Syscalls: Make system calls access arguments like a stack, not an array.

When accessing arguments for a syscall, the position of an argument depends on
the policies of the ISA, how much space preceding arguments took up, and the
"alignment" of the index for this particular argument into the number of
possible storate locations. This change adjusts getSyscallArg to take its
index parameter by reference instead of value and to adjust it to point to the
possible location of the next argument on the stack, basically just after the
current one. This way, the rules for the new argument can be applied locally
without knowing about other arguments since those have already been taken into
account implicitly.

All system calls have also been changed to reflect the new interface. In a
number of cases this made the implementation clearer since it encourages
arguments to be collected in one place in order and then used as necessary
later, as opposed to scattering them throughout the function or using them in
place in long expressions. It also discourages using getSyscallArg over and
over to retrieve the same value when a temporary would do the job.

1 files changed, 104 insertions, 66 deletions

diff --git a/src/sim/syscall_emul.hh b/src/sim/syscall_emul.hh
index 0c51c7dec..8fe53e266 100644
--- a/src/sim/syscall_emul.hh
+++ b/src/sim/syscall_emul.hh
@@ -481,8 +481,9 @@ SyscallReturn
 ioctlFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
           ThreadContext *tc)
 {
-    int fd = process->getSyscallArg(tc, 0);
-    unsigned req = process->getSyscallArg(tc, 1);
+    int index = 0;
+    int fd = process->getSyscallArg(tc, index);
+    unsigned req = process->getSyscallArg(tc, index);
 
     DPRINTF(SyscallVerbose, "ioctl(%d, 0x%x, ...)\n", fd, req);
 
@@ -517,7 +518,9 @@ openFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index)))
         return -EFAULT;
 
     if (path == "/dev/sysdev0") {
@@ -527,8 +530,8 @@ openFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
         return -ENOENT;
     }
 
-    int tgtFlags = process->getSyscallArg(tc, 1);
-    int mode = process->getSyscallArg(tc, 2);
+    int tgtFlags = process->getSyscallArg(tc, index);
+    int mode = process->getSyscallArg(tc, index);
     int hostFlags = 0;
 
     // translate open flags
@@ -573,14 +576,16 @@ sysinfoFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
          ThreadContext *tc)
 {
 
-   TypedBufferArg<typename OS::tgt_sysinfo> sysinfo(process->getSyscallArg(tc, 0));   
+    int index = 0;
+    TypedBufferArg<typename OS::tgt_sysinfo>
+        sysinfo(process->getSyscallArg(tc, index));   
 
-   sysinfo->uptime=seconds_since_epoch;
-   sysinfo->totalram=process->system->memSize();
+    sysinfo->uptime=seconds_since_epoch;
+    sysinfo->totalram=process->system->memSize();
 
-   sysinfo.copyOut(tc->getMemPort());
+    sysinfo.copyOut(tc->getMemPort());
 
-   return 0;
+    return 0;
 }
 
 /// Target chmod() handler.
@@ -591,10 +596,13 @@ chmodFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
         return -EFAULT;
+    }
 
-    uint32_t mode = process->getSyscallArg(tc, 1);
+    uint32_t mode = process->getSyscallArg(tc, index);
     mode_t hostMode = 0;
 
     // XXX translate mode flags via OS::something???
@@ -618,13 +626,14 @@ SyscallReturn
 fchmodFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
            ThreadContext *tc)
 {
-    int fd = process->getSyscallArg(tc, 0);
+    int index = 0;
+    int fd = process->getSyscallArg(tc, index);
     if (fd < 0 || process->sim_fd(fd) < 0) {
         // doesn't map to any simulator fd: not a valid target fd
         return -EBADF;
     }
 
-    uint32_t mode = process->getSyscallArg(tc, 1);
+    uint32_t mode = process->getSyscallArg(tc, index);
     mode_t hostMode = 0;
 
     // XXX translate mode flags via OS::someting???
@@ -643,10 +652,11 @@ template <class OS>
 SyscallReturn
 mremapFunc(SyscallDesc *desc, int callnum, LiveProcess *process, ThreadContext *tc)
 {
-    Addr start = process->getSyscallArg(tc, 0);
-    uint64_t old_length = process->getSyscallArg(tc, 1);
-    uint64_t new_length = process->getSyscallArg(tc, 2);
-    uint64_t flags = process->getSyscallArg(tc, 3);
+    int index = 0;
+    Addr start = process->getSyscallArg(tc, index);
+    uint64_t old_length = process->getSyscallArg(tc, index);
+    uint64_t new_length = process->getSyscallArg(tc, index);
+    uint64_t flags = process->getSyscallArg(tc, index);
 
     if ((start % TheISA::VMPageSize != 0) ||
             (new_length % TheISA::VMPageSize != 0)) {
@@ -692,8 +702,12 @@ statFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
-    return -EFAULT;
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
+        return -EFAULT;
+    }
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     // Adjust path for current working directory
     path = process->fullPath(path);
@@ -704,8 +718,7 @@ statFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStatBuf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-            &hostBuf);
+    copyOutStatBuf<OS>(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -719,8 +732,11 @@ stat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index)))
         return -EFAULT;
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     // Adjust path for current working directory
     path = process->fullPath(path);
@@ -736,8 +752,7 @@ stat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStat64Buf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-            &hostBuf);
+    copyOutStat64Buf<OS>(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -749,7 +764,9 @@ SyscallReturn
 fstat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
             ThreadContext *tc)
 {
-    int fd = process->getSyscallArg(tc, 0);
+    int index = 0;
+    int fd = process->getSyscallArg(tc, index);
+    Addr bufPtr = process->getSyscallArg(tc, index);
     if (fd < 0 || process->sim_fd(fd) < 0) {
         // doesn't map to any simulator fd: not a valid target fd
         return -EBADF;
@@ -766,8 +783,7 @@ fstat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStat64Buf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-        &hostBuf, (fd == 1));
+    copyOutStat64Buf<OS>(tc->getMemPort(), bufPtr, &hostBuf, (fd == 1));
 
     return 0;
 }
@@ -781,8 +797,12 @@ lstatFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
-      return -EFAULT;
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
+        return -EFAULT;
+    }
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     // Adjust path for current working directory
     path = process->fullPath(path);
@@ -793,8 +813,7 @@ lstatFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStatBuf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-            &hostBuf);
+    copyOutStatBuf<OS>(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -807,8 +826,12 @@ lstat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
-      return -EFAULT;
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
+        return -EFAULT;
+    }
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     // Adjust path for current working directory
     path = process->fullPath(path);
@@ -824,8 +847,7 @@ lstat64Func(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStat64Buf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-            &hostBuf);
+    copyOutStat64Buf<OS>(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -836,7 +858,9 @@ SyscallReturn
 fstatFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
           ThreadContext *tc)
 {
-    int fd = process->sim_fd(process->getSyscallArg(tc, 0));
+    int index = 0;
+    int fd = process->sim_fd(process->getSyscallArg(tc, index));
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     DPRINTF(SyscallVerbose, "fstat(%d, ...)\n", fd);
 
@@ -849,8 +873,7 @@ fstatFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    copyOutStatBuf<OS>(tc->getMemPort(), process->getSyscallArg(tc, 1),
-        &hostBuf, (fd == 1));
+    copyOutStatBuf<OS>(tc->getMemPort(), bufPtr, &hostBuf, (fd == 1));
 
     return 0;
 }
@@ -864,8 +887,12 @@ statfsFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
-      return -EFAULT;
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
+        return -EFAULT;
+    }
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     // Adjust path for current working directory
     path = process->fullPath(path);
@@ -876,8 +903,7 @@ statfsFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    OS::copyOutStatfsBuf(tc->getMemPort(),
-            (Addr)(process->getSyscallArg(tc, 1)), &hostBuf);
+    OS::copyOutStatfsBuf(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -889,7 +915,9 @@ SyscallReturn
 fstatfsFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
             ThreadContext *tc)
 {
-    int fd = process->sim_fd(process->getSyscallArg(tc, 0));
+    int index = 0;
+    int fd = process->sim_fd(process->getSyscallArg(tc, index));
+    Addr bufPtr = process->getSyscallArg(tc, index);
 
     if (fd < 0)
         return -EBADF;
@@ -900,8 +928,7 @@ fstatfsFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     if (result < 0)
         return -errno;
 
-    OS::copyOutStatfsBuf(tc->getMemPort(), process->getSyscallArg(tc, 1),
-        &hostBuf);
+    OS::copyOutStatfsBuf(tc->getMemPort(), bufPtr, &hostBuf);
 
     return 0;
 }
@@ -913,15 +940,16 @@ SyscallReturn
 writevFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
            ThreadContext *tc)
 {
-    int fd = process->getSyscallArg(tc, 0);
+    int index = 0;
+    int fd = process->getSyscallArg(tc, index);
     if (fd < 0 || process->sim_fd(fd) < 0) {
         // doesn't map to any simulator fd: not a valid target fd
         return -EBADF;
     }
 
     TranslatingPort *p = tc->getMemPort();
-    uint64_t tiov_base = process->getSyscallArg(tc, 1);
-    size_t count = process->getSyscallArg(tc, 2);
+    uint64_t tiov_base = process->getSyscallArg(tc, index);
+    size_t count = process->getSyscallArg(tc, index);
     struct iovec hiov[count];
     for (size_t i = 0; i < count; ++i) {
         typename OS::tgt_iovec tiov;
@@ -962,12 +990,13 @@ template <class OS>
 SyscallReturn
 mmapFunc(SyscallDesc *desc, int num, LiveProcess *p, ThreadContext *tc)
 {
-    Addr start = p->getSyscallArg(tc, 0);
-    uint64_t length = p->getSyscallArg(tc, 1);
-    // int prot = p->getSyscallArg(tc, 2);
-    int flags = p->getSyscallArg(tc, 3);
-    // int fd = p->sim_fd(p->getSyscallArg(tc, 4));
-    // int offset = p->getSyscallArg(tc, 5);
+    int index = 0;
+    Addr start = p->getSyscallArg(tc, index);
+    uint64_t length = p->getSyscallArg(tc, index);
+    index++; // int prot = p->getSyscallArg(tc, index);
+    int flags = p->getSyscallArg(tc, index);
+    int fd = p->sim_fd(p->getSyscallArg(tc, index));
+    // int offset = p->getSyscallArg(tc, index);
 
 
     if ((start  % TheISA::VMPageSize) != 0 ||
@@ -995,7 +1024,7 @@ mmapFunc(SyscallDesc *desc, int num, LiveProcess *p, ThreadContext *tc)
 
     if (!(flags & OS::TGT_MAP_ANONYMOUS)) {
         warn("allowing mmap of file @ fd %d. "
-             "This will break if not /dev/zero.", p->getSyscallArg(tc, 4));
+             "This will break if not /dev/zero.", fd);
     }
 
     return start;
@@ -1007,8 +1036,9 @@ SyscallReturn
 getrlimitFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
         ThreadContext *tc)
 {
-    unsigned resource = process->getSyscallArg(tc, 0);
-    TypedBufferArg<typename OS::rlimit> rlp(process->getSyscallArg(tc, 1));
+    int index = 0;
+    unsigned resource = process->getSyscallArg(tc, index);
+    TypedBufferArg<typename OS::rlimit> rlp(process->getSyscallArg(tc, index));
 
     switch (resource) {
         case OS::TGT_RLIMIT_STACK:
@@ -1042,7 +1072,8 @@ SyscallReturn
 gettimeofdayFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
         ThreadContext *tc)
 {
-    TypedBufferArg<typename OS::timeval> tp(process->getSyscallArg(tc, 0));
+    int index = 0;
+    TypedBufferArg<typename OS::timeval> tp(process->getSyscallArg(tc, index));
 
     getElapsedTime(tp->tv_sec, tp->tv_usec);
     tp->tv_sec += seconds_since_epoch;
@@ -1063,10 +1094,14 @@ utimesFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
 {
     std::string path;
 
-    if (!tc->getMemPort()->tryReadString(path, process->getSyscallArg(tc, 0)))
-      return -EFAULT;
+    int index = 0;
+    if (!tc->getMemPort()->tryReadString(path,
+                process->getSyscallArg(tc, index))) {
+        return -EFAULT;
+    }
 
-    TypedBufferArg<typename OS::timeval [2]> tp(process->getSyscallArg(tc, 1));
+    TypedBufferArg<typename OS::timeval [2]>
+        tp(process->getSyscallArg(tc, index));
     tp.copyIn(tc->getMemPort());
 
     struct timeval hostTimeval[2];
@@ -1092,8 +1127,9 @@ SyscallReturn
 getrusageFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
               ThreadContext *tc)
 {
-    int who = process->getSyscallArg(tc, 0);     // THREAD, SELF, or CHILDREN
-    TypedBufferArg<typename OS::rusage> rup(process->getSyscallArg(tc, 1));
+    int index = 0;
+    int who = process->getSyscallArg(tc, index); // THREAD, SELF, or CHILDREN
+    TypedBufferArg<typename OS::rusage> rup(process->getSyscallArg(tc, index));
 
     rup->ru_utime.tv_sec = 0;
     rup->ru_utime.tv_usec = 0;
@@ -1143,7 +1179,8 @@ SyscallReturn
 timesFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
            ThreadContext *tc)
 {
-    TypedBufferArg<typename OS::tms> bufp(process->getSyscallArg(tc, 0));
+    int index = 0;
+    TypedBufferArg<typename OS::tms> bufp(process->getSyscallArg(tc, index));
 
     // Fill in the time structure (in clocks)
     int64_t clocks = curTick * OS::_SC_CLK_TCK / Clock::Int::s;
@@ -1172,7 +1209,8 @@ timeFunc(SyscallDesc *desc, int callnum, LiveProcess *process,
     getElapsedTime(sec, usec);
     sec += seconds_since_epoch;
 
-    Addr taddr = (Addr)process->getSyscallArg(tc, 0);
+    int index = 0;
+    Addr taddr = (Addr)process->getSyscallArg(tc, index);
     if(taddr != 0) {
         typename OS::time_t t = sec;
         t = htog(t);