4 files changed, 180 insertions, 55 deletions

diff --git a/drivers/acpi/acpica/actables.h b/drivers/acpi/acpica/actables.h
index 7dd527f8ca1d..94be8a8e6c08 100644
--- a/drivers/acpi/acpica/actables.h
+++ b/drivers/acpi/acpica/actables.h
@@ -166,6 +166,12 @@ acpi_tb_install_table_with_override(struct acpi_table_desc *new_table_desc,
 
 acpi_status acpi_tb_parse_root_table(acpi_physical_address rsdp_address);
 
+acpi_status
+acpi_tb_get_table(struct acpi_table_desc *table_desc,
+		  struct acpi_table_header **out_table);
+
+void acpi_tb_put_table(struct acpi_table_desc *table_desc);
+
 /*
  * tbxfload
  */
diff --git a/drivers/acpi/acpica/tbfadt.c b/drivers/acpi/acpica/tbfadt.c
index 5fb838e592dc..81473a4880ce 100644
--- a/drivers/acpi/acpica/tbfadt.c
+++ b/drivers/acpi/acpica/tbfadt.c
@@ -311,6 +311,8 @@ void acpi_tb_parse_fadt(void)
 {
 	u32 length;
 	struct acpi_table_header *table;
+	struct acpi_table_desc *fadt_desc;
+	acpi_status status;
 
 	/*
 	 * The FADT has multiple versions with different lengths,
@@ -319,14 +321,12 @@ void acpi_tb_parse_fadt(void)
 	 * Get a local copy of the FADT and convert it to a common format
 	 * Map entire FADT, assumed to be smaller than one page.
 	 */
-	length = acpi_gbl_root_table_list.tables[acpi_gbl_fadt_index].length;
-
-	table =
-	    acpi_os_map_memory(acpi_gbl_root_table_list.
-			       tables[acpi_gbl_fadt_index].address, length);
-	if (!table) {
+	fadt_desc = &acpi_gbl_root_table_list.tables[acpi_gbl_fadt_index];
+	status = acpi_tb_get_table(fadt_desc, &table);
+	if (ACPI_FAILURE(status)) {
 		return;
 	}
+	length = fadt_desc->length;
 
 	/*
 	 * Validate the FADT checksum before we copy the table. Ignore
@@ -340,7 +340,7 @@ void acpi_tb_parse_fadt(void)
 
 	/* All done with the real FADT, unmap it */
 
-	acpi_os_unmap_memory(table, length);
+	acpi_tb_put_table(fadt_desc);
 
 	/* Obtain the DSDT and FACS tables via their addresses within the FADT */
 
diff --git a/drivers/acpi/acpica/tbutils.c b/drivers/acpi/acpica/tbutils.c
index 51eb07cf9898..86854e846800 100644
--- a/drivers/acpi/acpica/tbutils.c
+++ b/drivers/acpi/acpica/tbutils.c
@@ -381,3 +381,88 @@ next_table:
 	acpi_os_unmap_memory(table, length);
 	return_ACPI_STATUS(AE_OK);
 }
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_tb_get_table
+ *
+ * PARAMETERS:  table_desc          - Table descriptor
+ *              out_table           - Where the pointer to the table is returned
+ *
+ * RETURN:      Status and pointer to the requested table
+ *
+ * DESCRIPTION: Increase a reference to a table descriptor and return the
+ *              validated table pointer.
+ *              If the table descriptor is an entry of the root table list,
+ *              this API must be invoked with ACPI_MTX_TABLES acquired.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_tb_get_table(struct acpi_table_desc *table_desc,
+		  struct acpi_table_header **out_table)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(acpi_tb_get_table);
+
+	if (table_desc->validation_count == 0) {
+
+		/* Table need to be "VALIDATED" */
+
+		status = acpi_tb_validate_table(table_desc);
+		if (ACPI_FAILURE(status)) {
+			return_ACPI_STATUS(status);
+		}
+	}
+
+	table_desc->validation_count++;
+	if (table_desc->validation_count == 0) {
+		ACPI_ERROR((AE_INFO,
+			    "Table %p, Validation count is zero after increment\n",
+			    table_desc));
+		table_desc->validation_count--;
+		return_ACPI_STATUS(AE_LIMIT);
+	}
+
+	*out_table = table_desc->pointer;
+	return_ACPI_STATUS(AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_tb_put_table
+ *
+ * PARAMETERS:  table_desc          - Table descriptor
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Decrease a reference to a table descriptor and release the
+ *              validated table pointer if no references.
+ *              If the table descriptor is an entry of the root table list,
+ *              this API must be invoked with ACPI_MTX_TABLES acquired.
+ *
+ ******************************************************************************/
+
+void acpi_tb_put_table(struct acpi_table_desc *table_desc)
+{
+
+	ACPI_FUNCTION_TRACE(acpi_tb_put_table);
+
+	if (table_desc->validation_count == 0) {
+		ACPI_WARNING((AE_INFO,
+			      "Table %p, Validation count is zero before decrement\n",
+			      table_desc));
+		return_VOID;
+	}
+	table_desc->validation_count--;
+
+	if (table_desc->validation_count == 0) {
+
+		/* Table need to be "INVALIDATED" */
+
+		acpi_tb_invalidate_table(table_desc);
+	}
+
+	return_VOID;
+}
diff --git a/drivers/acpi/acpica/tbxface.c b/drivers/acpi/acpica/tbxface.c
index d5adb7ac4684..7684707b254b 100644
--- a/drivers/acpi/acpica/tbxface.c
+++ b/drivers/acpi/acpica/tbxface.c
@@ -282,7 +282,7 @@ ACPI_EXPORT_SYMBOL(acpi_get_table_header)
 
 /*******************************************************************************
  *
- * FUNCTION:    acpi_get_table_with_size
+ * FUNCTION:    acpi_get_table
  *
  * PARAMETERS:  signature           - ACPI signature of needed table
  *              instance            - Which instance (for SSDTs)
@@ -292,16 +292,21 @@ ACPI_EXPORT_SYMBOL(acpi_get_table_header)
  *
  * DESCRIPTION: Finds and verifies an ACPI table. Table must be in the
  *              RSDT/XSDT.
+ *              Note that an early stage acpi_get_table() call must be paired
+ *              with an early stage acpi_put_table() call. otherwise the table
+ *              pointer mapped by the early stage mapping implementation may be
+ *              erroneously unmapped by the late stage unmapping implementation
+ *              in an acpi_put_table() invoked during the late stage.
  *
  ******************************************************************************/
 acpi_status
-acpi_get_table_with_size(char *signature,
-	       u32 instance, struct acpi_table_header **out_table,
-	       acpi_size *tbl_size)
+acpi_get_table(char *signature,
+	       u32 instance, struct acpi_table_header ** out_table)
 {
 	u32 i;
 	u32 j;
-	acpi_status status;
+	acpi_status status = AE_NOT_FOUND;
+	struct acpi_table_desc *table_desc;
 
 	/* Parameter validation */
 
@@ -309,13 +314,22 @@ acpi_get_table_with_size(char *signature,
 		return (AE_BAD_PARAMETER);
 	}
 
+	/*
+	 * Note that the following line is required by some OSPMs, they only
+	 * check if the returned table is NULL instead of the returned status
+	 * to determined if this function is succeeded.
+	 */
+	*out_table = NULL;
+
+	(void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
+
 	/* Walk the root table list */
 
 	for (i = 0, j = 0; i < acpi_gbl_root_table_list.current_table_count;
 	     i++) {
-		if (!ACPI_COMPARE_NAME
-		    (&(acpi_gbl_root_table_list.tables[i].signature),
-		     signature)) {
+		table_desc = &acpi_gbl_root_table_list.tables[i];
+
+		if (!ACPI_COMPARE_NAME(&table_desc->signature, signature)) {
 			continue;
 		}
 
@@ -323,43 +337,65 @@ acpi_get_table_with_size(char *signature,
 			continue;
 		}
 
-		status =
-		    acpi_tb_validate_table(&acpi_gbl_root_table_list.tables[i]);
-		if (ACPI_SUCCESS(status)) {
-			*out_table = acpi_gbl_root_table_list.tables[i].pointer;
-			*tbl_size = acpi_gbl_root_table_list.tables[i].length;
-		}
-
-		if (!acpi_gbl_permanent_mmap) {
-			acpi_gbl_root_table_list.tables[i].pointer = NULL;
-		}
-
-		return (status);
+		status = acpi_tb_get_table(table_desc, out_table);
+		break;
 	}
 
-	return (AE_NOT_FOUND);
+	(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
+	return (status);
 }
 
-ACPI_EXPORT_SYMBOL(acpi_get_table_with_size)
+ACPI_EXPORT_SYMBOL(acpi_get_table)
 
-acpi_status
-acpi_get_table(char *signature,
-	       u32 instance, struct acpi_table_header **out_table)
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_put_table
+ *
+ * PARAMETERS:  table               - The pointer to the table
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Release a table returned by acpi_get_table() and its clones.
+ *              Note that it is not safe if this function was invoked after an
+ *              uninstallation happened to the original table descriptor.
+ *              Currently there is no OSPMs' requirement to handle such
+ *              situations.
+ *
+ ******************************************************************************/
+void acpi_put_table(struct acpi_table_header *table)
 {
-	acpi_size tbl_size;
+	u32 i;
+	struct acpi_table_desc *table_desc;
+
+	ACPI_FUNCTION_TRACE(acpi_put_table);
+
+	(void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
+
+	/* Walk the root table list */
+
+	for (i = 0; i < acpi_gbl_root_table_list.current_table_count; i++) {
+		table_desc = &acpi_gbl_root_table_list.tables[i];
 
-	return acpi_get_table_with_size(signature,
-		       instance, out_table, &tbl_size);
+		if (table_desc->pointer != table) {
+			continue;
+		}
+
+		acpi_tb_put_table(table_desc);
+		break;
+	}
+
+	(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
+	return_VOID;
 }
 
-ACPI_EXPORT_SYMBOL(acpi_get_table)
+ACPI_EXPORT_SYMBOL(acpi_put_table)
 
 /*******************************************************************************
  *
  * FUNCTION:    acpi_get_table_by_index
  *
  * PARAMETERS:  table_index         - Table index
- *              table               - Where the pointer to the table is returned
+ *              out_table           - Where the pointer to the table is returned
  *
  * RETURN:      Status and pointer to the requested table
  *
@@ -368,7 +404,7 @@ ACPI_EXPORT_SYMBOL(acpi_get_table)
  *
  ******************************************************************************/
 acpi_status
-acpi_get_table_by_index(u32 table_index, struct acpi_table_header **table)
+acpi_get_table_by_index(u32 table_index, struct acpi_table_header **out_table)
 {
 	acpi_status status;
 
@@ -376,35 +412,33 @@ acpi_get_table_by_index(u32 table_index, struct acpi_table_header **table)
 
 	/* Parameter validation */
 
-	if (!table) {
+	if (!out_table) {
 		return_ACPI_STATUS(AE_BAD_PARAMETER);
 	}
 
+	/*
+	 * Note that the following line is required by some OSPMs, they only
+	 * check if the returned table is NULL instead of the returned status
+	 * to determined if this function is succeeded.
+	 */
+	*out_table = NULL;
+
 	(void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
 
 	/* Validate index */
 
 	if (table_index >= acpi_gbl_root_table_list.current_table_count) {
-		(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
-		return_ACPI_STATUS(AE_BAD_PARAMETER);
+		status = AE_BAD_PARAMETER;
+		goto unlock_and_exit;
 	}
 
-	if (!acpi_gbl_root_table_list.tables[table_index].pointer) {
-
-		/* Table is not mapped, map it */
+	status =
+	    acpi_tb_get_table(&acpi_gbl_root_table_list.tables[table_index],
+			      out_table);
 
-		status =
-		    acpi_tb_validate_table(&acpi_gbl_root_table_list.
-					   tables[table_index]);
-		if (ACPI_FAILURE(status)) {
-			(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
-			return_ACPI_STATUS(status);
-		}
-	}
-
-	*table = acpi_gbl_root_table_list.tables[table_index].pointer;
+unlock_and_exit:
 	(void)acpi_ut_release_mutex(ACPI_MTX_TABLES);
-	return_ACPI_STATUS(AE_OK);
+	return_ACPI_STATUS(status);
 }
 
 ACPI_EXPORT_SYMBOL(acpi_get_table_by_index)