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Date: Thu, 07 May 2015 10:21:49 +1000
From: Benjamin Herrenschmidt <benh@...nel.crashing.org>
To: David Hildenbrand <dahi@...ux.vnet.ibm.com>
Cc: linux-kernel@...r.kernel.org, mingo@...hat.com,
peterz@...radead.org, yang.shi@...driver.com,
bigeasy@...utronix.de, paulus@...ba.org, akpm@...ux-foundation.org,
heiko.carstens@...ibm.com, schwidefsky@...ibm.com,
borntraeger@...ibm.com, mst@...hat.com, tglx@...utronix.de,
David.Laight@...LAB.COM, hughd@...gle.com, hocko@...e.cz,
ralf@...ux-mips.org, herbert@...dor.apana.org.au,
linux@....linux.org.uk, airlied@...ux.ie, daniel.vetter@...el.com,
linux-mm@...ck.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH RFC 13/15] powerpc: enable_kernel_altivec() requires
disabled preemption
On Wed, 2015-05-06 at 19:50 +0200, David Hildenbrand wrote:
> enable_kernel_altivec() has to be called with disabled preemption.
> Let's make this explicit, to prepare for pagefault_disable() not
> touching preemption anymore.
>
> Signed-off-by: David Hildenbrand <dahi@...ux.vnet.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> ---
> arch/powerpc/lib/vmx-helper.c | 11 ++++++-----
> drivers/crypto/vmx/aes.c | 8 +++++++-
> drivers/crypto/vmx/aes_cbc.c | 6 ++++++
> drivers/crypto/vmx/ghash.c | 8 ++++++++
> 4 files changed, 27 insertions(+), 6 deletions(-)
>
> diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c
> index 3cf529c..ac93a3b 100644
> --- a/arch/powerpc/lib/vmx-helper.c
> +++ b/arch/powerpc/lib/vmx-helper.c
> @@ -27,11 +27,11 @@ int enter_vmx_usercopy(void)
> if (in_interrupt())
> return 0;
>
> - /* This acts as preempt_disable() as well and will make
> - * enable_kernel_altivec(). We need to disable page faults
> - * as they can call schedule and thus make us lose the VMX
> - * context. So on page faults, we just fail which will cause
> - * a fallback to the normal non-vmx copy.
> + preempt_disable();
> + /*
> + * We need to disable page faults as they can call schedule and
> + * thus make us lose the VMX context. So on page faults, we just
> + * fail which will cause a fallback to the normal non-vmx copy.
> */
> pagefault_disable();
>
> @@ -47,6 +47,7 @@ int enter_vmx_usercopy(void)
> int exit_vmx_usercopy(void)
> {
> pagefault_enable();
> + preempt_enable();
> return 0;
> }
>
> diff --git a/drivers/crypto/vmx/aes.c b/drivers/crypto/vmx/aes.c
> index ab300ea..a9064e3 100644
> --- a/drivers/crypto/vmx/aes.c
> +++ b/drivers/crypto/vmx/aes.c
> @@ -78,12 +78,14 @@ static int p8_aes_setkey(struct crypto_tfm *tfm, const u8 *key,
> int ret;
> struct p8_aes_ctx *ctx = crypto_tfm_ctx(tfm);
>
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
> ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
> pagefault_enable();
> -
> + preempt_enable();
> +
> ret += crypto_cipher_setkey(ctx->fallback, key, keylen);
> return ret;
> }
> @@ -95,10 +97,12 @@ static void p8_aes_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
> if (in_interrupt()) {
> crypto_cipher_encrypt_one(ctx->fallback, dst, src);
> } else {
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> aes_p8_encrypt(src, dst, &ctx->enc_key);
> pagefault_enable();
> + preempt_enable();
> }
> }
>
> @@ -109,10 +113,12 @@ static void p8_aes_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
> if (in_interrupt()) {
> crypto_cipher_decrypt_one(ctx->fallback, dst, src);
> } else {
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> aes_p8_decrypt(src, dst, &ctx->dec_key);
> pagefault_enable();
> + preempt_enable();
> }
> }
>
> diff --git a/drivers/crypto/vmx/aes_cbc.c b/drivers/crypto/vmx/aes_cbc.c
> index 1a559b7..477284a 100644
> --- a/drivers/crypto/vmx/aes_cbc.c
> +++ b/drivers/crypto/vmx/aes_cbc.c
> @@ -79,11 +79,13 @@ static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
> int ret;
> struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
>
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
> ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
> pagefault_enable();
> + preempt_enable();
>
> ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
> return ret;
> @@ -106,6 +108,7 @@ static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
> if (in_interrupt()) {
> ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes);
> } else {
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
>
> @@ -119,6 +122,7 @@ static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
> }
>
> pagefault_enable();
> + preempt_enable();
> }
>
> return ret;
> @@ -141,6 +145,7 @@ static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
> if (in_interrupt()) {
> ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);
> } else {
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
>
> @@ -154,6 +159,7 @@ static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
> }
>
> pagefault_enable();
> + preempt_enable();
> }
>
> return ret;
> diff --git a/drivers/crypto/vmx/ghash.c b/drivers/crypto/vmx/ghash.c
> index d0ffe27..f255ec4 100644
> --- a/drivers/crypto/vmx/ghash.c
> +++ b/drivers/crypto/vmx/ghash.c
> @@ -114,11 +114,13 @@ static int p8_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
> if (keylen != GHASH_KEY_LEN)
> return -EINVAL;
>
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> enable_kernel_fp();
> gcm_init_p8(ctx->htable, (const u64 *) key);
> pagefault_enable();
> + preempt_enable();
> return crypto_shash_setkey(ctx->fallback, key, keylen);
> }
>
> @@ -140,23 +142,27 @@ static int p8_ghash_update(struct shash_desc *desc,
> }
> memcpy(dctx->buffer + dctx->bytes, src,
> GHASH_DIGEST_SIZE - dctx->bytes);
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> enable_kernel_fp();
> gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
> GHASH_DIGEST_SIZE);
> pagefault_enable();
> + preempt_enable();
> src += GHASH_DIGEST_SIZE - dctx->bytes;
> srclen -= GHASH_DIGEST_SIZE - dctx->bytes;
> dctx->bytes = 0;
> }
> len = srclen & ~(GHASH_DIGEST_SIZE - 1);
> if (len) {
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> enable_kernel_fp();
> gcm_ghash_p8(dctx->shash, ctx->htable, src, len);
> pagefault_enable();
> + preempt_enable();
> src += len;
> srclen -= len;
> }
> @@ -180,12 +186,14 @@ static int p8_ghash_final(struct shash_desc *desc, u8 *out)
> if (dctx->bytes) {
> for (i = dctx->bytes; i < GHASH_DIGEST_SIZE; i++)
> dctx->buffer[i] = 0;
> + preempt_disable();
> pagefault_disable();
> enable_kernel_altivec();
> enable_kernel_fp();
> gcm_ghash_p8(dctx->shash, ctx->htable, dctx->buffer,
> GHASH_DIGEST_SIZE);
> pagefault_enable();
> + preempt_enable();
> dctx->bytes = 0;
> }
> memcpy(out, dctx->shash, GHASH_DIGEST_SIZE);
--
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