Merge branch 'robadams-procfs' into 'linux-6.6.y-memorizer-dev'

Robadams procfs

See merge request ring0/memorizer!43

Documentation/memorizer/changelog.rst

@@ -10,6 +10,7 @@ Summary of memorizer-specific kernel versions
   - taskset "SMP" instructions
   - Add test using baremetal.config
   - Reorganize some of the documentation.
+  - Add /proc/<pid>/memorizer_enabled
 
 - v6.6.51-memorizer-26
 

Documentation/memorizer/reference.rst

@@ -151,6 +151,8 @@ Memorizer provides control, data, and status values through the
 Linux ``debugfs`` filesystem.  The ``debugfs`` filesystem is
 conventionally mounted at ``/sys/kernel/debug/`` and the Memorizer
 files are in the ``/sys/kernel/debug/memorizer/`` directory.
+Memorizer files are in the ``/sys/kernel/debug/memorizer/`` directory,
+with the single exception of ``/proc/<pid>/memorizer_enabled``.
 
 Control Files
 ~~~~~~~~~~~~~
@@ -202,6 +204,14 @@ Control Files
   - `READ` - The current Memorizer mode and, optionally, the
     process-id of a Memorizer-enabled process.
 
+``/proc/<pid>/memorizer_enabled``
+  - `WRITE` - Set or clear the memorizable status of the indicated
+    `process`. If a process is memorizable and memorizer is in mode
+    ``2`` or ``3``, then the process and all of its subsequently created
+    child processes will be tracked.
+    This value is unused in modes ``0`` and ``1``.
+  - `READ` - The current memorizable status of the indicated process.
+
 ``log_accesses_enabled``
   - `WRITE` - Writing any boolean value enables or disables the tracing
     of memory reads and writes.

fs/proc/base.c

@@ -3217,6 +3217,59 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,
 }
 #endif /* CONFIG_KSM */
 
+#ifdef CONFIG_MEMORIZER
+static int proc_memorizer_enabled_show(struct seq_file *m, void *v)
+{
+	struct inode *inode = m->private;
+	struct task_struct *task = get_proc_task(inode);
+
+	if (!task)
+		return -ESRCH;
+
+	seq_printf(m, "%d\n", task->memorizer_enabled);
+
+	put_task_struct(task);
+	return 0;
+}
+
+static ssize_t proc_memorizer_enabled_write(struct file *file,
+					    const char __user *buf,
+					    size_t count,
+					    loff_t *ppos)
+{
+	struct task_struct *task;
+	bool val;
+	int ret;
+
+	ret = kstrtobool_from_user(buf, count, &val);
+	if (ret < 0)
+		return ret;
+
+	task = get_proc_task(file_inode(file));
+	if (!task)
+		return -ESRCH;
+
+	task->memorizer_enabled = val;
+
+	put_task_struct(task);
+
+	return count;
+}
+
+static int proc_memorizer_enabled_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_memorizer_enabled_show, inode);
+}
+
+static const struct file_operations proc_memorizer_enabled_operations = {
+	.open		= proc_memorizer_enabled_open,
+	.read		= seq_read,
+	.write		= proc_memorizer_enabled_write,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+#endif
+
 #ifdef CONFIG_STACKLEAK_METRICS
 static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
 				struct pid *pid, struct task_struct *task)
@@ -3352,6 +3405,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 	ONE("ksm_merging_pages",  S_IRUSR, proc_pid_ksm_merging_pages),
 	ONE("ksm_stat",  S_IRUSR, proc_pid_ksm_stat),
 #endif
+#ifdef CONFIG_MEMORIZER
+	REG("memorizer_enabled",  S_IRUSR|S_IWUSR, proc_memorizer_enabled_operations),
+#endif
 };
 
 static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)

scripts/memorizer/test/root/test/mztest.bat

@@ -13,6 +13,27 @@
 	echo -n 0 > /sys/kernel/debug/memorizer/memorizer_enabled
 }
 
+@test "/proc/self/memorizer_enabled exists" {
+	[ "$(</proc/self/memorizer_enabled)" = "0" ]
+	[ "$(</proc/$$/memorizer_enabled)" = "0" ]
+}
+
+setup() {
+	echo -n 0 > /sys/kernel/debug/memorizer/memorizer_enabled
+	echo -n 0 > /proc/self/memorizer_enabled
+}
+
+@test "/proc/self/memorizer_enabled can be written/read" {
+	[ "$(</proc/self/memorizer_enabled)" = "0" ]
+	[ "$(</proc/$$/memorizer_enabled)" = "0" ]
+	echo -n yes > /proc/$$/memorizer_enabled
+	[ "$(</proc/self/memorizer_enabled)" = "1" ]
+	[ "$(</proc/$$/memorizer_enabled)" = "1" ]
+	echo -n no > /proc/self/memorizer_enabled
+	[ "$(</proc/self/memorizer_enabled)" = "0" ]
+	[ "$(</proc/$$/memorizer_enabled)" = "0" ]
+}
+
 @test "ls" {
 	echo -n 1 > /sys/kernel/debug/memorizer/clear_dead_objects
 	cp /sys/kernel/debug/memorizer/kmap /dev/null