Re: [PATCH 2/2] crypto: qat - Don't move data inside output buffer

From: Tadeusz Struk
Date: Fri Aug 14 2015 - 10:24:45 EST

Hi Herbert,
On 08/13/2015 11:26 PM, Herbert Xu wrote:
> On Thu, Aug 13, 2015 at 11:14:11PM -0700, Tadeusz Struk wrote:
>> Right, but we don't need that anymore.
> Why not? If you reduce the size without moving the buffer wouldn't
> it begin with a bunch of zeroes and wouldn't you lose the real bytes
> at the end?

Yes, that was wrong, sorry. The reason I wanted to change it is that
the SW implementation can return a number with leading zeros.
This is because mpi_read_buffer() returns the whole thing.

Because the format of the module signature starts with 0x00, 0x01
the two implementations return a different thing.
For instance SW returned a 512 bytes number starting with 0x00, 0x01
and HW returned 511 bytes number without the 0x00 at the beginning.
Technically both are correct, but then the rsa_signture_verify()
needs to check for both cases, which is not ideal.
To make it return the same thing as SW we can do something like this:


Allow for leading zeros in output to make it exactly the same as the
SW implementation.
Change memcpy to memmove because the copy is done within the same buffer.

diff --git a/drivers/crypto/qat/qat_common/qat_asym_algs.c b/drivers/crypto/qat/qat_common/qat_asym_algs.c
index fe352a6..cc450fa 100644
--- a/drivers/crypto/qat/qat_common/qat_asym_algs.c
+++ b/drivers/crypto/qat/qat_common/qat_asym_algs.c
@@ -118,7 +118,13 @@ static void qat_rsa_cb(struct icp_qat_fw_pke_resp *resp)
struct device *dev = &GET_DEV(req->ctx->inst->accel_dev);
- char *ptr = areq->dst;
+ u32 *ptr = areq->dst;
+#elif BYTES_PER_MPI_LIMB == 8
+ u64 *ptr = areq->dst;
+#error please implement for this limb size.

err = (err == ICP_QAT_FW_COMN_STATUS_FLAG_OK) ? 0 : -EINVAL;

@@ -140,12 +146,12 @@ static void qat_rsa_cb(struct icp_qat_fw_pke_resp *resp)
areq->dst_len = req->ctx->key_sz;
/* Need to set the corect length of the output */
while (!(*ptr) && areq->dst_len) {
- areq->dst_len--;
+ areq->dst_len -= sizeof(*ptr);

if (areq->dst_len != req->ctx->key_sz)
- memcpy(areq->dst, ptr, areq->dst_len);
+ memmove(areq->dst, ptr, areq->dst_len);

akcipher_request_complete(areq, err);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at