crypto: arm: workaround for building with old binutils

Old versions of binutils (before 2.23) do not yet understand the crypto-neon-fp-armv8 fpu instructions, and an attempt to build these files results in a build failure:

arch/arm/crypto/aes-ce-core.S:133: Error: selected processor does not support ARM mode vld1.8 {q10-q11},[ip]!' arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction aese.8 q0,q8' arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction aesmc.8 q0,q0' arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction aese.8 q0,q9' arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction `aesmc.8 q0,q0'

Since the affected versions are still in widespread use, and this breaks 'allmodconfig' builds, we should try to at least get a successful kernel build. Unfortunately, I could not come up with a way to make the Kconfig symbol depend on the binutils version, which would be the nicest solution.

This patch uses the 'as-option' Kbuild macro to find out whether the support is present in the assembler, and otherwise passes a macro definition to each affected file, which in turn disables that code entirely and results in empty modules.

In order to help users figure out what to do, we also add a #warning state in place of the removed to that tells users which version to use.

Signed-off-by Arnd Bergmann <[email protected]>

Link http://storage.kernelci.org/next/next-20150410/arm-allmodconfig/build.log

Fixes 864cbeed4ab22d ("crypto: arm - add support for SHA1 using ARMv8 Crypto Instructions")

arch/arm/crypto/Makefile +0 -0

index ef46e898f98b..60f2101e0586 100644

arch/arm/crypto/Makefile +0 -0

 quiet_cmd_perl = PERL    $@
       cmd_perl = $(PERL) $(<) > $(@)
 

arch/arm/crypto/aes-ce-core.S +6 -1

index 8cfa468ee570..f2132ba91353 100644
@@ -8,11 +8,14 @@
  * published by the Free Software Foundation.
  */
 
+#ifdef ARMV8_CE_DISABLED
+#warning ARMv8 Crypto Extensions need binutils 2.23 or higher
+#else
+
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
        .text
-       .fpu            crypto-neon-fp-armv8
        .align          3
 
        .macro          enc_round, state, key

@@ -516,3 +519,5 @@ ENTRY(ce_aes_invert)
        vst1.8          {q0}, [r0]
        bx              lr
 ENDPROC(ce_aes_invert)
+
+#endif

arch/arm/crypto/aes-ce-glue.c +4 -1

index b445a5d56f43..4cba201a64a9 100644
@@ -510,13 +510,16 @@ static struct crypto_alg aes_algs[] = { {
 
 static int __init aes_init(void)
 {
-       if (!(elf_hwcap2 & HWCAP2_AES))
+       if (IS_ENABLED(ARMV8_CE_DISABLED) || !(elf_hwcap2 & HWCAP2_AES))
                return -ENODEV;
        return crypto_register_algs(aes_algs, ARRAY_SIZE(aes_algs));
 }
 
 static void __exit aes_exit(void)
 {
+       if (IS_ENABLED(ARMV8_CE_DISABLED))
+               return;
+
        crypto_unregister_algs(aes_algs, ARRAY_SIZE(aes_algs));
 }
 

arch/arm/crypto/ghash-ce-core.S +6 -2

index f6ab8bcc9efe..4fe75df41162 100644
@@ -8,6 +8,10 @@
  * by the Free Software Foundation.
  */
 
+#ifdef ARMV8_CE_DISABLED
+#warning ARMv8 Crypto Extensions need binutils 2.23 or higher
+#else
+
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 

@@ -33,8 +37,6 @@
        XH_L            .req    d14
 
        .text
-       .fpu            crypto-neon-fp-armv8
-
        /*
         * void pmull_ghash_update(int blocks, u64 dg[], const char *src,
         *                         struct ghash_key const *k, const char *head)

@@ -92,3 +94,5 @@ ENTRY(pmull_ghash_update)
        vst1.64         {XL}, [r1]
        bx              lr
 ENDPROC(pmull_ghash_update)
+
+#endif

arch/arm/crypto/ghash-ce-glue.c +4 -1

index 03a39fe29246..880afe904e5d 100644
@@ -293,7 +293,7 @@ static int __init ghash_ce_mod_init(void)
 {
        int err;
 
-       if (!(elf_hwcap2 & HWCAP2_PMULL))
+       if (IS_ENABLED(ARMV8_CE_DISABLED) || !(elf_hwcap2 & HWCAP2_AES))
                return -ENODEV;
 
        err = crypto_register_shash(&ghash_alg);

@@ -312,6 +312,9 @@ err_shash:
 
 static void __exit ghash_ce_mod_exit(void)
 {
+       if (IS_ENABLED(ARMV8_CE_DISABLED))
+               return;
+
        crypto_unregister_ahash(&ghash_async_alg);
        crypto_unregister_shash(&ghash_alg);
 }

arch/arm/crypto/sha1-ce-core.S +6 -1

index 4aad520935d8..ab0fe554a6cf 100644
@@ -9,11 +9,14 @@
  * published by the Free Software Foundation.
  */
 
+#ifdef ARMV8_CE_DISABLED
+#warning ARMv8 Crypto Extensions need binutils 2.23 or higher
+#else
+
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
        .text
-       .fpu            crypto-neon-fp-armv8
 
        k0              .req    q0
        k1              .req    q1

@@ -132,3 +135,5 @@ ENTRY(sha1_ce_transform)
        vstr            dgbs, [r2, #16]
        bx              lr
 ENDPROC(sha1_ce_transform)
+
+#endif

arch/arm/crypto/sha1-ce-glue.c +4 -1

index a9dd90df9fd7..045cabad9296 100644
@@ -136,13 +136,16 @@ static struct shash_alg alg = {
 
 static int __init sha1_ce_mod_init(void)
 {
-       if (!(elf_hwcap2 & HWCAP2_SHA1))
+       if (IS_ENABLED(ARMV8_CE_DISABLED) || !(elf_hwcap2 & HWCAP2_AES))
                return -ENODEV;
        return crypto_register_shash(&alg);
 }
 
 static void __exit sha1_ce_mod_fini(void)
 {
+       if (IS_ENABLED(ARMV8_CE_DISABLED))
+               return;
+
        crypto_unregister_shash(&alg);
 }
 

arch/arm/crypto/sha2-ce-core.S +6 -1

index 96af09fe957b..3db821c5f4cd 100644
@@ -9,11 +9,14 @@
  * published by the Free Software Foundation.
  */
 
+#ifdef ARMV8_CE_DISABLED
+#warning ARMv8 Crypto Extensions need binutils 2.23 or higher
+#else
+
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
        .text
-       .fpu            crypto-neon-fp-armv8
 
        k0              .req    q7
        k1              .req    q8

@@ -132,3 +135,5 @@ ENTRY(sha2_ce_transform)
        vst1.32         {dga-dgb}, [r2]
        bx              lr
 ENDPROC(sha2_ce_transform)
+
+#endif

arch/arm/crypto/sha2-ce-glue.c +4 -1

index 0449eca3aab3..3f8010837310 100644
@@ -189,13 +189,16 @@ static struct shash_alg algs[] = { {
 
 static int __init sha2_ce_mod_init(void)
 {
-       if (!(elf_hwcap2 & HWCAP2_SHA2))
+       if (IS_ENABLED(ARMV8_CE_DISABLED) || !(elf_hwcap2 & HWCAP2_AES))
                return -ENODEV;
        return crypto_register_shashes(algs, ARRAY_SIZE(algs));
 }
 
 static void __exit sha2_ce_mod_fini(void)
 {
+       if (IS_ENABLED(ARMV8_CE_DISABLED))
+               return;
+
        crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
 }
 

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Could you perhaps put the rules that build these modules inside a

ifneq ($(armv8-ce-flags),-DARMV8_CE_DISABLED)
...
endif

Quoted 7 lines · On Saturday 11 April 2015 09:41:08 Ard Biesheuvel wrote:

Could you perhaps put the rules that build these modules inside a

ifneq ($(armv8-ce-flags),-DARMV8_CE_DISABLED)
...
endif

How about something like this:

ifeq ($(call as-option,-Wa$(comma)-mfpu=crypto-neon-fp-armv8),) $(warning ARMv8 Crypto Extensions need binutils 2.23 or higher) else
...
endif

That would basically be a reimplementation of the missing "as-option-yn" macro though, so we could also add that instead and do

ifeq ($(call as-option-yn,-Wa$(comma)-mfpu=crypto-neon-fp-armv8),y) $(warning ARMv8 Crypto Extensions need binutils 2.23 or higher) else
...
endif

Yes, that should work. Could we also move the CE objs to ce-obj-$() and put

ifneq ($(ce-obj-y)$(ce-obj-m),)
if <as check>
obj-y += $(ce-obj-y)
obj-m += $(ce-obj-m)
else
$(warning ...)
endif
endif

around it so you only get the warning if you have selected any of these modules?

In any case, I strongly prefer to leave the .S files themselves alone if at all possible