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SubjectRe: [PATCH] remoteproc: qcom_q6v5_mss: map/unmap mpss region before/after use
On Tue 17 Mar 12:19 PDT 2020, Sibi Sankar wrote:

> The application processor accessing the mpss region when the Q6 modem
> is running will lead to an XPU violation. Fix this by un-mapping the
> mpss region post copy during processor out of reset sequence and
> coredumps.
>

Does this problem not apply to the "mba" region?

> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
> ---
> drivers/remoteproc/qcom_q6v5_mss.c | 53 ++++++++++++++++--------------
> 1 file changed, 29 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index ce49c3236ff7c..b1ad4de179019 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -196,7 +196,6 @@ struct q6v5 {
>
> phys_addr_t mpss_phys;
> phys_addr_t mpss_reloc;
> - void *mpss_region;
> size_t mpss_size;
>
> struct qcom_rproc_glink glink_subdev;
> @@ -1061,6 +1060,18 @@ static int q6v5_reload_mba(struct rproc *rproc)
> return ret;
> }
>
> +static void *q6v5_da_to_va(struct rproc *rproc, u64 da, size_t len)
> +{
> + struct q6v5 *qproc = rproc->priv;
> + int offset;
> +
> + offset = da - qproc->mpss_reloc;
> + if (offset < 0 || offset + len > qproc->mpss_size)
> + return NULL;
> +
> + return devm_ioremap_wc(qproc->dev, qproc->mpss_phys + offset, len);

This function isn't expected to have side effects.

So I think you should add the ioremap/iounmap to the beginning/end of
mpss_load and the dump_segment directly instead.

> +}
> +
> static int q6v5_mpss_load(struct q6v5 *qproc)
> {
> const struct elf32_phdr *phdrs;
> @@ -1156,7 +1167,11 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> goto release_firmware;
> }
>
> - ptr = qproc->mpss_region + offset;
> + ptr = q6v5_da_to_va(qproc->rproc, phdr->p_paddr, phdr->p_memsz);

rproc_da_to_va() here.

> + if (!ptr) {
> + dev_err(qproc->dev, "failed to map memory\n");

Now this will be able to fail, so you should add this error handling
snippet, just with a slightly different message.

> + goto release_firmware;
> + }
>
> if (phdr->p_filesz && phdr->p_offset < fw->size) {
> /* Firmware is large enough to be non-split */
> @@ -1165,6 +1180,7 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> "failed to load segment %d from truncated file %s\n",
> i, fw_name);
> ret = -EINVAL;
> + devm_iounmap(qproc->dev, ptr);
> goto release_firmware;
> }
>
> @@ -1175,6 +1191,7 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> ret = request_firmware(&seg_fw, fw_name, qproc->dev);
> if (ret) {
> dev_err(qproc->dev, "failed to load %s\n", fw_name);
> + devm_iounmap(qproc->dev, ptr);
> goto release_firmware;
> }
>
> @@ -1187,6 +1204,7 @@ static int q6v5_mpss_load(struct q6v5 *qproc)
> memset(ptr + phdr->p_filesz, 0,
> phdr->p_memsz - phdr->p_filesz);
> }
> + devm_iounmap(qproc->dev, ptr);

Move this to the end an unmap the entire thing.

And generally, please avoid devm for things where you manually unmap.

Regards,
Bjorn

> size += phdr->p_memsz;
>
> code_length = readl(qproc->rmb_base + RMB_PMI_CODE_LENGTH_REG);
> @@ -1236,7 +1254,7 @@ static void qcom_q6v5_dump_segment(struct rproc *rproc,
> int ret = 0;
> struct q6v5 *qproc = rproc->priv;
> unsigned long mask = BIT((unsigned long)segment->priv);
> - void *ptr = rproc_da_to_va(rproc, segment->da, segment->size);
> + void *ptr = NULL;
>
> /* Unlock mba before copying segments */
> if (!qproc->dump_mba_loaded) {
> @@ -1250,10 +1268,15 @@ static void qcom_q6v5_dump_segment(struct rproc *rproc,
> }
> }
>
> - if (!ptr || ret)
> - memset(dest, 0xff, segment->size);
> - else
> + if (!ret)
> + ptr = rproc_da_to_va(rproc, segment->da, segment->size);
> +
> + if (ptr) {
> memcpy(dest, ptr, segment->size);
> + devm_iounmap(qproc->dev, ptr);
> + } else {
> + memset(dest, 0xff, segment->size);
> + }
>
> qproc->dump_segment_mask |= mask;
>
> @@ -1327,18 +1350,6 @@ static int q6v5_stop(struct rproc *rproc)
> return 0;
> }
>
> -static void *q6v5_da_to_va(struct rproc *rproc, u64 da, size_t len)
> -{
> - struct q6v5 *qproc = rproc->priv;
> - int offset;
> -
> - offset = da - qproc->mpss_reloc;
> - if (offset < 0 || offset + len > qproc->mpss_size)
> - return NULL;
> -
> - return qproc->mpss_region + offset;
> -}
> -
> static int qcom_q6v5_register_dump_segments(struct rproc *rproc,
> const struct firmware *mba_fw)
> {
> @@ -1595,12 +1606,6 @@ static int q6v5_alloc_memory_region(struct q6v5 *qproc)
>
> qproc->mpss_phys = qproc->mpss_reloc = r.start;
> qproc->mpss_size = resource_size(&r);
> - qproc->mpss_region = devm_ioremap_wc(qproc->dev, qproc->mpss_phys, qproc->mpss_size);
> - if (!qproc->mpss_region) {
> - dev_err(qproc->dev, "unable to map memory region: %pa+%zx\n",
> - &r.start, qproc->mpss_size);
> - return -EBUSY;
> - }
>
> return 0;
> }
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project

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