[RFC v3 5/5] Tasklist sample module

Signed-off-by: York Jasper Niebuhr <[email protected]>
---
 samples/Kconfig                   |  3 ++
 samples/Makefile                  |  1 +
 samples/spslr/Kconfig             | 17 ++++++++
 samples/spslr/Makefile            |  1 +
 samples/spslr/tasklist/Makefile   |  1 +
 samples/spslr/tasklist/tasklist.c | 67 +++++++++++++++++++++++++++++++
 6 files changed, 90 insertions(+)
 create mode 100644 samples/spslr/Kconfig
 create mode 100644 samples/spslr/Makefile
 create mode 100644 samples/spslr/tasklist/Makefile
 create mode 100644 samples/spslr/tasklist/tasklist.c

diff --git a/samples/Kconfig b/samples/Kconfig
index a75e8e78330d..8925820617c9 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -326,6 +326,8 @@ source "samples/rust/Kconfig"
 
 source "samples/damon/Kconfig"
 
+source "samples/spslr/Kconfig"
+
 endif # SAMPLES
 
 config HAVE_SAMPLE_FTRACE_DIRECT
@@ -333,3 +335,4 @@ config HAVE_SAMPLE_FTRACE_DIRECT
 
 config HAVE_SAMPLE_FTRACE_DIRECT_MULTI
 	bool
+
diff --git a/samples/Makefile b/samples/Makefile
index 07641e177bd8..1b727ceb2efa 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -45,3 +45,4 @@ obj-$(CONFIG_SAMPLE_DAMON_PRCL)		+= damon/
 obj-$(CONFIG_SAMPLE_DAMON_MTIER)	+= damon/
 obj-$(CONFIG_SAMPLE_HUNG_TASK)		+= hung_task/
 obj-$(CONFIG_SAMPLE_TSM_MR)		+= tsm-mr/
+obj-$(CONFIG_SAMPLES_SPSLR)		+= spslr/
diff --git a/samples/spslr/Kconfig b/samples/spslr/Kconfig
new file mode 100644
index 000000000000..ba163ea15006
--- /dev/null
+++ b/samples/spslr/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+
+menuconfig SAMPLES_SPSLR
+	bool "SPSLR samples"
+	depends on SPSLR
+	help
+	  You can build sample SPSLR kernel code here.
+
+	  If unsure, say N.
+
+if SAMPLES_SPSLR
+
+config SAMPLE_SPSLR_TASKLIST
+	tristate "SPSLR tasklist module example"
+	depends on m
+
+endif # SAMPLES_SPSLR
diff --git a/samples/spslr/Makefile b/samples/spslr/Makefile
new file mode 100644
index 000000000000..2d330b105c95
--- /dev/null
+++ b/samples/spslr/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_SPSLR_TASKLIST) += tasklist/
diff --git a/samples/spslr/tasklist/Makefile b/samples/spslr/tasklist/Makefile
new file mode 100644
index 000000000000..6a5bc5b29b34
--- /dev/null
+++ b/samples/spslr/tasklist/Makefile
@@ -0,0 +1 @@
+obj-m += tasklist.o
diff --git a/samples/spslr/tasklist/tasklist.c b/samples/spslr/tasklist/tasklist.c
new file mode 100644
index 000000000000..ea021742c8e9
--- /dev/null
+++ b/samples/spslr/tasklist/tasklist.c
@@ -0,0 +1,67 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/cred.h>
+#include <linux/uidgid.h>
+#include <linux/module.h>
+#include <linux/list.h>
+
+static const struct task_struct module_target_data = { .flags = 42 };
+
+static int __init taskinfo_init(void)
+{
+    struct task_struct *p;
+
+    pr_info("taskinfo: loaded\n");
+    pr_info("    offsetof(task_struct, pid)=%zu\n", offsetof(struct task_struct, pid));
+    pr_info("    offsetof(task_struct, tgid)=%zu\n", offsetof(struct task_struct, tgid));
+    pr_info("    offsetof(task_struct, cred)=%zu\n", offsetof(struct task_struct, cred));
+    pr_info("    offsetof(task_struct, real_parent)=%zu\n", offsetof(struct task_struct, real_parent));
+    pr_info("    offsetof(task_struct, comm)=%zu\n", offsetof(struct task_struct, comm));
+    pr_info("    offsetof(task_struct, __state)=%zu\n", offsetof(struct task_struct, __state));
+    pr_info("    offsetof(task_struct, flags)=%zu\n", offsetof(struct task_struct, flags));
+    pr_info("    offsetof(task_struct, prio)=%zu\n", offsetof(struct task_struct, prio));
+    pr_info("    offsetof(task_struct, policy)=%zu\n", offsetof(struct task_struct, policy));
+
+    pr_info("datapin flags value is %u (should be 42)\n", module_target_data.flags);
+
+    pr_info("=== Task List ===\n");
+
+    rcu_read_lock();
+
+    for_each_process(p) {
+        const struct cred *cred;
+        struct task_struct *parent;
+
+        cred = rcu_dereference(p->cred);
+        parent = rcu_dereference(p->real_parent);
+
+        pr_info("task: pid=%d tgid=%d ppid=%d uid=%u gid=%u comm=%s state=%u flags=0x%x prio=%d policy=%u\n",
+                p->pid,
+                p->tgid,
+                parent ? parent->tgid : -1,
+                __kuid_val(cred->uid),
+                __kgid_val(cred->gid),
+                p->comm,
+                READ_ONCE(p->__state),
+                p->flags,
+                p->prio,
+                p->policy);
+    }
+
+    rcu_read_unlock();
+
+    return 0;
+}
+
+static void __exit taskinfo_exit(void)
+{
+    pr_info("taskinfo: unloaded\n");
+}
+
+module_init(taskinfo_init);
+module_exit(taskinfo_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("List modules and tasks (task_struct stress)");
-- 
2.43.0