--- /dev/null
+/*
+ * 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(topa_output, 0, CR_ECX, BIT(0)),
+ PT_CAP(topa_multiple_entries, 0, CR_ECX, BIT(1)),
+ PT_CAP(payloads_lip, 0, CR_ECX, BIT(31)),
+};
+
+static u32 pt_cap_get(enum pt_capabilities cap)
+{
+ struct pt_cap_desc *cd = &pt_caps[cap];
+ u32 c = pt_pmu.caps[cd->leaf * 4 + 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(tsc, "config:10" );
+PMU_FORMAT_ATTR(noretcomp, "config:11" );
+
+static struct attribute *pt_formats_attr[] = {
+ &format_attr_tsc.attr,
+ &format_attr_noretcomp.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;
+ long i;
+
+ if (test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT)) {
+ for (i = 0; i < PT_CPUID_LEAVES; i++)
+ cpuid_count(20, i,
+ &pt_pmu.caps[CR_EAX + i * 4],
+ &pt_pmu.caps[CR_EBX + i * 4],
+ &pt_pmu.caps[CR_ECX + i * 4],
+ &pt_pmu.caps[CR_EDX + i * 4]);
+ } else {
+ return -ENODEV;
+ }
+
+ size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps) + 1);
+ attrs = kzalloc(size, GFP_KERNEL);
+ if (!attrs)
+ goto err_attrs;
+
+ size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps) + 1);
+ de_attrs = kzalloc(size, GFP_KERNEL);
+ if (!de_attrs)
+ goto err_de_attrs;
+
+ for (i = 0; i < ARRAY_SIZE(pt_caps); i++) {
+ de_attrs[i].attr.attr.name = pt_caps[i].name;
+
+ sysfs_attr_init(&de_attrs[i].attr.attr);
+ de_attrs[i].attr.attr.mode = S_IRUGO;
+ de_attrs[i].attr.show = pt_cap_show;
+ de_attrs[i].var = (void *)i;
+ attrs[i] = &de_attrs[i].attr.attr;
+ }
+
+ pt_cap_group.attrs = attrs;
+ return 0;
+
+err_de_attrs:
+ kfree(de_attrs);
+err_attrs:
+ kfree(attrs);
+
+ return -ENOMEM;
+}
+
+#define PT_CONFIG_MASK (RTIT_CTL_TSC_EN | RTIT_CTL_DISRETC)
+
+static bool pt_event_valid(struct perf_event *event)
+{
+ u64 config = event->attr.config;
+
+ if ((config & PT_CONFIG_MASK) != config)
+ return false;
+
+ return true;
+}
+
+/*
+ * PT configuration helpers
+ * These all are cpu affine and operate on a local PT
+ */
+
+static bool pt_is_running(void)
+{
+ u64 ctl;
+
+ rdmsrl(MSR_IA32_RTIT_CTL, ctl);
+
+ return !!(ctl & RTIT_CTL_TRACEEN);
+}
+
+static void pt_config(struct perf_event *event)
+{
+ u64 reg;
+
+ 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 (%p), off %llx size %zx\n", topa->table,
+ (void *)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.
+ */
+static int pt_buffer_reset_markers(struct pt_buffer *buf,
+ struct perf_output_handle *handle)
+
+{
+ unsigned long idx, npages, end;
+
+ if (buf->snapshot)
+ return 0;
+
+ /* 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;
+
+ if (pt_cap_get(PT_CAP_topa_multiple_entries)) {
+ npages = (handle->size + 1) >> PAGE_SHIFT;
+ end = (local64_read(&buf->head) >> PAGE_SHIFT) + npages;
+ /*if (end > handle->wakeup >> PAGE_SHIFT)
+ end = handle->wakeup >> PAGE_SHIFT;*/
+ idx = end & (buf->nr_pages - 1);
+ buf->stop_pos = idx;
+ idx = (local64_read(&buf->head) >> PAGE_SHIFT) + npages - 1;
+ 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, ntopa = 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);
+ ntopa++;
+ } 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.
+ */
+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);
+ 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);
+ wrmsrl(MSR_IA32_RTIT_STATUS, 0);
+ 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 (pt_is_running() || !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);
+ wrmsrl(MSR_IA32_RTIT_STATUS, 0);
+ 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 *pt = this_cpu_ptr(&pt_ctx);
+ 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 out;
+
+ buf = perf_aux_output_begin(&pt->handle, event);
+ if (!buf) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ pt_buffer_reset_offsets(buf, pt->handle.head);
+ if (!buf->snapshot) {
+ ret = pt_buffer_reset_markers(buf, &pt->handle);
+ if (ret) {
+ perf_aux_output_end(&pt->handle, 0, true);
+ goto out;
+ }
+ }
+
+ if (mode & PERF_EF_START) {
+ pt_event_start(event, 0);
+ if (hwc->state == PERF_HES_STOPPED) {
+ pt_event_del(event, 0);
+ ret = -EBUSY;
+ }
+ } else {
+ hwc->state = PERF_HES_STOPPED;
+ }
+
+ ret = 0;
+out:
+
+ if (ret)
+ hwc->state = PERF_HES_STOPPED;
+
+ 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);
+ 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;
+}
+
+module_init(pt_init);
projects / kernel.git / commitdiff