xtensa: disable preemption around cache alias management calls

BugLink: https://bugs.launchpad.net/bugs/1908561

commit 3a860d1 upstream.

Although cache alias management calls set up and tear down TLB entries
and fast_second_level_miss is able to restore TLB entry should it be
evicted they absolutely cannot preempt each other because they use the
same TLBTEMP area for different purposes.
Disable preemption around all cache alias management calls to enforce
that.

Cc: [email protected]
Signed-off-by: Max Filippov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
Signed-off-by: Ian May <[email protected]>

Author: jcmvbkbc

arch/xtensa/mm/cache.c

@@ -71,8 +71,10 @@ static inline void kmap_invalidate_coherent(struct page *page,
 			kvaddr = TLBTEMP_BASE_1 +
 				(page_to_phys(page) & DCACHE_ALIAS_MASK);
 
+			preempt_disable();
 			__invalidate_dcache_page_alias(kvaddr,
 						       page_to_phys(page));
+			preempt_enable();
 		}
 	}
 }
@@ -157,6 +159,7 @@ void flush_dcache_page(struct page *page)
 		if (!alias && !mapping)
 			return;
 
+		preempt_disable();
 		virt = TLBTEMP_BASE_1 + (phys & DCACHE_ALIAS_MASK);
 		__flush_invalidate_dcache_page_alias(virt, phys);
 
@@ -167,6 +170,7 @@ void flush_dcache_page(struct page *page)
 
 		if (mapping)
 			__invalidate_icache_page_alias(virt, phys);
+		preempt_enable();
 	}
 
 	/* There shouldn't be an entry in the cache for this page anymore. */
@@ -200,8 +204,10 @@ void local_flush_cache_page(struct vm_area_struct *vma, unsigned long address,
 	unsigned long phys = page_to_phys(pfn_to_page(pfn));
 	unsigned long virt = TLBTEMP_BASE_1 + (address & DCACHE_ALIAS_MASK);
 
+	preempt_disable();
 	__flush_invalidate_dcache_page_alias(virt, phys);
 	__invalidate_icache_page_alias(virt, phys);
+	preempt_enable();
 }
 EXPORT_SYMBOL(local_flush_cache_page);
 
@@ -228,11 +234,13 @@ update_mmu_cache(struct vm_area_struct * vma, unsigned long addr, pte_t *ptep)
 		unsigned long phys = page_to_phys(page);
 		unsigned long tmp;
 
+		preempt_disable();
 		tmp = TLBTEMP_BASE_1 + (phys & DCACHE_ALIAS_MASK);
 		__flush_invalidate_dcache_page_alias(tmp, phys);
 		tmp = TLBTEMP_BASE_1 + (addr & DCACHE_ALIAS_MASK);
 		__flush_invalidate_dcache_page_alias(tmp, phys);
 		__invalidate_icache_page_alias(tmp, phys);
+		preempt_enable();
 
 		clear_bit(PG_arch_1, &page->flags);
 	}
@@ -266,7 +274,9 @@ void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
 
 	if (alias) {
 		unsigned long t = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);
+		preempt_disable();
 		__flush_invalidate_dcache_page_alias(t, phys);
+		preempt_enable();
 	}
 
 	/* Copy data */
@@ -281,9 +291,11 @@ void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
 	if (alias) {
 		unsigned long t = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);
 
+		preempt_disable();
 		__flush_invalidate_dcache_range((unsigned long) dst, len);
 		if ((vma->vm_flags & VM_EXEC) != 0)
 			__invalidate_icache_page_alias(t, phys);
+		preempt_enable();
 
 	} else if ((vma->vm_flags & VM_EXEC) != 0) {
 		__flush_dcache_range((unsigned long)dst,len);
@@ -305,7 +317,9 @@ extern void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
 
 	if (alias) {
 		unsigned long t = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);
+		preempt_disable();
 		__flush_invalidate_dcache_page_alias(t, phys);
+		preempt_enable();
 	}
 
 	memcpy(dst, src, len);