x86, crypto: Check if gas supports CRC32

PATCH In review Borislav Petkov 2 participants 5 messages Jul 30, 2014 – Jul 31, 2014

Subsystems (2)

x86 Crypto API

lore

Share & tools

lore

Borislav Petkov

author maintainer

2014-07-30 16:47 UTC #0 lore raw

PATCH 1/1 x86, crypto: Check if gas supports CRC32

Building current kernel with some old toolchain (gcc 4.1.2 and gas 2.17) chokes with:

arch/x86/crypto/crc32c-pcl-intel-asm_64.S: Assembler messages:
arch/x86/crypto/crc32c-pcl-intel-asm_64.S:128: Error: no such instruction: crc32b %bl,%r8d' arch/x86/crypto/crc32c-pcl-intel-asm_64.S:204: Error: no such instruction: crc32q -i*8(%rcx),%r8'
...

due to the fact that gas doesn't know the CRC32 instruction. Check that before building.

Cc [email protected]

Signed-off-by Borislav Petkov <[email protected]>

---

So this is one possibility to address this. Code already
has the ifdeffery around crc_pcl() which is implemented in crc32c-pcl-intel-asm_64.S so we can piggyback on that and not build that file if gas doesn't know CRC32.

If no CRC32 support, it still builds fine silently, however it would be better to probably say that due to old toolchain, kernel doesn't include fast CRC32 stuff in crc32c-intel.ko.

Hmmm.

 arch/x86/crypto/Makefile            |  8 +++++++-
 arch/x86/crypto/crc32c-intel_glue.c |  7 ++++---
 scripts/gas-can-do-crc32.sh         | 12 ++++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100755 scripts/gas-can-do-crc32.sh

arch/x86/crypto/Makefile +7 -1

index 61d6e281898b..707bf7ecb903 100644
@@ -83,7 +83,13 @@ ifeq ($(avx2_supported),yes)
 sha1-ssse3-y += sha1_avx2_x86_64_asm.o
 endif
 crc32c-intel-y := crc32c-intel_glue.o
-crc32c-intel-$(CONFIG_64BIT) += crc32c-pcl-intel-asm_64.o
+
+gas_can_crc32 := $(srctree)/scripts/gas-can-do-crc32.sh
+CONFIG_GAS_SUPPORTS_CRC32=$(shell $(CONFIG_SHELL) $(gas_can_crc32) $(AS))
+
+ifdef CONFIG_64BIT
+crc32c-intel-$(CONFIG_GAS_SUPPORTS_CRC32) += crc32c-pcl-intel-asm_64.o
+endif
 crc32-pclmul-y := crc32-pclmul_asm.o crc32-pclmul_glue.o
 sha256-ssse3-y := sha256-ssse3-asm.o sha256-avx-asm.o sha256-avx2-asm.o sha256_ssse3_glue.o
 sha512-ssse3-y := sha512-ssse3-asm.o sha512-avx-asm.o sha512-avx2-asm.o sha512_ssse3_glue.o

arch/x86/crypto/crc32c-intel_glue.c +4 -3

index 6812ad98355c..4ce8e2db2984 100644
@@ -46,7 +46,7 @@
 #define REX_PRE
 #endif
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 /*
  * use carryless multiply version of crc32c when buffer
  * size is >= 512 (when eager fpu is enabled) or

@@ -181,7 +181,7 @@ static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
 	return 0;
 }
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
 			       unsigned int len)
 {

@@ -257,7 +257,8 @@ static int __init crc32c_intel_mod_init(void)
 {
 	if (!x86_match_cpu(crc32c_cpu_id))
 		return -ENODEV;
-#ifdef CONFIG_X86_64
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 	if (cpu_has_pclmulqdq) {
 		alg.update = crc32c_pcl_intel_update;
 		alg.finup = crc32c_pcl_intel_finup;

scripts/gas-can-do-crc32.sh new file +12 -0

new file mode 100755
index 000000000000..88ff476bd3cc
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+TMP=$(mktemp)
+
+echo "crc32 %rax,%rbx" | $* --warn - -o $TMP 2>/dev/null
+if [ "$?" -eq "0" ]; then
+	echo y
+else
+	echo n
+fi
+
+rm -f $TMP

Signature · 9 lines

2.0.0


-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Mathias Krause

2014-07-30 21:19 UTC #1 lore raw

Quoted 38 lines · Borislav Petkov

Building current kernel with some old toolchain (gcc 4.1.2 and gas 2.17) chokes with:
arch/x86/crypto/crc32c-pcl-intel-asm_64.S: Assembler messages:
arch/x86/crypto/crc32c-pcl-intel-asm_64.S:128: Error: no such instruction: crc32b %bl,%r8d' arch/x86/crypto/crc32c-pcl-intel-asm_64.S:204: Error: no such instruction: crc32q -i*8(%rcx),%r8'
...
due to the fact that gas doesn't know the CRC32 instruction. Check that before building.
Cc [email protected]
Signed-off-by Borislav Petkov <[email protected]>
---
So this is one possibility to address this. Code already
has the ifdeffery around crc_pcl() which is implemented in crc32c-pcl-intel-asm_64.S so we can piggyback on that and not build that file if gas doesn't know CRC32.
If no CRC32 support, it still builds fine silently, however it would be better to probably say that due to old toolchain, kernel doesn't include fast CRC32 stuff in crc32c-intel.ko.
Hmmm.
 arch/x86/crypto/Makefile            |  8 +++++++-
 arch/x86/crypto/crc32c-intel_glue.c |  7 ++++---
 scripts/gas-can-do-crc32.sh         | 12 ++++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100755 scripts/gas-can-do-crc32.sh
arch/x86/crypto/Makefile +0 -0
index 61d6e281898b..707bf7ecb903 100644

arch/x86/crypto/Makefile ifeq ($(avx2_supported),yes) · line 89

Quoted 8 lines

arch/x86/crypto/Makefile +4 -1

@@ -83,7 +83,13 @@ ifeq ($(avx2_supported),yes)
 sha1-ssse3-y += sha1_avx2_x86_64_asm.o
 endif
 crc32c-intel-y := crc32c-intel_glue.o
-crc32c-intel-$(CONFIG_64BIT) += crc32c-pcl-intel-asm_64.o
+
+gas_can_crc32 := $(srctree)/scripts/gas-can-do-crc32.sh
+CONFIG_GAS_SUPPORTS_CRC32=$(shell $(CONFIG_SHELL) $(gas_can_crc32) $(AS))
+

This looks too complicated. We do have as-instr for exactly those kind of tests. And, in fact, looking at arch/x86/Makefile we already have one for crc32:

  asinstr += $(call as-instr,crc32l %eax$(comma)%eax,-DCONFIG_AS_CRC32=1)

So you can just used CONFIG_AS_CRC32 for your tests and drop the shell script.

arch/x86/crypto/Makefile ifeq ($(avx2_supported),yes) · line 92

Quoted 3 lines

arch/x86/crypto/Makefile +3 -0

+ifdef CONFIG_64BIT
+crc32c-intel-$(CONFIG_GAS_SUPPORTS_CRC32) += crc32c-pcl-intel-asm_64.o
+endif

s/CONFIG_GAS_SUPPORTS_CRC32/CONFIG_AS_CRC32/ here and for all further uses.

Quoted 56 lines

arch/x86/crypto/Makefile +0 -0

 crc32-pclmul-y := crc32-pclmul_asm.o crc32-pclmul_glue.o
 sha256-ssse3-y := sha256-ssse3-asm.o sha256-avx-asm.o sha256-avx2-asm.o sha256_ssse3_glue.o
 sha512-ssse3-y := sha512-ssse3-asm.o sha512-avx-asm.o sha512-avx2-asm.o sha512_ssse3_glue.o

arch/x86/crypto/crc32c-intel_glue.c +4 -3

index 6812ad98355c..4ce8e2db2984 100644
@@ -46,7 +46,7 @@
 #define REX_PRE
 #endif
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 /*
  * use carryless multiply version of crc32c when buffer
  * size is >= 512 (when eager fpu is enabled) or

@@ -181,7 +181,7 @@ static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
 	return 0;
 }
 
-#ifdef CONFIG_X86_64
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
 			       unsigned int len)
 {

@@ -257,7 +257,8 @@ static int __init crc32c_intel_mod_init(void)
 {
 	if (!x86_match_cpu(crc32c_cpu_id))
 		return -ENODEV;
-#ifdef CONFIG_X86_64
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_GAS_SUPPORTS_CRC32)
 	if (cpu_has_pclmulqdq) {
 		alg.update = crc32c_pcl_intel_update;
 		alg.finup = crc32c_pcl_intel_finup;

scripts/gas-can-do-crc32.sh new file +12 -0

new file mode 100755
index 000000000000..88ff476bd3cc
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+TMP=$(mktemp)
+
+echo "crc32 %rax,%rbx" | $* --warn - -o $TMP 2>/dev/null
+if [ "$?" -eq "0" ]; then
+	echo y
+else
+	echo n
+fi
+
+rm -f $TMP

Signature · 1 line

2.0.0

Regards,
Mathias

Mathias Krause

2014-07-30 21:28 UTC #2 lore raw

Quoted 12 lines · Mathias Krause

Quoted 1 line · Borislav Petkov
[...]
This looks too complicated. We do have as-instr for exactly those kind of tests. And, in fact, looking at arch/x86/Makefile we already have one for crc32:
  asinstr += $(call as-instr,crc32l %eax$(comma)%eax,-DCONFIG_AS_CRC32=1)
So you can just used CONFIG_AS_CRC32 for your tests and drop the shell script.

Quoted 7 lines

arch/x86/crypto/Makefile ifeq ($(avx2_supported),yes) · line 92
Quoted 3 lines
arch/x86/crypto/Makefile +3 -0
+ifdef CONFIG_64BIT
+crc32c-intel-$(CONFIG_GAS_SUPPORTS_CRC32) += crc32c-pcl-intel-asm_64.o
+endif
s/CONFIG_GAS_SUPPORTS_CRC32/CONFIG_AS_CRC32/ here and for all further uses.

Gah, CONFIG_AS_CRC32 gets defined as a preprocessor symbol only so cannot be used in makefiles. So crc32c-pcl-intel-asm_64.S needs a "#ifdef CONFIG_AS_CRC32" guard and still be compiled for CONFIG_64BIT, as it is now. It'll be an empty object for older binutils versions not supporting the crc32 instruction.

Sorry for the confusion.

Regards,
Mathias

Borislav Petkov

author maintainer

2014-07-30 22:11 UTC #3 lore raw

Quoted 5 lines · Mathias Krause

Gah, CONFIG_AS_CRC32 gets defined as a preprocessor symbol only so cannot be used in makefiles. So crc32c-pcl-intel-asm_64.S needs a "#ifdef CONFIG_AS_CRC32" guard and still be compiled for CONFIG_64BIT, as it is now. It'll be an empty object for older binutils versions not supporting the crc32 instruction.

Yeah, that makes it all even simpler, thanks!

We're still b0rked though:

arch/x86/crypto/crct10dif-pcl-asm_64.S: Assembler messages:
arch/x86/crypto/crct10dif-pcl-asm_64.S:147: Error: no such instruction: pclmulqdq $0x0,%xmm10,%xmm0' arch/x86/crypto/crct10dif-pcl-asm_64.S:148: Error: no such instruction: pclmulqdq $0x11,%xmm10,%xmm8' arch/x86/crypto/crct10dif-pcl-asm_64.S:149: Error: no such instruction: `pclmulqdq $0x0,%xmm10,%xmm1'
...

and need checking for more instructions. I'll play with this more tomorrow.

Good night :-)

Signature · 5 lines

Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Mathias Krause

2014-07-31 05:57 UTC #4 lore raw

Quoted 12 lines · Borislav Petkov

Quoted 5 lines · Mathias Krause
Gah, CONFIG_AS_CRC32 gets defined as a preprocessor symbol only so cannot be used in makefiles. So crc32c-pcl-intel-asm_64.S needs a "#ifdef CONFIG_AS_CRC32" guard and still be compiled for CONFIG_64BIT, as it is now. It'll be an empty object for older binutils versions not supporting the crc32 instruction.
Yeah, that makes it all even simpler, thanks!
We're still b0rked though:

Quoted 9 lines

arch/x86/crypto/crct10dif-pcl-asm_64.S: Assembler messages:
arch/x86/crypto/crct10dif-pcl-asm_64.S:147: Error: no such instruction: pclmulqdq $0x0,%xmm10,%xmm0' arch/x86/crypto/crct10dif-pcl-asm_64.S:148: Error: no such instruction: pclmulqdq $0x11,%xmm10,%xmm8' arch/x86/crypto/crct10dif-pcl-asm_64.S:149: Error: no such instruction: `pclmulqdq $0x0,%xmm10,%xmm1'
...
and need checking for more instructions. I'll play with this more tomorrow.

You probably can reuse the AVX test for this -- either the CONFIG_AS_AVX preprocessor one or the $(avx_supported) make one, local to arch/x86/crypto/Makefile.
Even though the CLMUL feature has not much to with AVX (it has a dedicated CPUID feature bit), support for it in binutils was added together with AVX support, see
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c0f3af977b0f28a0dc5a620110b8dcf9d8286f84

Regards,
Mathias

Quoted 8 lines

Good night :-)
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine. --