Date:	Tue, 17 May 2016 00:29:37 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"Brown, Len" <len.brown@...el.com>
CC:	Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: RE: [PATCH v2 0/4] ACPI 2.0: Enable TermList interpretion for table
 loading

Hi, Rafael

Can we queue this up in linux-next?
ASLTS recursive tests are done in ACPICA upstream and no regressions can be seen.
We need more tests around this experimental change from the real users to have the chances to learn the unknown cases.
If they reported regressions, we could stop the regressions by reverting [PATCH 4/4].
So it should be safe to do such experiments in the Linux upstream.
Thanks in advance.

Best regards
-Lv

> From: Zheng, Lv
> Subject: [PATCH v2 0/4] ACPI 2.0: Enable TermList interpretion for table loading
> 
> MLC (module level code) is an ACPICA terminology describing the AML code
> out of any control method, currently only Type1Opcode (If/Else/While)
> wrapped MLC code blocks are executed by the AML interpreter after the table
> loading. But the issue which is fixed by this patchset is:
>    Not only Type1Opcode, but also Type2Opcode will be executed as MLC and
>    MLC is not executed after loading the table, but is executed right in
>    place.
> 
> The following AML code is assembled into a static loading SSDT, and used
> as an instrumentation to pry into the de-facto standard AML interpreter
> behaviors:
>   Name (ECOK, Zero)
>   Scope (\)
>   {
>       DBUG ("TermList 1")
>       If (LEqual (ECOK, Zero))
>       {
>           DBUG ("TermList 2")
>           Device (MDEV)
>           {
>               DEBUG (TermList 3")
>               If (CondRefOf (MDEV))
>               {
>                   DBUG ("MDEV exists")
>               }
>               If (CondRefOf (MDEV._STA))
>               {
>                   DBUG ("MDEV._STA exists")
>               }
>               If (CondRefOf (\_SB.PCI0.EC))
>               {
>                   DBUG ("\\_SB.PCI0.EC exists")
>               }
>               Name (_HID, EisaId ("PNP9999"))
>               Method (_STA, 0, Serialized)
>               {
>                   DEBUG ("\\_SB.MDEV._STA")
>                   Return (0x0F)
>               }
>           }
>           DBUG ("TermList 4")
>       }
>       Method (_INI, 0, Serialized)
>       {
>           DBUG ("\\_SB._INI")
>       }
>   }
>   Scope (_SB.PCI0)
>   {
>       Device (EC)
>       {
>           ...
>       }
>   }
> The DBUG function is a function to write the debugging messages into a
> SystemIo debug port.
> Running Windows with the BIOS providing this SSDT via RSDT, the following
> messages are obtained from the debug port:
>   TermList 1
>   TermList 2
>   TermList 3
>   \_SB.MDEV exists
>   TermList 4
>   \_SB._INI
>   ...
> 
> This test reveals the de-facto grammar for the AMLCode to us:
> 1. During the table loading, MLC will be executed by the interpreter, this
>    is partially supported by the current ACPICA;
> 2. For SystemIo, not only after the _REG(1, 1) is evaluated (current ACPICA
>    interpreter limitation), but when the table is being loaded, the
>    SystemIo (the debugging port) is accessible, this is recently fixed in
>    the upstream, now all early operation regions are accessible during the
>    table loading;
> 3. Not only Type1Opcode, but also Type2Opcode will be executed as MLC and
>    MLC is not executed after loading the table, but is executed right in
>    place, the Linux upstream is not compliant to this behavior.
> 
> The last compliance issue has already been clarified in ACPI 2.0
> specification, so the compliance issue is not that Linux is not compliant
> to the de-facto standard OS, but that Linux is not compliant to ACPI 2.0.
> Definition block tables in fact is defined by the spec as TermList, which
> has no difference than the control methods, thus the interpretion of the
> table should be no difference that the control method evaluation:
>      AMLCode := DefBlockHeader TermList
>      DefMethod := MethodOp PkgLength NameString MethodFlags TermList
> 
> Why ACPICA interpreter is acting so differently from this definition? This
> is because, there are many software entropies preventing this from being
> enabled, such entropies need to be cleaned up first in order not to trigger
> regressions for specific platforms. These entropies include:
> 1. ECDT support is broken. In fact, the original EC driver was correct, but
>    devlopers started to use the namespace EC instead of ECDT just because
>    several broken ECDT tables were reported on the bugzilla. They trusted
>    the namespace EC settings rather than the ECDT ones, this led to the
>    evaluation of _REG/_GPE/_CRS and namespace walk before executing the
>    module level AML opcodes. And the fixes in fact finally disable early EC
>    usages (used during table loading and early device enumeration
>    processes).
> 2. _REG evaluations are wrong. ACPICA provides APIs for OSPMs to register
>    operation region handlers. But for the early operation region accesses,
>    ACPI spec declares that the evaluations of _REG are not required, but
>    the ACPICA APIs do not avoid running _REG to meet this early
>    requirements. Code to fix this is partially upstreamed during previous
>    ACPICA release cycle.
> 3. _REG associations are wrong. ACPICA associates _REG control method to
>    all operation region objects before executing the _REG control method.
>    This can happen even when a control method is evaluated and operation
>    regions defined in the method is initialized
>    (acpi_ev_initialize_region). As a part of the ACPICA internal _REG
>    evaluation state machine, it requires the namespace walk, and all
>    namespace walk should be ensured to happen only "AFTER THE NAMESPACE
> IS
>    INITIALIZED". But when this logic happens during the table loading, it
>    may fail in finding the _REG method since the _REG method may not be
>    created by the interpreter just because _REG is defined after the
>    operation region object's declaration.
> 4. _REG(CONNECT)/_REG(DISCONNECT) executions are not balanced, this can
>    lead to wrong table loading/unloading results. Since _REG evaluations
>    require the releasing of all interpreter/namespace locks in order to
>    allow another evaluation to happen, and ACPICA operand object
>    destruction code can be invoked from different locking environment, this
>    becomes difficult for the developers to provide one single function to
>    make _REG(CONNECT)/_REG(DISCONNECT) balanced.
> 5. \_SB._INI is not the first control method evaluated by the interpreter.
>    Many platforms put initialization code in \_SB._INI in order to have
>    named objects initialized very early during the device enumeration
>    process. Without this order strictly ensured, early operation region
>    access enabling could break these platforms.
> 6. Linux initialization order is wrong, it is now:
>    a. load namespace without executing root scope If/Else/While module
>       level code blocks;
>    b. probe ECDT and instal EmbeddedControl operation region handler with
>       _REG evaluated;
>    c. install SystemMemory, SystemIo, PciConfig operation region handlers
>       without evaluating _REG;
>    d. run _REG for SystemMemory, SystemIo, PciConfig operation regions;
>    e. execute root scope If/Else/While module level code blocks;
>    f. enable GPE and namespace EC.
>    While the correct order should be:
>    a. probe ECDT and install EmbeddedControl operation region handler
>       without evaluating _REG;
>    b. install SystemMemory, SystemIo, PciConfig operation region handlers
>       without evaluating _REG;
>    c. load namespace, in the meanshile, execute all module level AML
>       opcodes;
>    d. run _REG for SystemMemory, SystemIo, PciConfig operation regions;
>    e. enable GPE and namespace EC which results in _REG evaluation for EC.
> 
> Until now we've upstreamed most of the entropy fixes into the Linux kernel,
> tested the grammar switch in the ACPICA upstream using ASLTS and no
> significant regressions can be seen while we need more tests before it is
> merged:
>   https://github.com/acpica/acpica/pull/134
> This is the ASLTS running result after applying the grammar switch, the
> test cases include new "module" case for which ACPICA interpreter cannot
> pass without this grammar switch applied:
>   ============================================================
>   Test cases specified for running:
>        arithmetic
>        bfield
>        constant
>        control
>        descriptor
>        logic
>        manipulation
>        name
>        reference
>        region
>        synchronization
>        table
>        misc
>        provoke
>        oarg
>        oconst
>        olocal
>        onamedloc
>        onamedglob
>        opackageel
>        oreftonamed
>        oreftopackageel
>        oreturn
>        rstore
>        roptional
>        rcopyobject
>        rindecrement
>        rexplicitconv
>        badasl
>        namespace
>        exc
>        exc_ref
>        exc_operand2
>        exc_result2
>        exc_tbl
>        mt_mutex
>        extra
>        extra_aslts
>        bdemo
>        bdemof
>        condbranches
>   TOTAL: (32-bit norm mode)
>     PASS       :  0
>     FAIL       :  0
>     BLOCKED    :  0
>     SKIPPED    :  0
>     Tests      :   0
>     Test Cases       : 40 (of 47)
>     Test Collections : 7 (of 8)
>     Outstanding allocations after execution : 0
>     Outstanding allocations (ACPI Error)    : 0
>     Large Reference Count   (ACPI Error)    : 0
>     Memory consumption total                : 0 Kb
>   TOTAL: (64-bit norm mode)
>     PASS       :  0
>     FAIL       :  0
>     BLOCKED    :  0
>     SKIPPED    :  0
>     Tests      :   0
>     Test Cases       : 40 (of 47)
>     Test Collections : 7 (of 8)
>     Outstanding allocations after execution : 0
>     Outstanding allocations (ACPI Error)    : 0
>     Large Reference Count   (ACPI Error)    : 0
>     Memory consumption total                : 0 Kb
>   TOTAL: (32-bit slack mode)
>     PASS       :  0
>     FAIL       :  0
>     BLOCKED    :  0
>     SKIPPED    :  0
>     Tests      :   0
>     Test Cases       : 40 (of 47)
>     Test Collections : 7 (of 8)
>     Outstanding allocations after execution : 0
>     Outstanding allocations (ACPI Error)    : 0
>     Large Reference Count   (ACPI Error)    : 0
>     Memory consumption total                : 0 Kb
>   TOTAL: (64-bit slack mode)
>     PASS       :  0
>     FAIL       :  0
>     BLOCKED    :  0
>     SKIPPED    :  0
>     Tests      :   0
>     Test Cases       : 40 (of 47)
>     Test Collections : 7 (of 8)
>     Outstanding allocations after execution : 0
>     Outstanding allocations (ACPI Error)    : 0
>     Large Reference Count   (ACPI Error)    : 0
>     Memory consumption total                : 0 Kb
>   ============================================================
> 
> Since we need more tests from the real users, we could make the grammar
> switch released from the Linux upstream. It's safe to do so because we have
> implemented regression protection (acpi_gbl_parse_table_as_term_list) in
> the fixes. The earlier the fix is tested by more real users, the better
> quality can be achieved by knowing the unknown cases (if any).
> 
> Lv Zheng (4):
>   ACPICA: Dispatcher: Fix an issue that the opregions created by the
>     linked MLC were not tracked
>   ACPICA: ACPI 2.0, Interpreter: Fix MLC issues by switching to new
>     TermList grammar for table loading
>   ACPI 2.0 / AML: Enable correct ACPI subsystem initialization order
>     for new table loading mode
>   ACPI 2.0 / AML: Fix module level execution by correctly parsing table
>     as TermList
> 
>  drivers/acpi/acpica/acnamesp.h |    3 +
>  drivers/acpi/acpica/acparser.h |    2 +
>  drivers/acpi/acpica/dsopcode.c |    6 ++
>  drivers/acpi/acpica/evrgnini.c |    3 +-
>  drivers/acpi/acpica/exconfig.c |    6 +-
>  drivers/acpi/acpica/nsload.c   |    3 +-
>  drivers/acpi/acpica/nsparse.c  |  163 ++++++++++++++++++++++++++++++++--
> ------
>  drivers/acpi/acpica/psparse.c  |    4 +-
>  drivers/acpi/acpica/psxface.c  |   73 ++++++++++++++++++
>  drivers/acpi/acpica/tbxfload.c |    3 +-
>  drivers/acpi/acpica/utxfinit.c |    3 +-
>  drivers/acpi/bus.c             |    6 +-
>  include/acpi/acpixf.h          |    6 ++
>  13 files changed, 241 insertions(+), 40 deletions(-)
> 
> --
> 1.7.10

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