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Message-ID: <ad106bb6-0223-61f4-0d35-3b7da43ece4f@foss.st.com>
Date: Fri, 26 Feb 2021 17:21:15 +0100
From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>, <ohad@...ery.com>,
<bjorn.andersson@...aro.org>, <arnaud.pouliquen@...com>
CC: <mcoquelin.stm32@...il.com>, <alexandre.torgue@...com>,
<linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 11/16] remoteproc: Properly deal with the resource
table when attached
On 2/24/21 12:35 AM, Mathieu Poirier wrote:
> If it is possible to detach the remote processor, keep an untouched
> copy of the resource table. That way we can start from the same
> resource table without having to worry about original values or what
> elements the startup code has changed when re-attaching to the remote
> processor.
>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
> New for V6:
> - Double free of the cached table has been fixed.
> - rproc_reset_loaded_rsc_table() has seen a complete re-write.
> - rproc_stop() now calls rproc_reset_loaded_rsc_table() rather than
> dealing with the cached. This allows to properly shutdown a
> remote processor that was attached to.
> ---
>
> drivers/remoteproc/remoteproc_core.c | 86 +++++++++++++++++++++++++++-
> include/linux/remoteproc.h | 3 +
> 2 files changed, 88 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index fc01b29290a6..3a4692cc5220 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1556,6 +1556,21 @@ static int rproc_set_loaded_rsc_table(struct rproc *rproc)
> return ret;
> }
>
> + /*
> + * If it is possible to detach the remote processor, keep an untouched
> + * copy of the resource table. That way we can start fresh again when
> + * the remote processor is re-attached, that is:
> + *
> + * DETACHED -> ATTACHED -> DETACHED -> ATTACHED
> + *
> + * Free'd in rproc_reset_loaded_rsc_table().
> + */
> + if (rproc->ops->detach) {
> + rproc->clean_table = kmemdup(table_ptr, table_sz, GFP_KERNEL);
> + if (!rproc->clean_table)
> + return -ENOMEM;
> + }
> +
> rproc->cached_table = NULL;
> rproc->table_ptr = table_ptr;
> rproc->table_sz = table_sz;
> @@ -1563,6 +1578,65 @@ static int rproc_set_loaded_rsc_table(struct rproc *rproc)
> return 0;
> }
>
> +static int rproc_reset_loaded_rsc_table(struct rproc *rproc)
I spent some time to review this function that handles both the resource table
for both the stop and detach. To make it easier to read, I would divide it into
two functions.
I added a proposal at the end of this mail.
Regards,
Arnaud
> +{
> + struct resource_table *table_ptr;
> +
> + /*
> + * The cached table is already set if the remote processor was started
> + * by the remoteproc core.
> + */
> + if (rproc->state == RPROC_RUNNING) {
> + rproc->table_ptr = rproc->cached_table;
> + return 0;
> + }
> +
> + /* A resource table was never retrieved, nothing to do here */
> + if (!rproc->table_ptr)
> + return 0;
> +
> + /*
> + * If we made it to this point a cached_table _must_ have been
> + * allocated in rproc_set_loaded_rsc_table(). If one isn't present
> + * something went really wrong and we must complain.
> + */
> + if (WARN_ON(!rproc->clean_table))
> + return -EINVAL;
> +
> + /* Remember where the external entity installed the resource table */
> + table_ptr = rproc->table_ptr;
> +
> + /*
> + * Make a copy of the resource table currently used by the remote
> + * processor. Free'd in rproc_detach() or rproc_shutdown().
> + */
> + rproc->cached_table = kmemdup(rproc->table_ptr,
> + rproc->table_sz, GFP_KERNEL);
> + if (!rproc->cached_table)
> + return -ENOMEM;
> +
> + /*
> + * Use a copy of the resource table for the remainder of the
> + * shutdown process.
> + */
> + rproc->table_ptr = rproc->cached_table;
> +
> + /*
> + * Reset the memory area where the firmware loaded the resource table
> + * to its original value. That way when we re-attach the remote
> + * processor the resource table is clean and ready to be used again.
> + */
> + memcpy(table_ptr, rproc->clean_table, rproc->table_sz);
> +
> + /*
> + * The clean resource table is no longer needed. Allocated in
> + * rproc_set_loaded_rsc_table().
> + */
> + kfree(rproc->clean_table);
> +
> + return 0;
> +}
> +
> /*
> * Attach to remote processor - similar to rproc_fw_boot() but without
> * the steps that deal with the firmware image.
> @@ -1688,7 +1762,11 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
> rproc_stop_subdevices(rproc, crashed);
>
> /* the installed resource table is no longer accessible */
> - rproc->table_ptr = rproc->cached_table;
> + ret = rproc_reset_loaded_rsc_table(rproc);
> + if (ret) {
> + dev_err(dev, "can't reset resource table: %d\n", ret);
> + return ret;
> + }
>
> /* power off the remote processor */
> ret = rproc->ops->stop(rproc);
> @@ -1721,6 +1799,9 @@ static int __rproc_detach(struct rproc *rproc)
> /* Stop any subdevices for the remote processor */
> rproc_stop_subdevices(rproc, false);
>
> + /* the installed resource table is no longer accessible */
> + ret = rproc_reset_loaded_rsc_table(rproc);
> +
> /* Tell the remote processor the core isn't available anymore */
> ret = rproc->ops->detach(rproc);
> if (ret) {
> @@ -1997,6 +2078,9 @@ int rproc_detach(struct rproc *rproc)
>
> rproc_disable_iommu(rproc);
>
> + /* Free the copy of the resource table */
> + kfree(rproc->cached_table);
> + rproc->cached_table = NULL;
> rproc->table_ptr = NULL;
> out:
> mutex_unlock(&rproc->lock);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index e1c843c19cc6..e5f52a12a650 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -514,6 +514,8 @@ struct rproc_dump_segment {
> * @recovery_disabled: flag that state if recovery was disabled
> * @max_notifyid: largest allocated notify id.
> * @table_ptr: pointer to the resource table in effect
> + * @clean_table: copy of the resource table without modifications. Used
> + * when a remote processor is attached or detached from the core
> * @cached_table: copy of the resource table
> * @table_sz: size of @cached_table
> * @has_iommu: flag to indicate if remote processor is behind an MMU
> @@ -550,6 +552,7 @@ struct rproc {
> bool recovery_disabled;
> int max_notifyid;
> struct resource_table *table_ptr;
> + struct resource_table *clean_table;
> struct resource_table *cached_table;
> size_t table_sz;
> bool has_iommu;
>
---
drivers/remoteproc/remoteproc_core.c | 101 ++++++++++++++++++++++++++-
include/linux/remoteproc.h | 3 +
2 files changed, 103 insertions(+), 1 deletion(-)
diff --git a/drivers/remoteproc/remoteproc_core.c
b/drivers/remoteproc/remoteproc_core.c
index fc01b29290a6..cc24c360eb8b 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1556,6 +1556,21 @@ static int rproc_set_loaded_rsc_table(struct rproc *rproc)
return ret;
}
+ /*
+ * If it is possible to detach the remote processor, keep an untouched
+ * copy of the resource table. That way we can start fresh again when
+ * the remote processor is re-attached, that is:
+ *
+ * DETACHED -> ATTACHED -> DETACHED -> ATTACHED
+ *
+ * Free'd in rproc_reset_loaded_rsc_table().
+ */
+ if (rproc->ops->detach) {
+ rproc->clean_table = kmemdup(table_ptr, table_sz, GFP_KERNEL);
+ if (!rproc->clean_table)
+ return -ENOMEM;
+ }
+
rproc->cached_table = NULL;
rproc->table_ptr = table_ptr;
rproc->table_sz = table_sz;
@@ -1563,6 +1578,79 @@ static int rproc_set_loaded_rsc_table(struct rproc *rproc)
return 0;
}
+static int rproc_set_to_cached_rsc_table(struct rproc *rproc)
+{
+ /* A resource table was never retrieved, nothing to do here */
+ if (!rproc->table_ptr)
+ return 0;
+
+ /*
+ * The cached table is already set if the remote processor was started
+ * by the remoteproc core.
+ */
+ if (!rproc->cached_table) {
+ rproc->table_ptr = rproc->cached_table;
+ return 0;
+ }
+
+ /*
+ * Make a copy of the resource table currently used by the remote
+ * processor. Free'd in rproc_detach() or rproc_shutdown().
+ */
+ rproc->cached_table = kmemdup(rproc->table_ptr,
+ rproc->table_sz, GFP_KERNEL);
+ if (!rproc->cached_table)
+ return -ENOMEM;
+
+ /*
+ * Use a copy of the resource table for the remainder of the
+ * shutdown process.
+ */
+ rproc->table_ptr = rproc->cached_table;
+
+ return 0;
+}
+
+static int rproc_reset_loaded_rsc_table(struct rproc *rproc)
+{
+ struct resource_table *table_ptr;
+ int ret;
+
+ /* A resource table was never retrieved, nothing to do here */
+ if (!rproc->table_ptr)
+ return 0;
+
+ /*
+ * If we made it to this point a cached_table _mst_ have been
+ * allocated in rproc_set_loaded_rsc_table(). If one isn't present
+ * something went really wrong and we must complain.
+ */
+ if (WARN_ON(!rproc->clean_table))
+ return -EINVAL;
+
+ /* Remember where the external entity installed the resource table */
+ table_ptr = rproc->table_ptr;
+
+ ret = rproc_set_to_cached_rsc_table(rproc);
+ if (ret)
+ return ret;
+
+ /*
+ * Reset the memory area where the firmware loaded the resource table
+ * to its original value. That way when we re-attach the remote
+ * processor the resource table is clean and ready to be used again.
+ */
+ memcpy(table_ptr, rproc->clean_table, rproc->table_sz);
+
+ /*
+ * The clean resource table is no longer needed. Allocated in
+ * rproc_set_loaded_rsc_table().
+ */
+ kfree(rproc->clean_table);
+
+ return 0;
+}
+
/*
* Attach to remote processor - similar to rproc_fw_boot() but without
* the steps that deal with the firmware image.
@@ -1688,7 +1776,11 @@ static int rproc_stop(struct rproc *rproc, bool crashed)
rproc_stop_subdevices(rproc, crashed);
/* the installed resource table is no longer accessible */
- rproc->table_ptr = rproc->cached_table;
+ ret = rproc_set_to_cached_rsc_table(rproc);
+ if (ret) {
+ dev_err(dev, "can't reset resource table: %d\n", ret);
+ return ret;
+ }
/* power off the remote processor */
ret = rproc->ops->stop(rproc);
@@ -1721,6 +1813,9 @@ static int __rproc_detach(struct rproc *rproc)
/* Stop any subdevices for the remote processor */
rproc_stop_subdevices(rproc, false);
+ /* The installed resource table need to be reset and no longer accessible */
+ ret = rproc_reset_loaded_rsc_table(rproc);
+
/* Tell the remote processor the core isn't available anymore */
ret = rproc->ops->detach(rproc);
if (ret) {
@@ -1941,6 +2036,7 @@ void rproc_shutdown(struct rproc *rproc)
/* Free the copy of the resource table */
kfree(rproc->cached_table);
+ kfree(rproc->clean_table);
rproc->cached_table = NULL;
rproc->table_ptr = NULL;
out:
@@ -1997,6 +2093,9 @@ int rproc_detach(struct rproc *rproc)
rproc_disable_iommu(rproc);
+ /* Free the copy of the resource table */
+ kfree(rproc->cached_table);
+ rproc->cached_table = NULL;
rproc->table_ptr = NULL;
out:
mutex_unlock(&rproc->lock);
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index e1c843c19cc6..e5f52a12a650 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -514,6 +514,8 @@ struct rproc_dump_segment {
* @recovery_disabled: flag that state if recovery was disabled
* @max_notifyid: largest allocated notify id.
* @table_ptr: pointer to the resource table in effect
+ * @clean_table: copy of the resource table without modifications. Used
+ * when a remote processor is attached or detached from the core
* @cached_table: copy of the resource table
* @table_sz: size of @cached_table
* @has_iommu: flag to indicate if remote processor is behind an MMU
@@ -550,6 +552,7 @@ struct rproc {
bool recovery_disabled;
int max_notifyid;
struct resource_table *table_ptr;
+ struct resource_table *clean_table;
struct resource_table *cached_table;
size_t table_sz;
bool has_iommu;
--
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