[PATCH 05/21] acpi: Introduce acpi_invalid_table() to check if a table is invalid.

[Tang Chen <tangchen@cn.fujitsu.com>]

In acpi_initrd_override(), it checks several things to ensure the
table it found is valid. In later patches, we need to do these check
somewhere else. So this patch introduces a common function
acpi_invalid_table() to do all these checks, and reuse it in different
places. The function will be used in the subsequent patches.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
 drivers/acpi/osl.c |   82 ++++++++++++++++++++++++++++++++++++----------------
 1 files changed, 57 insertions(+), 25 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 91d9f54..4531920 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -572,9 +572,64 @@ static const char * const table_sigs[] = {
 /* Must not increase 10 or needs code modification below */
 #define ACPI_OVERRIDE_TABLES 10
 
+/**
+ * acpi_invalid_table - Check if an acpi table found in initrd is invalid.
+ * @file: The cpio file returned by find_cpio_data().
+ * @path: The path storing acpi overriding tables in cpio file.
+ * @signature: The table signature to be checked.
+ *
+ * @signature can be NULL. If it is NULL, the function will check if the
+ * table signature matches any signature in table_sigs[].
+ *
+ * Return 0 if it passes all the checks, -EINVAL if any check fails.
+ */
+int __init acpi_invalid_table(struct cpio_data *file,
+			      const char *path, const char *signature)
+{
+	int idx;
+	struct acpi_table_header *table = file->data;
+
+	if (file->size < sizeof(struct acpi_table_header)) {
+		INVALID_TABLE("Table smaller than ACPI header",
+			      path, file->name);
+		return -EINVAL;
+	}
+
+	if (signature) {
+		if (memcmp(table->signature, signature, 4)) {
+			INVALID_TABLE("Table signature does not match",
+				      path, file->name);
+			return -EINVAL;
+		}
+	} else {
+		for (idx = 0; table_sigs[idx]; idx++)
+			if (!memcmp(table->signature, table_sigs[idx], 4))
+				break;
+
+		if (!table_sigs[idx]) {
+			INVALID_TABLE("Unknown signature", path, file->name);
+			return -EINVAL;
+		}
+	}
+
+	if (file->size != table->length) {
+		INVALID_TABLE("File length does not match table length",
+			      path, file->name);
+		return -EINVAL;
+	}
+
+	if (acpi_table_checksum(file->data, table->length)) {
+		INVALID_TABLE("Bad table checksum",
+			      path, file->name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 void __init acpi_initrd_override(void *data, size_t size)
 {
-	int sig, no, table_nr = 0, total_offset = 0;
+	int no, table_nr = 0, total_offset = 0;
 	long offset = 0;
 	struct acpi_table_header *table;
 	char cpio_path[32] = "kernel/firmware/acpi/";
@@ -593,33 +648,10 @@ void __init acpi_initrd_override(void *data, size_t size)
 		data += offset;
 		size -= offset;
 
-		if (file.size < sizeof(struct acpi_table_header)) {
-			INVALID_TABLE("Table smaller than ACPI header",
-				      cpio_path, file.name);
-			continue;
-		}
-
 		table = file.data;
 
-		for (sig = 0; table_sigs[sig]; sig++)
-			if (!memcmp(table->signature, table_sigs[sig], 4))
-				break;
-
-		if (!table_sigs[sig]) {
-			INVALID_TABLE("Unknown signature",
-				      cpio_path, file.name);
-			continue;
-		}
-		if (file.size != table->length) {
-			INVALID_TABLE("File length does not match table length",
-				      cpio_path, file.name);
-			continue;
-		}
-		if (acpi_table_checksum(file.data, table->length)) {
-			INVALID_TABLE("Bad table checksum",
-				      cpio_path, file.name);
+		if (acpi_invalid_table(&file, cpio_path, NULL))
 			continue;
-		}
 
 		pr_info("%4.4s ACPI table found in initrd [%s%s][0x%x]\n",
 			table->signature, cpio_path, file.name, table->length);
-- 
1.7.1