diff options
Diffstat (limited to 'arch/x86/events/intel/pt.c')
| -rw-r--r-- | arch/x86/events/intel/pt.c | 1188 |
1 files changed, 1188 insertions, 0 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c new file mode 100644 index 000000000000..6af7cf71d6b2 --- /dev/null +++ b/arch/x86/events/intel/pt.c @@ -0,0 +1,1188 @@ +/* + * 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 <asm/intel_pt.h> + +#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); +} + +/** + * 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; +} + +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 (!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); |