On Tue, May 01, 2018 at 10:10:47AM +0100, Suzuki K Poulose wrote:
> Add support for creating buffers which can be used in save-restore
> mode (e.g, for use by perf). If the TMC-ETR supports save-restore
> feature, we could support the mode in all buffer backends. However,
> if it doesn't, we should fall back to using in built SG mechanism,
> where we can rotate the SG table by making some adjustments in the
> page table.
>
> Cc: Mathieu Poirier <[email protected]>
> Signed-off-by: Suzuki K Poulose <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etr.c | 142
> +++++++++++++++++++++++-
> drivers/hwtracing/coresight/coresight-tmc.h | 16 +++
> 2 files changed, 153 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index fde3fa6..25e7feb 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -604,7 +604,7 @@ tmc_etr_sg_table_index_to_daddr(struct tmc_sg_table
> *sg_table, u32 index)
> * which starts @base_offset.
> * 2) Mark the page at the base_offset + size as LAST.
> */
> -static int __maybe_unused
> +static int
> tmc_etr_sg_table_rotate(struct etr_sg_table *etr_table,
> unsigned long base_offset, unsigned long size)
> {
> @@ -736,6 +736,9 @@ static int tmc_etr_alloc_flat_buf(struct tmc_drvdata
> *drvdata,
> flat_buf->size = etr_buf->size;
> flat_buf->dev = drvdata->dev;
> etr_buf->hwaddr = flat_buf->daddr;
> + etr_buf->rrp = flat_buf->daddr;
> + etr_buf->rwp = flat_buf->daddr;
> + etr_buf->status = 0;
> etr_buf->mode = ETR_MODE_FLAT;
> etr_buf->private = flat_buf;
> return 0;
> @@ -777,11 +780,36 @@ static ssize_t tmc_etr_get_data_flat_buf(struct etr_buf
> *etr_buf,
> return len;
> }
>
> +/*
> + * tmc_etr_restore_flat_buf: Restore the flat buffer pointers.
> + * This is only possible with in-built ETR capability to save-restore
> + * the pointers. The DBA will still point to the original start of the
> + * buffer.
> + */
> +static int tmc_etr_restore_flat_buf(struct etr_buf *etr_buf,
> + unsigned long r_offset,
> + unsigned long w_offset,
> + unsigned long size,
> + u32 status,
> + bool has_save_restore)
> +{
> + struct etr_flat_buf *flat_buf = etr_buf->private;
> +
> + if (!has_save_restore || !flat_buf || size > flat_buf->size)
> + return -EINVAL;
> + etr_buf->rrp = flat_buf->daddr + (r_offset % flat_buf->size);
> + etr_buf->rwp = flat_buf->daddr + (w_offset % flat_buf->size);
> + etr_buf->size = size;
> + etr_buf->status = status;
> + return 0;
> +}
> +
> static const struct etr_buf_operations etr_flat_buf_ops = {
> .alloc = tmc_etr_alloc_flat_buf,
> .free = tmc_etr_free_flat_buf,
> .sync = tmc_etr_sync_flat_buf,
> .get_data = tmc_etr_get_data_flat_buf,
> + .restore = tmc_etr_restore_flat_buf,
> };
>
> /*
> @@ -799,6 +827,7 @@ static int tmc_etr_alloc_sg_buf(struct tmc_drvdata
> *drvdata,
> if (IS_ERR(etr_table))
> return -ENOMEM;
> etr_buf->hwaddr = etr_table->hwaddr;
> + etr_buf->status = 0;
> etr_buf->mode = ETR_MODE_ETR_SG;
> etr_buf->private = etr_table;
> return 0;
> @@ -825,9 +854,11 @@ static ssize_t tmc_etr_get_data_sg_buf(struct etr_buf
> *etr_buf, u64 offset,
> static void tmc_etr_sync_sg_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
> {
> long r_offset, w_offset;
> + unsigned long buf_size;
> struct etr_sg_table *etr_table = etr_buf->private;
> struct tmc_sg_table *table = etr_table->sg_table;
>
> + buf_size = tmc_sg_table_buf_size(table);
> /* Convert hw address to offset in the buffer */
> r_offset = tmc_sg_get_data_page_offset(table, rrp);
> if (r_offset < 0) {
> @@ -849,16 +880,62 @@ static void tmc_etr_sync_sg_buf(struct etr_buf
> *etr_buf, u64 rrp, u64 rwp)
> if (etr_buf->full)
> etr_buf->len = etr_buf->size;
> else
> - etr_buf->len = ((w_offset < r_offset) ? etr_buf->size : 0) +
> + etr_buf->len = ((w_offset < r_offset) ? buf_size : 0) +
> w_offset - r_offset;
> tmc_sg_table_sync_data_range(table, r_offset, etr_buf->len);
> }
>
> +static int tmc_etr_restore_sg_buf(struct etr_buf *etr_buf,
> + unsigned long r_offset,
> + unsigned long w_offset,
> + unsigned long size,
> + u32 __always_unused status,
> + bool has_save_restore)
> +{
> + int rc;
> + struct etr_sg_table *etr_table = etr_buf->private;
> + struct device *dev = etr_table->sg_table->dev;
> +
> + /*
> + * It is highly unlikely that we have an ETR with in-built SG and
> + * Save-Restore capability and we are not sure if the PTRs will
> + * be updated.
> + */
> + if (has_save_restore) {
> + dev_warn_once(dev,
> + "Unexpected feature combination of SG and save-restore\n");
> + return -EINVAL;
> + }
> +
> + /*
> + * Since we cannot program RRP/RWP different from DBAL, the offsets
> + * should match.
> + */
> + if (r_offset != w_offset) {
> + dev_dbg(dev, "Mismatched RRP/RWP offsets\n");
> + return -EINVAL;
> + }
> +
> + /* Make sure the size is aligned */
> + size &= ~(ETR_SG_PAGE_SIZE - 1);
> +
> + rc = tmc_etr_sg_table_rotate(etr_table, w_offset, size);
> + if (!rc) {
> + etr_buf->hwaddr = etr_table->hwaddr;
> + etr_buf->rrp = etr_table->hwaddr;
> + etr_buf->rwp = etr_table->hwaddr;
> + etr_buf->size = size;
> + }
> +
> + return rc;
> +}
> +
> static const struct etr_buf_operations etr_sg_buf_ops = {
> .alloc = tmc_etr_alloc_sg_buf,
> .free = tmc_etr_free_sg_buf,
> .sync = tmc_etr_sync_sg_buf,
> .get_data = tmc_etr_get_data_sg_buf,
> + .restore = tmc_etr_restore_sg_buf,
> };
>
> static const struct etr_buf_operations *etr_buf_ops[] = {
> @@ -899,10 +976,42 @@ static struct etr_buf *tmc_alloc_etr_buf(struct
> tmc_drvdata *drvdata,
> {
> int rc = -ENOMEM;
> bool has_etr_sg, has_iommu;
> + bool has_flat, has_save_restore;
> struct etr_buf *etr_buf;
>
> has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
> has_iommu = iommu_get_domain_for_dev(drvdata->dev);
> + has_save_restore = tmc_etr_has_cap(drvdata, TMC_ETR_SAVE_RESTORE);
> +
> + /*
> + * We can normally use flat DMA buffer provided that the buffer
> + * is not used in save restore fashion without hardware support.
> + */
> + has_flat = !(flags & ETR_BUF_F_RESTORE_PTRS) || has_save_restore;
> +
> + /*
> + * To support save-restore on a given ETR we have the following
> + * conditions:
> + * 1) If the buffer requires save-restore of a pointers as well
> + * as the Status bit, we require ETR support for it and we coul
/coul/could
> + * support all the backends.
> + * 2) If the buffer requires only save-restore of pointers, then
> + * we could exploit a circular ETR SG list. None of the other
> + * backends can support it without the ETR feature.
> + *
> + * If the buffer will be used in a save-restore mode without
> + * the ETR support for SAVE_RESTORE, we can only support TMC
> + * ETR in-built SG tables which can be rotated to make it work.
> + */
> + if ((flags & ETR_BUF_F_RESTORE_STATUS) && !has_save_restore)
> + return ERR_PTR(-EINVAL);
> +
> + if (!has_flat && !has_etr_sg) {
> + dev_dbg(drvdata->dev,
> + "No available backends for ETR buffer with flags %x\n",
> + flags);
> + return ERR_PTR(-EINVAL);
> + }
>
> etr_buf = kzalloc(sizeof(*etr_buf), GFP_KERNEL);
> if (!etr_buf)
> @@ -922,7 +1031,7 @@ static struct etr_buf *tmc_alloc_etr_buf(struct
> tmc_drvdata *drvdata,
> * Fallback to available mechanisms.
> *
> */
> - if (!pages &&
> + if (!pages && has_flat &&
> (!has_etr_sg || has_iommu || size < SZ_1M))
> rc = tmc_etr_mode_alloc_buf(ETR_MODE_FLAT, drvdata,
> etr_buf, node, pages);
> @@ -999,6 +1108,29 @@ static void tmc_sync_etr_buf(struct tmc_drvdata
> *drvdata)
> tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
> }
>
> +static int __maybe_unused
> +tmc_restore_etr_buf(struct tmc_drvdata *drvdata, struct etr_buf *etr_buf,
> + unsigned long r_offset, unsigned long w_offset,
> + unsigned long size, u32 status)
> +{
> + bool has_save_restore = tmc_etr_has_cap(drvdata, TMC_ETR_SAVE_RESTORE);
> +
> + if (WARN_ON_ONCE(!has_save_restore && etr_buf->mode != ETR_MODE_ETR_SG))
> + return -EINVAL;
> + /*
> + * If we use a circular SG list without ETR support, we can't
> + * support restoring "Full" bit.
> + */
> + if (WARN_ON_ONCE(!has_save_restore && status))
> + return -EINVAL;
> + if (status & ~TMC_STS_FULL)
> + return -EINVAL;
> + if (etr_buf->ops->restore)
> + return etr_buf->ops->restore(etr_buf, r_offset, w_offset, size,
> + status, has_save_restore);
> + return -EINVAL;
> +}
> +
> static inline void tmc_etr_enable_catu(struct tmc_drvdata *drvdata)
> {
> struct coresight_device *catu = tmc_etr_get_catu_device(drvdata);
> @@ -1058,8 +1190,8 @@ static void tmc_etr_enable_hw(struct tmc_drvdata
> *drvdata)
> * STS to "not full").
> */
> if (tmc_etr_has_cap(drvdata, TMC_ETR_SAVE_RESTORE)) {
> - tmc_write_rrp(drvdata, etr_buf->hwaddr);
> - tmc_write_rwp(drvdata, etr_buf->hwaddr);
> + tmc_write_rrp(drvdata, etr_buf->rrp);
> + tmc_write_rwp(drvdata, etr_buf->rwp);
> sts = readl_relaxed(drvdata->base + TMC_STS) & ~TMC_STS_FULL;
> writel_relaxed(sts, drvdata->base + TMC_STS);
> }
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h
> b/drivers/hwtracing/coresight/coresight-tmc.h
> index 6f7bec7..1bdfb38 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -141,12 +141,22 @@ enum etr_mode {
> ETR_MODE_ETR_SG, /* Uses in-built TMC ETR SG mechanism */
> };
>
> +/* ETR buffer should support save-restore */
> +#define ETR_BUF_F_RESTORE_PTRS 0x1
> +#define ETR_BUF_F_RESTORE_STATUS 0x2
> +
> +#define ETR_BUF_F_RESTORE_MINIMAL ETR_BUF_F_RESTORE_PTRS
> +#define ETR_BUF_F_RESTORE_FULL (ETR_BUF_F_RESTORE_PTRS |\
> + ETR_BUF_F_RESTORE_STATUS)
> struct etr_buf_operations;
>
> /**
> * struct etr_buf - Details of the buffer used by ETR
> * @mode : Mode of the ETR buffer, contiguous, Scatter Gather etc.
> * @full : Trace data overflow
> + * @status : Value for STATUS if the ETR supports save-restore.
> + * @rrp : Value for RRP{LO:HI} if the ETR supports save-restore
> + * @rwp : Value for RWP{LO:HI} if the ETR supports save-restore
> * @size : Size of the buffer.
> * @hwaddr : Address to be programmed in the TMC:DBA{LO,HI}
> * @offset : Offset of the trace data in the buffer for consumption.
> @@ -157,6 +167,9 @@ struct etr_buf_operations;
> struct etr_buf {
> enum etr_mode mode;
> bool full;
> + u32 status;
> + dma_addr_t rrp;
> + dma_addr_t rwp;
> ssize_t size;
> dma_addr_t hwaddr;
> unsigned long offset;
> @@ -207,6 +220,9 @@ struct etr_buf_operations {
> int (*alloc)(struct tmc_drvdata *drvdata, struct etr_buf *etr_buf,
> int node, void **pages);
> void (*sync)(struct etr_buf *etr_buf, u64 rrp, u64 rwp);
> + int (*restore)(struct etr_buf *etr_buf, unsigned long r_offset,
> + unsigned long w_offset, unsigned long size,
> + u32 status, bool has_save_restore);
> ssize_t (*get_data)(struct etr_buf *etr_buf, u64 offset, size_t len,
> char **bufpp);
> void (*free)(struct etr_buf *etr_buf);
> --
> 2.7.4
>
