[PATCH net-next v2 1/4] net: ipa: fix assumptions about DMA address size
From: Alex Elder
Date: Thu Mar 18 2021 - 09:52:41 EST
Some build time checks in ipa_table_validate_build() assume that a
DMA address is 64 bits wide. That is more restrictive than it has
to be. A route or filter table is 64 bits wide no matter what the
size of a DMA address is on the AP. The code actually uses a
pointer to __le64 to access table entries, and a fixed constant
IPA_TABLE_ENTRY_SIZE to describe the size of those entries.
Loosen up two checks so they still verify some requirements, but
such that they do not assume the size of a DMA address is 64 bits.
Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
drivers/net/ipa/ipa_table.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index 7450e27068f19..dd07fe9dd87a3 100644
@@ -126,13 +126,15 @@ static void ipa_table_validate_build(void)
BUILD_BUG_ON(ARCH_DMA_MINALIGN % IPA_TABLE_ALIGN);
- /* Filter and route tables contain DMA addresses that refer to
- * filter or route rules. We use a fixed constant to represent
- * the size of either type of table entry. Code in ipa_table_init()
- * uses a pointer to __le64 to initialize table entriews.
+ /* Filter and route tables contain DMA addresses that refer
+ * to filter or route rules. But the size of a table entry
+ * is 64 bits regardless of what the size of an AP DMA address
+ * is. A fixed constant defines the size of an entry, and
+ * code in ipa_table_init() uses a pointer to __le64 to
+ * initialize tables.
- BUILD_BUG_ON(IPA_TABLE_ENTRY_SIZE != sizeof(dma_addr_t));
- BUILD_BUG_ON(sizeof(dma_addr_t) != sizeof(__le64));
+ BUILD_BUG_ON(sizeof(dma_addr_t) > IPA_TABLE_ENTRY_SIZE);
+ BUILD_BUG_ON(sizeof(__le64) != IPA_TABLE_ENTRY_SIZE);
/* A "zero rule" is used to represent no filtering or no routing.
* It is a 64-bit block of zeroed memory. Code in ipa_table_init()