From 529ceba1f90f995c690fdb71143bc4b293ace55e Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Fri, 11 Jul 2025 22:17:08 -0400
Subject: kernel/amd64: Return NULL if IA32_GS_BASE is unset

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 sys/arch/amd64/amd64/machdep.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'sys')

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index af00c5a..d310460 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -298,6 +298,10 @@ this_cpu(void)
 {
     struct cpu_info *ci;
 
+    if (rdmsr(IA32_GS_BASE) == 0) {
+        return NULL;
+    }
+
     /*
      * This might look crazy but we are just leveraging the "m"
      * constraint to add the offset of the self field within
-- 
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