[PATCH V3 5/5] ARM CoreSight: ETM: Add PID control support
Adrien Vergé
adrienverge at gmail.com
Thu Jan 30 11:11:10 EST 2014
In the same manner as for enabling tracing, an entry is created in
sysfs to set the PID that triggers tracing. This change is effective
only if CONFIG_PID_IN_CONTEXTIDR is set.
When using PID namespaces, the virtual PID given by the user is
converted to the globally unique ID (task_pid_nr) that is present
in the Context ID register.
Signed-off-by: Adrien Vergé <adrienverge at gmail.com>
---
arch/arm/include/asm/hardware/coresight.h | 5 ++
arch/arm/kernel/etm.c | 131 ++++++++++++++++++++++++++++--
2 files changed, 129 insertions(+), 7 deletions(-)
diff --git a/arch/arm/include/asm/hardware/coresight.h b/arch/arm/include/asm/hardware/coresight.h
index 8c50cf6..2051af0 100644
--- a/arch/arm/include/asm/hardware/coresight.h
+++ b/arch/arm/include/asm/hardware/coresight.h
@@ -98,6 +98,11 @@
#define ETMR_ADDRCOMP_VAL(x) (0x40 + (x) * 4)
#define ETMR_ADDRCOMP_ACC_TYPE(x) (0x80 + (x) * 4)
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+#define ETMR_CTXIDCOMP_VAL(x) (0x1b0 + (x) * 4)
+#define ETMR_CTXIDCOMP_MASK (0x1bc)
+#endif
+
/* 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 fa42e32..e8db9e2 100644
--- a/arch/arm/kernel/etm.c
+++ b/arch/arm/kernel/etm.c
@@ -25,6 +25,7 @@
#include <linux/vmalloc.h>
#include <linux/mutex.h>
#include <linux/module.h>
+#include <linux/sched.h>
#include <asm/hardware/coresight.h>
#include <asm/sections.h>
@@ -40,12 +41,17 @@ 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;
+ pid_t pid; /* globally unique PID */
+#ifdef CONFIG_PID_NS
+ pid_t vpid; /* virtual PID as seen in namespace */
+#endif
};
static struct tracectx tracer;
@@ -55,18 +61,42 @@ static inline bool trace_isrunning(struct tracectx *t)
return !!(t->flags & TRACER_RUNNING);
}
+#if defined(CONFIG_PID_IN_CONTEXTIDR) && defined(CONFIG_PID_NS)
+/*
+ * Returns the globally unique ID of a task referenced
+ * with its virtual namespace PID
+ */
+static inline pid_t pid_vnr_to_pid_nr(pid_t vpid)
+{
+ struct task_struct *task = find_task_by_vpid(vpid);
+
+ if (!task) {
+ printk(KERN_WARNING "CoreSight ETM: cannot track PID %d: "
+ "no such PID in current namespace\n",
+ vpid);
+ return -EINVAL;
+ }
+
+ return task_pid_nr(task);
+}
+#endif
+
/*
* 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,
+ pid_t 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 +105,23 @@ static int etm_setup_address_range(struct tracectx *t, int n,
* to bits in a word */
n--;
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+ 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);
+ }
+#else
+ flags |= ETMAAT_IGNCONTEXTID;
+#endif
+
if (data)
flags |= ETMAAT_DLOADSTORE;
else
@@ -124,8 +171,10 @@ 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);
@@ -489,6 +538,7 @@ static ssize_t trace_info_show(struct device *dev,
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"
@@ -497,6 +547,7 @@ static ssize_t trace_info_show(struct device *dev,
"ETMR_STATUS:\t%08x\n",
datalen,
tracer.naddrcmppairs,
+ tracer.nctxidcmp,
etb_wa,
etb_ra,
etb_st,
@@ -569,6 +620,61 @@ static ssize_t trace_addrrange_store(struct device *dev,
DEVICE_ATTR(trace_addrrange, S_IRUGO|S_IWUSR,
trace_addrrange_show, trace_addrrange_store);
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+static ssize_t trace_pid_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+#ifdef CONFIG_PID_NS
+ return sprintf(buf, "%d\n", tracer.vpid);
+#else
+ return sprintf(buf, "%d\n", tracer.pid);
+#endif
+}
+
+static ssize_t trace_pid_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t n)
+{
+ pid_t pid;
+#ifdef CONFIG_PID_NS
+ pid_t vpid;
+#endif
+
+ if (tracer.flags & TRACER_RUNNING)
+ return -EBUSY;
+
+ if (sscanf(buf, "%i", &pid) != 1)
+ return -EINVAL;
+
+#ifdef CONFIG_PID_NS
+ /* the value written to the Context ID register is the global PID */
+ vpid = pid;
+
+ /* -1 means trace everything,
+ 0 means kernel tracing,
+ > 0 process tracing */
+ if (pid > 0) {
+ pid = pid_vnr_to_pid_nr(vpid);
+
+ if (pid < 0)
+ return pid;
+ }
+#endif
+
+ mutex_lock(&tracer.mutex);
+ tracer.pid = pid;
+#ifdef CONFIG_PID_NS
+ tracer.vpid = vpid;
+#endif
+ mutex_unlock(&tracer.mutex);
+
+ return n;
+}
+
+DEVICE_ATTR(trace_pid, S_IRUGO|S_IWUSR, trace_pid_show, trace_pid_store);
+#endif
+
static int etm_probe(struct amba_device *dev, const struct amba_id *id)
{
struct tracectx *t = &tracer;
@@ -598,6 +704,7 @@ 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);
@@ -605,6 +712,7 @@ 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);
@@ -612,7 +720,7 @@ 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 = device_create_file(&dev->dev, &dev_attr_trace_info);
if (ret)
dev_dbg(&dev->dev, "Failed to create trace_info in sysfs\n");
@@ -625,6 +733,12 @@ 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");
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+ ret = device_create_file(&dev->dev, &dev_attr_trace_pid);
+ if (ret)
+ dev_dbg(&dev->dev, "Failed to create trace_pid in sysfs\n");
+#endif
+
dev_dbg(t->dev, "ETM AMBA driver initialized.\n");
out:
@@ -655,6 +769,9 @@ static int etm_remove(struct amba_device *dev)
device_remove_file(&dev->dev, &dev_attr_trace_info);
device_remove_file(&dev->dev, &dev_attr_trace_mode);
device_remove_file(&dev->dev, &dev_attr_trace_addrrange);
+#ifdef CONFIG_PID_IN_CONTEXTIDR
+ device_remove_file(&dev->dev, &dev_attr_trace_pid);
+#endif
return 0;
}
--
1.8.5.3
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