[dpdk-dev,v2] hash: fix CRC32c computation
Commit Message
As demonstrated by the following code, CRC32c computation is not valid
when buffer length is not a multiple of 4 bytes:
(Output obtained by code below)
CRC of 1 NULL bytes expected: 0x527d5351
soft: 527d5351
rte accelerated: 48674bc7
rte soft: 48674bc7
CRC of 2 NULL bytes expected: 0xf16177d2
soft: f16177d2
rte accelerated: 48674bc7
rte soft: 48674bc7
CRC of 2x1 NULL bytes expected: 0xf16177d2
soft: f16177d2
rte accelerated: 8c28b28a
rte soft: 8c28b28a
CRC of 3 NULL bytes expected: 0x6064a37a
soft: 6064a37a
rte accelerated: 48674bc7
rte soft: 48674bc7
CRC of 4 NULL bytes expected: 0x48674bc7
soft: 48674bc7
rte accelerated: 48674bc7
rte soft: 48674bc7
Values returned by rte_hash_crc functions does not match the one
computed by a trivial crc32c implementation.
ARM code is not tested.
code showing the problem:
uint8_t null_test[32] = {0};
static uint32_t crc32c_trivial(uint8_t *buffer, uint32_t length, uint32_t crc)
{
uint32_t i, j;
for (i = 0; i < length; ++i)
{
crc = crc ^ buffer[i];
for (j = 0; j < 8; j++)
crc = (crc >> 1) ^ 0x80000000 ^ ((~crc & 1) * 0x82f63b78);
}
return crc;
}
void hash_test(void);
void hash_test(void)
{
printf("CRC of 1 nul byte expected: 0x527d5351\n");
printf(" soft: %08x\n", crc32c_trivial(null_test, 1, 0));
rte_hash_crc_init_alg();
printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 1, 0xFFFFFFFF));
rte_hash_crc_set_alg(CRC32_SW);
printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 1, 0xFFFFFFFF));
printf("CRC of 2 nul bytes expected: 0xf16177d2\n");
printf(" soft: %08x\n", crc32c_trivial(null_test, 2, 0));
rte_hash_crc_init_alg();
printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 2, 0xFFFFFFFF));
rte_hash_crc_set_alg(CRC32_SW);
printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 2, 0xFFFFFFFF));
printf("CRC of 2x1 nul bytes expected: 0xf16177d2\n");
printf(" soft: %08x\n", crc32c_trivial(null_test, 1, crc32c_trivial(null_test, 1, 0)));
rte_hash_crc_init_alg();
printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 1, rte_hash_crc(null_test, 1, 0xFFFFFFFF)));
rte_hash_crc_set_alg(CRC32_SW);
printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 1, rte_hash_crc(null_test, 1, 0xFFFFFFFF)));
printf("CRC of 3 nul bytes expected: 0x6064a37a\n");
printf(" soft: %08x\n", crc32c_trivial(null_test, 3, 0));
rte_hash_crc_init_alg();
printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 3, 0xFFFFFFFF));
rte_hash_crc_set_alg(CRC32_SW);
printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 3, 0xFFFFFFFF));
printf("CRC of 4 nul bytes expected: 0x48674bc7\n");
printf(" soft: %08x\n", crc32c_trivial(null_test, 4, 0));
rte_hash_crc_init_alg();
printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 4, 0xFFFFFFFF));
rte_hash_crc_set_alg(CRC32_SW);
printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 4, 0xFFFFFFFF));
}
Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
Acked-by: David Marchand <david.marchand@6wind.com>
---
v2: Fix ARM64 compilation issue.
v1: Initial version.
lib/librte_hash/rte_crc_arm64.h | 64 ++++++++++++++++++++
lib/librte_hash/rte_hash_crc.h | 125 +++++++++++++++++++++++++++++++---------
2 files changed, 162 insertions(+), 27 deletions(-)
Comments
Hi Didier,
> -----Original Message-----
> From: Didier Pallard [mailto:didier.pallard@6wind.com]
> Sent: Tuesday, February 09, 2016 9:34 AM
> To: dev@dpdk.org; Richardson, Bruce; De Lara Guarch, Pablo
> Cc: jean-mickael.guerin@6wind.com; thomas.monjalon@6wind.com
> Subject: [PATCH v2] hash: fix CRC32c computation
>
> As demonstrated by the following code, CRC32c computation is not valid
> when buffer length is not a multiple of 4 bytes:
> (Output obtained by code below)
>
> CRC of 1 NULL bytes expected: 0x527d5351
> soft: 527d5351
> rte accelerated: 48674bc7
> rte soft: 48674bc7
> CRC of 2 NULL bytes expected: 0xf16177d2
> soft: f16177d2
> rte accelerated: 48674bc7
> rte soft: 48674bc7
> CRC of 2x1 NULL bytes expected: 0xf16177d2
> soft: f16177d2
> rte accelerated: 8c28b28a
> rte soft: 8c28b28a
> CRC of 3 NULL bytes expected: 0x6064a37a
> soft: 6064a37a
> rte accelerated: 48674bc7
> rte soft: 48674bc7
> CRC of 4 NULL bytes expected: 0x48674bc7
> soft: 48674bc7
> rte accelerated: 48674bc7
> rte soft: 48674bc7
>
> Values returned by rte_hash_crc functions does not match the one
> computed by a trivial crc32c implementation.
>
> ARM code is not tested.
>
> code showing the problem:
>
> uint8_t null_test[32] = {0};
>
> static uint32_t crc32c_trivial(uint8_t *buffer, uint32_t length, uint32_t crc)
> {
> uint32_t i, j;
> for (i = 0; i < length; ++i)
> {
> crc = crc ^ buffer[i];
> for (j = 0; j < 8; j++)
> crc = (crc >> 1) ^ 0x80000000 ^ ((~crc & 1) * 0x82f63b78);
> }
> return crc;
> }
>
> void hash_test(void);
> void hash_test(void)
> {
> printf("CRC of 1 nul byte expected: 0x527d5351\n");
> printf(" soft: %08x\n", crc32c_trivial(null_test, 1, 0));
> rte_hash_crc_init_alg();
> printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 1,
> 0xFFFFFFFF));
> rte_hash_crc_set_alg(CRC32_SW);
> printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 1, 0xFFFFFFFF));
>
> printf("CRC of 2 nul bytes expected: 0xf16177d2\n");
> printf(" soft: %08x\n", crc32c_trivial(null_test, 2, 0));
> rte_hash_crc_init_alg();
> printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 2,
> 0xFFFFFFFF));
> rte_hash_crc_set_alg(CRC32_SW);
> printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 2, 0xFFFFFFFF));
>
> printf("CRC of 2x1 nul bytes expected: 0xf16177d2\n");
> printf(" soft: %08x\n", crc32c_trivial(null_test, 1,
> crc32c_trivial(null_test, 1, 0)));
> rte_hash_crc_init_alg();
> printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 1,
> rte_hash_crc(null_test, 1, 0xFFFFFFFF)));
> rte_hash_crc_set_alg(CRC32_SW);
> printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 1,
> rte_hash_crc(null_test, 1, 0xFFFFFFFF)));
>
> printf("CRC of 3 nul bytes expected: 0x6064a37a\n");
> printf(" soft: %08x\n", crc32c_trivial(null_test, 3, 0));
> rte_hash_crc_init_alg();
> printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 3,
> 0xFFFFFFFF));
> rte_hash_crc_set_alg(CRC32_SW);
> printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 3, 0xFFFFFFFF));
>
> printf("CRC of 4 nul bytes expected: 0x48674bc7\n");
> printf(" soft: %08x\n", crc32c_trivial(null_test, 4, 0));
> rte_hash_crc_init_alg();
> printf(" rte accelerated: %08x\n", ~rte_hash_crc(null_test, 4,
> 0xFFFFFFFF));
> rte_hash_crc_set_alg(CRC32_SW);
> printf(" rte soft: %08x\n", ~rte_hash_crc(null_test, 4, 0xFFFFFFFF));
> }
>
> Signed-off-by: Didier Pallard <didier.pallard@6wind.com>
> Acked-by: David Marchand <david.marchand@6wind.com>
It compiles fine now, thanks!
Could you add also tests for not multiple of 4 bytes keys in test_hash_functions.c,
so we make sure from now on that it works (and you can demonstrate that your fix works)?
You could send a patchset with those new tests first and then the fix.
Also, a note in release notes would be welcome :)
Thanks!
Pablo
CRC32c computation is not valid when buffer length is not a multiple of 4 bytes.
Values returned by rte_hash_crc functions does not match the one
computed by a trivial crc32c implementation.
First patch fixes crc hash function autotests, to outline the problem.
Second patch fixes CRC32c computation.
Didier Pallard (2):
test: fix CRC hash function autotest
hash: fix CRC32c computation
app/test/test_hash_functions.c | 17 +++--
doc/guides/rel_notes/release_16_04.rst | 5 ++
lib/librte_hash/rte_crc_arm64.h | 64 +++++++++++++++++
lib/librte_hash/rte_hash_crc.h | 125 ++++++++++++++++++++++++++-------
4 files changed, 178 insertions(+), 33 deletions(-)
> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Didier Pallard
> Sent: Friday, February 19, 2016 11:00 AM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v3 0/2] Fix CRC32c computation
>
> CRC32c computation is not valid when buffer length is not a multiple of 4
> bytes.
> Values returned by rte_hash_crc functions does not match the one
> computed by a trivial crc32c implementation.
>
> First patch fixes crc hash function autotests, to outline the problem.
> Second patch fixes CRC32c computation.
>
> Didier Pallard (2):
> test: fix CRC hash function autotest
> hash: fix CRC32c computation
>
> app/test/test_hash_functions.c | 17 +++--
> doc/guides/rel_notes/release_16_04.rst | 5 ++
> lib/librte_hash/rte_crc_arm64.h | 64 +++++++++++++++++
> lib/librte_hash/rte_hash_crc.h | 125 ++++++++++++++++++++++++++-----
> --
> 4 files changed, 178 insertions(+), 33 deletions(-)
>
> --
> 2.1.4
Series-acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Not sure if you need to include a "Fixes" line in the commit messages.
In the first commit, probably you should, the commit that you are fixing is
6298d2c55ae8 ("app/test: add new functional tests for hash functions").
In the second commit, it is a bit more difficult, as we don't know that the commit is,
that code was integrated a while ago, before 1.2.3, which is the first public release in dpdk.org.
Also, there is a typo "lengthes", in both commit messages.
You can leave the ack in both patches. Thanks!!
> > CRC32c computation is not valid when buffer length is not a multiple of 4
> > bytes.
> > Values returned by rte_hash_crc functions does not match the one
> > computed by a trivial crc32c implementation.
> >
> > First patch fixes crc hash function autotests, to outline the problem.
> > Second patch fixes CRC32c computation.
> >
> > Didier Pallard (2):
> > test: fix CRC hash function autotest
> > hash: fix CRC32c computation
>
> Series-acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
>
> Not sure if you need to include a "Fixes" line in the commit messages.
> In the first commit, probably you should, the commit that you are fixing is
> 6298d2c55ae8 ("app/test: add new functional tests for hash functions").
Thanks
> In the second commit, it is a bit more difficult, as we don't know that the commit is,
> that code was integrated a while ago, before 1.2.3, which is the first public release in dpdk.org.
Yes it helps to know the bug was there since the beginning.
> Also, there is a typo "lengthes", in both commit messages.
>
> You can leave the ack in both patches. Thanks!!
Applied, thanks
@@ -50,6 +50,28 @@ extern "C" {
#include <rte_common.h>
static inline uint32_t
+crc32c_arm64_u8(uint8_t data, uint32_t init_val)
+{
+ asm(".arch armv8-a+crc");
+ __asm__ volatile(
+ "crc32cb %w[crc], %w[crc], %w[value]"
+ : [crc] "+r" (init_val)
+ : [value] "r" (data));
+ return init_val;
+}
+
+static inline uint32_t
+crc32c_arm64_u16(uint16_t data, uint32_t init_val)
+{
+ asm(".arch armv8-a+crc");
+ __asm__ volatile(
+ "crc32ch %w[crc], %w[crc], %w[value]"
+ : [crc] "+r" (init_val)
+ : [value] "r" (data));
+ return init_val;
+}
+
+static inline uint32_t
crc32c_arm64_u32(uint32_t data, uint32_t init_val)
{
asm(".arch armv8-a+crc");
@@ -103,6 +125,48 @@ rte_hash_crc_init_alg(void)
}
/**
+ * Use single crc32 instruction to perform a hash on a 1 byte value.
+ * Fall back to software crc32 implementation in case arm64 crc intrinsics is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_1byte(uint8_t data, uint32_t init_val)
+{
+ if (likely(crc32_alg & CRC32_ARM64))
+ return crc32c_arm64_u8(data, init_val);
+
+ return crc32c_1byte(data, init_val);
+}
+
+/**
+ * Use single crc32 instruction to perform a hash on a 2 bytes value.
+ * Fall back to software crc32 implementation in case arm64 crc intrinsics is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_2byte(uint16_t data, uint32_t init_val)
+{
+ if (likely(crc32_alg & CRC32_ARM64))
+ return crc32c_arm64_u16(data, init_val);
+
+ return crc32c_2bytes(data, init_val);
+}
+
+/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
* Fall back to software crc32 implementation in case arm64 crc intrinsics is
* not supported
@@ -328,6 +328,28 @@ static const uint32_t crc32c_tables[8][256] = {{
crc32c_tables[(n)-1][((crc) >> 8) & 0xFF])
static inline uint32_t
+crc32c_1byte(uint8_t data, uint32_t init_val)
+{
+ uint32_t crc;
+ crc = init_val;
+ crc ^= data;
+
+ return crc32c_tables[0][crc & 0xff] ^ (crc >> 8);
+}
+
+static inline uint32_t
+crc32c_2bytes(uint16_t data, uint32_t init_val)
+{
+ uint32_t crc;
+ crc = init_val;
+ crc ^= data;
+
+ crc = CRC32_UPD(crc, 1) ^ (crc >> 16);
+
+ return crc;
+}
+
+static inline uint32_t
crc32c_1word(uint32_t data, uint32_t init_val)
{
uint32_t crc, term1, term2;
@@ -367,6 +389,26 @@ crc32c_2words(uint64_t data, uint32_t init_val)
#if defined(RTE_ARCH_I686) || defined(RTE_ARCH_X86_64)
static inline uint32_t
+crc32c_sse42_u8(uint8_t data, uint32_t init_val)
+{
+ __asm__ volatile(
+ "crc32b %[data], %[init_val];"
+ : [init_val] "+r" (init_val)
+ : [data] "rm" (data));
+ return init_val;
+}
+
+static inline uint32_t
+crc32c_sse42_u16(uint16_t data, uint32_t init_val)
+{
+ __asm__ volatile(
+ "crc32w %[data], %[init_val];"
+ : [init_val] "+r" (init_val)
+ : [data] "rm" (data));
+ return init_val;
+}
+
+static inline uint32_t
crc32c_sse42_u32(uint32_t data, uint32_t init_val)
{
__asm__ volatile(
@@ -453,6 +495,52 @@ rte_hash_crc_init_alg(void)
}
/**
+ * Use single crc32 instruction to perform a hash on a byte value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_1byte(uint8_t data, uint32_t init_val)
+{
+#if defined RTE_ARCH_I686 || defined RTE_ARCH_X86_64
+ if (likely(crc32_alg & CRC32_SSE42))
+ return crc32c_sse42_u8(data, init_val);
+#endif
+
+ return crc32c_1byte(data, init_val);
+}
+
+/**
+ * Use single crc32 instruction to perform a hash on a byte value.
+ * Fall back to software crc32 implementation in case SSE4.2 is
+ * not supported
+ *
+ * @param data
+ * Data to perform hash on.
+ * @param init_val
+ * Value to initialise hash generator.
+ * @return
+ * 32bit calculated hash value.
+ */
+static inline uint32_t
+rte_hash_crc_2byte(uint16_t data, uint32_t init_val)
+{
+#if defined RTE_ARCH_I686 || defined RTE_ARCH_X86_64
+ if (likely(crc32_alg & CRC32_SSE42))
+ return crc32c_sse42_u16(data, init_val);
+#endif
+
+ return crc32c_2bytes(data, init_val);
+}
+
+/**
* Use single crc32 instruction to perform a hash on a 4 byte value.
* Fall back to software crc32 implementation in case SSE4.2 is
* not supported
@@ -521,7 +609,6 @@ static inline uint32_t
rte_hash_crc(const void *data, uint32_t data_len, uint32_t init_val)
{
unsigned i;
- uint64_t temp = 0;
uintptr_t pd = (uintptr_t) data;
for (i = 0; i < data_len / 8; i++) {
@@ -529,35 +616,19 @@ rte_hash_crc(const void *data, uint32_t data_len, uint32_t init_val)
pd += 8;
}
- switch (7 - (data_len & 0x07)) {
- case 0:
- temp |= (uint64_t) *((const uint8_t *)pd + 6) << 48;
- /* Fallthrough */
- case 1:
- temp |= (uint64_t) *((const uint8_t *)pd + 5) << 40;
- /* Fallthrough */
- case 2:
- temp |= (uint64_t) *((const uint8_t *)pd + 4) << 32;
- temp |= *(const uint32_t *)pd;
- init_val = rte_hash_crc_8byte(temp, init_val);
- break;
- case 3:
+ if (data_len & 0x4) {
init_val = rte_hash_crc_4byte(*(const uint32_t *)pd, init_val);
- break;
- case 4:
- temp |= *((const uint8_t *)pd + 2) << 16;
- /* Fallthrough */
- case 5:
- temp |= *((const uint8_t *)pd + 1) << 8;
- /* Fallthrough */
- case 6:
- temp |= *(const uint8_t *)pd;
- init_val = rte_hash_crc_4byte(temp, init_val);
- /* Fallthrough */
- default:
- break;
+ pd += 4;
+ }
+
+ if (data_len & 0x2) {
+ init_val = rte_hash_crc_2byte(*(const uint16_t *)pd, init_val);
+ pd += 2;
}
+ if (data_len & 0x1)
+ init_val = rte_hash_crc_1byte(*(const uint8_t *)pd, init_val);
+
return init_val;
}