From f3621c7bcc04476ba7561e5ecba9269b539a7b5b Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Fri, 1 Jul 2022 15:04:57 +0200
Subject: [PATCH] acpi: Add EBDA address sanity checks and work around bogus
 GCC warning

---
 .github/workflows/check.yml |  3 +++
 common/lib/acpi.h           | 14 +++++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 20de8938..14d06ab8 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -20,3 +20,6 @@ jobs:
 
       - name: Build the bootloader (LLVM)
         run: ./bootstrap && ./configure TOOLCHAIN=llvm --enable-werror --enable-all && make all && make maintainer-clean
+
+      - name: Build the bootloader (GCC)
+        run: ./bootstrap && ./configure LIMINE_CC=gcc LIMINE_LD=ld LIMINE_OBJCOPY=objcopy LIMINE_OBJDUMP=objdump LIMINE_READELF=readelf --enable-werror --enable-all && make all && make maintainer-clean
diff --git a/common/lib/acpi.h b/common/lib/acpi.h
index b1d37c9f..58361e72 100644
--- a/common/lib/acpi.h
+++ b/common/lib/acpi.h
@@ -3,8 +3,20 @@
 
 #include <stdint.h>
 #include <stddef.h>
+#include <sys/cpu.h>
 
-#define EBDA ((size_t)(*((volatile uint16_t *)0x40e)) * 16)
+#define EBDA (ebda_get())
+
+static inline uintptr_t ebda_get(void) {
+    uintptr_t ebda = (uintptr_t)mminw(0x40e) << 4;
+
+    // Sanity checks
+    if (ebda < 0x80000 || ebda >= 0xa0000) {
+        ebda = 0x80000;
+    }
+
+    return ebda;
+}
 
 struct sdt {
     char     signature[4];