On Wed, 13 Mar 2019 at 06:15, Eric Biggers <ebiggers@xxxxxxxxxx> wrote:
>
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> So that the no-SIMD fallback code can be tested by the crypto
> self-tests, add a macro crypto_simd_usable() which wraps may_use_simd(),
> but also returns false if the crypto self-tests have set a per-CPU bool
> to disable SIMD in crypto code on the current CPU.
>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> crypto/testmgr.c | 26 +++++++++++++++++++++++++-
> include/crypto/internal/simd.h | 24 ++++++++++++++++++++++++
> 2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 5d56b2990762..52417dde811f 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -37,6 +37,7 @@
> #include <crypto/akcipher.h>
> #include <crypto/kpp.h>
> #include <crypto/acompress.h>
> +#include <crypto/internal/simd.h>
>
> #include "internal.h"
>
> @@ -52,6 +53,9 @@ MODULE_PARM_DESC(noextratests, "disable expensive crypto self-tests");
> static unsigned int fuzz_iterations = 100;
> module_param(fuzz_iterations, uint, 0644);
> MODULE_PARM_DESC(fuzz_iterations, "number of fuzz test iterations");
> +
> +DEFINE_PER_CPU(bool, crypto_simd_disabled_for_test);
> +EXPORT_PER_CPU_SYMBOL_GPL(crypto_simd_disabled_for_test);
> #endif
>
> #ifdef CONFIG_CRYPTO_MANAGER_DISABLE_TESTS
> @@ -838,7 +842,27 @@ static void generate_random_testvec_config(struct testvec_config *cfg,
>
> WARN_ON_ONCE(!valid_testvec_config(cfg));
> }
> -#endif /* CONFIG_CRYPTO_MANAGER_EXTRA_TESTS */
> +
> +static void crypto_disable_simd_for_test(void)
> +{
> + preempt_disable();
> + __this_cpu_write(crypto_simd_disabled_for_test, true);
> +}
> +
> +static void crypto_reenable_simd_for_test(void)
> +{
> + __this_cpu_write(crypto_simd_disabled_for_test, false);
> + preempt_enable();
> +}
> +#else /* !CONFIG_CRYPTO_MANAGER_EXTRA_TESTS */
> +static void crypto_disable_simd_for_test(void)
> +{
> +}
> +
> +static void crypto_reenable_simd_for_test(void)
> +{
> +}
> +#endif /* !CONFIG_CRYPTO_MANAGER_EXTRA_TESTS */
>
> static int check_nonfinal_hash_op(const char *op, int err,
> u8 *result, unsigned int digestsize,
> diff --git a/include/crypto/internal/simd.h b/include/crypto/internal/simd.h
> index a23b18b6ad61..d2316242a988 100644
> --- a/include/crypto/internal/simd.h
> +++ b/include/crypto/internal/simd.h
> @@ -6,6 +6,9 @@
> #ifndef _CRYPTO_INTERNAL_SIMD_H
> #define _CRYPTO_INTERNAL_SIMD_H
>
> +#include <linux/percpu.h>
> +#include <linux/types.h>
> +
> /* skcipher support */
>
> struct simd_skcipher_alg;
> @@ -42,4 +45,25 @@ int simd_register_aeads_compat(struct aead_alg *algs, int count,
> void simd_unregister_aeads(struct aead_alg *algs, int count,
> struct simd_aead_alg **simd_algs);
>
> +/*
> + * crypto_simd_usable() - is it allowed at this time to use SIMD instructions or
> + * access the SIMD register file?
> + *
> + * This delegates to may_use_simd(), except that this also returns false if SIMD
> + * in crypto code has been temporarily disabled on this CPU by the crypto
> + * self-tests, in order to test the no-SIMD fallback code. This override is
> + * currently limited to configurations where the extra self-tests are enabled,
> + * because it might be a bit too invasive to be part of the regular self-tests.
> + *
> + * This is a macro so that <asm/simd.h>, which some architectures don't have,
> + * doesn't have to be included directly here.
> + */
> +#ifdef CONFIG_CRYPTO_MANAGER_EXTRA_TESTS
> +DECLARE_PER_CPU(bool, crypto_simd_disabled_for_test);
> +#define crypto_simd_usable() \
> + (may_use_simd() && !this_cpu_read(crypto_simd_disabled_for_test))
> +#else
> +#define crypto_simd_usable() may_use_simd()
> +#endif
> +
> #endif /* _CRYPTO_INTERNAL_SIMD_H */
> --
> 2.21.0
>
