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authorLv Zheng <lv.zheng@intel.com>2016-09-07 09:06:54 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-09-10 03:43:02 +0300
commitde56ba95e8d6d760910711744a548b50b3a4262d (patch)
tree2e1e05a6c198aadce4073fd9daa9920337125130 /drivers/acpi/acpica/exconfig.c
parent955f485dc40cdee265a85ad4af378f2a2cfaf11b (diff)
downloadlinux-de56ba95e8d6d760910711744a548b50b3a4262d.tar.xz
ACPICA: Interpreter: Fix MLC issues by switching to new term_list grammar for table loading
ACPICA commit 0e24fb67cde08d7df7671d7d7b183490dc79707e The MLC (Module Level Code) is an ACPICA terminology describing the AML code out of any control method, its support is an indication of the interpreter behavior during the table loading. The original implementation of MLC in ACPICA had several issues: 1. Out of any control method, besides of the object creating opcodes, only the code blocks wrapped by "If/Else/While" opcodes were supported. 2. The supported MLC code blocks were executed after loading the table rather than being executed right in place. ============================================================ The demo of this order issue is as follows: Name (OBJ1, 1) If (CND1 == 1) { Name (OBJ2, 2) } Name (OBJ3, 3) The original MLC support created OBJ2 after OBJ3's creation. ============================================================ Other than these limitations, MLC support in ACPICA looks correct. And supporting this should be easy/natural for ACPICA, but enabling of this was blocked by some ACPICA internal and OSPM specific initialization order issues we've fixed recently. The wrong support started from the following false bug fixing commit: Commit: 7f0c826a437157d2b19662977e9cf3b472cf24a6 Subject: ACPICA: Add support for module-level executable AML code Commit: 9a884ab64a4d092b4c3bf24fd9a30f7fbd4591e7 Subject: ACPICA: Add additional module-level code support ... We can confirm Windows interpreter behavior via reverse engineering means. It can be proven that not only If/Else/While wrapped code blocks, all opcodes can be executed at the module level, including operation region accesses. And it can be proven that the MLC should be executed right in place, not in such a deferred way executed after loading the table. And the above facts indeed reflect the spec words around ACPI definition block tables (DSDT/SSDT/...), the entire table and the Scope object is defined by the AML specification in BNF style as: AMLCode := def_block_header term_list def_scope := scope_op pkg_length name_string term_list The bodies of the scope opening terms (AMLCode/Scope) are all term_list, thus the table loading should be no difference than the control method evaluations as the body of the Method is also defined by the AML specification as term_list: def_method := method_op pkg_length name_string method_flags term_list The only difference is: after evaluating control method, created named objects may be freed due to no reference, while named objects created by the table loading should only be freed after unloading the table. So this patch follows the spec and the de-facto standard behavior, enables the new grammar (term_list) for the table loading. By doing so, beyond the fixes to the above issues, we can see additional differences comparing to the old grammar based table loading: 1. Originally, beyond the scope opening terms (AMLCode/Scope), If/Else/While wrapped code blocks under the scope creating terms (Device/power_resource/Processor/thermal_zone) are also supported as deferred MLC, which violates the spec defined grammar where object_list is enforced. With MLC support improved as non-deferred, the interpreter parses such scope creating terms as term_list rather object_list like the scope opening terms. After probing the Windows behavior and proving that it also parses these terms as term_list, we submitted an ECR (Engineering Change Request) to the ASWG (ACPI Specification Working Group) to clarify this. The ECR is titled as "ASL Grammar Clarification for Executable AML Opcodes" and has been accepted by the ASWG. The new grammar will appear in ACPI specification 6.2. 2. Originally, Buffer/Package/operation_region/create_XXXField/bank_field arguments are evaluated in a deferred way after loading the table. With MLC support improved, they are also parsed right in place during the table loading. This is also Windows compliant and the only difference is the removal of the debugging messages implemented before acpi_ds_execute_arguments(), see Link # [1] for the details. A previous commit should have ensured that acpi_check_address_range() won't regress. Note that enabling this feature may cause regressions due to long term Linux ACPI support on top of the wrong grammar. So this patch also prepares a global option to be used to roll back to the old grammar during the period between a regression is reported and the regression is root-cause-fixed. Lv Zheng. Link: https://bugzilla.kernel.org/show_bug.cgi?id=112911 # [1] Link: https://bugzilla.kernel.org/show_bug.cgi?id=117671 # [1] Link: https://bugzilla.kernel.org/show_bug.cgi?id=153541 # [1] Link: https://github.com/acpica/acpica/issues/122 Link: https://bugs.acpica.org/show_bug.cgi?id=963 Link: https://github.com/acpica/acpica/commit/0e24fb67 Reported-and-tested-by: Chris Bainbridge <chris.bainbridge@gmail.com> Reported-by: Ehsan <dashesy@gmail.com> Reported-and-tested-by: Dutch Guy <lucht_piloot@gmx.net> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Lv Zheng <lv.zheng@intel.com> Signed-off-by: Bob Moore <robert.moore@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/acpica/exconfig.c')
-rw-r--r--drivers/acpi/acpica/exconfig.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/acpi/acpica/exconfig.c b/drivers/acpi/acpica/exconfig.c
index a1d177d58254..74dd5bac8422 100644
--- a/drivers/acpi/acpica/exconfig.c
+++ b/drivers/acpi/acpica/exconfig.c
@@ -118,7 +118,8 @@ acpi_ex_add_table(u32 table_index,
/* Execute any module-level code that was found in the table */
acpi_ex_exit_interpreter();
- if (acpi_gbl_group_module_level_code) {
+ if (!acpi_gbl_parse_table_as_term_list
+ && acpi_gbl_group_module_level_code) {
acpi_ns_exec_module_code_list();
}
acpi_ex_enter_interpreter();