From cac7dc8d716c37e9365ecc62471b31bf90c1978d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Holz?= <sholz8530@gmail.com>
Date: Thu, 4 Jan 2024 18:16:55 +0100
Subject: [PATCH] Kernel/riscv64: Add support for legacy "System Shutdown" SBI
 extension

---
 Kernel/Arch/riscv64/SBI.cpp | 18 ++++++++++++++++++
 Kernel/Arch/riscv64/SBI.h   |  5 +++++
 2 files changed, 23 insertions(+)

diff --git a/Kernel/Arch/riscv64/SBI.cpp b/Kernel/Arch/riscv64/SBI.cpp
index e636d83dac..dcd6902912 100644
--- a/Kernel/Arch/riscv64/SBI.cpp
+++ b/Kernel/Arch/riscv64/SBI.cpp
@@ -86,6 +86,17 @@ SBIErrorOr<long> get_mimpid()
 
 namespace Legacy {
 
+static long sbi_legacy_ecall0(LegacyEID extension_id)
+{
+    register unsigned long a0 asm("a0");
+    register unsigned long a7 asm("a7") = to_underlying(extension_id);
+    asm volatile("ecall"
+                 : "=r"(a0)
+                 : "r"(a7)
+                 : "memory");
+    return static_cast<long>(a0);
+}
+
 static long sbi_legacy_ecall1(LegacyEID extension_id, unsigned long arg0)
 {
     register unsigned long a0 asm("a0") = arg0;
@@ -115,6 +126,13 @@ LegacySBIErrorOr<void> console_putchar(int ch)
     return err;
 }
 
+void shutdown()
+{
+    sbi_legacy_ecall0(LegacyEID::SystemShutdown);
+
+    VERIFY_NOT_REACHED();
+}
+
 }
 
 namespace Timer {
diff --git a/Kernel/Arch/riscv64/SBI.h b/Kernel/Arch/riscv64/SBI.h
index 218e7d434e..20fad2f3fe 100644
--- a/Kernel/Arch/riscv64/SBI.h
+++ b/Kernel/Arch/riscv64/SBI.h
@@ -133,6 +133,11 @@ LegacySBIErrorOr<void> set_timer(u64 stime_value);
 // Write data present in ch to debug console.
 LegacySBIErrorOr<void> console_putchar(int ch);
 
+// System Shutdown (EID #0x08)
+// Puts all the harts to shutdown state from supervisor point of view.
+// This SBI call doesn’t return irrespective whether it succeeds or fails.
+[[noreturn]] void shutdown();
+
 }
 
 // Chapter 6. Timer Extension (EID #0x54494D45 "TIME")