From 658cb2d3c86aa97b541eca2cf00197cdb96cbb7a Mon Sep 17 00:00:00 2001
From: Rafal Kupiec <belliash@codingworkshop.eu.org>
Date: Thu, 6 Jun 2024 22:05:32 +0200
Subject: [PATCH] Get system information based on the ACPI (currently only
 number of CPUs)

---
 xtoskrnl/hl/acpi.c          | 59 +++++++++++++++++++++++++++++++++++++
 xtoskrnl/hl/globals.c       |  3 ++
 xtoskrnl/hl/init.c          |  7 +++++
 xtoskrnl/includes/globals.h |  3 ++
 xtoskrnl/includes/hli.h     |  4 +++
 5 files changed, 76 insertions(+)

diff --git a/xtoskrnl/hl/acpi.c b/xtoskrnl/hl/acpi.c
index ede4a22..89bd8bc 100644
--- a/xtoskrnl/hl/acpi.c
+++ b/xtoskrnl/hl/acpi.c
@@ -254,6 +254,65 @@ HlpInitializeAcpiSystemDescriptionTable(OUT PACPI_DESCRIPTION_HEADER *AcpiTable)
     return STATUS_SUCCESS;
 }
 
+/**
+ * Initializes System Information structure based on the ACPI provided data.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+XTSTATUS
+HlpInitializeAcpiSystemInformation(VOID)
+{
+    PUCHAR MadtTable;
+    PACPI_MADT Madt;
+    XTSTATUS Status;
+    ULONG CpuCount;
+
+    /* Zero the ACPI system information structure */
+    RtlZeroMemory(&HlpAcpiSystemInfo, sizeof(ACPI_SYSTEM_INFO));
+
+    /* Get Multi-APIC Description Table (MADT) */
+    Status = HlGetAcpiTable(ACPI_MADT_SIGNATURE, (PACPI_DESCRIPTION_HEADER*)&Madt);
+    if(Status != STATUS_SUCCESS)
+    {
+        /* Failed to get MADT, return error */
+        return STATUS_NOT_FOUND;
+    }
+
+    /* Set APIC table traverse pointer and initialize number of CPUs */
+    MadtTable = (PUCHAR)Madt->ApicTables;
+    CpuCount = 0;
+
+    /* Traverse all MADT tables to get number of processors */
+    while(MadtTable <= ((PUCHAR)Madt + Madt->Header.Length))
+    {
+        /* Check if this is a local APIC subtable */
+        if((((PACPI_MADT_TABLE_LOCAL_APIC)MadtTable)->Header.Type == ACPI_MADT_LOCAL_APIC) &&
+           (((PACPI_MADT_TABLE_LOCAL_APIC)MadtTable)->Header.Length == sizeof(ACPI_MADT_TABLE_LOCAL_APIC)))
+        {
+            /* Make sure, this CPU can be enabled */
+            if(((PACPI_MADT_TABLE_LOCAL_APIC)MadtTable)->LapicFlags & ACPI_MADT_PLAOC_ENABLED)
+            {
+                /* Increment number of CPUs */
+                CpuCount++;
+            }
+
+            /* Go to the next MADT table */
+            MadtTable += ((PACPI_MADT_TABLE_LOCAL_APIC)MadtTable)->Header.Length;
+        }
+        else
+        {
+            /* Any other MADT table, try to go to the next one byte-by-byte */
+            MadtTable += 1;
+        }
+    }
+
+    /* Return success */
+    return STATUS_SUCCESS;
+}
+
 /**
  * Initializes the ACPI Timer.
  *
diff --git a/xtoskrnl/hl/globals.c b/xtoskrnl/hl/globals.c
index be5fb40..a7bf5c0 100644
--- a/xtoskrnl/hl/globals.c
+++ b/xtoskrnl/hl/globals.c
@@ -15,6 +15,9 @@ LIST_ENTRY HlpAcpiCacheList;
 /* ACPI Root System Description Pointer (RSDP) */
 PACPI_RSDP HlpAcpiRsdp;
 
+/* ACPI system information */
+ACPI_SYSTEM_INFO HlpAcpiSystemInfo;
+
 /* ACPI timer information */
 ACPI_TIMER_INFO HlpAcpiTimerInfo;
 
diff --git a/xtoskrnl/hl/init.c b/xtoskrnl/hl/init.c
index 7b14e51..6119f9a 100644
--- a/xtoskrnl/hl/init.c
+++ b/xtoskrnl/hl/init.c
@@ -29,6 +29,13 @@ HlInitializeSystem(VOID)
         return Status;
     }
 
+    /* Get system information from ACPI */
+    Status = HlpInitializeAcpiSystemInformation();
+    if(Status != STATUS_SUCCESS)
+    {
+        return Status;
+    }
+
     /* Return success */
     return STATUS_SUCCESS;
 }
diff --git a/xtoskrnl/includes/globals.h b/xtoskrnl/includes/globals.h
index 8f4cf1b..7d2997c 100644
--- a/xtoskrnl/includes/globals.h
+++ b/xtoskrnl/includes/globals.h
@@ -18,6 +18,9 @@ EXTERN LIST_ENTRY HlpAcpiCacheList;
 /* ACPI Root System Description Pointer (RSDP) */
 EXTERN PACPI_RSDP HlpAcpiRsdp;
 
+/* ACPI system information */
+EXTERN ACPI_SYSTEM_INFO HlpAcpiSystemInfo;
+
 /* ACPI timer information */
 EXTERN ACPI_TIMER_INFO HlpAcpiTimerInfo;
 
diff --git a/xtoskrnl/includes/hli.h b/xtoskrnl/includes/hli.h
index b323110..0b869e7 100644
--- a/xtoskrnl/includes/hli.h
+++ b/xtoskrnl/includes/hli.h
@@ -99,6 +99,10 @@ XTAPI
 XTSTATUS
 HlpInitializeAcpiSystemDescriptionTable(OUT PACPI_DESCRIPTION_HEADER *AcpiTable);
 
+XTAPI
+XTSTATUS
+HlpInitializeAcpiSystemInformation(VOID);
+
 XTAPI
 XTSTATUS
 HlpInitializeAcpiTimer(VOID);