Seccomp sandbox changes (performance and correctness fixes, primarily targetting x86-32)

sandbox/linux/seccomp/securemem.h

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 #ifndef SECURE_MEM_H__
 #define SECURE_MEM_H__
 
 #include <stdlib.h>
 
 namespace playground {
 
 class SecureMem {
  public:
   // Each thread is associated with two memory pages (i.e. 8192 bytes). This
@@ skipping 32 matching lines @@
             void*        rdi;
             void*        r8;
             void*        r9;
             void*        r10;
             void*        r11;
             void*        r12;
             void*        r13;
             void*        r14;
             void*        r15;
             #elif defined(__i386__)
-            void*        ret2;
             void*        ebp;
             void*        edi;
             void*        esi;
             void*        edx;
             void*        ecx;
             void*        ebx;
             #else
             #error Unsupported target platform
             #endif
 
@@ skipping 15 matching lines @@
             long long    threadFdPub;
           } __attribute__((packed));
           char           header[512];
         };
         // Used for calls such as open() and stat().
         char             pathname[4096 - 512];
       } __attribute__((packed));
       char               securePage[4096];
     };
     union {
-      // This scratch space is used by the trusted thread to read parameters
-      // for unrestricted system calls.
       struct {
+        // This scratch space is used by the trusted thread to read parameters
+        // for unrestricted system calls.
         long             tmpSyscallNum;
         void*            tmpArg1;
         void*            tmpArg2;
         void*            tmpArg3;
         void*            tmpArg4;
         void*            tmpArg5;
         void*            tmpArg6;
         void*            tmpReturnValue;
+
+        // We often have long sequences of calls to gettimeofday(). This is
+        // needlessly expensive. Coalesce them into a single call.
+        long             lastSyscallNum;
+        int              gettimeofdayCounter;
       } __attribute__((packed));
       char               scratchPage[4096];
     };
   } __attribute__((packed)) Args;
 
   // Allows the trusted process to check whether the parent process still
   // exists. If it doesn't, kill the trusted process.
   static void dieIfParentDied(int parentProc);
 
   // The trusted process received a system call that it intends to deny.
@@ skipping 60 matching lines @@
   static void sendSystemCallInternal(int fd, bool locked, int parentProc,
                                      Args* mem, int syscallNum, void* arg1 = 0,
                                      void* arg2 = 0, void* arg3 = 0,
                                      void* arg4 = 0, void* arg5 = 0,
                                      void* arg6 = 0);
 };
 
 } // namespace
 
 #endif // SECURE_MEM_H__