feat: add support for aarch64 timer/interrupts, port MontaukOS userspace

kernel/src/Arch/aarch64/Platform.cpp

@@ -7,6 +7,8 @@
 #include <Arch/Platform.hpp>
 #include <Arch/Cpu.hpp>
 #include <Arch/Smp.hpp>
+#include <Arch/aarch64/Gic.hpp>
+#include <ACPI/FADT.hpp>
 #include <Terminal/Terminal.hpp>
 #include <CppLib/Stream.hpp>
 
@@ -18,6 +20,42 @@ namespace Arch {
 
     // SCTLR_EL1.WXN: writable memory is execute-never
     static constexpr uint64_t SctlrWxn = 1ULL << 19;
+    // SCTLR_EL1.UCT/UCI: EL0 may read CTR_EL0 and clean/invalidate caches
+    // by address (what __builtin___clear_cache needs for generated code).
+    static constexpr uint64_t SctlrUct = 1ULL << 15;
+    static constexpr uint64_t SctlrUci = 1ULL << 26;
+
+    // PSCI 0.2+ function IDs (SMC32 calling convention)
+    static constexpr uint64_t PsciSystemOff   = 0x84000008;
+    static constexpr uint64_t PsciSystemReset = 0x84000009;
+
+    // How the firmware takes PSCI calls, from the FADT's ARM_BOOT_ARCH.
+    enum class PsciConduit { None, Smc, Hvc };
+    static PsciConduit g_psci = PsciConduit::None;
+
+    static uint64_t PsciCall(uint64_t function) {
+        register uint64_t x0 asm("x0") = function;
+        register uint64_t x1 asm("x1") = 0;
+        register uint64_t x2 asm("x2") = 0;
+        register uint64_t x3 asm("x3") = 0;
+        if (g_psci == PsciConduit::Hvc) {
+            asm volatile("hvc #0" : "+r"(x0), "+r"(x1), "+r"(x2), "+r"(x3) :: "memory");
+        } else if (g_psci == PsciConduit::Smc) {
+            asm volatile("smc #0" : "+r"(x0), "+r"(x1), "+r"(x2), "+r"(x3) :: "memory");
+        }
+        return x0;
+    }
+
+    static void InitializePsci(Hal::ACPI::CommonSDTHeader* xsdt) {
+        Hal::FADT::ParsedFADT fadt{};
+        if (!Hal::FADT::Parse(xsdt, fadt) || !fadt.Valid) return;
+        if (!(fadt.ArmBootArchFlags & Hal::FADT::ArmBootPsciCompliant)) {
+            KernelLogStream(WARNING, "PSCI") << "Firmware is not PSCI compliant: no reset or power-off";
+            return;
+        }
+        g_psci = (fadt.ArmBootArchFlags & Hal::FADT::ArmBootPsciUseHvc) ? PsciConduit::Hvc : PsciConduit::Smc;
+        KernelLogStream(OK, "PSCI") << "PSCI through " << (g_psci == PsciConduit::Hvc ? "HVC" : "SMC");
+    }
 
     void EarlyInitialize() {
         // No per-CPU data yet: Smp::TryGetCurrentCpuData must see null.
@@ -32,10 +70,11 @@ namespace Arch {
         asm volatile("msr vbar_el1, %0\n\tisb" :: "r"(ArchExceptionVectors) : "memory");
 
         // Kernel mappings are RWX (Paging.cpp), so writable must not
-        // imply execute-never.
+        // imply execute-never; user code may maintain its own caches.
         uint64_t sctlr;
         asm volatile("mrs %0, sctlr_el1" : "=r"(sctlr));
         sctlr &= ~SctlrWxn;
+        sctlr |= SctlrUct | SctlrUci;
         asm volatile("msr sctlr_el1, %0\n\tisb" :: "r"(sctlr));
 
         // CPACR_EL1.FPEN = 0b11: FP/SIMD usable at EL0 and EL1 (the kernel
@@ -57,10 +96,12 @@ namespace Arch {
     void InitializeMemoryAttributes() {
     }
 
-    // TODO(aarch64): GIC distributor/redistributor from the ACPI MADT.
-    void InitializeInterrupts(Hal::ACPI::CommonSDTHeader*) {
+    void InitializeInterrupts(Hal::ACPI::CommonSDTHeader* xsdt) {
         Smp::InitBsp();
-        KernelLogStream(WARNING, "Arch") << "aarch64: no interrupt controller driver";
+        if (!Gic::Initialize(xsdt)) {
+            KernelLogStream(ERROR, "Arch") << "aarch64: no interrupt controller, running without IRQs";
+        }
+        InitializePsci(xsdt);
     }
 
     void InitializePlatformDevices() {
@@ -73,12 +114,22 @@ namespace Arch {
     void LateInitialize() {
     }
 
-    void ListPlatformDevices(PlatformDeviceSink, void*) {
+    void ListPlatformDevices(PlatformDeviceSink sink, void* context) {
+        if (Gic::IsInitialized()) {
+            sink(context, 1, "GICv2", "ARM Generic Interrupt Controller");
+            sink(context, 2, "Generic Timer", "ARM architected timer (EL1 virtual)");
+        }
     }
 
-    // TODO(aarch64): PSCI SYSTEM_RESET through the conduit the FADT names.
     void Reboot() {
+        PsciCall(PsciSystemReset);
         HaltForever();
     }
 
+    void PowerOff() {
+        if (g_psci != PsciConduit::None) {
+            PsciCall(PsciSystemOff);
+        }
+    }
+
 }