Messages in this thread | | | Date | Tue, 25 Jul 2023 11:16:59 +0530 | From | Pavan Kondeti <> | Subject | Re: [PATCH 3/3] interconnect: Add debugfs test client |
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On Mon, Jul 24, 2023 at 06:28:59PM -0700, Mike Tipton wrote: > It's often useful during test, debug, and development to issue path > votes from shell. Add a debugfs client for this purpose. > > Example usage: > cd /sys/kernel/debug/interconnect/test-client/ > > # Configure node endpoints for the path from CPU to DDR on > # qcom/sm8550. > echo chm_apps > src_node > echo ebi > dst_node > > # Get path between src_node and dst_node. This is only > # necessary after updating the node endpoints. > echo 1 > get > > # Set desired BW to 1GBps avg and 2GBps peak. > echo 1000000 > avg_bw > echo 2000000 > peak_bw > > # Vote for avg_bw and peak_bw on the latest path from "get". > # Voting for multiple paths is possible by repeating this > # process for different nodes endpoints. > echo 1 > commit >
Can Documentation/driver-api/interconnect.rst be updated with this information?
> Allowing userspace to directly enable and set bus rates can be dangerous > So, following in the footsteps of the regmap [0] and clk [1] frameworks, > keep these userspace controls compile-time disabled without Kconfig > options to enable them. Enabling this will require code changes to > define INTERCONNECT_ALLOW_WRITE_DEBUGFS. >
Completely agree with your argument here.
> [0] commit 09c6ecd39410 ("regmap: Add support for writing to regmap registers via debugfs") > [1] commit 37215da5553e ("clk: Add support for setting clk_rate via debugfs") > > Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com> > --- > drivers/interconnect/Makefile | 2 +- > drivers/interconnect/core.c | 3 + > drivers/interconnect/debugfs-client.c | 156 ++++++++++++++++++++++++++ > drivers/interconnect/internal.h | 2 + > 4 files changed, 162 insertions(+), 1 deletion(-) > create mode 100644 drivers/interconnect/debugfs-client.c > > diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile > index 5604ce351a9f..d0888babb9a1 100644 > --- a/drivers/interconnect/Makefile > +++ b/drivers/interconnect/Makefile > @@ -1,7 +1,7 @@ > # SPDX-License-Identifier: GPL-2.0 > > CFLAGS_core.o := -I$(src) > -icc-core-objs := core.o bulk.o > +icc-core-objs := core.o bulk.o debugfs-client.o > > obj-$(CONFIG_INTERCONNECT) += icc-core.o > obj-$(CONFIG_INTERCONNECT_IMX) += imx/ > diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c > index 511152398790..bc82571ff2a8 100644 > --- a/drivers/interconnect/core.c > +++ b/drivers/interconnect/core.c > @@ -1117,6 +1117,9 @@ static int __init icc_init(void) > icc_debugfs_dir, NULL, &icc_summary_fops); > debugfs_create_file("interconnect_graph", 0444, > icc_debugfs_dir, NULL, &icc_graph_fops); > + > + icc_debugfs_client_init(icc_debugfs_dir); > + > return 0; > } > > diff --git a/drivers/interconnect/debugfs-client.c b/drivers/interconnect/debugfs-client.c > new file mode 100644 > index 000000000000..990dd2ff6df7 > --- /dev/null > +++ b/drivers/interconnect/debugfs-client.c > @@ -0,0 +1,156 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved. > + */ > +#include <linux/debugfs.h> > +#include <linux/interconnect.h> > +#include <linux/platform_device.h> > +#include <linux/uaccess.h> > +
Since you are not dealing with user copy directly, I wonder why this header inclusion is needed?
> +/* > + * This can be dangerous, therefore don't provide any real compile time > + * configuration option for this feature. > + * People who want to use this will need to modify the source code directly. > + */ > +#undef INTERCONNECT_ALLOW_WRITE_DEBUGFS > +
Would it be nice to throw a compile error when DEBUG_FS is not enabled but INTERCONNECT_ALLOW_WRITE_DEBUGFS is enabled?
> +#if defined(INTERCONNECT_ALLOW_WRITE_DEBUGFS) && defined(CONFIG_DEBUG_FS) > + > +static LIST_HEAD(debugfs_paths); > +static DEFINE_MUTEX(debugfs_lock); > + > +static struct platform_device *pdev; > +static struct icc_path *cur_path; > + > +static char *src_node; > +static char *dst_node; > +static u32 avg_bw; > +static u32 peak_bw; > +static u32 tag; > + > +struct debugfs_path { > + const char *src; > + const char *dst; > + struct icc_path *path; > + struct list_head list; > +}; > + > +static struct icc_path *get_path(const char *src, const char *dst) > +{ > + struct debugfs_path *path; > + > + list_for_each_entry(path, &debugfs_paths, list) { > + if (!strcmp(path->src, src) && !strcmp(path->dst, dst)) > + return path->path; > + } > + > + return NULL; > +} > + > +static int icc_get_set(void *data, u64 val) > +{ > + struct debugfs_path *debugfs_path; > + int ret = 0; > + > + mutex_lock(&debugfs_lock); > + > + /* > + * If we've already looked up a path, then use the existing one instead > + * of calling icc_get() again. This allows for updating previous BW > + * votes when "get" is written to multiple times for multiple paths. > + */ > + cur_path = get_path(src_node, dst_node); > + if (cur_path) > + goto out; > + > + cur_path = icc_get(&pdev->dev, src_node, dst_node); > + if (IS_ERR(cur_path)) { > + ret = PTR_ERR(cur_path); > + goto out; > + }
From the debugfs_write_file_str() implementation introduced in 1/3 of this series, these values (src_node/dst_node) needs RCU protection. Othewise, there is a potential UAF issue here, correct?
> + > + debugfs_path = kzalloc(sizeof(*debugfs_path), GFP_KERNEL); > + if (!debugfs_path) { > + ret = -ENOMEM; > + goto err_put; > + } > + > + debugfs_path->path = cur_path; > + debugfs_path->src = kstrdup(src_node, GFP_KERNEL); > + debugfs_path->dst = kstrdup(dst_node, GFP_KERNEL); > + if (!debugfs_path->src || !debugfs_path->dst) { > + ret = -ENOMEM; > + goto err_free; > + } > + > + list_add_tail(&debugfs_path->list, &debugfs_paths); > + goto out; > + > +err_free: > + kfree(debugfs_path->src); > + kfree(debugfs_path->dst); > + kfree(debugfs_path); > +err_put: > + icc_put(cur_path); > +out: > + mutex_unlock(&debugfs_lock); > + return ret; > +} > + > +DEFINE_DEBUGFS_ATTRIBUTE(icc_get_fops, NULL, icc_get_set, "%llu\n"); > + > +static int icc_commit_set(void *data, u64 val) > +{ > + int ret; > + > + mutex_lock(&debugfs_lock); > + > + if (IS_ERR_OR_NULL(cur_path)) { > + ret = PTR_ERR(cur_path); > + goto out; > + } > + > + icc_set_tag(cur_path, tag); > + ret = icc_set_bw(cur_path, avg_bw, peak_bw); > +out: > + mutex_unlock(&debugfs_lock); > + return ret; > +} > + > +DEFINE_DEBUGFS_ATTRIBUTE(icc_commit_fops, NULL, icc_commit_set, "%llu\n"); > + > +int icc_debugfs_client_init(struct dentry *icc_dir) > +{ > + struct dentry *client_dir; > + int ret; > + > + pdev = platform_device_alloc("icc-debugfs-client", PLATFORM_DEVID_AUTO); > +
In interconnect_summary debugfs file, it appears as "icc-debugfs-client.0.auto". Since we will only ever support one instance of this device, would PLATFORM_DEVID_NONE be more appropriate?
> + ret = platform_device_add(pdev); > + if (ret) { > + pr_err("%s: failed to add platform device: %d\n", __func__, ret); > + platform_device_put(pdev); > + return ret; > + } > + > + client_dir = debugfs_create_dir("test_client", icc_dir); > + > + debugfs_create_str("src_node", 0600, client_dir, &src_node); > + debugfs_create_str("dst_node", 0600, client_dir, &dst_node); > + debugfs_create_file("get", 0200, client_dir, NULL, &icc_get_fops); > + debugfs_create_u32("avg_bw", 0600, client_dir, &avg_bw); > + debugfs_create_u32("peak_bw", 0600, client_dir, &peak_bw); > + debugfs_create_u32("tag", 0600, client_dir, &tag); > + debugfs_create_file("commit", 0200, client_dir, NULL, &icc_commit_fops); > + > + return 0; > +} > + > +#else > + > +int icc_debugfs_client_init(struct dentry *icc_dir) > +{ > + return 0; > +} > + > +#endif > diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h > index f5f82a5c939e..87152e70a99b 100644 > --- a/drivers/interconnect/internal.h > +++ b/drivers/interconnect/internal.h > @@ -41,4 +41,6 @@ struct icc_path { > struct icc_req reqs[]; > }; > > +int icc_debugfs_client_init(struct dentry *icc_dir); > + > #endif > -- > 2.17.1 >
Thanks, Pavan
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