A mechanism to identify/forbid/"rewrite" non-temporal instructions (and other)

src/trusted/service_runtime/sel_validate_image.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "native_client/src/include/concurrency_ops.h"
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/shared/utils/types.h"
 #include "native_client/src/trusted/service_runtime/sel_ldr.h"
@@ skipping 17 matching lines @@
       return LOAD_VALIDATION_FAILED;
   }
 }
 
 int NaClValidateCode(struct NaClApp *nap, uintptr_t guest_addr,
                      uint8_t *data, size_t size,
                      const struct NaClValidationMetadata *metadata) {
   NaClValidationStatus status = NaClValidationSucceeded;
   struct NaClValidationCache *cache = nap->validation_cache;
   const struct NaClValidatorInterface *validator = nap->validator;
+  uint32_t flags = nap->pnacl_mode ? DISABLE_NONTEMPORALS : 0;
 
   if (size < kMinimumCachedCodeSize) {
     /*
      * Don't cache the validation of small code chunks for three reasons:
      * 1) The size of the validation cache will be bounded.  Cache entries are
      *    better used for bigger code.
      * 2) The per-transaction overhead of validation caching is more noticeable
      *    for small code.
      * 3) JITs tend to generate a lot of small code chunks, and JITed code may
      *    never be seen again.  Currently code size is the best mechanism we
@@ skipping 18 matching lines @@
   }
   if (nap->validator_stub_out_mode) {
     /* Validation caching is currently incompatible with stubout. */
     metadata = NULL;
     cache = NULL;
     /* In stub out mode, we do two passes.  The second pass acts as a
        sanity check that bad instructions were indeed overwritten with
        allowable HLTs. */
     status = validator->Validate(guest_addr, data, size,
                                  TRUE, /* stub out */
+                                 flags,
                                  FALSE, /* text is not read-only */
                                  nap->cpu_features,
                                  metadata,
                                  cache);
   }
   if (status == NaClValidationSucceeded) {
     /* Fixed feature CPU mode implies read-only. */
     int readonly_text = nap->fixed_feature_cpu_mode;
     status = validator->Validate(guest_addr, data, size,
                                  FALSE, /* do not stub out */
+                                 flags,
                                  readonly_text,
                                  nap->cpu_features,
                                  metadata,
                                  cache);
   }
   return NaClValidateStatus(status);
 }
 
 int NaClValidateCodeReplacement(struct NaClApp *nap, uintptr_t guest_addr,
                                 uint8_t *data_old, uint8_t *data_new,
@@ skipping 68 matching lines @@
         NaClLog(LOG_ERROR,
                 "Run sel_ldr in debug mode to ignore validation failure.\n");
         NaClLog(LOG_ERROR,
                 "Run ncval <module-name> for validation error details.\n");
         rcode = LOAD_VALIDATION_FAILED;
       }
     }
   }
   return rcode;
 }