Re: [PATCH v2] x86: fix early boot crash on gcc-10
From: Borislav Petkov
Date: Wed Apr 22 2020 - 06:23:38 EST
Ok,
let's try the simple and clean fix first. Nick, would that work on LLVM
too?
And I hope this will remain working and the compiler won't jump over an
inline asm and go nuts.
Thx.
---
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3b9bf8c7e29d..06d2e16bedbb 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -266,6 +266,13 @@ static void notrace start_secondary(void *unused)
wmb();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+
+ /*
+ * Prevent tail call to cpu_startup_entry() because the stack protector
+ * guard has been changed in the middle of this function and must not be
+ * checked before tail calling another function.
+ */
+ asm ("");
}
/**
--
Regards/Gruss,
Boris.
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