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simple-pt.c
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/* Minimal Linux Intel Processor Trace driver. */
/*
* Copyright (c) 2015, Intel Corporation
* Author: Andi Kleen
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Alternatively you can use this file under the GPLv2.
*/
/* Notebook:
Auto probe largest buffer
Test old kernels
Test 32bit
*/
#define DEBUG 1
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/cpu.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/dcache.h>
#include <linux/ctype.h>
#include <linux/syscore_ops.h>
#include <trace/events/sched.h>
#include <asm/msr.h>
#include <asm/processor.h>
#define CREATE_TRACE_POINTS
#include "pttp.h"
#include "compat.h"
#include "simple-pt.h"
#define MSR_IA32_RTIT_OUTPUT_BASE 0x00000560
#define MSR_IA32_RTIT_OUTPUT_MASK_PTRS 0x00000561
#define MSR_IA32_RTIT_CTL 0x00000570
#define TRACE_EN BIT_ULL(0)
#define CYC_EN BIT_ULL(1)
#define CTL_OS BIT_ULL(2)
#define CTL_USER BIT_ULL(3)
#define PT_ERROR BIT_ULL(4)
#define CR3_FILTER BIT_ULL(7)
#define TO_PA BIT_ULL(8)
#define MTC_EN BIT_ULL(9)
#define TSC_EN BIT_ULL(10)
#define DIS_RETC BIT_ULL(11)
#define BRANCH_EN BIT_ULL(13)
#define MTC_MASK (0xf << 14)
#define CYC_MASK (0xf << 19)
#define PSB_MASK (0xf << 24)
#define ADDR0_SHIFT 32
#define ADDR1_SHIFT 36
#define ADDR0_MASK (0xfULL << ADDR0_SHIFT)
#define ADDR1_MASK (0xfULL << ADDR1_SHIFT)
#define MSR_IA32_RTIT_STATUS 0x00000571
#define MSR_IA32_CR3_MATCH 0x00000572
#define TOPA_STOP BIT_ULL(4)
#define TOPA_INT BIT_ULL(2)
#define TOPA_END BIT_ULL(0)
#define TOPA_SIZE_SHIFT 6
#define MSR_IA32_ADDR0_START 0x00000580
#define MSR_IA32_ADDR0_END 0x00000581
#define MSR_IA32_ADDR1_START 0x00000582
#define MSR_IA32_ADDR1_END 0x00000583
static bool delay_start;
static void restart(void);
static void stop_pt_all(void);
static int resync_set(const char *val, const struct kernel_param *kp)
{
int ret = param_set_int(val, kp);
restart();
return ret;
}
static struct kernel_param_ops resync_ops = {
.set = resync_set,
.get = param_get_int,
};
static int start_set(const char *val, const struct kernel_param *kp)
{
int ret = resync_set(val, kp);
delay_start = false;
return ret;
}
static struct kernel_param_ops start_ops = {
.set = start_set,
.get = param_get_int,
};
static void do_enumerate_all(void);
static int enumerate_all;
static int enumerate_set(const char *val, const struct kernel_param *kp)
{
int ret = param_set_int(val, kp);
if (enumerate_all)
do_enumerate_all();
return ret;
}
static struct kernel_param_ops enumerate_ops = {
.set = enumerate_set,
.get = param_get_int,
};
static unsigned addr_range_num;
static int symbol_set(const char *val, const struct kernel_param *kp)
{
int ret = -EIO;
if (!isdigit(val[0])) {
char sym[128];
unsigned offset = 0;
unsigned long addr;
char *plus, *nl;
snprintf(sym, 128, "%s", val);
nl = strchr(sym, '\n');
if (nl)
*nl = 0;
plus = strchr(sym, '+');
if (plus) {
*plus = 0;
if (kstrtouint(plus + 1, 0, &offset) < 0) {
pr_err("Invalid offset\n");
return -EIO;
}
}
addr = kallsyms_lookup_name(sym);
if (!addr)
pr_err("Lookup of '%s' symbol failed\n", sym);
if (addr && offset)
addr += offset;
if (addr) {
*(unsigned long *)(kp->arg) = addr;
ret = 0;
}
} else {
ret = param_set_ulong(val, kp);
}
return ret;
}
static int start = 0;
static int addr_set(const char *val, const struct kernel_param *kp)
{
int ret;
if (addr_range_num == 0)
return -EINVAL;
ret = symbol_set(val, kp);
if (start)
restart();
return ret;
}
static struct kernel_param_ops addr_ops = {
.set = addr_set,
.get = param_get_ulong,
};
/* Protects start/stop_kprobe_set and the kprobes */
/* If you are porting this driver this kprobes related code is all
* optional and can be removed.
*/
static DEFINE_MUTEX(kprobe_mutex);
static int probe_start(struct kprobe *kp, struct pt_regs *regs);
static int probe_stop(struct kprobe *kp, struct pt_regs *regs);
static struct kprobe start_kprobe = {
.pre_handler = probe_start
};
static struct kprobe stop_kprobe = {
.pre_handler = probe_stop
};
static int kprobe_set(const char *val, const struct kernel_param *kp,
struct kprobe *kprobe)
{
int ret = symbol_set(val, kp);
unsigned long addr = *(unsigned long *)(kp->arg);
mutex_lock(&kprobe_mutex);
if (kprobe->addr) {
unregister_kprobe(kprobe);
kprobe->addr = NULL;
}
if (addr) {
int (*handler)(struct kprobe *kp, struct pt_regs *regs);
handler = kprobe->pre_handler;
/* Linux doesn't like reusing an old kprobes structure.
* Always clear and reinitialize.
*/
memset(kprobe, 0, sizeof(struct kprobe));
kprobe->addr = (kprobe_opcode_t *)addr;
kprobe->pre_handler = handler;
ret = register_kprobe(kprobe);
if (ret)
pr_err("registering kprobe failed\n");
}
mutex_unlock(&kprobe_mutex);
return ret;
}
static int trace_start_set(const char *val, const struct kernel_param *kp)
{
int ret = kprobe_set(val, kp, &start_kprobe);
if (start_kprobe.addr)
delay_start = true;
return ret;
}
static int trace_stop_set(const char *val, const struct kernel_param *kp)
{
return kprobe_set(val, kp, &stop_kprobe);
}
static struct kernel_param_ops trace_start_ops = {
.set = trace_start_set,
.get = param_get_ulong,
};
static struct kernel_param_ops trace_stop_ops = {
.set = trace_stop_set,
.get = param_get_ulong,
};
/* Support for Linux panic dumps (optional) */
static int pt_num_buffers = 1;
static int log_dump = 0;
static void print_last_branches(int num_psbs);
static int log_dump_set(const char *val, const struct kernel_param *kp)
{
int ret = param_set_int(val, kp);
if (start && log_dump && pt_num_buffers == 1) {
stop_pt_all();
print_last_branches(log_dump);
}
return ret;
}
static struct kernel_param_ops log_dump_ops = {
.set = log_dump_set,
.get = param_get_ulong,
};
/* End of optional code */
static DEFINE_PER_CPU(unsigned long, pt_buffer_cpu);
static DEFINE_PER_CPU(u64 *, topa_cpu);
static DEFINE_PER_CPU(bool, pt_running);
static DEFINE_PER_CPU(u64, pt_offset);
static bool initialized;
static bool has_cr3_match;
static unsigned psb_freq_mask;
static unsigned cyc_thresh_mask;
static unsigned mtc_freq_mask;
static unsigned addr_cfg_max;
static bool disable_branch;
module_param(disable_branch, bool, 0644);
MODULE_PARM_DESC(disable_branch, "Don't enable branch tracing (if supported)");
static int pt_buffer_order = 9;
module_param(pt_buffer_order, int, 0444);
MODULE_PARM_DESC(pt_buffer_order, "Order of PT buffer size per CPU (2^n pages)");
module_param(pt_num_buffers, int, 0444);
MODULE_PARM_DESC(pt_num_buffers, "Number of PT buffers per CPU (if supported)");
module_param_cb(start, &start_ops, &start, 0644);
MODULE_PARM_DESC(start, "Set to 1 to start trace, or 0 to stop");
static int user = 1;
module_param_cb(user, &resync_ops, &user, 0644);
MODULE_PARM_DESC(user, "Set to 0 to not trace user space");
static int kernel = 1;
module_param_cb(kernel, &resync_ops, &kernel, 0644);
MODULE_PARM_DESC(kernel, "Set to 0 to not trace kernel space");
static int tsc_en = 1;
module_param_cb(tsc, &resync_ops, &tsc_en, 0644);
MODULE_PARM_DESC(tsc, "Set to 0 to not trace timing");
static char comm_filter[100];
module_param_string(comm_filter, comm_filter, sizeof(comm_filter), 0644);
MODULE_PARM_DESC(comm_filter, "Process name to set CR3 filter for");
static int cr3_filter = 0;
module_param_cb(cr3_filter, &resync_ops, &cr3_filter, 0644);
MODULE_PARM_DESC(cr3_filter, "Enable CR3 filter");
static int dis_retc = 0;
module_param_cb(dis_retc, &resync_ops, &dis_retc, 0644);
MODULE_PARM_DESC(dis_retc, "Disable return compression");
static bool clear_on_start = true;
module_param(clear_on_start, bool, 0644);
MODULE_PARM_DESC(clear_on_start, "Clear PT buffer before start");
static bool single_range = false;
module_param(single_range, bool, 0444);
MODULE_PARM_DESC(single_range, "Use single range output");
static int enumerate_all = 0;
module_param_cb(enumerate_all, &enumerate_ops, &enumerate_all, 0644);
MODULE_PARM_DESC(enumerate_all, "Enumerate all processes CR3s (only use after initialization)");
static int cyc_thresh = 0;
module_param_cb(cyc_thresh, &resync_ops, &cyc_thresh, 0644);
MODULE_PARM_DESC(cyc_thresh, "Send cycle packets at every 2^(n-1) cycles (if supported)");
static int mtc_freq = 0;
module_param_cb(mtc_freq, &resync_ops, &mtc_freq, 0644);
MODULE_PARM_DESC(mtc_freq, "Enable MTC packets at frequency 2^(n-1) (if supported)");
static int psb_freq = 0;
module_param_cb(psb_freq, &resync_ops, &psb_freq, 0644);
MODULE_PARM_DESC(psb_freq, "Send PSB packets every 2K^n bytes (if supported)");
static u64 addr0_start;
module_param_cb(addr0_start, &addr_ops, &addr0_start, 0644);
MODULE_PARM_DESC(addr0_start, "Virtual start address of address range 0. Hex or kernel symbol+offset");
static u64 addr0_end;
module_param_cb(addr0_end, &addr_ops, &addr0_end, 0644);
MODULE_PARM_DESC(addr0_end, "Virtual end address of address range 0. Hex or kernel symbol+offset");
static unsigned addr0_cfg;
module_param_cb(addr0_cfg, &resync_ops, &addr0_cfg, 0644);
MODULE_PARM_DESC(addr0_end, "Mode of address range 0: 0 = off, 1 = filter, 2 = trace-stop (if supported)");
static u64 addr1_start;
module_param_cb(addr1_start, &addr_ops, &addr1_start, 0644);
MODULE_PARM_DESC(addr1_start, "Virtual start address of address range 1. Hex or kernel symbol+offset");
static u64 addr1_end;
module_param_cb(addr1_end, &addr_ops, &addr1_end, 0644);
MODULE_PARM_DESC(addr1_end, "Virtual end address of address range 1. Hex or kernel symbol+offset");
static unsigned addr1_cfg;
module_param_cb(addr1_cfg, &resync_ops, &addr1_cfg, 0644);
MODULE_PARM_DESC(addr1_end, "Mode of address range 1: 0 = off, 1 = filter, 2 = trace-stop (if supported)");
static unsigned long trace_stop;
module_param_cb(trace_stop, &trace_stop_ops, &trace_stop, 0644);
MODULE_PARM_DESC(trace_stop, "Stop trace when reaching kernel address. Can be kernel symbol+offset or 0 to disable");
static unsigned long trace_start;
module_param_cb(trace_start, &trace_start_ops, &trace_start, 0644);
MODULE_PARM_DESC(trace_start, "Start trace when reaching kernel address. Can be kernel symbol+offset or 0 to disable");
static bool force = false;
module_param(force, bool, 0644);
MODULE_PARM_DESC(force, "Force PT initialization even when already active");
static unsigned long tasklist_lock_ptr;
module_param(tasklist_lock_ptr, ulong, 0400);
MODULE_PARM_DESC(tasklist_lock_ptr, "Set address of tasklist_lock (for kernels without CONFIG_KALLSYMS_ALL)");
static int print_panic_psbs = 0;
module_param(print_panic_psbs, int, 0644);
MODULE_PARM_DESC(print_panic_psbs, "Print as many PSBs from PT log into kernel log on panic");
module_param_cb(log_dump, &log_dump_ops, &log_dump, 0644);
static DEFINE_MUTEX(restart_mutex);
static inline int pt_wrmsrl_safe(unsigned msr, u64 val)
{
int ret = wrmsrl_safe(msr, val);
trace_msr(msr, val, ret != 0, 0);
return ret;
}
static inline int pt_rdmsrl_safe(unsigned msr, u64 *val)
{
int ret = rdmsrl_safe(msr, val);
trace_msr(msr, *val, ret != 0, 1);
return ret;
}
static void init_mask_ptrs(void)
{
if (single_range)
pt_wrmsrl_safe(MSR_IA32_RTIT_OUTPUT_MASK_PTRS,
((1ULL << (PAGE_SHIFT + pt_buffer_order)) - 1));
else
pt_wrmsrl_safe(MSR_IA32_RTIT_OUTPUT_MASK_PTRS, 0ULL);
}
static int start_pt(void)
{
u64 val, oldval;
if (pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &val) < 0)
return -1;
oldval = val;
/* Disable trace for reconfiguration */
if (val & TRACE_EN)
pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val & ~TRACE_EN);
if (clear_on_start && !(val & TRACE_EN)) {
memset((void *)__this_cpu_read(pt_buffer_cpu), 0, PAGE_SIZE << pt_buffer_order);
init_mask_ptrs();
pt_wrmsrl_safe(MSR_IA32_RTIT_STATUS, 0ULL);
}
val &= ~(TSC_EN | CTL_OS | CTL_USER | CR3_FILTER | DIS_RETC | TO_PA |
CYC_EN | TRACE_EN | BRANCH_EN | CYC_EN | MTC_EN |
MTC_EN | MTC_MASK | CYC_MASK | PSB_MASK | ADDR0_MASK | ADDR1_MASK);
/* Otherwise wait for start trigger */
if (!delay_start)
val |= TRACE_EN;
if (!disable_branch)
val |= BRANCH_EN;
if (!single_range)
val |= TO_PA;
if (tsc_en)
val |= TSC_EN;
if (kernel)
val |= CTL_OS;
if (user)
val |= CTL_USER;
if (cr3_filter && has_cr3_match) {
if (!(oldval & CR3_FILTER))
pt_wrmsrl_safe(MSR_IA32_CR3_MATCH, 0ULL);
val |= CR3_FILTER;
}
if (dis_retc)
val |= DIS_RETC;
if (cyc_thresh && ((1U << (cyc_thresh-1)) & cyc_thresh_mask))
val |= ((cyc_thresh - 1) << 19) | CYC_EN;
if (mtc_freq && ((1U << (mtc_freq-1)) & mtc_freq_mask))
val |= ((mtc_freq - 1) << 14) | MTC_EN;
if (psb_freq && ((1U << (psb_freq-1)) & psb_freq_mask))
val |= (psb_freq - 1) << 24;
if (addr0_cfg && (addr0_cfg <= addr_cfg_max) && addr_range_num >= 1) {
val |= ((u64)addr0_cfg << ADDR0_SHIFT);
pt_wrmsrl_safe(MSR_IA32_ADDR0_START, addr0_start);
pt_wrmsrl_safe(MSR_IA32_ADDR0_END, addr0_end);
}
if (addr1_cfg && (addr1_cfg <= addr_cfg_max) && addr_range_num >= 2) {
val |= ((u64)addr1_cfg << ADDR1_SHIFT);
pt_wrmsrl_safe(MSR_IA32_ADDR1_START, addr1_start);
pt_wrmsrl_safe(MSR_IA32_ADDR1_END, addr1_end);
}
if (pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val) < 0)
return -1;
__this_cpu_write(pt_running, true);
return 0;
}
static void do_start_pt(void *arg)
{
int cpu = smp_processor_id();
if (start_pt() < 0)
pr_err("cpu %d, RTIT_CTL enable failed\n", cpu);
}
static void stop_pt(void *arg)
{
u64 offset;
u64 ctl, status, extra;
if (!__this_cpu_read(pt_running))
return;
pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &ctl);
pt_rdmsrl_safe(MSR_IA32_RTIT_STATUS, &status);
if (!(ctl & TRACE_EN))
pr_debug("cpu %d, trace was not enabled on stop, ctl %llx, status %llx\n",
raw_smp_processor_id(), ctl, status);
if (status & PT_ERROR) {
pr_info("cpu %d, error happened: status %llx\n",
raw_smp_processor_id(), status);
pt_wrmsrl_safe(MSR_IA32_RTIT_STATUS, 0);
}
pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, 0LL);
pt_rdmsrl_safe(MSR_IA32_RTIT_OUTPUT_MASK_PTRS, &offset);
extra = 0;
if (!single_range)
extra = ((offset & 0xffffffff) >> 7) <<
(pt_buffer_order + PAGE_SHIFT);
__this_cpu_write(pt_offset, (offset >> 32) + extra);
__this_cpu_write(pt_running, false);
}
static void stop_pt_all(void)
{
mutex_lock(&restart_mutex);
on_each_cpu(stop_pt, NULL, 1);
start = 0;
mutex_unlock(&restart_mutex);
}
static void restart(void)
{
if (!initialized)
return;
mutex_lock(&restart_mutex);
on_each_cpu(start ? do_start_pt : stop_pt, NULL, 1);
mutex_unlock(&restart_mutex);
}
static int probe_start(struct kprobe *kp, struct pt_regs *regs)
{
if (__this_cpu_read(pt_running)) {
u64 val;
pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &val);
val |= TRACE_EN;
pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val);
}
return 0;
}
static int probe_stop(struct kprobe *kp, struct pt_regs *regs)
{
if (__this_cpu_read(pt_running)) {
u64 val;
pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &val);
val &= ~TRACE_EN;
pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val);
}
return 0;
}
/* Log CR3 of all already running processes. */
static void do_enumerate_all(void)
{
struct task_struct *t;
/* XXX, better way? */
rwlock_t *my_tasklist_lock = (rwlock_t *)tasklist_lock_ptr;
if (!my_tasklist_lock)
my_tasklist_lock = (rwlock_t *)kallsyms_lookup_name("tasklist_lock");
if (!my_tasklist_lock) {
pr_err("Cannot find tasklist_lock. CONFIG_KALLSYMS_ALL disabled?\n");
pr_err("Specify tasklist_lock_ptr parameter at module load\n");
return;
}
read_lock(my_tasklist_lock);
for_each_process (t) {
if ((t->flags & PF_KTHREAD) || !t->mm)
continue;
/* Cannot get the file name here, leave that to user space */
trace_process_cr3(t->pid, __pa(t->mm->pgd), t->comm);
}
read_unlock(my_tasklist_lock);
}
static void simple_pt_init_msrs(void)
{
if (!single_range) {
u64 *topa;
topa = __this_cpu_read(topa_cpu);
pt_wrmsrl_safe(MSR_IA32_RTIT_OUTPUT_BASE, __pa(topa));
} else {
unsigned long pt_buffer;
pt_buffer = __this_cpu_read(pt_buffer_cpu);
pt_wrmsrl_safe(MSR_IA32_RTIT_OUTPUT_BASE, __pa(pt_buffer));
}
init_mask_ptrs();
pt_wrmsrl_safe(MSR_IA32_RTIT_STATUS, 0ULL);
}
static int simple_pt_buffer_init(int cpu)
{
unsigned long pt_buffer;
u64 *topa;
/* allocate buffer */
pt_buffer = per_cpu(pt_buffer_cpu, cpu);
if (!pt_buffer) {
pt_buffer = __get_free_pages(GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO, pt_buffer_order);
if (!pt_buffer) {
pr_err("cpu %d, Cannot allocate %ld KB buffer\n", cpu,
(PAGE_SIZE << pt_buffer_order) / 1024);
return -ENOMEM;
}
per_cpu(pt_buffer_cpu, cpu) = pt_buffer;
}
if (!single_range) {
/* allocate topa */
topa = per_cpu(topa_cpu, cpu);
if (!topa) {
int n;
topa = (u64 *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
if (!topa) {
pr_err("cpu %d, Cannot allocate topa page\n", cpu);
goto out_pt_buffer;
}
per_cpu(topa_cpu, cpu) = topa;
/* create circular topa table */
n = 0;
topa[n++] = (u64)__pa(pt_buffer) |
(pt_buffer_order << TOPA_SIZE_SHIFT);
for (; n < pt_num_buffers; n++) {
void *buf = (void *)__get_free_pages(
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO,
pt_buffer_order);
if (!buf) {
pr_warn("Cannot allocate %d'th PT buffer\n", n);
break;
}
topa[n] = __pa(buf) |
(pt_buffer_order << TOPA_SIZE_SHIFT);
}
topa[n] = (u64)__pa(topa) | TOPA_END; /* circular buffer */
}
}
return 0;
out_pt_buffer:
free_pages(pt_buffer, pt_buffer_order);
per_cpu(pt_buffer_cpu, cpu) = 0;
return -ENOMEM;
}
static unsigned topa_entries(int cpu)
{
u64 *topa = per_cpu(topa_cpu, cpu);
int n;
if (single_range)
return 1;
if (!topa)
return 0;
for (n = 0; !(topa[n] & TOPA_END); n++)
;
return n;
}
static int simple_pt_cpu_init(void *arg)
{
int cpu = smp_processor_id();
u64 ctl;
/* check for pt already active */
if (pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &ctl) < 0) {
pr_err("cpu %d, Cannot access RTIT_CTL\n", cpu);
return -EIO;
}
if (ctl & TRACE_EN) {
if (!force) {
pr_err("cpu %d, PT already active: %llx\n", cpu, ctl);
return -EBUSY;
}
pr_info("forcibly taking over PT on %d: %llx\n", cpu, ctl);
}
simple_pt_init_msrs();
return 0;
}
static inline int file_get_cpu(struct file *file)
{
return (long)file->private_data;
}
static int simple_pt_mmap(struct file *file, struct vm_area_struct *vma)
{
unsigned long len = vma->vm_end - vma->vm_start;
int cpu = file_get_cpu(file);
unsigned num = topa_entries(cpu);
int i, err;
u64 *topa;
unsigned long buffer_size = PAGE_SIZE << pt_buffer_order;
vma->vm_flags &= ~VM_MAYWRITE;
if (len % PAGE_SIZE || len != num * buffer_size || vma->vm_pgoff)
return -EINVAL;
if (vma->vm_flags & VM_WRITE)
return -EPERM;
if (!cpu_online(cpu))
return -EIO;
if (num <= 1) {
return remap_pfn_range(vma, vma->vm_start,
__pa(per_cpu(pt_buffer_cpu, cpu)) >> PAGE_SHIFT,
buffer_size,
vma->vm_page_prot);
}
topa = per_cpu(topa_cpu, cpu);
err = 0;
for (i = 0; i < num; i++) {
err = remap_pfn_range(vma,
vma->vm_start + i*buffer_size,
topa[i] >> PAGE_SHIFT,
buffer_size,
vma->vm_page_prot);
if (err)
break;
}
return err;
}
static long simple_pt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
case SIMPLE_PT_SET_CPU: {
unsigned long cpu = arg;
if (cpu >= NR_CPUS || !cpu_online(cpu))
return -EINVAL;
file->private_data = (void *)cpu;
return 0;
}
case SIMPLE_PT_GET_SIZE: {
int num = topa_entries(file_get_cpu(file));
return put_user(num * (PAGE_SIZE << pt_buffer_order),
(int *)arg);
}
case SIMPLE_PT_GET_OFFSET: {
unsigned offset;
int ret = 0;
mutex_lock(&restart_mutex);
if (per_cpu(pt_running, file_get_cpu(file)))
ret = -EIO;
else
offset = per_cpu(pt_offset, file_get_cpu(file));
mutex_unlock(&restart_mutex);
if (!ret)
ret = put_user(offset, (int *)arg);
return ret;
}
default:
return -ENOTTY;
}
}
static const struct file_operations simple_pt_fops = {
.owner = THIS_MODULE,
.mmap = simple_pt_mmap,
.unlocked_ioctl = simple_pt_ioctl,
.llseek = noop_llseek,
};
static struct miscdevice simple_pt_miscdev = {
MISC_DYNAMIC_MINOR,
"simple-pt",
&simple_pt_fops
};
static void set_cr3_filter(void *arg)
{
u64 val;
if (pt_rdmsrl_safe(MSR_IA32_RTIT_CTL, &val) < 0)
return;
if ((val & TRACE_EN) && pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val & ~TRACE_EN) < 0)
return;
if (pt_wrmsrl_safe(MSR_IA32_CR3_MATCH, *(u64 *)arg) < 0)
pr_err("cpu %d, cannot set cr3 filter\n", smp_processor_id());
if ((val & TRACE_EN) && pt_wrmsrl_safe(MSR_IA32_RTIT_CTL, val) < 0)
return;
}
static bool match_comm(void)
{
char *s;
s = strchr(comm_filter, '\n');
if (s)
*s = 0;
if (comm_filter[0] == 0)
return true;
return !strcmp(current->comm, comm_filter);
}
static u64 retrieve_cr3(void)
{
u64 cr3;
asm volatile("mov %%cr3,%0" : "=r" (cr3));
return cr3;
}
static void probe_sched_process_exec(void *arg,
struct task_struct *p, pid_t old_pid,
struct linux_binprm *bprm)
{
u64 cr3 = retrieve_cr3();
char *pathbuf, *path;
if (!match_comm())
return;
pathbuf = (char *)__get_free_page(GFP_KERNEL);
if (!pathbuf)
return;
/* mmap_sem needed? */
path = d_path(¤t->mm->exe_file->f_path, pathbuf, PAGE_SIZE);
if (IS_ERR(path))
goto out;
trace_exec_cr3(cr3, path, current->pid);
if (comm_filter[0] && has_cr3_match) {
mutex_lock(&restart_mutex);
on_each_cpu(set_cr3_filter, &cr3, 1);
mutex_unlock(&restart_mutex);
}
out:
free_page((unsigned long)pathbuf);
}
static int probe_mmap_region(struct kprobe *kp, struct pt_regs *regs)
{
#ifdef CONFIG_X86_64
struct file *file = (struct file *)regs->di;
unsigned long addr = regs->si;
unsigned long len = regs->dx;
unsigned long vm_flags = regs->cx;
unsigned long pgoff = regs->r8;
#else
/* Assume regparm(3) */
struct file *file = (struct file *)regs->ax;
unsigned long addr = regs->dx;
unsigned long len = regs->cx;
unsigned long vm_flags = ((u32 *)(regs->sp))[1];
unsigned long pgoff = ((u32 *)(regs->sp))[2];
#endif
char *pathbuf, *path;
if (!(vm_flags & VM_EXEC) || !file)
return 0;
if (!match_comm())
return 0;
pathbuf = (char *)__get_free_page(GFP_KERNEL);
if (!pathbuf)
return 0;
path = d_path(&file->f_path, pathbuf, PAGE_SIZE);
if (IS_ERR(path))
goto out;
trace_mmap_cr3(retrieve_cr3(), path, pgoff, addr, len,
current->pid);
out:
free_page((unsigned long)pathbuf);
return 0;
}
static struct kprobe mmap_kp = {
.symbol_name = "mmap_region",
.pre_handler = probe_mmap_region,
};
static bool is_psb(void *p)
{
return *(u64 *)p == 0x8202820282028202ULL && ((u64 *)p)[1] == 0x8202820282028202ULL;
}
static const char base64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define LINELEN 75
static void print_base64(char *start, char *end)
{
char line[LINELEN + 1];
char *o = line;
while (start < end) {
unsigned b;
*o++ = base64[(start[0] & 0xfc) >> 2];
b = (start[0] & 3) << 4;
if (start + 1 < end) {
b |= (start[1] & 0xf0) >> 4;
*o++ = base64[b];
b = (start[1] & 0xf) << 2;
if (start + 2 < end) {
b |= (start[2] & 0xc0) >> 6;
*o++ = base64[b];
b = start[2] & 0x3f;
*o++ = base64[b];
} else {
*o++ = base64[b];
*o++ = '=';
}
} else {
*o++ = base64[b];
*o++ = '=';
*o++ = '=';
}
if (o - line >= LINELEN) {
*o = 0;
printk("%s\n", line);
o = line;
}
start += 3;
}
if (o > line) {
*o = 0;
printk("%s\n", line);
}
}
/*
* This should rather go into pstore, but pstore doesn't support
* writing from modules currently, so we just write it to the
* kernel log.
*/
static void print_last_branches(int num_psbs)
{
u64 offset = __this_cpu_read(pt_offset);
char *base = (char *)__this_cpu_read(pt_buffer_cpu);
u64 end;
end = offset;
if (offset <= 16)
return;
offset -= 16;
printk(KERN_INFO "PT DUMP START OFF %llx CPU %d BUF %p\n", offset,
raw_smp_processor_id(), base);
for (;;) {
if (is_psb(base + offset) &&
--num_psbs <= 0)
break;
if (offset == 0)
break;
offset--;
}
print_base64(base + offset, base + end);
printk(KERN_INFO "PT DUMP END %llx\n", offset);
}
/* Stop PT on all CPUs so that a crash dump has a good log */
static int simple_pt_panic(struct notifier_block *nb, unsigned long action,
void *v)
{
/* Assumes the interrupts are still on. Should send a NMI?
* We don't wait to avoid any deadlocks.
* Could also only stop on the current CPU.
*/
if (!start)
return NOTIFY_OK;
on_each_cpu(stop_pt, NULL, 0);
if (print_panic_psbs && pt_num_buffers == 1)
print_last_branches(print_panic_psbs);
return NOTIFY_OK;
}
static struct notifier_block panic_notifier = {
.notifier_call = simple_pt_panic,
};
/* No tracing over suspend for now. */
static int simple_pt_suspend(void)
{
stop_pt(NULL);
start = 0;
return 0;
}
static void simple_pt_resume(void)
{
simple_pt_cpu_init(NULL);
}
static struct syscore_ops simple_pt_syscore = {
.suspend = simple_pt_suspend,
.resume = simple_pt_resume,
};
static int simple_pt_cpuid(void)
{