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@xxxxxxxxxx>
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
lib/arm/mmu.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index 3d38c8397f5a..161f7a8e607c 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -66,8 +66,12 @@ 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();
--
2.20.1
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