fix: kernel concurrency, interrupt context, and user VA safety

kernel/src/ACPI/FADT.cpp

@@ -21,6 +21,21 @@ namespace Hal {
             return true;
         }
 
+        static uint32_t ExtendedSystemIoAddress(const Table* fadt,
+                                                const uint8_t gas[12],
+                                                size_t fieldOffset) {
+            // Generic Address Structure: byte 0 is AddressSpaceId and bytes
+            // 4..11 are the little-endian address. This event code uses x86
+            // port I/O, so accept only SystemIO GAS entries that fit the
+            // architectural 16-bit port space.
+            if (fadt->Header.Length < fieldOffset + 12 || gas[0] != 1) return 0;
+
+            uint64_t address = 0;
+            for (int i = 0; i < 8; i++)
+                address |= (uint64_t)gas[4 + i] << (i * 8);
+            return address <= 0xFFFF ? (uint32_t)address : 0;
+        }
+
         static Table* FindFADTInXSDT(ACPI::CommonSDTHeader* xsdt) {
             uint32_t entryCount = (xsdt->Length - sizeof(ACPI::CommonSDTHeader)) / 8;
             uint64_t* entries = (uint64_t*)((uint64_t)xsdt + sizeof(ACPI::CommonSDTHeader));
@@ -73,6 +88,14 @@ namespace Hal {
             result.PMTimerBlock     = fadt->PMTimerBlock;
             result.GPE0Block        = fadt->GPE0Block;
             result.GPE1Block        = fadt->GPE1Block;
+            if (result.GPE0Block == 0) {
+                result.GPE0Block = ExtendedSystemIoAddress(
+                    fadt, fadt->X_GPE0Block, offsetof(Table, X_GPE0Block));
+            }
+            if (result.GPE1Block == 0) {
+                result.GPE1Block = ExtendedSystemIoAddress(
+                    fadt, fadt->X_GPE1Block, offsetof(Table, X_GPE1Block));
+            }
             result.SMI_CommandPort  = fadt->SMI_CommandPort;
             result.SCI_Interrupt    = fadt->SCI_Interrupt;
             result.PM1EventLength   = fadt->PM1EventLength;