sched/preempt, powerpc: Disable preemption in enable_kernel_altivec() explicitly

enable_kernel_altivec() has to be called with disabled preemption.
Let's make this explicit, to prepare for pagefault_disable() not
touching preemption anymore.

Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-14-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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;
 }
 

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();
     }
 }
 

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;

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);