Commit 58cf93f8 authored by Suzuki Poulose's avatar Suzuki Poulose Committed by Robert Walker
Browse files

coresight: etm-perf: Add support for ETR backend



Add support for using TMC-ETR as backend for ETM perf tracing.
We use software double buffering at the moment. i.e, the TMC-ETR
uses a separate buffer than the perf ring buffer. The data is
copied to the perf ring buffer once a session completes.

The TMC-ETR would try to match the larger of perf ring buffer
or the ETR buffer size configured via sysfs, scaling down to
a minimum limit of 1MB.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki Poulose's avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Cherry-pick from: https://git.linaro.org/kernel/coresight.git:a154bd6aec530330125a0d6439fc60dbc1306ea7
parent df47b43d
......@@ -21,6 +21,7 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include "coresight-catu.h"
#include "coresight-etm-perf.h"
#include "coresight-priv.h"
#include "coresight-tmc.h"
......@@ -31,6 +32,28 @@ struct etr_flat_buf {
size_t size;
};
/*
* etr_perf_buffer - Perf buffer used for ETR
* @etr_buf - Actual buffer used by the ETR
* @snaphost - Perf session mode
* @head - handle->head at the beginning of the session.
* @nr_pages - Number of pages in the ring buffer.
* @pages - Array of Pages in the ring buffer.
*/
struct etr_perf_buffer {
struct etr_buf *etr_buf;
bool snapshot;
unsigned long head;
int nr_pages;
void **pages;
};
/* Convert the perf index to an offset within the ETR buffer */
#define PERF_IDX2OFF(idx, buf) ((idx) % ((buf)->nr_pages << PAGE_SHIFT))
/* Lower limit for ETR hardware buffer */
#define TMC_ETR_PERF_MIN_BUF_SIZE SZ_1M
/*
* The TMC ETR SG has a page size of 4K. The SG table contains pointers
* to 4KB buffers. However, the OS may use a PAGE_SIZE different from
......@@ -1114,10 +1137,228 @@ out:
return ret;
}
/*
* tmc_etr_setup_perf_buf: Allocate ETR buffer for use by perf.
* The size of the hardware buffer is dependent on the size configured
* via sysfs and the perf ring buffer size. We prefer to allocate the
* largest possible size, scaling down the size by half until it
* reaches a minimum limit (1M), beyond which we give up.
*/
static struct etr_perf_buffer *
tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, int node, int nr_pages,
void **pages, bool snapshot)
{
struct etr_buf *etr_buf;
struct etr_perf_buffer *etr_perf;
unsigned long size;
etr_perf = kzalloc_node(sizeof(*etr_perf), GFP_KERNEL, node);
if (!etr_perf)
return ERR_PTR(-ENOMEM);
/*
* Try to match the perf ring buffer size if it is larger
* than the size requested via sysfs.
*/
if ((nr_pages << PAGE_SHIFT) > drvdata->size) {
etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT),
0, node, NULL);
if (!IS_ERR(etr_buf))
goto done;
}
/*
* Else switch to configured size for this ETR
* and scale down until we hit the minimum limit.
*/
size = drvdata->size;
do {
etr_buf = tmc_alloc_etr_buf(drvdata, size, 0, node, NULL);
if (!IS_ERR(etr_buf))
goto done;
size /= 2;
} while (size >= TMC_ETR_PERF_MIN_BUF_SIZE);
kfree(etr_perf);
return ERR_PTR(-ENOMEM);
done:
etr_perf->etr_buf = etr_buf;
return etr_perf;
}
static void *tmc_alloc_etr_buffer(struct coresight_device *csdev,
int cpu, void **pages, int nr_pages,
bool snapshot)
{
struct etr_perf_buffer *etr_perf;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
if (cpu == -1)
cpu = smp_processor_id();
etr_perf = tmc_etr_setup_perf_buf(drvdata, cpu_to_node(cpu),
nr_pages, pages, snapshot);
if (IS_ERR(etr_perf)) {
dev_dbg(drvdata->dev, "Unable to allocate ETR buffer\n");
return NULL;
}
etr_perf->snapshot = snapshot;
etr_perf->nr_pages = nr_pages;
etr_perf->pages = pages;
return etr_perf;
}
static void tmc_free_etr_buffer(void *config)
{
struct etr_perf_buffer *etr_perf = config;
if (etr_perf->etr_buf)
tmc_free_etr_buf(etr_perf->etr_buf);
kfree(etr_perf);
}
/*
* tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware
* buffer to the perf ring buffer.
*/
static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf)
{
long bytes, to_copy;
long pg_idx, pg_offset, src_offset;
unsigned long head = etr_perf->head;
char **dst_pages, *src_buf;
struct etr_buf *etr_buf = etr_perf->etr_buf;
head = etr_perf->head;
pg_idx = head >> PAGE_SHIFT;
pg_offset = head & (PAGE_SIZE - 1);
dst_pages = (char **)etr_perf->pages;
src_offset = etr_buf->offset;
to_copy = etr_buf->len;
while (to_copy > 0) {
/*
* In one iteration, we can copy minimum of :
* 1) what is available in the source buffer,
* 2) what is available in the source buffer, before it
* wraps around.
* 3) what is available in the destination page.
* in one iteration.
*/
bytes = tmc_etr_buf_get_data(etr_buf, src_offset, to_copy,
&src_buf);
if (WARN_ON_ONCE(bytes <= 0))
break;
bytes = min(bytes, (long)(PAGE_SIZE - pg_offset));
memcpy(dst_pages[pg_idx] + pg_offset, src_buf, bytes);
to_copy -= bytes;
/* Move destination pointers */
pg_offset += bytes;
if (pg_offset == PAGE_SIZE) {
pg_offset = 0;
if (++pg_idx == etr_perf->nr_pages)
pg_idx = 0;
}
/* Move source pointers */
src_offset += bytes;
if (src_offset >= etr_buf->size)
src_offset -= etr_buf->size;
}
}
/*
* tmc_update_etr_buffer : Update the perf ring buffer with the
* available trace data. We use software double buffering at the moment.
*
* TODO: Add support for reusing the perf ring buffer.
*/
static unsigned long
tmc_update_etr_buffer(struct coresight_device *csdev,
struct perf_output_handle *handle,
void *config)
{
bool lost = false;
unsigned long flags, size = 0;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
struct etr_perf_buffer *etr_perf = config;
struct etr_buf *etr_buf = etr_perf->etr_buf;
spin_lock_irqsave(&drvdata->spinlock, flags);
if (WARN_ON(drvdata->perf_data != etr_perf)) {
lost = true;
spin_unlock_irqrestore(&drvdata->spinlock, flags);
goto out;
}
CS_UNLOCK(drvdata->base);
tmc_flush_and_stop(drvdata);
tmc_sync_etr_buf(drvdata);
CS_LOCK(drvdata->base);
/* Reset perf specific data */
drvdata->perf_data = NULL;
spin_unlock_irqrestore(&drvdata->spinlock, flags);
size = etr_buf->len;
tmc_etr_sync_perf_buffer(etr_perf);
/*
* Update handle->head in snapshot mode. Also update the size to the
* hardware buffer size if there was an overflow.
*/
if (etr_perf->snapshot) {
handle->head += size;
if (etr_buf->full)
size = etr_buf->size;
}
lost |= etr_buf->full;
out:
if (lost)
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
return size;
}
static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
{
/* We don't support perf mode yet ! */
return -EINVAL;
int rc = 0;
unsigned long flags;
struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
struct perf_output_handle *handle = data;
struct etr_perf_buffer *etr_perf = etm_perf_sink_config(handle);
spin_lock_irqsave(&drvdata->spinlock, flags);
/*
* There can be only one writer per sink in perf mode. If the sink
* is already open in SYSFS mode, we can't use it.
*/
if (drvdata->mode != CS_MODE_DISABLED || WARN_ON(drvdata->perf_data)) {
rc = -EBUSY;
goto unlock_out;
}
if (WARN_ON(!etr_perf || !etr_perf->etr_buf)) {
rc = -EINVAL;
goto unlock_out;
}
etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);
drvdata->perf_data = etr_perf;
drvdata->mode = CS_MODE_PERF;
tmc_etr_enable_hw(drvdata, etr_perf->etr_buf);
unlock_out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);
return rc;
}
static int tmc_enable_etr_sink(struct coresight_device *csdev,
......@@ -1159,6 +1400,9 @@ static void tmc_disable_etr_sink(struct coresight_device *csdev)
static const struct coresight_ops_sink tmc_etr_sink_ops = {
.enable = tmc_enable_etr_sink,
.disable = tmc_disable_etr_sink,
.alloc_buffer = tmc_alloc_etr_buffer,
.update_buffer = tmc_update_etr_buffer,
.free_buffer = tmc_free_etr_buffer,
};
const struct coresight_ops tmc_etr_cs_ops = {
......
......@@ -181,6 +181,7 @@ struct etr_buf {
* @trigger_cntr: amount of words to store after a trigger.
* @etr_caps: Bitmask of capabilities of the TMC ETR, inferred from the
* device configuration register (DEVID)
* @perf_data: PERF buffer for ETR.
* @sysfs_data: SYSFS buffer for ETR.
*/
struct tmc_drvdata {
......@@ -202,6 +203,7 @@ struct tmc_drvdata {
u32 trigger_cntr;
u32 etr_caps;
struct etr_buf *sysfs_buf;
void *perf_data;
};
struct etr_buf_operations {
......
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