linux-kernel - [PATCH v2 11/16] x86: Convert unreachable() to BUG()

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Message-ID: <20241128094312.028316261@infradead.org>
Date: Thu, 28 Nov 2024 10:39:02 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: jpoimboe@...nel.org
Cc: chenhuacai@...nel.org,
 kernel@...0n.name,
 x86@...nel.org,
 peterz@...radead.org,
 loongarch@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: [PATCH v2 11/16] x86: Convert unreachable() to BUG()

Avoid unreachable() as it can (and will in the absence of UBSAN)
generate fallthrough code. Use BUG() so we get a UD2 trap (with
unreachable annotation).

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/process.c |    2 +-
 arch/x86/kernel/reboot.c  |    2 +-
 arch/x86/kvm/svm/sev.c    |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -838,7 +838,7 @@ void __noreturn stop_this_cpu(void *dumm
 #ifdef CONFIG_SMP
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 #endif
 
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -883,7 +883,7 @@ static int crash_nmi_callback(unsigned i
 
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 
 	/* Assume hlt works */
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3820,7 +3820,7 @@ static int snp_begin_psc(struct vcpu_svm
 		goto next_range;
 	}
 
-	unreachable();
+	BUG();
 }
 
 static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)