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[PULL,kvm-unit-tests,14/17] lib: arm/arm64: Refuse to disable the MMU with non-identity stack pointer

Message ID 20200106100347.1559-15-drjones@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,kvm-unit-tests,01/17] arm: Add missing test name prefix for pl031 and spinlock | expand

Commit Message

Andrew Jones Jan. 6, 2020, 10:03 a.m. UTC 
From: Alexandru Elisei <alexandru.elisei@arm.com>

When the MMU is off, all addresses are physical addresses. If the stack
pointer is not an identity mapped address (the virtual address is not the
same as the physical address), then we end up trying to access an invalid
memory region. This can happen if we call mmu_disable from a secondary CPU,
which has its stack allocated from the vmalloc region.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 lib/arm/mmu.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index 928a3702c563..111e3a52591a 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -68,8 +68,12 @@  void mmu_enable(pgd_t *pgtable)
 extern void asm_mmu_disable(void);
 void mmu_disable(void)
 {
+	unsigned long sp = current_stack_pointer;
 	int cpu = current_thread_info()->cpu;
 
+	assert_msg(__virt_to_phys(sp) == sp,
+			"Attempting to disable MMU with non-identity mapped stack");
+
 	mmu_mark_disabled(cpu);
 
 	asm_mmu_disable();