linux-kernel - [PATCH AUTOSEL 6.12 4/7] x86: Convert unreachable() to BUG()

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Message-Id: <20250126145027.925851-4-sashal@kernel.org>
Date: Sun, 26 Jan 2025 09:50:23 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	seanjc@...gle.com,
	pbonzini@...hat.com,
	dave.jiang@...el.com,
	kees@...nel.org,
	jgross@...e.com,
	kirill.shutemov@...ux.intel.com,
	kai.huang@...el.com,
	bhe@...hat.com,
	kvm@...r.kernel.org
Subject: [PATCH AUTOSEL 6.12 4/7] x86: Convert unreachable() to BUG()

From: Peter Zijlstra <peterz@...radead.org>

[ Upstream commit 2190966fbc14ca2cd4ea76eefeb96a47d8e390df ]

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>
Acked-by: Josh Poimboeuf <jpoimboe@...nel.org>
Link: https://lore.kernel.org/r/20241128094312.028316261@infradead.org
Signed-off-by: Sasha Levin <sashal@...nel.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(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index f63f8fd00a91f..15507e739c255 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -838,7 +838,7 @@ void __noreturn stop_this_cpu(void *dummy)
 #ifdef CONFIG_SMP
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 #endif
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 615922838c510..dc1dd3f3e67fc 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -883,7 +883,7 @@ static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
 
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 
 	/* Assume hlt works */
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index fb854cf20ac3b..e9af87b128140 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3833,7 +3833,7 @@ static int snp_begin_psc(struct vcpu_svm *svm, struct psc_buffer *psc)
 		goto next_range;
 	}
 
-	unreachable();
+	BUG();
 }
 
 static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
-- 
2.39.5