diff options
| author | Alex Elder <elder@linaro.org> | 2021-03-22 20:05:05 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-23 17:15:23 -0700 |
| commit | 437c78f976f5b39fc4b2a1c65903a229f55912dd (patch) | |
| tree | a37b648b0968bcdb419dd4e6c8ad33adb53ed45e /drivers/net/ipa/ipa_table.c | |
| parent | ed97143e00982e1cab3544977f33b94a6de2e6fa (diff) | |
| download | linux-437c78f976f5b39fc4b2a1c65903a229f55912dd.tar.bz2 | |
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/ipa_table.c')
| -rw-r--r-- | drivers/net/ipa/ipa_table.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c index 988f2c2886b9..4236a50ff03a 100644 --- a/drivers/net/ipa/ipa_table.c +++ b/drivers/net/ipa/ipa_table.c @@ -658,10 +658,13 @@ int ipa_table_init(struct ipa *ipa) return -ENOMEM; /* We put the "zero rule" at the base of our table area. The IPA - * hardware requires rules to be aligned on a 128-byte boundary. - * Make sure the allocation satisfies this constraint. + * hardware requires route and filter table rules to be aligned + * on a 128-byte boundary. As long as the alignment constraint + * is a power of 2, we can check alignment using just the bottom + * 32 bits for a DMA address of any size. */ - if (addr % IPA_TABLE_ALIGN) { + BUILD_BUG_ON(!is_power_of_2(IPA_TABLE_ALIGN)); + if (lower_32_bits(addr) % IPA_TABLE_ALIGN) { dev_err(dev, "table address %pad not %u-byte aligned\n", &addr, IPA_TABLE_ALIGN); dma_free_coherent(dev, size, virt, addr); |