Commit c5d6c770 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Russell King
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ARM: 5841/1: a driver for on-chip ETM and ETB

This driver implements support for on-chip Embedded Tracing Macrocell and
Embedded Trace Buffer. It allows to trigger tracing of kernel execution flow
and exporting trace output to userspace via character device and a sysrq
combo.

Trace output can then be decoded by a fairly simple open source tool [1]
which is already sufficient to get the idea of what the kernel is doing.

[1]: http://github.com/virtuoso/etm2human

Signed-off-by: default avatarAlexander Shishkin <virtuoso@slind.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 29e55363
......@@ -83,6 +83,14 @@ config DEBUG_ICEDCC
It does include a timeout to ensure that the system does not
totally freeze when there is nothing connected to read.
config OC_ETM
bool "On-chip ETM and ETB"
select ARM_AMBA
help
Enables the on-chip embedded trace macrocell and embedded trace
buffer driver that will allow you to collect traces of the
kernel code.
config DEBUG_DC21285_PORT
bool "Kernel low-level debugging messages via footbridge serial port"
depends on DEBUG_LL && FOOTBRIDGE
......
/*
* linux/arch/arm/include/asm/hardware/coresight.h
*
* CoreSight components' registers
*
* Copyright (C) 2009 Nokia Corporation.
* Alexander Shishkin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_HARDWARE_CORESIGHT_H
#define __ASM_HARDWARE_CORESIGHT_H
#define TRACER_ACCESSED_BIT 0
#define TRACER_RUNNING_BIT 1
#define TRACER_CYCLE_ACC_BIT 2
#define TRACER_ACCESSED BIT(TRACER_ACCESSED_BIT)
#define TRACER_RUNNING BIT(TRACER_RUNNING_BIT)
#define TRACER_CYCLE_ACC BIT(TRACER_CYCLE_ACC_BIT)
struct tracectx {
unsigned int etb_bufsz;
void __iomem *etb_regs;
void __iomem *etm_regs;
unsigned long flags;
int ncmppairs;
int etm_portsz;
struct device *dev;
struct clk *emu_clk;
struct mutex mutex;
};
#define TRACER_TIMEOUT 10000
#define etm_writel(t, v, x) \
(__raw_writel((v), (t)->etm_regs + (x)))
#define etm_readl(t, x) (__raw_readl((t)->etm_regs + (x)))
/* CoreSight Management Registers */
#define CSMR_LOCKACCESS 0xfb0
#define CSMR_LOCKSTATUS 0xfb4
#define CSMR_AUTHSTATUS 0xfb8
#define CSMR_DEVID 0xfc8
#define CSMR_DEVTYPE 0xfcc
/* CoreSight Component Registers */
#define CSCR_CLASS 0xff4
#define CSCR_PRSR 0x314
#define UNLOCK_MAGIC 0xc5acce55
/* ETM control register, "ETM Architecture", 3.3.1 */
#define ETMR_CTRL 0
#define ETMCTRL_POWERDOWN 1
#define ETMCTRL_PROGRAM (1 << 10)
#define ETMCTRL_PORTSEL (1 << 11)
#define ETMCTRL_DO_CONTEXTID (3 << 14)
#define ETMCTRL_PORTMASK1 (7 << 4)
#define ETMCTRL_PORTMASK2 (1 << 21)
#define ETMCTRL_PORTMASK (ETMCTRL_PORTMASK1 | ETMCTRL_PORTMASK2)
#define ETMCTRL_PORTSIZE(x) ((((x) & 7) << 4) | (!!((x) & 8)) << 21)
#define ETMCTRL_DO_CPRT (1 << 1)
#define ETMCTRL_DATAMASK (3 << 2)
#define ETMCTRL_DATA_DO_DATA (1 << 2)
#define ETMCTRL_DATA_DO_ADDR (1 << 3)
#define ETMCTRL_DATA_DO_BOTH (ETMCTRL_DATA_DO_DATA | ETMCTRL_DATA_DO_ADDR)
#define ETMCTRL_BRANCH_OUTPUT (1 << 8)
#define ETMCTRL_CYCLEACCURATE (1 << 12)
/* ETM configuration code register */
#define ETMR_CONFCODE (0x04)
/* ETM trace start/stop resource control register */
#define ETMR_TRACESSCTRL (0x18)
/* ETM trigger event register */
#define ETMR_TRIGEVT (0x08)
/* address access type register bits, "ETM architecture",
* table 3-27 */
/* - access type */
#define ETMAAT_IFETCH 0
#define ETMAAT_IEXEC 1
#define ETMAAT_IEXECPASS 2
#define ETMAAT_IEXECFAIL 3
#define ETMAAT_DLOADSTORE 4
#define ETMAAT_DLOAD 5
#define ETMAAT_DSTORE 6
/* - comparison access size */
#define ETMAAT_JAVA (0 << 3)
#define ETMAAT_THUMB (1 << 3)
#define ETMAAT_ARM (3 << 3)
/* - data value comparison control */
#define ETMAAT_NOVALCMP (0 << 5)
#define ETMAAT_VALMATCH (1 << 5)
#define ETMAAT_VALNOMATCH (3 << 5)
/* - exact match */
#define ETMAAT_EXACTMATCH (1 << 7)
/* - context id comparator control */
#define ETMAAT_IGNCONTEXTID (0 << 8)
#define ETMAAT_VALUE1 (1 << 8)
#define ETMAAT_VALUE2 (2 << 8)
#define ETMAAT_VALUE3 (3 << 8)
/* - security level control */
#define ETMAAT_IGNSECURITY (0 << 10)
#define ETMAAT_NSONLY (1 << 10)
#define ETMAAT_SONLY (2 << 10)
#define ETMR_COMP_VAL(x) (0x40 + (x) * 4)
#define ETMR_COMP_ACC_TYPE(x) (0x80 + (x) * 4)
/* ETM status register, "ETM Architecture", 3.3.2 */
#define ETMR_STATUS (0x10)
#define ETMST_OVERFLOW (1 << 0)
#define ETMST_PROGBIT (1 << 1)
#define ETMST_STARTSTOP (1 << 2)
#define ETMST_TRIGGER (1 << 3)
#define etm_progbit(t) (etm_readl((t), ETMR_STATUS) & ETMST_PROGBIT)
#define etm_started(t) (etm_readl((t), ETMR_STATUS) & ETMST_STARTSTOP)
#define etm_triggered(t) (etm_readl((t), ETMR_STATUS) & ETMST_TRIGGER)
#define ETMR_TRACEENCTRL2 0x1c
#define ETMR_TRACEENCTRL 0x24
#define ETMTE_INCLEXCL (1 << 24)
#define ETMR_TRACEENEVT 0x20
#define ETMCTRL_OPTS (ETMCTRL_DO_CPRT | \
ETMCTRL_DATA_DO_ADDR | \
ETMCTRL_BRANCH_OUTPUT | \
ETMCTRL_DO_CONTEXTID)
/* ETB registers, "CoreSight Components TRM", 9.3 */
#define ETBR_DEPTH 0x04
#define ETBR_STATUS 0x0c
#define ETBR_READMEM 0x10
#define ETBR_READADDR 0x14
#define ETBR_WRITEADDR 0x18
#define ETBR_TRIGGERCOUNT 0x1c
#define ETBR_CTRL 0x20
#define ETBR_FORMATTERCTRL 0x304
#define ETBFF_ENFTC 1
#define ETBFF_ENFCONT (1 << 1)
#define ETBFF_FONFLIN (1 << 4)
#define ETBFF_MANUAL_FLUSH (1 << 6)
#define ETBFF_TRIGIN (1 << 8)
#define ETBFF_TRIGEVT (1 << 9)
#define ETBFF_TRIGFL (1 << 10)
#define etb_writel(t, v, x) \
(__raw_writel((v), (t)->etb_regs + (x)))
#define etb_readl(t, x) (__raw_readl((t)->etb_regs + (x)))
#define etm_lock(t) do { etm_writel((t), 0, CSMR_LOCKACCESS); } while (0)
#define etm_unlock(t) \
do { etm_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
#define etb_lock(t) do { etb_writel((t), 0, CSMR_LOCKACCESS); } while (0)
#define etb_unlock(t) \
do { etb_writel((t), UNLOCK_MAGIC, CSMR_LOCKACCESS); } while (0)
#endif /* __ASM_HARDWARE_CORESIGHT_H */
......@@ -17,6 +17,8 @@ obj-y := compat.o elf.o entry-armv.o entry-common.o irq.o \
process.o ptrace.o return_address.o setup.o signal.o \
sys_arm.o stacktrace.o time.o traps.o
obj-$(CONFIG_OC_ETM) += etm.o
obj-$(CONFIG_ISA_DMA_API) += dma.o
obj-$(CONFIG_ARCH_ACORN) += ecard.o
obj-$(CONFIG_FIQ) += fiq.o
......
/*
* linux/arch/arm/kernel/etm.c
*
* Driver for ARM's Embedded Trace Macrocell and Embedded Trace Buffer.
*
* Copyright (C) 2009 Nokia Corporation.
* Alexander Shishkin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/sysrq.h>
#include <linux/device.h>
#include <linux/clk.h>
#include <linux/amba/bus.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/vmalloc.h>
#include <linux/mutex.h>
#include <asm/hardware/coresight.h>
#include <asm/sections.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Shishkin");
static struct tracectx tracer;
static inline bool trace_isrunning(struct tracectx *t)
{
return !!(t->flags & TRACER_RUNNING);
}
static int etm_setup_address_range(struct tracectx *t, int n,
unsigned long start, unsigned long end, int exclude, int data)
{
u32 flags = ETMAAT_ARM | ETMAAT_IGNCONTEXTID | ETMAAT_NSONLY | \
ETMAAT_NOVALCMP;
if (n < 1 || n > t->ncmppairs)
return -EINVAL;
/* comparators and ranges are numbered starting with 1 as opposed
* to bits in a word */
n--;
if (data)
flags |= ETMAAT_DLOADSTORE;
else
flags |= ETMAAT_IEXEC;
/* first comparator for the range */
etm_writel(t, flags, ETMR_COMP_ACC_TYPE(n * 2));
etm_writel(t, start, ETMR_COMP_VAL(n * 2));
/* second comparator is right next to it */
etm_writel(t, flags, ETMR_COMP_ACC_TYPE(n * 2 + 1));
etm_writel(t, end, ETMR_COMP_VAL(n * 2 + 1));
flags = exclude ? ETMTE_INCLEXCL : 0;
etm_writel(t, flags | (1 << n), ETMR_TRACEENCTRL);
return 0;
}
static int trace_start(struct tracectx *t)
{
u32 v;
unsigned long timeout = TRACER_TIMEOUT;
etb_unlock(t);
etb_writel(t, 0, ETBR_FORMATTERCTRL);
etb_writel(t, 1, ETBR_CTRL);
etb_lock(t);
/* configure etm */
v = ETMCTRL_OPTS | ETMCTRL_PROGRAM | ETMCTRL_PORTSIZE(t->etm_portsz);
if (t->flags & TRACER_CYCLE_ACC)
v |= ETMCTRL_CYCLEACCURATE;
etm_unlock(t);
etm_writel(t, v, ETMR_CTRL);
while (!(etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM) && --timeout)
;
if (!timeout) {
dev_dbg(t->dev, "Waiting for progbit to assert timed out\n");
etm_lock(t);
return -EFAULT;
}
etm_setup_address_range(t, 1, (unsigned long)_stext,
(unsigned long)_etext, 0, 0);
etm_writel(t, 0, ETMR_TRACEENCTRL2);
etm_writel(t, 0, ETMR_TRACESSCTRL);
etm_writel(t, 0x6f, ETMR_TRACEENEVT);
v &= ~ETMCTRL_PROGRAM;
v |= ETMCTRL_PORTSEL;
etm_writel(t, v, ETMR_CTRL);
timeout = TRACER_TIMEOUT;
while (etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM && --timeout)
;
if (!timeout) {
dev_dbg(t->dev, "Waiting for progbit to deassert timed out\n");
etm_lock(t);
return -EFAULT;
}
etm_lock(t);
t->flags |= TRACER_RUNNING;
return 0;
}
static int trace_stop(struct tracectx *t)
{
unsigned long timeout = TRACER_TIMEOUT;
etm_unlock(t);
etm_writel(t, 0x440, ETMR_CTRL);
while (!(etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM) && --timeout)
;
if (!timeout) {
dev_dbg(t->dev, "Waiting for progbit to assert timed out\n");
etm_lock(t);
return -EFAULT;
}
etm_lock(t);
etb_unlock(t);
etb_writel(t, ETBFF_MANUAL_FLUSH, ETBR_FORMATTERCTRL);
timeout = TRACER_TIMEOUT;
while (etb_readl(t, ETBR_FORMATTERCTRL) &
ETBFF_MANUAL_FLUSH && --timeout)
;
if (!timeout) {
dev_dbg(t->dev, "Waiting for formatter flush to commence "
"timed out\n");
etb_lock(t);
return -EFAULT;
}
etb_writel(t, 0, ETBR_CTRL);
etb_lock(t);
t->flags &= ~TRACER_RUNNING;
return 0;
}
static int etb_getdatalen(struct tracectx *t)
{
u32 v;
int rp, wp;
v = etb_readl(t, ETBR_STATUS);
if (v & 1)
return t->etb_bufsz;
rp = etb_readl(t, ETBR_READADDR);
wp = etb_readl(t, ETBR_WRITEADDR);
if (rp > wp) {
etb_writel(t, 0, ETBR_READADDR);
etb_writel(t, 0, ETBR_WRITEADDR);
return 0;
}
return wp - rp;
}
/* sysrq+v will always stop the running trace and leave it at that */
static void etm_dump(void)
{
struct tracectx *t = &tracer;
u32 first = 0;
int length;
if (!t->etb_regs) {
printk(KERN_INFO "No tracing hardware found\n");
return;
}
if (trace_isrunning(t))
trace_stop(t);
etb_unlock(t);
length = etb_getdatalen(t);
if (length == t->etb_bufsz)
first = etb_readl(t, ETBR_WRITEADDR);
etb_writel(t, first, ETBR_READADDR);
printk(KERN_INFO "Trace buffer contents length: %d\n", length);
printk(KERN_INFO "--- ETB buffer begin ---\n");
for (; length; length--)
printk("%08x", cpu_to_be32(etb_readl(t, ETBR_READMEM)));
printk(KERN_INFO "\n--- ETB buffer end ---\n");
/* deassert the overflow bit */
etb_writel(t, 1, ETBR_CTRL);
etb_writel(t, 0, ETBR_CTRL);
etb_writel(t, 0, ETBR_TRIGGERCOUNT);
etb_writel(t, 0, ETBR_READADDR);
etb_writel(t, 0, ETBR_WRITEADDR);
etb_lock(t);
}
static void sysrq_etm_dump(int key, struct tty_struct *tty)
{
dev_dbg(tracer.dev, "Dumping ETB buffer\n");
etm_dump();
}
static struct sysrq_key_op sysrq_etm_op = {
.handler = sysrq_etm_dump,
.help_msg = "ETM buffer dump",
.action_msg = "etm",
};
static int etb_open(struct inode *inode, struct file *file)
{
if (!tracer.etb_regs)
return -ENODEV;
file->private_data = &tracer;
return nonseekable_open(inode, file);
}
static ssize_t etb_read(struct file *file, char __user *data,
size_t len, loff_t *ppos)
{
int total, i;
long length;
struct tracectx *t = file->private_data;
u32 first = 0;
u32 *buf;
mutex_lock(&t->mutex);
if (trace_isrunning(t)) {
length = 0;
goto out;
}
etb_unlock(t);
total = etb_getdatalen(t);
if (total == t->etb_bufsz)
first = etb_readl(t, ETBR_WRITEADDR);
etb_writel(t, first, ETBR_READADDR);
length = min(total * 4, (int)len);
buf = vmalloc(length);
dev_dbg(t->dev, "ETB buffer length: %d\n", total);
dev_dbg(t->dev, "ETB status reg: %x\n", etb_readl(t, ETBR_STATUS));
for (i = 0; i < length / 4; i++)
buf[i] = etb_readl(t, ETBR_READMEM);
/* the only way to deassert overflow bit in ETB status is this */
etb_writel(t, 1, ETBR_CTRL);
etb_writel(t, 0, ETBR_CTRL);
etb_writel(t, 0, ETBR_WRITEADDR);
etb_writel(t, 0, ETBR_READADDR);
etb_writel(t, 0, ETBR_TRIGGERCOUNT);
etb_lock(t);
length -= copy_to_user(data, buf, length);
vfree(buf);
out:
mutex_unlock(&t->mutex);
return length;
}
static int etb_release(struct inode *inode, struct file *file)
{
/* there's nothing to do here, actually */
return 0;
}
static const struct file_operations etb_fops = {
.owner = THIS_MODULE,
.read = etb_read,
.open = etb_open,
.release = etb_release,
};
static struct miscdevice etb_miscdev = {
.name = "tracebuf",
.minor = 0,
.fops = &etb_fops,
};
static int __init etb_probe(struct amba_device *dev, struct amba_id *id)
{
struct tracectx *t = &tracer;
int ret = 0;
ret = amba_request_regions(dev, NULL);
if (ret)
goto out;
t->etb_regs = ioremap_nocache(dev->res.start, resource_size(&dev->res));
if (!t->etb_regs) {
ret = -ENOMEM;
goto out_release;
}
amba_set_drvdata(dev, t);
etb_miscdev.parent = &dev->dev;
ret = misc_register(&etb_miscdev);
if (ret)
goto out_unmap;
t->emu_clk = clk_get(&dev->dev, "emu_src_ck");
if (IS_ERR(t->emu_clk)) {
dev_dbg(&dev->dev, "Failed to obtain emu_src_ck.\n");
return -EFAULT;
}
clk_enable(t->emu_clk);
etb_unlock(t);
t->etb_bufsz = etb_readl(t, ETBR_DEPTH);
dev_dbg(&dev->dev, "Size: %x\n", t->etb_bufsz);
/* make sure trace capture is disabled */
etb_writel(t, 0, ETBR_CTRL);
etb_writel(t, 0x1000, ETBR_FORMATTERCTRL);
etb_lock(t);
dev_dbg(&dev->dev, "ETB AMBA driver initialized.\n");
out:
return ret;
out_unmap:
amba_set_drvdata(dev, NULL);
iounmap(t->etb_regs);
out_release:
amba_release_regions(dev);
return ret;
}
static int etb_remove(struct amba_device *dev)
{
struct tracectx *t = amba_get_drvdata(dev);
amba_set_drvdata(dev, NULL);
iounmap(t->etb_regs);
t->etb_regs = NULL;
clk_disable(t->emu_clk);
clk_put(t->emu_clk);
amba_release_regions(dev);
return 0;
}
static struct amba_id etb_ids[] = {
{
.id = 0x0003b907,
.mask = 0x0007ffff,
},
{ 0, 0 },
};
static struct amba_driver etb_driver = {
.drv = {
.name = "etb",
.owner = THIS_MODULE,
},
.probe = etb_probe,
.remove = etb_remove,
.id_table = etb_ids,
};
/* use a sysfs file "trace_running" to start/stop tracing */
static ssize_t trace_running_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%x\n", trace_isrunning(&tracer));
}
static ssize_t trace_running_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t n)
{
unsigned int value;
int ret;
if (sscanf(buf, "%u", &value) != 1)
return -EINVAL;
mutex_lock(&tracer.mutex);
ret = value ? trace_start(&tracer) : trace_stop(&tracer);
mutex_unlock(&tracer.mutex);
return ret ? : n;
}