From 17871bb3cac4e6724851bbf2c69d7001a770a668 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 12 Apr 2024 12:39:46 +0300
Subject: [PATCH] Kernel: Fix ACPI namespace initialization

ACPI spec says that only SSDTS with unique OEM table IDs are to be
loaded.

Add loading of ACPI 1.0 PSDTs
---
 kernel/kernel/ACPI/AML.cpp           | 61 ++++++++++++++++++++++------
 kernel/kernel/ACPI/AML/Namespace.cpp |  2 -
 2 files changed, 49 insertions(+), 14 deletions(-)

diff --git a/kernel/kernel/ACPI/AML.cpp b/kernel/kernel/ACPI/AML.cpp
index b71863e8..6637c359 100644
--- a/kernel/kernel/ACPI/AML.cpp
+++ b/kernel/kernel/ACPI/AML.cpp
@@ -6,34 +6,71 @@
 namespace Kernel::ACPI
 {
 
+	// https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html#secondary-system-description-table-ssdt
+	// https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html#persistent-system-description-table-psdt
+	static bool load_all_unique(AML::Namespace& ns, BAN::StringView signature)
+	{
+		// Only SSDT and PSDT that have unique OEM Table ID are loaded in order they appear in the RSDT/XSDT
+		BAN::Vector<uint64_t> loaded_oem_table_ids;
+
+		for (uint32_t i = 0;; i++)
+		{
+			auto* header = ACPI::ACPI::get().get_header(signature, i);
+			if (!header)
+				break;
+
+			bool need_to_parse = true;
+			for (uint64_t id : loaded_oem_table_ids)
+			{
+				if (id == header->oem_table_id)
+				{
+					need_to_parse = false;
+					break;
+				}
+			}
+
+			if (!need_to_parse)
+			{
+				dprintln("Skipping {}{} ({} bytes)", signature, i, header->length);
+				continue;
+			}
+
+			dprintln("Parsing {}{} ({} bytes)", signature, i, header->length);
+			if (!ns.parse(*header))
+			{
+				dwarnln("Failed to parse {}", signature);
+				return false;
+			}
+
+			MUST(loaded_oem_table_ids.push_back(header->oem_table_id));
+		}
+
+		return true;
+	}
+
 	BAN::RefPtr<AML::Namespace> AML::initialize_namespace()
 	{
 		auto ns = AML::Namespace::create_root_namespace();
 
-		// Parse DSDT
+		// https://uefi.org/htmlspecs/ACPI_Spec_6_4_html/05_ACPI_Software_Programming_Model/ACPI_Software_Programming_Model.html#differentiated-system-description-table-dsdt
 		auto* dsdt = ACPI::ACPI::get().get_header("DSDT", 0);
 		if (!dsdt)
 		{
 			dwarnln("Failed to get DSDT");
 			return {};
 		}
+		dprintln("Parsing DSDT ({} bytes)", dsdt->length);
 		if (!ns->parse(*dsdt))
 		{
 			dwarnln("Failed to parse DSDT");
 			return {};
 		}
 
-		for (uint32_t i = 0;; i++)
-		{
-			auto* ssdt = ACPI::ACPI::get().get_header("SSDT", i);
-			if (!ssdt)
-				break;
-			if (!ns->parse(*ssdt))
-			{
-				dwarnln("Failed to parse SSDT");
-				return {};
-			}
-		}
+		if (!load_all_unique(*ns, "SSDT"))
+			return {};
+
+		if (!load_all_unique(*ns, "PSDT"))
+			return {};
 
 #if AML_DEBUG_LEVEL >= 1
 		ns->debug_print(0);
diff --git a/kernel/kernel/ACPI/AML/Namespace.cpp b/kernel/kernel/ACPI/AML/Namespace.cpp
index 72b12c94..3d702e77 100644
--- a/kernel/kernel/ACPI/AML/Namespace.cpp
+++ b/kernel/kernel/ACPI/AML/Namespace.cpp
@@ -225,8 +225,6 @@ namespace Kernel::ACPI
 	{
 		ASSERT(this == s_root_namespace.ptr());
 
-		dprintln("Parsing {}, {} bytes of AML", header, header.length);
-
 		AML::ParseContext context;
 		context.scope = AML::NameString("\\"sv);
 		context.aml_data = BAN::ConstByteSpan(reinterpret_cast<const uint8_t*>(&header), header.length).slice(sizeof(header));