/* * 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 #include #include #include #include #include #include #include "../perf_event.h" #include "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); } /** * 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 hw_perf_event *hwc = &event->hw; struct pt *pt = this_cpu_ptr(&pt_ctx); struct pt_buffer *buf; buf = perf_aux_output_begin(&pt->handle, event); if (!buf) goto fail_stop; pt_buffer_reset_offsets(buf, pt->handle.head); if (!buf->snapshot) { if (pt_buffer_reset_markers(buf, &pt->handle)) goto fail_end_stop; } ACCESS_ONCE(pt->handle_nmi) = 1; hwc->state = 0; pt_config_buffer(buf->cur->table, buf->cur_idx, buf->output_off); pt_config(event); return; fail_end_stop: perf_aux_output_end(&pt->handle, 0, true); fail_stop: hwc->state = PERF_HES_STOPPED; } 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); 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 void pt_event_del(struct perf_event *event, int mode) { pt_event_stop(event, PERF_EF_UPDATE); } static int pt_event_add(struct perf_event *event, int mode) { struct pt *pt = this_cpu_ptr(&pt_ctx); struct hw_perf_event *hwc = &event->hw; int ret = -EBUSY; if (pt->handle.event) goto fail; if (mode & PERF_EF_START) { pt_event_start(event, 0); ret = -EINVAL; if (hwc->state == PERF_HES_STOPPED) goto fail; } else { hwc->state = PERF_HES_STOPPED; } ret = 0; 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; } void cpu_emergency_stop_pt(void) { struct pt *pt = this_cpu_ptr(&pt_ctx); if (pt->handle.event) pt_event_stop(pt->handle.event, PERF_EF_UPDATE); } static __init int pt_init(void) { int ret, cpu, prior_warn = 0; BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE); if (!boot_cpu_has(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);