[PATCH v6 2/7] coresight: tmc-etr: Add support to use reserved trace memory
Suzuki K Poulose
suzuki.poulose at arm.com
Fri Jan 5 06:17:23 PST 2024
On 05/01/2024 05:58, Linu Cherian wrote:
> Add support to use reserved memory for coresight ETR trace buffer.
>
> Introduce a new ETR buffer mode called ETR_MODE_RESRV, which
> becomes available when ETR device tree node is supplied with a valid
> reserved memory region.
>
> ETR_MODE_RESRV can be selected only by explicit user request.
>
> $ echo resrv >/sys/bus/coresight/devices/tmc_etr<N>/buf_mode_preferred
>
> Signed-off-by: Anil Kumar Reddy <areddy3 at marvell.com>
> Signed-off-by: Linu Cherian <lcherian at marvell.com>
> ---
> Changelog from v5:
> * No changes
>
> .../hwtracing/coresight/coresight-tmc-core.c | 51 +++++++++++
> .../hwtracing/coresight/coresight-tmc-etr.c | 87 ++++++++++++++++++-
> drivers/hwtracing/coresight/coresight-tmc.h | 27 ++++++
> 3 files changed, 164 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index 7ec5365e2b64..224b969d7d90 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -22,6 +22,7 @@
> #include <linux/spinlock.h>
> #include <linux/pm_runtime.h>
> #include <linux/of.h>
> +#include <linux/of_address.h>
> #include <linux/coresight.h>
> #include <linux/amba/bus.h>
>
> @@ -370,6 +371,54 @@ static inline bool tmc_etr_has_non_secure_access(struct tmc_drvdata *drvdata)
> return (auth & TMC_AUTH_NSID_MASK) == 0x3;
> }
>
> +static struct device_node *tmc_get_region_byname(struct device_node *node,
> + char *name)
> +{
> + int index;
> +
> + index = of_property_match_string(node, "memory-region-names", name);
> + if (index < 0)
> + return ERR_PTR(-ENODEV);
> +
> + return of_parse_phandle(node, "memory-region", index);
> +}
> +
> +static void tmc_get_reserved_region(struct device *parent)
> +{
> + struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
> + struct device_node *node;
> + struct resource res;
> + int rc;
> +
> + node = tmc_get_region_byname(parent->of_node, "tracedata");
> + if (IS_ERR_OR_NULL(node)) {
> + dev_dbg(parent, "No reserved trace buffer specified\n");
> + goto out;
Given we don't return anything , the goto is pointless, you could return
from here.
> + }
> +
> + rc = of_address_to_resource(node, 0, &res);
> + of_node_put(node);
> + if (rc || res.start == 0 || resource_size(&res) == 0) {
> + dev_err(parent, "Reserved trace buffer memory is invalid\n");
> + goto out;
Same here.
> + }
> +
> + drvdata->crash_tbuf.vaddr = memremap(res.start,
> + resource_size(&res),
> + MEMREMAP_WC);
> + if (IS_ERR_OR_NULL(drvdata->crash_tbuf.vaddr)) {
> + dev_err(parent, "Reserved trace buffer mapping failed\n");
> + rc = PTR_ERR(drvdata->crash_tbuf.vaddr);
This is pointless, as we never use this.
> + goto out;
return
> + }
> +
> + drvdata->crash_tbuf.paddr = res.start;
> + drvdata->crash_tbuf.size = resource_size(&res);
> +
> +out:
> + return;
> +}
> +
> /* Detect and initialise the capabilities of a TMC ETR */
> static int tmc_etr_setup_caps(struct device *parent, u32 devid, void *dev_caps)
> {
> @@ -482,6 +531,8 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
> drvdata->size = readl_relaxed(drvdata->base + TMC_RSZ) * 4;
> }
>
> + tmc_get_reserved_region(dev);
> +
> desc.dev = dev;
>
> switch (drvdata->config_type) {
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index af02ba5d5f15..7fd8c4afef74 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -30,6 +30,7 @@ struct etr_buf_hw {
> bool has_iommu;
> bool has_etr_sg;
> bool has_catu;
> + bool has_resrv;
> };
>
> /*
> @@ -694,6 +695,74 @@ static const struct etr_buf_operations etr_flat_buf_ops = {
> .get_data = tmc_etr_get_data_flat_buf,
> };
>
> +/*
> + * tmc_etr_alloc_resrv_buf: Allocate a contiguous DMA buffer from reserved region.
> + */
> +static int tmc_etr_alloc_resrv_buf(struct tmc_drvdata *drvdata,
> + struct etr_buf *etr_buf, int node,
> + void **pages)
> +{
> + struct etr_flat_buf *resrv_buf;
> + struct device *real_dev = drvdata->csdev->dev.parent;
> +
> + /* We cannot reuse existing pages for resrv buf */
> + if (pages)
> + return -EINVAL;
> +
> + resrv_buf = kzalloc(sizeof(*resrv_buf), GFP_KERNEL);
> + if (!resrv_buf)
> + return -ENOMEM;
Shouldn't we also ensure the etr_buf->size < crash_tbuf.size ? Or we
could simply allocate the full reserve buf, as we can't use it for
anything else. In any case, the buffer should be bounded by the reserved
space.
> +
> + resrv_buf->daddr = dma_map_resource(real_dev, drvdata->crash_tbuf.paddr,
> + etr_buf->size, DMA_FROM_DEVICE, 0);
> + if (dma_mapping_error(real_dev, resrv_buf->daddr)) {
> + dev_err(real_dev, "failed to map source buffer address\n");
> + kfree(resrv_buf);
> + return -ENOMEM;
> + }
> +
> + resrv_buf->vaddr = drvdata->crash_tbuf.vaddr;
> + resrv_buf->size = etr_buf->size;
> + resrv_buf->dev = &drvdata->csdev->dev;
> + etr_buf->hwaddr = resrv_buf->daddr;
> + etr_buf->mode = ETR_MODE_RESRV;
> + etr_buf->private = resrv_buf;
> + return 0;
> +}
> +
> +static void tmc_etr_free_resrv_buf(struct etr_buf *etr_buf)
> +{
> + struct etr_flat_buf *resrv_buf = etr_buf->private;
> +
> + if (resrv_buf && resrv_buf->daddr) {
> + struct device *real_dev = resrv_buf->dev->parent;
> +
> + dma_unmap_resource(real_dev, resrv_buf->daddr,
> + resrv_buf->size, DMA_FROM_DEVICE, 0);
> + }
> + kfree(resrv_buf);
> +}
> +
> +static void tmc_etr_sync_resrv_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
> +{
> + /*
> + * Adjust the buffer to point to the beginning of the trace data
> + * and update the available trace data.
> + */
> + etr_buf->offset = rrp - etr_buf->hwaddr;
> + if (etr_buf->full)
> + etr_buf->len = etr_buf->size;
> + else
> + etr_buf->len = rwp - rrp;
Don't we need to sync the buffer for CPU via dma_sync_single_for_cpu() ?
Otherwise, we could be reading stale data ?
> +}
> +
> +static const struct etr_buf_operations etr_resrv_buf_ops = {
> + .alloc = tmc_etr_alloc_resrv_buf,
> + .free = tmc_etr_free_resrv_buf,
> + .sync = tmc_etr_sync_resrv_buf,
> + .get_data = tmc_etr_get_data_flat_buf,
> +};
> +
> /*
> * tmc_etr_alloc_sg_buf: Allocate an SG buf @etr_buf. Setup the parameters
> * appropriately.
> @@ -800,6 +869,7 @@ static const struct etr_buf_operations *etr_buf_ops[] = {
> [ETR_MODE_FLAT] = &etr_flat_buf_ops,
> [ETR_MODE_ETR_SG] = &etr_sg_buf_ops,
> [ETR_MODE_CATU] = NULL,
> + [ETR_MODE_RESRV] = &etr_resrv_buf_ops
> };
>
> void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu)
> @@ -825,6 +895,7 @@ static inline int tmc_etr_mode_alloc_buf(int mode,
> case ETR_MODE_FLAT:
> case ETR_MODE_ETR_SG:
> case ETR_MODE_CATU:
> + case ETR_MODE_RESRV:
> if (etr_buf_ops[mode] && etr_buf_ops[mode]->alloc)
> rc = etr_buf_ops[mode]->alloc(drvdata, etr_buf,
> node, pages);
> @@ -843,6 +914,7 @@ static void get_etr_buf_hw(struct device *dev, struct etr_buf_hw *buf_hw)
> buf_hw->has_iommu = iommu_get_domain_for_dev(dev->parent);
> buf_hw->has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
> buf_hw->has_catu = !!tmc_etr_get_catu_device(drvdata);
> + buf_hw->has_resrv = is_tmc_reserved_region_valid(dev->parent);
> }
>
> static bool etr_can_use_flat_mode(struct etr_buf_hw *buf_hw, ssize_t etr_buf_size)
> @@ -874,13 +946,19 @@ static struct etr_buf *tmc_alloc_etr_buf(struct tmc_drvdata *drvdata,
> if (!etr_buf)
> return ERR_PTR(-ENOMEM);
>
> - etr_buf->size = size;
> + /* Overiride the buffer size here for reserved mode */
minor nit: "Override"
> + etr_buf->size = (drvdata->etr_mode == ETR_MODE_RESRV) ?
> + drvdata->crash_tbuf.size : size;
Isn't it better to do this from the actual code where we are successful
in allocating the buffer ? That way, it works for the AUTO mode too ?
>
> /* If there is user directive for buffer mode, try that first */
> if (drvdata->etr_mode != ETR_MODE_AUTO)
> rc = tmc_etr_mode_alloc_buf(drvdata->etr_mode, drvdata,
> etr_buf, node, pages);
>
> + /* Fallback mechanism is not valid for reserved mode */
> + if (rc && (drvdata->etr_mode == ETR_MODE_RESRV))
> + goto done;
> +
> /*
> * If we have to use an existing list of pages, we cannot reliably
> * use a contiguous DMA memory (even if we have an IOMMU). Otherwise,
> @@ -902,6 +980,7 @@ static struct etr_buf *tmc_alloc_etr_buf(struct tmc_drvdata *drvdata,
> if (rc && buf_hw.has_catu)
> rc = tmc_etr_mode_alloc_buf(ETR_MODE_CATU, drvdata,
> etr_buf, node, pages);
> +done:
> if (rc) {
> kfree(etr_buf);
> return ERR_PTR(rc);
> @@ -1829,6 +1908,7 @@ static const char *const buf_modes_str[] = {
> [ETR_MODE_FLAT] = "flat",
> [ETR_MODE_ETR_SG] = "tmc-sg",
> [ETR_MODE_CATU] = "catu",
> + [ETR_MODE_RESRV] = "resrv",
> [ETR_MODE_AUTO] = "auto",
> };
>
> @@ -1847,6 +1927,9 @@ static ssize_t buf_modes_available_show(struct device *dev,
> if (buf_hw.has_catu)
> size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_CATU]);
>
> + if (buf_hw.has_resrv)
> + size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_RESRV]);
> +
> size += sysfs_emit_at(buf, size, "\n");
> return size;
> }
> @@ -1874,6 +1957,8 @@ static ssize_t buf_mode_preferred_store(struct device *dev,
> drvdata->etr_mode = ETR_MODE_ETR_SG;
> else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu)
> drvdata->etr_mode = ETR_MODE_CATU;
> + else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv)
> + drvdata->etr_mode = ETR_MODE_RESRV;
> else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO]))
> drvdata->etr_mode = ETR_MODE_AUTO;
> else
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 8dcb426ac3e7..10dba9f7d76a 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -135,6 +135,7 @@ enum etr_mode {
> ETR_MODE_FLAT, /* Uses contiguous flat buffer */
> ETR_MODE_ETR_SG, /* Uses in-built TMC ETR SG mechanism */
> ETR_MODE_CATU, /* Use SG mechanism in CATU */
> + ETR_MODE_RESRV, /* Use reserved region contiguous buffer */
> ETR_MODE_AUTO, /* Use the default mechanism */
> };
>
> @@ -164,6 +165,17 @@ struct etr_buf {
> void *private;
> };
>
> +/**
> + * @paddr : Start address of reserved memory region.
> + * @vaddr : Corresponding CPU virtual address.
> + * @size : Size of reserved memory region.
> + */
> +struct tmc_resrv_buf {
> + phys_addr_t paddr;
> + void *vaddr;
> + size_t size;
> +};
> +
> /**
> * struct tmc_drvdata - specifics associated to an TMC component
> * @base: memory mapped base address for this component.
> @@ -188,6 +200,10 @@ struct etr_buf {
> * @idr_mutex: Access serialisation for idr.
> * @sysfs_buf: SYSFS buffer for ETR.
> * @perf_buf: PERF buffer for ETR.
> + * @crash_tbuf: Used by ETR as hardware trace buffer and for trace data
> + * retention (after crash) only when ETR_MODE_RESRV buffer
> + * mode is enabled. Used by ETF for trace data retention
> + * (after crash) by default.
minor nit: Please align the comment like the other fields.
Suzuki
> */
> struct tmc_drvdata {
> void __iomem *base;
> @@ -213,6 +229,7 @@ struct tmc_drvdata {
> struct mutex idr_mutex;
> struct etr_buf *sysfs_buf;
> struct etr_buf *perf_buf;
> + struct tmc_resrv_buf crash_tbuf;
> };
>
> struct etr_buf_operations {
> @@ -330,6 +347,16 @@ tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
> return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT;
> }
>
> +static inline bool is_tmc_reserved_region_valid(struct device *dev)
> +{
> + struct tmc_drvdata *drvdata = dev_get_drvdata(dev);
> +
> + if (drvdata->crash_tbuf.paddr &&
> + drvdata->crash_tbuf.size)
> + return true;
> + return false;
> +}
> +
> struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
>
> void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu);
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