4 files changed, 76 insertions, 1 deletions

diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index f7feae4ebb5e..128202e18fc9 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -31,6 +31,7 @@
 #include <asm/io.h>
 #include <asm/msr.h>
 #include <asm/cpufeature.h>
+#include <asm/i387.h>
 
 
 #define PFX     KBUILD_MODNAME ": "
@@ -67,16 +68,23 @@ enum {
  * Another possible performance boost may come from simply buffering
  * until we have 4 bytes, thus returning a u32 at a time,
  * instead of the current u8-at-a-time.
+ *
+ * Padlock instructions can generate a spurious DNA fault, so
+ * we have to call them in the context of irq_ts_save/restore()
  */
 
 static inline u32 xstore(u32 *addr, u32 edx_in)
 {
         u32 eax_out;
+        int ts_state;
+
+        ts_state = irq_ts_save();
 
         asm(".byte 0x0F,0xA7,0xC0 /* xstore %%edi (addr=%0) */"
                 :"=m"(*addr), "=a"(eax_out)
                 :"D"(addr), "d"(edx_in));
 
+        irq_ts_restore(ts_state);
         return eax_out;
 }
 
diff --git a/drivers/crypto/padlock-aes.c b/drivers/crypto/padlock-aes.c
index 54a2a166e566..bf2917d197a0 100644
--- a/drivers/crypto/padlock-aes.c
+++ b/drivers/crypto/padlock-aes.c
@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <asm/byteorder.h>
+#include <asm/i387.h>
 #include "padlock.h"
 
 /* Control word. */
@@ -141,6 +142,12 @@ static inline void padlock_reset_key(void)
         asm volatile ("pushfl; popfl");
 }
 
+/*
+ * While the padlock instructions don't use FP/SSE registers, they
+ * generate a spurious DNA fault when cr0.ts is '1'. These instructions
+ * should be used only inside the irq_ts_save/restore() context
+ */
+
 static inline void padlock_xcrypt(const u8 *input, u8 *output, void *key,
                                   void *control_word)
 {
@@ -205,15 +212,23 @@ static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 {
         struct aes_ctx *ctx = aes_ctx(tfm);
+        int ts_state;
         padlock_reset_key();
+
+        ts_state = irq_ts_save();
         aes_crypt(in, out, ctx->E, &ctx->cword.encrypt);
+        irq_ts_restore(ts_state);
 }
 
 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 {
         struct aes_ctx *ctx = aes_ctx(tfm);
+        int ts_state;
         padlock_reset_key();
+
+        ts_state = irq_ts_save();
         aes_crypt(in, out, ctx->D, &ctx->cword.decrypt);
+        irq_ts_restore(ts_state);
 }
 
 static struct crypto_alg aes_alg = {
@@ -244,12 +259,14 @@ static int ecb_aes_encrypt(struct blkcipher_desc *desc,
         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
         struct blkcipher_walk walk;
         int err;
+        int ts_state;
 
         padlock_reset_key();
 
         blkcipher_walk_init(&walk, dst, src, nbytes);
         err = blkcipher_walk_virt(desc, &walk);
 
+        ts_state = irq_ts_save();
         while ((nbytes = walk.nbytes)) {
                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
                                    ctx->E, &ctx->cword.encrypt,
@@ -257,6 +274,7 @@ static int ecb_aes_encrypt(struct blkcipher_desc *desc,
                 nbytes &= AES_BLOCK_SIZE - 1;
                 err = blkcipher_walk_done(desc, &walk, nbytes);
         }
+        irq_ts_restore(ts_state);
 
         return err;
 }
@@ -268,12 +286,14 @@ static int ecb_aes_decrypt(struct blkcipher_desc *desc,
         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
         struct blkcipher_walk walk;
         int err;
+        int ts_state;
 
         padlock_reset_key();
 
         blkcipher_walk_init(&walk, dst, src, nbytes);
         err = blkcipher_walk_virt(desc, &walk);
 
+        ts_state = irq_ts_save();
         while ((nbytes = walk.nbytes)) {
                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
                                    ctx->D, &ctx->cword.decrypt,
@@ -281,7 +301,7 @@ static int ecb_aes_decrypt(struct blkcipher_desc *desc,
                 nbytes &= AES_BLOCK_SIZE - 1;
                 err = blkcipher_walk_done(desc, &walk, nbytes);
         }
-
+        irq_ts_restore(ts_state);
         return err;
 }
 
@@ -314,12 +334,14 @@ static int cbc_aes_encrypt(struct blkcipher_desc *desc,
         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
         struct blkcipher_walk walk;
         int err;
+        int ts_state;
 
         padlock_reset_key();
 
         blkcipher_walk_init(&walk, dst, src, nbytes);
         err = blkcipher_walk_virt(desc, &walk);
 
+        ts_state = irq_ts_save();
         while ((nbytes = walk.nbytes)) {
                 u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
                                             walk.dst.virt.addr, ctx->E,
@@ -329,6 +351,7 @@ static int cbc_aes_encrypt(struct blkcipher_desc *desc,
                 nbytes &= AES_BLOCK_SIZE - 1;
                 err = blkcipher_walk_done(desc, &walk, nbytes);
         }
+        irq_ts_restore(ts_state);
 
         return err;
 }
@@ -340,12 +363,14 @@ static int cbc_aes_decrypt(struct blkcipher_desc *desc,
         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
         struct blkcipher_walk walk;
         int err;
+        int ts_state;
 
         padlock_reset_key();
 
         blkcipher_walk_init(&walk, dst, src, nbytes);
         err = blkcipher_walk_virt(desc, &walk);
 
+        ts_state = irq_ts_save();
         while ((nbytes = walk.nbytes)) {
                 padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
                                    ctx->D, walk.iv, &ctx->cword.decrypt,
@@ -354,6 +379,7 @@ static int cbc_aes_decrypt(struct blkcipher_desc *desc,
                 err = blkcipher_walk_done(desc, &walk, nbytes);
         }
 
+        irq_ts_restore(ts_state);
         return err;
 }
 
diff --git a/drivers/crypto/padlock-sha.c b/drivers/crypto/padlock-sha.c
index 40d5680fa013..a7fbadebf623 100644
--- a/drivers/crypto/padlock-sha.c
+++ b/drivers/crypto/padlock-sha.c
@@ -22,6 +22,7 @@
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/scatterlist.h>
+#include <asm/i387.h>
 #include "padlock.h"
 
 #define SHA1_DEFAULT_FALLBACK   "sha1-generic"
@@ -102,6 +103,7 @@ static void padlock_do_sha1(const char *in, char *out, int count)
          *     PadLock microcode needs it that big. */
         char buf[128+16];
         char *result = NEAREST_ALIGNED(buf);
+        int ts_state;
 
         ((uint32_t *)result)[0] = SHA1_H0;
         ((uint32_t *)result)[1] = SHA1_H1;
@@ -109,9 +111,12 @@ static void padlock_do_sha1(const char *in, char *out, int count)
         ((uint32_t *)result)[3] = SHA1_H3;
         ((uint32_t *)result)[4] = SHA1_H4;
  
+        /* prevent taking the spurious DNA fault with padlock. */
+        ts_state = irq_ts_save();
         asm volatile (".byte 0xf3,0x0f,0xa6,0xc8" /* rep xsha1 */
                       : "+S"(in), "+D"(result)
                       : "c"(count), "a"(0));
+        irq_ts_restore(ts_state);
 
         padlock_output_block((uint32_t *)result, (uint32_t *)out, 5);
 }
@@ -123,6 +128,7 @@ static void padlock_do_sha256(const char *in, char *out, int count)
          *     PadLock microcode needs it that big. */
         char buf[128+16];
         char *result = NEAREST_ALIGNED(buf);
+        int ts_state;
 
         ((uint32_t *)result)[0] = SHA256_H0;
         ((uint32_t *)result)[1] = SHA256_H1;
@@ -133,9 +139,12 @@ static void padlock_do_sha256(const char *in, char *out, int count)
         ((uint32_t *)result)[6] = SHA256_H6;
         ((uint32_t *)result)[7] = SHA256_H7;
 
+        /* prevent taking the spurious DNA fault with padlock. */
+        ts_state = irq_ts_save();
         asm volatile (".byte 0xf3,0x0f,0xa6,0xd0" /* rep xsha256 */
                       : "+S"(in), "+D"(result)
                       : "c"(count), "a"(0));
+        irq_ts_restore(ts_state);
 
         padlock_output_block((uint32_t *)result, (uint32_t *)out, 8);
 }
diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
index 96fa8449ff11..6d3b21063419 100644
--- a/include/asm-x86/i387.h
+++ b/include/asm-x86/i387.h
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/kernel_stat.h>
 #include <linux/regset.h>
+#include <linux/hardirq.h>
 #include <asm/asm.h>
 #include <asm/processor.h>
 #include <asm/sigcontext.h>
@@ -236,6 +237,37 @@ static inline void kernel_fpu_end(void)
         preempt_enable();
 }
 
+/*
+ * Some instructions like VIA's padlock instructions generate a spurious
+ * DNA fault but don't modify SSE registers. And these instructions
+ * get used from interrupt context aswell. To prevent these kernel instructions
+ * in interrupt context interact wrongly with other user/kernel fpu usage, we
+ * should use them only in the context of irq_ts_save/restore()
+ */
+static inline int irq_ts_save(void)
+{
+        /*
+         * If we are in process context, we are ok to take a spurious DNA fault.
+         * Otherwise, doing clts() in process context require pre-emption to
+         * be disabled or some heavy lifting like kernel_fpu_begin()
+         */
+        if (!in_interrupt())
+                return 0;
+
+        if (read_cr0() & X86_CR0_TS) {
+                clts();
+                return 1;
+        }
+
+        return 0;
+}
+
+static inline void irq_ts_restore(int TS_state)
+{
+        if (TS_state)
+                stts();
+}
+
 #ifdef CONFIG_X86_64
 
 static inline void save_init_fpu(struct task_struct *tsk)