syscall_emul: Put BufferArg classes in a separate header.

Move the BufferArg classes that support syscall buffer args
(i.e., pointers into simulated user space) out of syscall_emul.hh
and into a new header syscall_emul_buf.hh so they are accessible
to emulated driver implementations.

Take the opportunity to add some comments as well.

1 files changed, 168 insertions, 0 deletions

diff --git a/src/sim/syscall_emul_buf.hh b/src/sim/syscall_emul_buf.hh
new file mode 100644
index 000000000..cbd10f2f6
--- /dev/null
+++ b/src/sim/syscall_emul_buf.hh
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2003-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Steve Reinhardt
+ */
+
+#ifndef __SIM_SYSCALL_EMUL_BUF_HH__
+#define __SIM_SYSCALL_EMUL_BUF_HH__
+
+///
+/// @file syscall_emul_buf.hh
+///
+/// This file defines buffer classes used to handle pointer arguments
+/// in emulated syscalls.
+
+#include <cstring>
+
+#include "base/types.hh"
+#include "mem/se_translating_port_proxy.hh"
+
+/**
+ * Base class for BufferArg and TypedBufferArg, Not intended to be
+ * used directly.
+ *
+ * The BufferArg classes represent buffers in target user space that
+ * are passed by reference to an (emulated) system call.  Each
+ * instance provides an internal (simulator-space) buffer of the
+ * appropriate size and tracks the user-space address.  The copyIn()
+ * and copyOut() methods copy the user-space buffer to and from the
+ * simulator-space buffer, respectively.
+ */
+class BaseBufferArg {
+
+  public:
+
+    /**
+     * Allocate a buffer of size 'size' representing the memory at
+     * target address 'addr'.
+     */
+    BaseBufferArg(Addr _addr, int _size)
+        : addr(_addr), size(_size), bufPtr(new uint8_t[size])
+    {
+        // clear out buffer: in case we only partially populate this,
+        // and then do a copyOut(), we want to make sure we don't
+        // introduce any random junk into the simulated address space
+        memset(bufPtr, 0, size);
+    }
+
+    virtual ~BaseBufferArg() { delete [] bufPtr; }
+
+    /**
+     * copy data into simulator space (read from target memory)
+     */
+    virtual bool copyIn(SETranslatingPortProxy &memproxy)
+    {
+        memproxy.readBlob(addr, bufPtr, size);
+        return true;    // no EFAULT detection for now
+    }
+
+    /**
+     * copy data out of simulator space (write to target memory)
+     */
+    virtual bool copyOut(SETranslatingPortProxy &memproxy)
+    {
+        memproxy.writeBlob(addr, bufPtr, size);
+        return true;    // no EFAULT detection for now
+    }
+
+  protected:
+    const Addr addr;        ///< address of buffer in target address space
+    const int size;         ///< buffer size
+    uint8_t * const bufPtr; ///< pointer to buffer in simulator space
+};
+
+/**
+ * BufferArg represents an untyped buffer in target user space that is
+ * passed by reference to an (emulated) system call.
+ */
+class BufferArg : public BaseBufferArg
+{
+  public:
+    /**
+     * Allocate a buffer of size 'size' representing the memory at
+     * target address 'addr'.
+     */
+    BufferArg(Addr _addr, int _size) : BaseBufferArg(_addr, _size) { }
+
+    /**
+     * Return a pointer to the internal simulator-space buffer.
+     */
+    void *bufferPtr() { return bufPtr; }
+};
+
+/**
+ * TypedBufferArg is a class template; instances of this template
+ * represent typed buffers in target user space that are passed by
+ * reference to an (emulated) system call.
+ *
+ * This template provides operator overloads for convenience, allowing
+ * for example the use of '->' to reference fields within a struct
+ * type.
+ */
+template <class T>
+class TypedBufferArg : public BaseBufferArg
+{
+  public:
+    /**
+     * Allocate a buffer of type T representing the memory at target
+     * address 'addr'. The user can optionally specify a specific
+     * number of bytes to allocate to deal with structs that have
+     * variable-size arrays at the end.
+     */
+    TypedBufferArg(Addr _addr, int _size = sizeof(T))
+        : BaseBufferArg(_addr, _size)
+    { }
+
+    /**
+     * Convert TypedBufferArg<T> to a pointer to T that points to the
+     * internal buffer.
+     */
+    operator T*() { return (T *)bufPtr; }
+
+    /**
+     * Convert TypedBufferArg<T> to a reference to T that references the
+     * internal buffer value.
+     */
+    T &operator*()       { return *((T *)bufPtr); }
+
+
+    /**
+     * Enable the use of '->' to reference fields where T is a struct
+     * type.
+     */
+    T* operator->()      { return (T *)bufPtr; }
+
+    /**
+     * Enable the use of '[]' to reference fields where T is an array
+     * type.
+     */
+    T &operator[](int i) { return ((T *)bufPtr)[i]; }
+};
+
+
+#endif // __SIM_SYSCALL_EMUL_BUF_HH__