From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 12 Feb 2009 20:30:48 +0000 (+0100)
Subject: x86: warn if arch_flush_lazy_mmu_cpu is called in preemptible context
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=34b0900d323122113683685b200aae9f9b75e63b;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

x86: warn if arch_flush_lazy_mmu_cpu is called in preemptible context

Impact: Catch cases where lazy MMU state is active in a preemtible context

arch_flush_lazy_mmu_cpu() has been changed to disable preemption so
the checks in enter/leave will never trigger. Put the preemtible()
check into arch_flush_lazy_mmu_cpu() to catch such cases.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index dcba6c567a2a..c6520a4e85d4 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -273,6 +273,7 @@ void arch_flush_lazy_mmu_mode(void)
 	preempt_disable();
 
 	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
+		WARN_ON(preempt_count() == 1);
 		arch_leave_lazy_mmu_mode();
 		arch_enter_lazy_mmu_mode();
 	}
@@ -285,6 +286,7 @@ void arch_flush_lazy_cpu_mode(void)
 	preempt_disable();
 
 	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
+		WARN_ON(preempt_count() == 1);
 		arch_leave_lazy_cpu_mode();
 		arch_enter_lazy_cpu_mode();
 	}