_ATTR(mtc, "config:9" );
PMU_FORMAT_ATTR(tsc, "config:10" );
PMU_FORMAT_ATTR(noretcomp, "config:11" );
PMU_FORMAT_ATTR(mtc_period, "config:14-17" );
PMU_FORMAT_ATTR(cyc_thresh, "config:19-22" );
PMU_FORMAT_ATTR(psb_period, "config:24-27" );
static struct attribute *pt_formats_attr[] = {
&format_attr_cyc.attr,
&format_attr_mtc.attr,
&format_attr_tsc.attr,
&format_attr_noretcomp.attr,
&format_attr_mtc_period.attr,
&format_attr_cyc_thresh.attr,
&format_attr_psb_period.attr,
NULL,
};
static struct attribute_group pt_format_group = {
.name = "format",
.attrs = pt_formats_attr,
};
static const struct attribute_group *pt_attr_groups[] = {
&pt_cap_group,
&pt_format_group,
NULL,
};
static int __init pt_pmu_hw_init(void)
{
struct dev_ext_attribute *de_attrs;
struct attribute **attrs;
size_t size;
int ret;
long i;
attrs = NULL;
for (i = 0; i < PT_CPUID_LEAVES; i++) {
cpuid_count(20, i,
&pt_pmu.caps[CR_EAX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CR_EBX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CR_ECX + i*PT_CPUID_REGS_NUM],
&pt_pmu.caps[CR_EDX + i*PT_CPUID_REGS_NUM]);
}
ret = -ENOMEM;
size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps)+1);
attrs = kzalloc(size, GFP_KERNEL);
if (!attrs)
goto fail;
size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps)+1);
de_attrs = kzalloc(size, GFP_KERNEL);
if (!de_attrs)
goto fail;
for (i = 0; i < ARRAY_SIZE(pt_caps); i++) {
struct dev_ext_attribute *de_attr = de_attrs + i;
de_attr->attr.attr.name = pt_caps[i].name;
sysfs_attr_init(&de_attr->attr.attr);
de_attr->attr.attr.mode = S_IRUGO;
de_attr->attr.show = pt_cap_show;
de_attr->var = (void *)i;
attrs[i] = &de_attr->attr.attr;
}
pt_cap_group.attrs = attrs;
return 0;
fail:
kfree(attrs);
return ret;
}
#define RTIT_CTL_CYC_PSB (RTIT_CTL_CYCLEACC | \
RTIT_CTL_CYC_THRESH | \
RTIT_CTL_PSB_FREQ)
#define RTIT_CTL_MTC (RTIT_CTL_MTC_EN | \
RTIT_CTL_MTC_RANGE)
#define PT_CONFIG_MASK (RTIT_CTL_TSC_EN | \
RTIT_CTL_DISRETC | \
RTIT_CTL_CYC_PSB | \
RTIT_CTL_MTC)
static bool pt_event_valid(struct perf_event *event)
{
u64 config = event->attr.config;
u64 allowed, requested;
if ((config & PT_CONFIG_MASK) != config)
return false;
if (config & RTIT_CTL_CYC_PSB) {
if (!pt_cap_get(PT_CAP_psb_cyc))
return false;
allowed = pt_cap_get(PT_CAP_psb_periods);
requested = (config & RTIT_CTL_PSB_FREQ) >>
RTIT_CTL_PSB_FREQ_OFFSET;
if (requested && (!(allowed & BIT(requested))))
return false;
allowed = pt_cap_get(PT_CAP_cycle_thresholds);
requested = (config & RTIT_CTL_CYC_THRESH) >>
RTIT_CTL_CYC_THRESH_OFFSET;
if (requested && (!(allowed & BIT(requested))))
return false;
}
if (config & RTIT_CTL_MTC) {
/*
* In the unlikely case that CPUID lists valid mtc periods,
* but not the mtc capability, drop out here.
*
* Spec says that setting mtc period bits while mtc bit in
* CPUID is 0 will #GP, so better safe than sorry.
*/
if (!pt_cap_get(PT_CAP_mtc))
return false;
allowed = pt_cap_get(PT_CAP_mtc_periods);
if (!allowed)
return false;
requested = (config & RTIT_CTL_MTC_RANGE) >>
RTIT_CTL_MTC_RANGE_OFFSET;
if (!(allowed & BIT(requested)))
return false;
}
return true;
}
/*
* PT configuration helpers
* These all are cpu affine and operate on a local PT
*/
static void pt_config(struct perf_event *event)
{
u64 reg;
if (!event->hw.itrace_started) {
event->hw.itrace_started = 1;
wrmsrl(MSR_IA32_RTIT_STATUS, 0);
}
reg = RTIT_CTL_TOPA | RTIT_CTL_BRANCH_EN | RTIT_CTL_TRACEEN;
if (!event->attr.exclude_kernel)
reg |= RTIT_CTL_OS;
if (!event->attr.exclude_user)
reg |= RTIT_CTL_USR;
reg |= (event->attr.config & PT_CONFIG_MASK);
wrmsrl(MSR_IA32_RTIT_CTL, reg);
}
static void pt_config_start(bool start)
{
u64 ctl;
rdmsrl(MSR_IA32_RTIT_CTL, ctl);
if (start)
ctl |= RTIT_CTL_TRACEEN;
else
ctl &= ~RTIT_CTL_TRACEEN;
wrmsrl(MSR_IA32_RTIT_CTL, ctl);
/*
* A wrmsr that disables trace generation serializes other PT
* registers and causes all data packets to be written to memory,
* but a fence is required for the data to become globally visible.
*
* The below WMB, separating data store and aux_head store matches
* the consumer's RMB that separates aux_head load and data load.
*/
if (!start)
wmb();
}
static void pt_config_buffer(void *buf, unsigned int topa_idx,
unsigned int output_off)
{
u64 reg;
wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, virt_to_phys(buf));
reg = 0x7f | ((u64)topa_idx << 7) | ((u64)output_off << 32);
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
* @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
* @size: total size of all entries in this table
* @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;
size_t size;
int last;
};
/* make -1 stand for the last table entry */
#define TOPA_ENTRY(t, i) ((i) == -1 ? &(t)->table[(t)->last] : &(t)->table[(i)])
/**
* topa_alloc() - allocate page-sized ToPA table
* @cpu: CPU on which to allocate.
* @gfp: Allocation flags.
*
* Return: On success, return the pointer to ToPA table page.
*/
static struct topa *topa_alloc(int cpu, gfp_t gfp)
{
int node = cpu_to_node(cpu);
struct topa *topa;
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);
/*
* In case of singe-entry ToPA, always put the self-referencing END
* link as the 2nd entry in the table
*/
if (!pt_cap_get(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(topa, 1)->base = topa->phys >> TOPA_SHIFT;
TOPA_ENTRY(topa, 1)->end = 1;
}
return topa;
}
/**
* topa_free() - free a page-sized ToPA table
* @topa: Table to deallocate.
*/
static void topa_free(struct topa *topa)
{
free_page((unsigned long)topa);
}
/**
* topa_insert_table() - insert a ToPA table into a buffer
* @buf: PT buffer that's being extended.
* @topa: New topa table to be inserted.
*
* If it's the first table in this buffer, set up buffer's pointers
* accordingly; otherwise, add a END=1 link entry to @topa to the current
* "last" table and adjust the last table pointer to @topa.
*/
static void topa_insert_table(struct pt_buffer *buf, struct topa *topa)
{
struct topa *last = buf->last;
list_add_tail(&topa->list, &buf->tables);
if (!buf->first) {
buf->first = buf->last = buf->cur = topa;
return;
}
topa->offset = last->offset + last->size;
buf->last = topa;
if (!pt_cap_get(PT_CAP_topa_multiple_entries))
return;
BUG_ON(last->last != TENTS_PER_PAGE - 1);
TOPA_ENTRY(last, -1)->base = topa->phys >> TOPA_SHIFT;
TOPA_ENTRY(last, -1)->end = 1;
}
/**
* topa_table_full() - check if a ToPA table is filled up
* @topa: ToPA table.
*/
static bool topa_table_full(struct topa *topa)
{
/* single-entry ToPA is a special case */
if (!pt_cap_get(PT_CAP_topa_multiple_entries))
return !!topa->last;
return topa->last == TENTS_PER_PAGE - 1;
}
/**
* topa_insert_pages() - create a list of ToPA tables
* @buf: PT buffer being initialized.
* @gfp: Allocation flags.
*
* This initializes a list of ToPA tables with entries from
* the data_pages provided by rb_alloc_aux().
*
* Return: 0 on success or error code.
*/
static int topa_insert_pages(struct pt_buffer *buf, gfp_t gfp)
{
struct topa *topa = buf->last;
int order = 0;
struct page *p;
p = virt_to_page(buf->data_pages[buf->nr_pages]);
if (PagePrivate(p))
order = page_private(p);
if (topa_table_full(topa)) {
topa = topa_alloc(buf->cpu, gfp);
if (!topa)
return -ENOMEM;
topa_insert_table(buf, topa);
}
TOPA_ENTRY(topa, -1)->base = page_to_phys(p) >> TOPA_SHIFT;
TOPA_ENTRY(topa, -1)->size = order;
if (!buf->snapshot && !pt_cap_get(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(topa, -1)->intr = 1;
TOPA_ENTRY(topa, -1)->stop = 1;
}
topa->last++;
topa->size += sizes(order);
buf->nr_pages += 1ul << order;
return 0;
}
/**
* pt_topa_dump() - print ToPA tables and their entries
* @buf: PT buffer.
*/
static void pt_topa_dump(struct pt_buffer *buf)
{
struct topa *topa;
list_for_each_entry(topa, &buf->tables, list) {
int i;
pr_debug("# table @%p (%016Lx), off %llx size %zx\n", topa->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]);
if ((pt_cap_get(PT_CAP_topa_multiple_entries) &&
topa->table[i].stop) ||
topa->table[i].end)
break;
}
}
}
/**
* pt_buffer_advance() - advance to the next output region
* @buf: PT buffer.
*
* Advance the current pointers in the buffer to the next ToPA entry.
*/
static void pt_buffer_advance(struct pt_buffer *buf)
{
buf->output_off = 0;
buf->cur_idx++;
if (buf->cur_idx == buf->cur->last) {
if (buf->cur == buf->last)
buf->cur = buf->first;
else
buf->cur = list_entry(buf->cur->list.next, struct topa,
list);
buf->cur_idx = 0;
}
}
/**
* pt_update_head() - calculate current offsets and sizes
* @pt: Per-cpu pt context.
*
* Update buffer's current write pointer position and data size.
*/
static void pt_update_head(struct pt *pt)
{
struct pt_buffer *buf = perf_get_aux(&pt->handle);
u64 topa_idx, base, old;
/* offset of the first region in this table from the beginning of buf */
base = buf->cur->offset + buf->output_off;
/* offset of the current output region within this table */
for (topa_idx = 0; topa_idx < buf->cur_idx; topa_idx++)
base += sizes(buf->cur->table[topa_idx].size);
if (buf->snapshot) {
local_set(&buf->data_size, base);
} else {
old = (local64_xchg(&buf->head, base) &
((buf->nr_pages << PAGE_SHIFT) - 1));
if (base < old)
base += buf->nr_pages << PAGE_SHIFT;
local_add(base - old, &buf->data_size);
}
}
/**
* pt_buffer_region() - obtain current output region's address
* @buf: PT buffer.
*/
static void *pt_buffer_region(struct pt_buffer *buf)
{
return phys_to_virt(buf->cur->table[buf->cur_idx].base << TOPA_SHIFT);
}
/**
* pt_buffer_region_size() - obtain current output region's size
* @buf: PT buffer.
*/
static size_t pt_buffer_region_size(struct pt_buffer *buf)
{
return sizes(buf->cur->table[buf->cur_idx].size);
}
/**
* pt_handle_status() - take care of possible status conditions
* @pt: Per-cpu pt context.
*/
static void pt_handle_status(struct pt *pt)
{
struct pt_buffer *buf = perf_get_aux(&pt->handle);
int advance = 0;
u64 status;
rdmsrl(MSR_IA32_RTIT_STATUS, status);
if (status & RTIT_STATUS_ERROR) {
pr_err_ratelimited("ToPA ERROR encountered, trying to recover\n");
pt_topa_dump(buf);
status &= ~RTIT_STATUS_ERROR;
}
if (status & RTIT_STATUS_STOPPED) {
status &= ~RTIT_STATUS_STOPPED;
/*
* On systems that only do single-entry ToPA, hitting STOP
* means we are already losing data; need to let the decoder
* know.
*/
if (!pt_cap_get(PT_CAP_topa_multiple_entries) ||
buf->output_off == sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size)) {
local_inc(&buf->lost);
advance++;
}
}
/*
* Also on single-entry ToPA implementations, interrupt will come
* before the output reaches its output region's boundary.
*/
if (!pt_cap_get(PT_CAP_topa_multiple_entries) && !buf->snapshot &&
pt_buffer_region_size(buf) - buf->output_off <= TOPA_PMI_MARGIN) {
void *head = pt_buffer_region(buf);
/* everything within this margin needs to be zeroed out */
memset(head + buf->output_off, 0,
pt_buffer_region_size(buf) -
buf->output_off);
advance++;
}
if (advance)
pt_buffer_advance(buf);
wrmsrl(MSR_IA32_RTIT_STATUS, status);
}
/**
* pt_read_offset() - translate registers into buffer pointers
* @buf: PT buffer.
*
* Set buffer's output pointers from MSR values.
*/
static void pt_read_offset(struct pt_buffer *buf)
{
u64 offset, base_topa;
rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, base_topa);
buf->cur = phys_to_virt(base_topa);
rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, offset);
/* offset within current output region */
buf->output_off = offset >> 32;
/* index of current output region within this table */
buf->cur_idx = (offset & 0xffffff80) >> 7;
}
/**
* pt_topa_next_entry() - obtain index of the first page in the next ToPA entry
* @buf: PT buffer.
* @pg: Page offset in the buffer.
*
* When advancing to the next output region (ToPA entry), given a page offset
* into the buffer, we need to find the offset of the first page in the next
* region.
*/
static unsigned int pt_topa_next_entry(struct pt_buffer *buf, unsigned int pg)
{
struct topa_entry *te = buf->topa_index[pg];
/* one region */
if (buf->first == buf->last && buf->first->last == 1)
return pg;
do {
pg++;
pg &= buf->nr_pages - 1;
} while (buf->topa_index[pg] == te);
return pg;
}
/**
* pt_buffer_reset_markers() - place interrupt and stop bits in the buffer
* @buf: PT buffer.
* @handle: Current output handle.
*
* Place INT and STOP marks to prevent overwriting old data that the consumer
* hasn't yet collected and waking up the consumer after a certain fraction of
* the buffer has filled up. Only needed and sensible for non-snapshot counters.
*
* This obviously relies on buf::head to figure out buffer markers, so it has
* to be called after pt_buffer_reset_offsets() and before the hardware tracing
* is enabled.
*/
static int pt_buffer_reset_markers(struct pt_buffer *buf,
struct perf_output_handle *handle)
{
unsigned long head = local64_read(&buf->head);
unsigned long idx, npages, wakeup;
/* can't stop in the middle of an output region */
if (buf->output_off + handle->size + 1 <
sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size))
return -EINVAL;
/* single entry ToPA is handled by marking all regions STOP=1 INT=1 */
if (!pt_cap_get(PT_CAP_topa_multiple_entries))
return 0;
/* clear STOP and INT from current entry */
buf->topa_index[buf->stop_pos]->stop = 0;
buf->topa_index[buf->intr_pos]->intr = 0;
/* how many pages till the STOP marker */
npages = handle->size >> PAGE_SHIFT;
/* if it's on a page boundary, fill up one more page */
if (!offset_in_page(head + handle->size + 1))
npages++;
idx = (head >> PAGE_SHIFT) + npages;
idx &= buf->nr_pages - 1;
buf->stop_pos = idx;
wakeup = handle->wakeup >> PAGE_SHIFT;
/* in the worst case, wake up the consumer one page before hard stop */
idx = (head >> PAGE_SHIFT) + npages - 1;
if (idx > wakeup)
idx = wakeup;
idx &= buf->nr_pages - 1;
buf->intr_pos = idx;
buf->topa_index[buf->stop_pos]->stop = 1;
buf->topa_index[buf->intr_pos]->intr = 1;
return 0;
}
/**
* pt_buffer_setup_topa_index() - build topa_index[] table of regions
* @buf: PT buffer.
*
* topa_index[] references output regions indexed by offset into the
* buffer for purposes of quick reverse lookup.
*/
static void pt_buffer_setup_topa_index(struct pt_buffer *buf)
{
struct topa *cur = buf->first, *prev = buf->last;
struct topa_entry *te_cur = TOPA_ENTRY(cur, 0),
*te_prev = TOPA_ENTRY(prev, prev->last - 1);
int pg = 0, idx = 0;
while (pg < buf->nr_pages) {
int tidx;
/* pages within one topa entry */
for (tidx = 0; tidx < 1 << te_cur->size; tidx++, pg++)
buf->topa_index[pg] = te_prev;
te_prev = te_cur;
if (idx == cur->last - 1) {
/* advance to next topa table */
idx = 0;
cur = list_entry(cur->list.next, struct topa, list);
} else {
idx++;
}
te_cur = TOPA_ENTRY(cur, idx);
}
}
/**
* pt_buffer_reset_offsets() - adjust buffer's write pointers from aux_head
* @buf: PT buffer.
* @head: Write pointer (aux_head) from AUX buffer.
*
* Find the ToPA table and entry corresponding to given @head and set buffer's
* "current" pointers accordingly. This is done after we have obtained the
* current aux_head position from a successful call to perf_aux_output_begin()
* to make sure the hardware is writing to the right place.
*
* This function modifies buf::{cur,cur_idx,output_off} that will be programmed
* into PT msrs when the tracing is enabled and buf::head and buf::data_size,
* which are used to determine INT and STOP markers' locations by a subsequent
* call to pt_buffer_reset_markers().
*/
static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head)
{
int pg;
if (buf->snapshot)
head &= (buf->nr_pages << PAGE_SHIFT) - 1;
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);
buf->cur_idx = ((unsigned long)buf->topa_index[pg] -
(unsigned long)buf->cur) / sizeof(struct topa_entry);
buf->output_off = head & (sizes(buf->cur->table[buf->cur_idx].size) - 1);
local64_set(&buf->head, head);
local_set(&buf->data_size, 0);
}
/**
* pt_buffer_fini_topa() - deallocate ToPA structure of a buffer
* @buf: PT buffer.
*/
static void pt_buffer_fini_topa(struct pt_buffer *buf)
{
struct topa *topa, *iter;
list_for_each_entry_safe(topa, iter, &buf->tables, list) {
/*
* right now, this is in free_aux() path only, so
* no need to unlink this table from the list
*/
topa_free(topa);
}
}
/**
* pt_buffer_init_topa() - initialize ToPA table for pt buffer
* @buf: PT buffer.
* @size: Total size of all regions within this ToPA.
* @gfp: Allocation flags.
*/
static int pt_buffer_init_topa(struct pt_buffer *buf, unsigned long nr_pages,
gfp_t gfp)
{
struct topa *topa;
int err;
topa = topa_alloc(buf->cpu, gfp);
if (!topa)
return -ENOMEM;
topa_insert_table(buf, topa);
while (buf->nr_pages < nr_pages) {
err = topa_insert_pages(buf, gfp);
if (err) {
pt_buffer_fini_topa(buf);
return -ENOMEM;
}
}
pt_buffer_setup_topa_index(buf);
/* link last table to the first one, unless we're double buffering */
if (pt_cap_get(PT_CAP_topa_multiple_entries)) {
TOPA_ENTRY(buf->last, -1)->base = buf->first->phys >> TOPA_SHIFT;
TOPA_ENTRY(buf->last, -1)->end = 1;
}
pt_topa_dump(buf);
return 0;
}
/**
* pt_buffer_setup_aux() - set up topa tables for a PT buffer
* @cpu: Cpu on which to allocate, -1 means current.
* @pages: Array of pointers to buffer pages passed from perf core.
* @nr_pages: Number of pages in the buffer.
* @snapshot: If this is a snapshot/overwrite counter.
*
* This is a pmu::setup_aux callback that sets up ToPA tables and all the
* bookkeeping for an AUX buffer.
*
* Return: Our private PT buffer structure.
*/
static void *
pt_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool snapshot)
{
struct pt_buffer *buf;
int node, ret;
if (!nr_pages)
return NULL;
if (cpu == -1)
cpu = raw_smp_processor_id();
node = cpu_to_node(cpu);
buf = kzalloc_node(offsetof(struct pt_buffer, topa_index[nr_pages]),
GFP_KERNEL, node);
if (!buf)
return NULL;
buf->cpu = cpu;
buf->snapshot = snapshot;
buf->data_pages = pages;
INIT_LIST_HEAD(&buf->tables);
ret = pt_buffer_init_topa(buf, nr_pages, GFP_KERNEL);
if (ret) {
kfree(buf);
return NULL;
}
return buf;
}
/**
* pt_buffer_free_aux() - perf AUX deallocation path callback
* @data: PT buffer.
*/
static void pt_buffer_free_aux(void *data)
{
struct pt_buffer *buf = data;
pt_buffer_fini_topa(buf);
kfree(buf);
}
/**
* pt_buffer_is_full() - check if the buffer is full
* @buf: PT buffer.
* @pt: Per-cpu pt handle.
*
* If the user hasn't read data from the output region that aux_head
* points to, the buffer is considered full: the user needs to read at
* least this region and update aux_tail to point past it.
*/
static bool pt_buffer_is_full(struct pt_buffer *buf, struct pt *pt)
{
if (buf->snapshot)
return false;
if (local_read(&buf->data_size) >= pt->handle.size)
return true;
return false;
}
/**
* intel_pt_interrupt() - PT PMI handler
*/
void intel_pt_interrupt(void)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf;
struct perf_event *event = pt->handle.event;
/*
* There may be a dangling PT bit in the interrupt status register
* after PT has been disabled by pt_event_stop(). Make sure we don't
* do anything (particularly, re-enable) for this event here.
*/
if (!ACCESS_ONCE(pt->handle_nmi))
return;
pt_config_start(false);
if (!event)
return;
buf = perf_get_aux(&pt->handle);
if (!buf)
return;
pt_read_offset(buf);
pt_handle_status(pt);
pt_update_head(pt);
perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0),
local_xchg(&buf->lost, 0));
if (!event->hw.state) {
int ret;
buf = perf_aux_output_begin(&pt->handle, event);
if (!buf) {
event->hw.state = PERF_HES_STOPPED;
return;
}
pt_buffer_reset_offsets(buf, pt->handle.head);
/* snapshot counters don't use PMI, so it's safe */
ret = pt_buffer_reset_markers(buf, &pt->handle);
if (ret) {
perf_aux_output_end(&pt->handle, 0, true);
return;
}
pt_config_buffer(buf->cur->table, buf->cur_idx,
buf->output_off);
pt_config(event);
}
}
/*
* PMU callbacks
*/
static void pt_event_start(struct perf_event *event, int mode)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf = perf_get_aux(&pt->handle);
if (!buf || pt_buffer_is_full(buf, pt)) {
event->hw.state = PERF_HES_STOPPED;
return;
}
ACCESS_ONCE(pt->handle_nmi) = 1;
event->hw.state = 0;
pt_config_buffer(buf->cur->table, buf->cur_idx,
buf->output_off);
pt_config(event);
}
static void pt_event_stop(struct perf_event *event, int mode)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
/*
* Protect against the PMI racing with disabling wrmsr,
* see comment in intel_pt_interrupt().
*/
ACCESS_ONCE(pt->handle_nmi) = 0;
pt_config_start(false);
if (event->hw.state == PERF_HES_STOPPED)
return;
event->hw.state = PERF_HES_STOPPED;
if (mode & PERF_EF_UPDATE) {
struct pt_buffer *buf = perf_get_aux(&pt->handle);
if (!buf)
return;
if (WARN_ON_ONCE(pt->handle.event != event))
return;
pt_read_offset(buf);
pt_handle_status(pt);
pt_update_head(pt);
}
}
static void pt_event_del(struct perf_event *event, int mode)
{
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct pt_buffer *buf;
pt_event_stop(event, PERF_EF_UPDATE);
buf = perf_get_aux(&pt->handle);
if (buf) {
if (buf->snapshot)
pt->handle.head =
local_xchg(&buf->data_size,
buf->nr_pages << PAGE_SHIFT);
perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0),
local_xchg(&buf->lost, 0));
}
}
static int pt_event_add(struct perf_event *event, int mode)
{
struct pt_buffer *buf;
struct pt *pt = this_cpu_ptr(&pt_ctx);
struct hw_perf_event *hwc = &event->hw;
int ret = -EBUSY;
if (pt->handle.event)
goto fail;
buf = perf_aux_output_begin(&pt->handle, event);
ret = -EINVAL;
if (!buf)
goto fail_stop;
pt_buffer_reset_offsets(buf, pt->handle.head);
if (!buf->snapshot) {
ret = pt_buffer_reset_markers(buf, &pt->handle);
if (ret)
goto fail_end_stop;
}
if (mode & PERF_EF_START) {
pt_event_start(event, 0);
ret = -EBUSY;
if (hwc->state == PERF_HES_STOPPED)
goto fail_end_stop;
} else {
hwc->state = PERF_HES_STOPPED;
}
return 0;
fail_end_stop:
perf_aux_output_end(&pt->handle, 0, true);
fail_stop:
hwc->state = PERF_HES_STOPPED;
fail:
return ret;
}
static void pt_event_read(struct perf_event *event)
{
}
static void pt_event_destroy(struct perf_event *event)
{
x86_del_exclusive(x86_lbr_exclusive_pt);
}
static int pt_event_init(struct perf_event *event)
{
if (event->attr.type != pt_pmu.pmu.type)
return -ENOENT;
if (!pt_event_valid(event))
return -EINVAL;
if (x86_add_exclusive(x86_lbr_exclusive_pt))
return -EBUSY;
event->destroy = pt_event_destroy;
return 0;
}
static __init int pt_init(void)
{
int ret, cpu, prior_warn = 0;
BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);
if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT))
return -ENODEV;
get_online_cpus();
for_each_online_cpu(cpu) {
u64 ctl;
ret = rdmsrl_safe_on_cpu(cpu, MSR_IA32_RTIT_CTL, &ctl);
if (!ret && (ctl & RTIT_CTL_TRACEEN))
prior_warn++;
}
put_online_cpus();
if (prior_warn) {
x86_add_exclusive(x86_lbr_exclusive_pt);
pr_warn("PT is enabled at boot time, doing nothing\n");
return -EBUSY;
}
ret = pt_pmu_hw_init();
if (ret)
return ret;
if (!pt_cap_get(PT_CAP_topa_output)) {
pr_warn("ToPA output is not supported on this CPU\n");
return -ENODEV;
}
if (!pt_cap_get(PT_CAP_topa_multiple_entries))
pt_pmu.pmu.capabilities =
PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_SW_DOUBLEBUF;
pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE;
pt_pmu.pmu.attr_groups = pt_attr_groups;
pt_pmu.pmu.task_ctx_nr = perf_sw_context;
pt_pmu.pmu.event_init = pt_event_init;
pt_pmu.pmu.add = pt_event_add;
pt_pmu.pmu.del = pt_event_del;
pt_pmu.pmu.start = pt_event_start;
pt_pmu.pmu.stop = pt_event_stop;
pt_pmu.pmu.read = pt_event_read;
pt_pmu.pmu.setup_aux = pt_buffer_setup_aux;
pt_pmu.pmu.free_aux = pt_buffer_free_aux;
ret = perf_pmu_register(&pt_pmu.pmu, "intel_pt", -1);
return ret;
}
arch_initcall(pt_init);