[U-Boot] [PATCH 1/4] efi_loader: support non-volatile variable behavior

[AKASHI Takahiro]

An EFI variable is nothing but a wrapper of a corresponding u-boot
environment variable (See efi_variable.c), but under the current
implementation, NON_VOLATILE attribute is not honored while u-boot
environment variables can be saved/restored in storage.

With this patch, the expected semantics will be mimicked by deleting
all the EFI variables *without* NON_VOLATILE attribute when loading
them from storage at boot time.

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 env/env.c                     |  4 +++
 include/efi_loader.h          |  1 +
 lib/efi_loader/efi_variable.c | 64 +++++++++++++++++++++++++++++++++--
 3 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/env/env.c b/env/env.c
index afed0f3c95c3..c507a4ac5f78 100644
--- a/env/env.c
+++ b/env/env.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <efi_loader.h>
 #include <environment.h>
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -195,6 +196,9 @@ int env_load(void)
 		if (ret) {
 			debug("Failed (%d)\n", ret);
 		} else {
+#ifdef CONFIG_EFI_LOADER
+			efi_purge_volatile_variables();
+#endif
 			printf("OK\n");
 			return 0;
 		}
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 9f7a4068efa6..9cad1dcd62bb 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -533,6 +533,7 @@ efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
 efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
 				     u32 attributes, efi_uintn_t data_size,
 				     void *data);
+int efi_purge_volatile_variables(void);
 
 /*
  * See section 3.1.3 in the v2.7 UEFI spec for more details on
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 19d9cb865f25..ad8cd36fa1e1 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -8,6 +8,8 @@
 #include <malloc.h>
 #include <charset.h>
 #include <efi_loader.h>
+#include <environment.h>
+#include <search.h>
 
 #define READ_ONLY BIT(31)
 
@@ -142,6 +144,8 @@ static const char *parse_attr(const char *str, u32 *attrp)
 
 		if ((s = prefix(str, "ro"))) {
 			attr |= READ_ONLY;
+		} else if ((s = prefix(str, "nv"))) {
+			attr |= EFI_VARIABLE_NON_VOLATILE;
 		} else if ((s = prefix(str, "boot"))) {
 			attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
 		} else if ((s = prefix(str, "run"))) {
@@ -293,7 +297,7 @@ efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
 		}
 	}
 
-	val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1);
+	val = malloc(2 * data_size + strlen("{ro,run,boot,nv}(blob)") + 1);
 	if (!val) {
 		ret = EFI_OUT_OF_RESOURCES;
 		goto out;
@@ -302,12 +306,16 @@ efi_status_t EFIAPI efi_set_variable(u16 *variable_name, efi_guid_t *vendor,
 	s = val;
 
 	/* store attributes: */
-	attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS);
+	attributes &= (EFI_VARIABLE_NON_VOLATILE |
+		       EFI_VARIABLE_BOOTSERVICE_ACCESS |
+		       EFI_VARIABLE_RUNTIME_ACCESS);
 	s += sprintf(s, "{");
 	while (attributes) {
 		u32 attr = 1 << (ffs(attributes) - 1);
 
-		if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
+		if (attr == EFI_VARIABLE_NON_VOLATILE)
+			s += sprintf(s, "nv");
+		else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
 			s += sprintf(s, "boot");
 		else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
 			s += sprintf(s, "run");
@@ -334,3 +342,53 @@ out:
 
 	return EFI_EXIT(ret);
 }
+
+/*
+ * Purge all the variables which are not marked non volatile.
+ * This function is assumed to be called only once at boot time.
+ */
+int efi_purge_volatile_variables(void)
+{
+	char regex[256];
+	char * const regexlist[] = {regex};
+	char *list = NULL, *name, *value;
+	int len, ret = 0;
+	u32 attr;
+
+	snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
+
+	len = hexport_r(&env_htab, '\n', H_MATCH_REGEX | H_MATCH_KEY,
+			&list, 0, 1, regexlist);
+
+	if (len < 0)
+		return -1;
+	else if (!len)
+		return 0;
+
+	name = list;
+	while (*name) {
+		/* variable name */
+		value = strchr(name, '=');
+		if (!value)
+			break;
+		*value = '\0';
+		value++;
+
+		parse_attr(value, &attr);
+		if (!(attr & EFI_VARIABLE_NON_VOLATILE)) {
+			if (env_set(name, NULL)) {
+				printf("cannot purge efi variable: %s\n", name);
+				ret = -1;
+			}
+		}
+
+		name = strchr(value, '\n');
+		if (!name)
+			break;
+		name++;
+	}
+
+	free(list);
+
+	return ret;
+}
-- 
2.19.1