Merge tag 'perf-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-microblaze.git] / drivers / remoteproc / remoteproc_debugfs.c

diff --git a/drivers/remoteproc/remoteproc_debugfs.c b/drivers/remoteproc/remoteproc_debugfs.c
index 732770e..2e3b3e2 100644 (file)
--- a/drivers/remoteproc/remoteproc_debugfs.c
+++ b/drivers/remoteproc/remoteproc_debugfs.c
@@ -27,6 +27,94 @@
 /* remoteproc debugfs parent dir */
 static struct dentry *rproc_dbg;
 
+/*
+ * A coredump-configuration-to-string lookup table, for exposing a
+ * human readable configuration via debugfs. Always keep in sync with
+ * enum rproc_coredump_mechanism
+ */
+static const char * const rproc_coredump_str[] = {
+       [RPROC_COREDUMP_DEFAULT]        = "default",
+       [RPROC_COREDUMP_INLINE]         = "inline",
+       [RPROC_COREDUMP_DISABLED]       = "disabled",
+};
+
+/* Expose the current coredump configuration via debugfs */
+static ssize_t rproc_coredump_read(struct file *filp, char __user *userbuf,
+                                  size_t count, loff_t *ppos)
+{
+       struct rproc *rproc = filp->private_data;
+       char buf[20];
+       int len;
+
+       len = scnprintf(buf, sizeof(buf), "%s\n",
+                       rproc_coredump_str[rproc->dump_conf]);
+
+       return simple_read_from_buffer(userbuf, count, ppos, buf, len);
+}
+
+/*
+ * By writing to the 'coredump' debugfs entry, we control the behavior of the
+ * coredump mechanism dynamically. The default value of this entry is "default".
+ *
+ * The 'coredump' debugfs entry supports these commands:
+ *
+ * default:    This is the default coredump mechanism. When the remoteproc
+ *             crashes the entire coredump will be copied to a separate buffer
+ *             and exposed to userspace.
+ *
+ * inline:     The coredump will not be copied to a separate buffer and the
+ *             recovery process will have to wait until data is read by
+ *             userspace. But this avoid usage of extra memory.
+ *
+ * disabled:   This will disable coredump. Recovery will proceed without
+ *             collecting any dump.
+ */
+static ssize_t rproc_coredump_write(struct file *filp,
+                                   const char __user *user_buf, size_t count,
+                                   loff_t *ppos)
+{
+       struct rproc *rproc = filp->private_data;
+       int ret, err = 0;
+       char buf[20];
+
+       if (count > sizeof(buf))
+               return -EINVAL;
+
+       ret = copy_from_user(buf, user_buf, count);
+       if (ret)
+               return -EFAULT;
+
+       /* remove end of line */
+       if (buf[count - 1] == '\n')
+               buf[count - 1] = '\0';
+
+       if (rproc->state == RPROC_CRASHED) {
+               dev_err(&rproc->dev, "can't change coredump configuration\n");
+               err = -EBUSY;
+               goto out;
+       }
+
+       if (!strncmp(buf, "disable", count)) {
+               rproc->dump_conf = RPROC_COREDUMP_DISABLED;
+       } else if (!strncmp(buf, "inline", count)) {
+               rproc->dump_conf = RPROC_COREDUMP_INLINE;
+       } else if (!strncmp(buf, "default", count)) {
+               rproc->dump_conf = RPROC_COREDUMP_DEFAULT;
+       } else {
+               dev_err(&rproc->dev, "Invalid coredump configuration\n");
+               err = -EINVAL;
+       }
+out:
+       return err ? err : count;
+}
+
+static const struct file_operations rproc_coredump_fops = {
+       .read = rproc_coredump_read,
+       .write = rproc_coredump_write,
+       .open = simple_open,
+       .llseek = generic_file_llseek,
+};
+
 /*
  * Some remote processors may support dumping trace logs into a shared
  * memory buffer. We expose this trace buffer using debugfs, so users
@@ -337,6 +425,8 @@ void rproc_create_debug_dir(struct rproc *rproc)
                            rproc, &rproc_rsc_table_fops);
        debugfs_create_file("carveout_memories", 0400, rproc->dbg_dir,
                            rproc, &rproc_carveouts_fops);
+       debugfs_create_file("coredump", 0600, rproc->dbg_dir,
+                           rproc, &rproc_coredump_fops);
 }
 
 void __init rproc_init_debugfs(void)