Commit 35e60a6b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'acpi-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 

Pull ACPI fixes from Rafael Wysocki:
 "These revert an ACPICA commit from the 4.11 cycle that causes problems
  to happen on some systems and add a protection against possible kernel
  crashes due to table reference counter imbalance.

  Specifics:

   - Revert a 4.11 ACPICA change that made assumptions which are not
     satisfied on some systems and caused the enumeration of resources
     to fail on them (Rafael Wysocki).

   - Add a mechanism to prevent tables from being unmapped prematurely
     due to reference counter overflows (Lv Zheng)"

* tag 'acpi-4.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Tables: Mechanism to handle late stage acpi_get_table() imbalance
  Revert "ACPICA: Disassembler: Enhance resource descriptor detection"
parents 92091c43 95229334

drivers/acpi/acpica/tbutils.c

+25 −9
Original line number Diff line number Diff line
@@ -416,9 +416,18 @@ acpi_tb_get_table(struct acpi_table_desc *table_desc, 
		}

	}



	if (table_desc->validation_count < ACPI_MAX_TABLE_VALIDATIONS) {

		table_desc->validation_count++;

	if (table_desc->validation_count == 0) {

		table_desc->validation_count--;



		/*

		 * Detect validation_count overflows to ensure that the warning

		 * message will only be printed once.

		 */

		if (table_desc->validation_count >= ACPI_MAX_TABLE_VALIDATIONS) {

			ACPI_WARNING((AE_INFO,

				      "Table %p, Validation count overflows\n",

				      table_desc));

		}

	}



	*out_table = table_desc->pointer;
@@ -445,13 +454,20 @@ void acpi_tb_put_table(struct acpi_table_desc *table_desc) 


	ACPI_FUNCTION_TRACE(acpi_tb_put_table);



	if (table_desc->validation_count == 0) {

	if (table_desc->validation_count < ACPI_MAX_TABLE_VALIDATIONS) {

		table_desc->validation_count--;



		/*

		 * Detect validation_count underflows to ensure that the warning

		 * message will only be printed once.

		 */

		if (table_desc->validation_count >= ACPI_MAX_TABLE_VALIDATIONS) {

			ACPI_WARNING((AE_INFO,

			      "Table %p, Validation count is zero before decrement\n",

				      "Table %p, Validation count underflows\n",

				      table_desc));

			return_VOID;

		}

	table_desc->validation_count--;

	}



	if (table_desc->validation_count == 0) {

drivers/acpi/acpica/utresrc.c

+0 −9
Original line number Diff line number Diff line
@@ -474,15 +474,6 @@ acpi_ut_walk_aml_resources(struct acpi_walk_state *walk_state, 
				return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);

			}



			/*

			 * The end_tag opcode must be followed by a zero byte.

			 * Although this byte is technically defined to be a checksum,

			 * in practice, all ASL compilers set this byte to zero.

			 */

			if (*(aml + 1) != 0) {

				return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);

			}



			/* Return the pointer to the end_tag if requested */



			if (!user_function) {

include/acpi/actbl.h

+14 −0
Original line number Diff line number Diff line
@@ -374,6 +374,20 @@ struct acpi_table_desc { 
	u16 validation_count;

};



/*

 * Maximum value of the validation_count field in struct acpi_table_desc.

 * When reached, validation_count cannot be changed any more and the table will

 * be permanently regarded as validated.

 *

 * This is to prevent situations in which unbalanced table get/put operations

 * may cause premature table unmapping in the OS to happen.

 *

 * The maximum validation count can be defined to any value, but should be

 * greater than the maximum number of OS early stage mapping slots to avoid

 * leaking early stage table mappings to the late stage.

 */

#define ACPI_MAX_TABLE_VALIDATIONS          ACPI_UINT16_MAX



/* Masks for Flags field above */



#define ACPI_TABLE_ORIGIN_EXTERNAL_VIRTUAL  (0)	/* Virtual address, external maintained */

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