Date:	Tue, 3 Dec 2013 23:40:59 -0500
From:	Adrien Vergé <adrienverge@...il.com>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	Russell King <linux@....linux.org.uk>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Will Deacon <will.deacon@....com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"zhangwei(Jovi)" <jovi.zhangwei@...wei.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Randy Dunlap <rdunlap@...radead.org>
Subject: [PATCH 3/3] ARM Coresight: Add PID control support for ETM tracing

In the same manner as for enabling tracing, an entry is created in
sysfs to set the PID that triggers tracing. This change requires
CONFIG_PID_IN_CONTEXTIDR to be set when using on-chip ETM.

Signed-off-by: Adrien Vergé <adrienverge@...il.com>
Cc: Russell King <linux@....linux.org.uk>
Cc: Ben Dooks <ben.dooks@...ethink.co.uk>
Cc: Will Deacon <will.deacon@....com>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: "zhangwei(Jovi)" <jovi.zhangwei@...wei.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Randy Dunlap <rdunlap@...radead.org>
---
 arch/arm/Kconfig.debug                    |  1 +
 arch/arm/include/asm/hardware/coresight.h |  3 ++
 arch/arm/kernel/etm.c                     | 73 ++++++++++++++++++++++++++++---
 3 files changed, 70 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 5765abf..fef32e15 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -1130,6 +1130,7 @@ config EARLY_PRINTK
 config OC_ETM
  bool "On-chip ETM and ETB"
  depends on ARM_AMBA
+ select PID_IN_CONTEXTIDR
  help
   Enables the on-chip embedded trace macrocell and embedded trace
   buffer driver that will allow you to collect traces of the
diff --git a/arch/arm/include/asm/hardware/coresight.h
b/arch/arm/include/asm/hardware/coresight.h
index 8c50cf6..009cdf9 100644
--- a/arch/arm/include/asm/hardware/coresight.h
+++ b/arch/arm/include/asm/hardware/coresight.h
@@ -98,6 +98,9 @@
 #define ETMR_ADDRCOMP_VAL(x) (0x40 + (x) * 4)
 #define ETMR_ADDRCOMP_ACC_TYPE(x) (0x80 + (x) * 4)

+#define ETMR_CTXIDCOMP_VAL(x) (0x1b0 + (x) * 4)
+#define ETMR_CTXIDCOMP_MASK (0x1bc)
+
 /* ETM status register, "ETM Architecture", 3.3.2 */
 #define ETMR_STATUS (0x10)
 #define ETMST_OVERFLOW BIT(0)
diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c
index a72382b..18afed1 100644
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -40,12 +40,14 @@ struct tracectx {
  void __iomem *etm_regs;
  unsigned long flags;
  int naddrcmppairs;
+ int nctxidcmp;
  int etm_portsz;
  struct device *dev;
  struct clk *emu_clk;
  struct mutex mutex;
  unsigned long addrrange_start;
  unsigned long addrrange_end;
+ long pid;
 };

 static struct tracectx tracer;
@@ -59,14 +61,18 @@ static inline bool trace_isrunning(struct tracectx *t)
  * Setups ETM to trace only when:
  *   - address between start and end
  *     or address not between start and end (if exclude)
+ *   - in user-space when process id equals pid,
+ *     in kernel-space (if pid == 0),
+ *     always (if pid == -1)
  *   - trace executed instructions
  *     or trace loads and stores (if data)
  */
-static int etm_setup_address_range(struct tracectx *t, int n,
- unsigned long start, unsigned long end, int exclude, int data)
+static int etm_setup(struct tracectx *t, int n,
+     unsigned long start, unsigned long end, int exclude,
+     long pid,
+     int data)
 {
- u32 flags = ETMAAT_ARM | ETMAAT_IGNCONTEXTID | ETMAAT_NSONLY | \
-    ETMAAT_NOVALCMP;
+ u32 flags = ETMAAT_ARM | ETMAAT_NSONLY | ETMAAT_NOVALCMP;

  if (n < 1 || n > t->naddrcmppairs)
  return -EINVAL;
@@ -75,6 +81,19 @@ static int etm_setup_address_range(struct tracectx *t, int n,
  * to bits in a word */
  n--;

+ if (pid < 0) {
+ /* ignore Context ID */
+ flags |= ETMAAT_IGNCONTEXTID;
+ } else {
+ flags |= ETMAAT_VALUE1;
+
+ /* Set up the first Context ID comparator.
+   Process ID is found in the 24 first bits of Context ID
+   (provided by CONFIG_PID_IN_CONTEXTIDR) */
+ etm_writel(t, pid << 8, ETMR_CTXIDCOMP_VAL(0));
+ etm_writel(t, 0xff, ETMR_CTXIDCOMP_MASK);
+ }
+
  if (data)
  flags |= ETMAAT_DLOADSTORE;
  else
@@ -124,8 +143,10 @@ static int trace_start(struct tracectx *t)
  return -EFAULT;
  }

- etm_setup_address_range(t, 1, t->addrrange_start, t->addrrange_end,
- 0, 0);
+ etm_setup(t, 1,
+  t->addrrange_start, t->addrrange_end, 0,
+  t->pid,
+  0);
  etm_writel(t, 0, ETMR_TRACEENCTRL2);
  etm_writel(t, 0, ETMR_TRACESSCTRL);
  etm_writel(t, 0x6f, ETMR_TRACEENEVT);
@@ -488,6 +509,7 @@ static ssize_t trace_info_show(struct kobject *kobj,

  return sprintf(buf, "Trace buffer len: %d\n"
  "Addr comparator pairs: %d\n"
+ "Ctx ID comparators: %d\n"
  "ETBR_WRITEADDR:\t%08x\n"
  "ETBR_READADDR:\t%08x\n"
  "ETBR_STATUS:\t%08x\n"
@@ -496,6 +518,7 @@ static ssize_t trace_info_show(struct kobject *kobj,
  "ETMR_STATUS:\t%08x\n",
  datalen,
  tracer.naddrcmppairs,
+ tracer.nctxidcmp,
  etb_wa,
  etb_ra,
  etb_st,
@@ -572,6 +595,35 @@ static ssize_t trace_addrrange_store(struct kobject *kobj,
 static struct kobj_attribute trace_addrrange_attr =
  __ATTR(trace_addrrange, 0644, trace_addrrange_show, trace_addrrange_store);

+static ssize_t trace_pid_show(struct kobject *kobj,
+      struct kobj_attribute *attr,
+      char *buf)
+{
+ return sprintf(buf, "%ld\n", tracer.pid);
+}
+
+static ssize_t trace_pid_store(struct kobject *kobj,
+       struct kobj_attribute *attr,
+       const char *buf, size_t n)
+{
+ long pid;
+
+ if (tracer.flags & TRACER_RUNNING)
+ return -EBUSY;
+
+ if (sscanf(buf, "%li", &pid) != 1)
+ return -EINVAL;
+
+ mutex_lock(&tracer.mutex);
+ tracer.pid = pid;
+ mutex_unlock(&tracer.mutex);
+
+ return n;
+}
+
+static struct kobj_attribute trace_pid_attr =
+ __ATTR(trace_pid, 0644, trace_pid_show, trace_pid_store);
+
 static int etm_probe(struct amba_device *dev, const struct amba_id *id)
 {
  struct tracectx *t = &tracer;
@@ -601,6 +653,7 @@ static int etm_probe(struct amba_device *dev,
const struct amba_id *id)
  t->etm_portsz = 1;
  t->addrrange_start = (unsigned long) _stext;
  t->addrrange_end = (unsigned long) _etext;
+ t->pid = -1; /* trace everything */

  etm_unlock(t);
  (void)etm_readl(t, ETMMR_PDSR);
@@ -608,6 +661,7 @@ static int etm_probe(struct amba_device *dev,
const struct amba_id *id)
  (void)etm_readl(&tracer, ETMMR_OSSRR);

  t->naddrcmppairs = etm_readl(t, ETMR_CONFCODE) & 0xf;
+ t->nctxidcmp = (etm_readl(t, ETMR_CONFCODE) >> 24) & 0x3;
  etm_writel(t, 0x440, ETMR_CTRL);
  etm_lock(t);

@@ -616,7 +670,7 @@ static int etm_probe(struct amba_device *dev,
const struct amba_id *id)
  if (ret)
  goto out_unmap;

- /* failing to create any of these three is not fatal */
+ /* failing to create any of these four is not fatal */
  ret = sysfs_create_file(&dev->dev.kobj, &trace_info_attr.attr);
  if (ret)
  dev_dbg(&dev->dev, "Failed to create trace_info in sysfs\n");
@@ -629,6 +683,10 @@ static int etm_probe(struct amba_device *dev,
const struct amba_id *id)
  if (ret)
  dev_dbg(&dev->dev, "Failed to create trace_addrrange in sysfs\n");

+ ret = sysfs_create_file(&dev->dev.kobj, &trace_pid_attr.attr);
+ if (ret)
+ dev_dbg(&dev->dev, "Failed to create trace_pid in sysfs\n");
+
  dev_dbg(t->dev, "ETM AMBA driver initialized.\n");

 out:
@@ -659,6 +717,7 @@ static int etm_remove(struct amba_device *dev)
  sysfs_remove_file(&dev->dev.kobj, &trace_info_attr.attr);
  sysfs_remove_file(&dev->dev.kobj, &trace_mode_attr.attr);
  sysfs_remove_file(&dev->dev.kobj, &trace_addrrange_attr.attr);
+ sysfs_remove_file(&dev->dev.kobj, &trace_pid_attr.attr);

  return 0;
 }
-- 
1.8.3.1
--
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