diff options
| author | Alex Elder | 2021-03-22 20:05:05 -0500 |
|---|---|---|
| committer | David S. Miller | 2021-03-23 17:15:23 -0700 |
| commit | 437c78f976f5b39fc4b2a1c65903a229f55912dd (patch) | |
| tree | a37b648b0968bcdb419dd4e6c8ad33adb53ed45e /drivers/net/ipa/gsi.c | |
| parent | ed97143e00982e1cab3544977f33b94a6de2e6fa (diff) | |
net: ipa: avoid 64-bit modulus
It is possible for a 32 bit x86 build to use a 64 bit DMA address.
There are two remaining spots where the IPA driver does a modulo
operation to check alignment of a DMA address, and under certain
conditions this can lead to a build error on i386 (at least).
The alignment checks we're doing are for power-of-2 values, and this
means the lower 32 bits of the DMA address can be used. This ensures
both operands to the modulo operator are 32 bits wide.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ipa/gsi.c')
| -rw-r--r-- | drivers/net/ipa/gsi.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c index 7f3e338ca7a7..b6355827bf90 100644 --- a/drivers/net/ipa/gsi.c +++ b/drivers/net/ipa/gsi.c @@ -1436,15 +1436,18 @@ static void gsi_evt_ring_rx_update(struct gsi_evt_ring *evt_ring, u32 index) /* Initialize a ring, including allocating DMA memory for its entries */ static int gsi_ring_alloc(struct gsi *gsi, struct gsi_ring *ring, u32 count) { - size_t size = count * GSI_RING_ELEMENT_SIZE; + u32 size = count * GSI_RING_ELEMENT_SIZE; struct device *dev = gsi->dev; dma_addr_t addr; - /* Hardware requires a 2^n ring size, with alignment equal to size */ + /* Hardware requires a 2^n ring size, with alignment equal to size. + * The size is a power of 2, so we can check alignment using just + * the bottom 32 bits for a DMA address of any size. + */ ring->virt = dma_alloc_coherent(dev, size, &addr, GFP_KERNEL); - if (ring->virt && addr % size) { + if (ring->virt && lower_32_bits(addr) % size) { dma_free_coherent(dev, size, ring->virt, addr); - dev_err(dev, "unable to alloc 0x%zx-aligned ring buffer\n", + dev_err(dev, "unable to alloc 0x%x-aligned ring buffer\n", size); return -EINVAL; /* Not a good error value, but distinct */ } else if (!ring->virt) { |