Re: [PATCH v5 11/25] powerpc/secvar: Allow backend to populate static list of variable names

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On 1/31/23 01:39, Andrew Donnellan wrote:
Currently, the list of variables is populated by calling
secvar_ops->get_next() repeatedly, which is explicitly modelled on the
OPAL API (including the keylen parameter).

For the upcoming PLPKS backend, we have a static list of variable names.
It is messy to fit that into get_next(), so instead, let the backend put
a NULL-terminated array of variable names into secvar_ops->var_names,
which will be used if get_next() is undefined.

Signed-off-by: Andrew Donnellan <ajd@xxxxxxxxxxxxx>
Signed-off-by: Russell Currey <ruscur@xxxxxxxxxx>

---

v3: New patch (ajd/mpe)
---
  arch/powerpc/include/asm/secvar.h  |  4 ++
  arch/powerpc/kernel/secvar-sysfs.c | 67 ++++++++++++++++++++----------
  2 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/include/asm/secvar.h b/arch/powerpc/include/asm/secvar.h
index 011a53a8076c..4828e0ab7e3c 100644
--- a/arch/powerpc/include/asm/secvar.h
+++ b/arch/powerpc/include/asm/secvar.h
@@ -21,6 +21,10 @@ struct secvar_operations {
  	ssize_t (*format)(char *buf, size_t bufsize);
  	int (*max_size)(u64 *max_size);
  	const struct attribute **config_attrs;
+
+	// NULL-terminated array of fixed variable names
+	// Only used if get_next() isn't provided
+	const char * const *var_names;
  };
#ifdef CONFIG_PPC_SECURE_BOOT
diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c
index 7df32be86507..2cbc60b37e4e 100644
--- a/arch/powerpc/kernel/secvar-sysfs.c
+++ b/arch/powerpc/kernel/secvar-sysfs.c
@@ -157,9 +157,31 @@ static int secvar_sysfs_config(struct kobject *kobj)
  	return 0;
  }
-static int secvar_sysfs_load(void)
+static int add_var(const char *name)
  {
  	struct kobject *kobj;
+	int rc;
+
+	kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
+	if (!kobj)
+		return -ENOMEM;
+
+	kobject_init(kobj, &secvar_ktype);
+
+	rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
+	if (rc) {
+		pr_warn("kobject_add error %d for attribute: %s\n", rc,
+			name);
+		kobject_put(kobj);
+		return rc;
+	}
+
+	kobject_uevent(kobj, KOBJ_ADD);
+	return 0;
+}
+
+static int secvar_sysfs_load(void)
+{
  	u64 namesize = 0;
  	char *name;
  	int rc;
@@ -179,31 +201,26 @@ static int secvar_sysfs_load(void)
  			break;
  		}
- kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
-		if (!kobj) {
-			rc = -ENOMEM;
-			break;
-		}
-
-		kobject_init(kobj, &secvar_ktype);
-
-		rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
-		if (rc) {
-			pr_warn("kobject_add error %d for attribute: %s\n", rc,
-				name);
-			kobject_put(kobj);
-			kobj = NULL;
-		}
-
-		if (kobj)
-			kobject_uevent(kobj, KOBJ_ADD);
-
+		rc = add_var(name);
  	} while (!rc);
kfree(name);
  	return rc;
  }
+static int secvar_sysfs_load_static(void)
+{
+	const char * const *name_ptr = secvar_ops->var_names;
+	int rc;

Missing newline ?

+	while (*name_ptr) {
+		rc = add_var(*name_ptr);
+		if (rc)
+			return rc;
+		name_ptr++;
+	}
+	return 0;
+}
+
  static int secvar_sysfs_init(void)
  {
  	int rc;
@@ -245,7 +262,15 @@ static int secvar_sysfs_init(void)
  		goto err;
  	}
- secvar_sysfs_load();
+	if (secvar_ops->get_next)
+		rc = secvar_sysfs_load();
+	else
+		rc = secvar_sysfs_load_static();
+
+	if (rc) {
+		pr_err("Failed to create variable attributes\n");
+		goto err;
+	}
return 0;
  err:

With the above change:

Reviewed-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>



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