From a77b8b9b14a4923b6c29627138d88b55ace9397d Mon Sep 17 00:00:00 2001
From: antifallobst <antifallobst@systemausfall.org>
Date: Sat, 11 Mar 2023 13:25:48 +0100
Subject: [PATCH] feature (acpi): implemented RSDP descriptor verification

---
 kernel/inc/drivers/acpi/rsdp.h |  3 +++
 kernel/src/drivers/acpi/acpi.c | 24 +++++++++++++++++++++++-
 kernel/src/drivers/acpi/rsdp.c | 28 ++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/kernel/inc/drivers/acpi/rsdp.h b/kernel/inc/drivers/acpi/rsdp.h
index e9e8044..6e60f0c 100644
--- a/kernel/inc/drivers/acpi/rsdp.h
+++ b/kernel/inc/drivers/acpi/rsdp.h
@@ -21,4 +21,7 @@ typedef struct {
     uint8_t                 reserved            [3];
 } __attribute__((packed)) rsdp_descriptor_v2_T;
 
+bool    rsdp_descriptor_v1_verify(rsdp_descriptor_v1_T* descriptor);
+bool    rsdp_descriptor_v2_verify(rsdp_descriptor_v2_T* descriptor);
+
 #endif //NOX_RSDP_H
diff --git a/kernel/src/drivers/acpi/acpi.c b/kernel/src/drivers/acpi/acpi.c
index dde12e3..a5b2a3e 100644
--- a/kernel/src/drivers/acpi/acpi.c
+++ b/kernel/src/drivers/acpi/acpi.c
@@ -1,8 +1,30 @@
 // This file is part of noxos and licensed under the MIT open source license
 
 #include "drivers/acpi/acpi.h"
+#include "drivers/acpi/rsdp.h"
 #include "utils/logger.h"
 
 void acpi_init(boot_info_T* boot_info) {
-    log(LOG_DEBUG, "Initializing ACPI  -  RSDP: 0x%x", boot_info->rsdp);
+    log(LOG_INFO, "Initializing ACPI  -  RSDP: 0x%x", boot_info->rsdp);
+    rsdp_descriptor_v1_T* rsdp = boot_info->rsdp;
+    switch (rsdp->revision) {
+        case 0: {
+            log(LOG_INFO, "    Version: 1.0");
+            if (!rsdp_descriptor_v1_verify(boot_info->rsdp)) {
+                log(LOG_WARNING, "<ACPI> RSDP header verification failed");
+            }
+            break;
+        }
+        case 2: {
+            log(LOG_INFO, "    Version: 2.0+");
+            if (!rsdp_descriptor_v2_verify(boot_info->rsdp)) {
+                log(LOG_WARNING, "<ACPI> RSDP header verification failed");
+            }
+            break;
+        }
+        default: {
+            log(LOG_ERROR, "<ACPI> failed to parse RSDP table (invalid revision)");
+            break;
+        }
+    }
 }
\ No newline at end of file
diff --git a/kernel/src/drivers/acpi/rsdp.c b/kernel/src/drivers/acpi/rsdp.c
index b92bff6..fd73a18 100644
--- a/kernel/src/drivers/acpi/rsdp.c
+++ b/kernel/src/drivers/acpi/rsdp.c
@@ -1 +1,29 @@
 // This file is part of noxos and licensed under the MIT open source license
+
+#include "drivers/acpi/rsdp.h"
+
+bool rsdp_descriptor_v1_verify(rsdp_descriptor_v1_T* descriptor) {
+    uint8_t* data = (uint8_t*)descriptor;
+    uint32_t num  = 0;
+
+    for (uint8_t i = 0; i < sizeof(rsdp_descriptor_v1_T); i++) {
+        num += data[i];
+    }
+
+    return ((num & 0xFF) == 0);
+}
+
+bool rsdp_descriptor_v2_verify(rsdp_descriptor_v2_T* descriptor) {
+    if (!rsdp_descriptor_v1_verify(&descriptor->descriptor_v1)) {
+        return false;
+    }
+
+    uint8_t* data = (uint8_t*)descriptor + sizeof(rsdp_descriptor_v1_T);
+    uint32_t num  = 0;
+
+    for (uint8_t i = 0; i < sizeof(rsdp_descriptor_v2_T) - sizeof(rsdp_descriptor_v1_T); i++) {
+        num += data[i];
+    }
+
+    return ((num & 0xFF) == 0);
+}