crypto: padlock-aes - work around Nano CPU errata in CBC mode

Extend previous workarounds for the prefetch bug to cover CBC mode,
clean up the code a bit.

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Acked-by: Harald Welte <HaraldWelte@viatech.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 65 insertions, 18 deletions

diff --git a/drivers/crypto/padlock-aes.c b/drivers/crypto/padlock-aes.c
index e1d8776c697..a9952b1236b 100644
--- a/drivers/crypto/padlock-aes.c
+++ b/drivers/crypto/padlock-aes.c
@@ -22,11 +22,16 @@
 #include <asm/i387.h>
 #include "padlock.h"
 
-/* number of data blocks actually fetched for each xcrypt insn */
+/*
+ * Number of data blocks actually fetched for each xcrypt insn.
+ * Processors with prefetch errata will fetch extra blocks.
+ */
 static unsigned int ecb_fetch_blocks = 2;
-static unsigned int cbc_fetch_blocks = 1;
-
+#define MAX_ECB_FETCH_BLOCKS (8)
 #define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)
+
+static unsigned int cbc_fetch_blocks = 1;
+#define MAX_CBC_FETCH_BLOCKS (4)
 #define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)
 
 /* Control word. */
@@ -180,7 +185,7 @@ static inline void padlock_store_cword(struct cword *cword)
  * should be used only inside the irq_ts_save/restore() context
  */
 
-static inline void padlock_xcrypt(const u8 *input, u8 *output, void *key,
+static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
                                   struct cword *control_word, int count)
 {
         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
@@ -188,32 +193,65 @@ static inline void padlock_xcrypt(const u8 *input, u8 *output, void *key,
                       : "d"(control_word), "b"(key), "c"(count));
 }
 
-static void aes_crypt_copy(const u8 *in, u8 *out, u32 *key,
+static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
+                                 u8 *iv, struct cword *control_word, int count)
+{
+        asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
+                      : "+S" (input), "+D" (output), "+a" (iv)
+                      : "d" (control_word), "b" (key), "c" (count));
+        return iv;
+}
+
+static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
                            struct cword *cword, int count)
 {
         /*
          * Padlock prefetches extra data so we must provide mapped input buffers.
          * Assume there are at least 16 bytes of stack already in use.
          */
-        u8 buf[AES_BLOCK_SIZE * 7 + PADLOCK_ALIGNMENT - 1];
+        u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
         u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
 
         memcpy(tmp, in, count * AES_BLOCK_SIZE);
-        padlock_xcrypt(tmp, out, key, cword, count);
+        rep_xcrypt_ecb(tmp, out, key, cword, count);
 }
 
-static inline void aes_crypt(const u8 *in, u8 *out, u32 *key,
+static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
+                           u8 *iv, struct cword *cword, int count)
+{
+        /*
+         * Padlock prefetches extra data so we must provide mapped input buffers.
+         * Assume there are at least 16 bytes of stack already in use.
+         */
+        u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
+        u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
+
+        memcpy(tmp, in, count * AES_BLOCK_SIZE);
+        return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
+}
+
+static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
                              struct cword *cword, int count)
 {
         /* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
          * We could avoid some copying here but it's probably not worth it.
          */
         if (unlikely(((unsigned long)in & PAGE_SIZE) + ecb_fetch_bytes > PAGE_SIZE)) {
-                aes_crypt_copy(in, out, key, cword, count);
+                ecb_crypt_copy(in, out, key, cword, count);
                 return;
         }
 
-        padlock_xcrypt(in, out, key, cword, count);
+        rep_xcrypt_ecb(in, out, key, cword, count);
+}
+
+static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
+                            u8 *iv, struct cword *cword, int count)
+{
+        /* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
+        if (unlikely(((unsigned long)in & PAGE_SIZE) + cbc_fetch_bytes > PAGE_SIZE))
+                return cbc_crypt_copy(in, out, key, iv, cword, count);
+
+        return rep_xcrypt_cbc(in, out, key, iv, cword, count);
 }
 
 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
@@ -222,7 +260,7 @@ static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
         u32 initial = count & (ecb_fetch_blocks - 1);
 
         if (count < ecb_fetch_blocks) {
-                aes_crypt(input, output, key, control_word, count);
+                ecb_crypt(input, output, key, control_word, count);
                 return;
         }
 
@@ -239,10 +277,19 @@ static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
                                      u8 *iv, void *control_word, u32 count)
 {
-        /* rep xcryptcbc */
-        asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"
+        u32 initial = count & (cbc_fetch_blocks - 1);
+
+        if (count < cbc_fetch_blocks)
+                return cbc_crypt(input, output, key, iv, control_word, count);
+
+        if (initial)
+                asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
+                              : "+S" (input), "+D" (output), "+a" (iv)
+                              : "d" (control_word), "b" (key), "c" (count));
+
+        asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
                       : "+S" (input), "+D" (output), "+a" (iv)
-                      : "d" (control_word), "b" (key), "c" (count));
+                      : "d" (control_word), "b" (key), "c" (count-initial));
         return iv;
 }
 
@@ -253,7 +300,7 @@ static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 
         padlock_reset_key(&ctx->cword.encrypt);
         ts_state = irq_ts_save();
-        aes_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
+        ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
         irq_ts_restore(ts_state);
         padlock_store_cword(&ctx->cword.encrypt);
 }
@@ -265,7 +312,7 @@ static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 
         padlock_reset_key(&ctx->cword.encrypt);
         ts_state = irq_ts_save();
-        aes_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
+        ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
         irq_ts_restore(ts_state);
         padlock_store_cword(&ctx->cword.encrypt);
 }
@@ -482,8 +529,8 @@ static int __init padlock_init(void)
         printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
 
         if (c->x86 == 6 && c->x86_model == 15 && c->x86_mask == 2) {
-                ecb_fetch_blocks = 8;
-                cbc_fetch_blocks = 4; /* NOTE: notused */
+                ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
+                cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
                 printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
         }