@@ -310,6 +310,16 @@ alternative_cb_end
lsl \reg, \reg, \tmp // actual cache line size
.endm
+/*
+ * tcache_line_size - get the safe tag cache line size across all CPUs
+ */
+ .macro tcache_line_size, reg, tmp
+ read_ctr \tmp
+ ubfm \tmp, \tmp, #32, #37 // tag cache line size encoding
+ mov \reg, #4 // bytes per word
+ lsl \reg, \reg, \tmp // actual tag cache line size
+ .endm
+
/*
* raw_icache_line_size - get the minimum I-cache line size on this CPU
* from the CTR register.
@@ -7,6 +7,8 @@
#include <linux/mm_types.h>
+extern void dcache_inval_tags_poc(unsigned long start, unsigned long end);
+
#ifdef CONFIG_ARM64_MTE_TAG_STORAGE
void mte_tag_storage_init(void);
bool page_tag_storage_reserved(struct page *page);
@@ -19,6 +19,7 @@
#include <linux/vm_event_item.h>
#include <linux/xarray.h>
+#include <asm/cacheflush.h>
#include <asm/memory_metadata.h>
#include <asm/mte_tag_storage.h>
@@ -470,8 +471,13 @@ static bool tag_storage_block_is_reserved(unsigned long block)
static int tag_storage_reserve_block(unsigned long block, struct tag_region *region, int order)
{
+ unsigned long block_va;
int ret;
+ block_va = (unsigned long)page_to_virt(pfn_to_page(block));
+ /* Avoid writeback of dirty data cache lines corrupting tags. */
+ dcache_inval_poc(block_va, block_va + region->block_size * PAGE_SIZE);
+
ret = xa_err(xa_store(&tag_blocks_reserved, block, pfn_to_page(block), GFP_KERNEL));
if (!ret)
block_ref_add(block, region, order);
@@ -584,6 +590,7 @@ void free_metadata_storage(struct page *page, int order)
{
unsigned long block, start_block, end_block;
struct tag_region *region;
+ unsigned long page_va;
unsigned long flags;
int ret;
@@ -594,6 +601,13 @@ void free_metadata_storage(struct page *page, int order)
if (WARN_ONCE(ret, "Missing tag storage block for pfn 0x%lx", page_to_pfn(page)))
return;
+ page_va = (unsigned long)page_to_virt(page);
+ /*
+ * Remove dirty tag cache lines to avoid corruption of the tag storage
+ * page contents when it gets freed back to the page allocator.
+ */
+ dcache_inval_tags_poc(page_va, page_va + (PAGE_SIZE << order));
+
end_block = start_block + order_to_num_blocks(order) * region->block_size;
xa_lock_irqsave(&tag_blocks_reserved, flags);
@@ -175,3 +175,19 @@ SYM_FUNC_START(mte_restore_page_tags_from_mem)
ret
SYM_FUNC_END(mte_restore_page_tags_from_mem)
+
+/*
+ * dcache_inval_tags_poc(start, end)
+ *
+ * Ensure that any tags in the D-cache for the interval [start, end)
+ * are invalidated to PoC.
+ *
+ * - start - virtual start address of region
+ * - end - virtual end address of region
+ */
+SYM_FUNC_START(__pi_dcache_inval_tags_poc)
+ tcache_line_size x2, x3
+ dcache_by_myline_op igvac, sy, x0, x1, x2, x3
+ ret
+SYM_FUNC_END(__pi_dcache_inval_tags_poc)
+SYM_FUNC_ALIAS(dcache_inval_tags_poc, __pi_dcache_inval_tags_poc)
Make sure that the contents of the tag storage block is not corrupted by performing: 1. A tag dcache inval when the associated tagged pages are freed, to avoid dirty tag cache lines being evicted and corrupting the tag storage block when it's being used to store data. 2. A data cache inval when the tag storage block is being reserved, to ensure that no dirty data cache lines are present, which would trigger a writeback that could corrupt the tags stored in the block. Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- arch/arm64/include/asm/assembler.h | 10 ++++++++++ arch/arm64/include/asm/mte_tag_storage.h | 2 ++ arch/arm64/kernel/mte_tag_storage.c | 14 ++++++++++++++ arch/arm64/lib/mte.S | 16 ++++++++++++++++ 4 files changed, 42 insertions(+)