x86: Convert unreachable() to BUG()

Peter Zijlstra · Peter Zijlstra · commit 2190966fbc14 · 2024-12-02T12:01:43.000+01:00
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@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lore.kernel.org/r/20241128094312.028316261@infradead.org
diff --git 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
@@ -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
@@ -3820,7 +3820,7 @@ 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)

Original file line number	Diff line number	Diff line change
`@@ -838,7 +838,7 @@ void __noreturn stop_this_cpu(void *dummy)`
`838`	`838`	`#ifdef CONFIG_SMP`
`839`	`839`	`if (smp_ops.stop_this_cpu) {`
`840`	`840`	`smp_ops.stop_this_cpu();`
`841`		`- unreachable();`
	`841`	`+ BUG();`
`842`	`842`	`}`
`843`	`843`	`#endif`
`844`	`844`
Original file line number	Diff line number	Diff line change
`@@ -883,7 +883,7 @@ static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)`
`883`	`883`
`884`	`884`	`if (smp_ops.stop_this_cpu) {`
`885`	`885`	`smp_ops.stop_this_cpu();`
`886`		`- unreachable();`
	`886`	`+ BUG();`
`887`	`887`	`}`
`888`	`888`
`889`	`889`	`/* Assume hlt works */`
Original file line number	Diff line number	Diff line change
`@@ -3820,7 +3820,7 @@ static int snp_begin_psc(struct vcpu_svm svm, struct psc_buffer psc)`
`3820`	`3820`	`goto next_range;`
`3821`	`3821`	`}`
`3822`	`3822`
`3823`		`- unreachable();`
	`3823`	`+ BUG();`
`3824`	`3824`	`}`
`3825`	`3825`
`3826`	`3826`	`static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)`