From 0172089203592037f99fc89126285896c73e6a60 Mon Sep 17 00:00:00 2001
From: Gabe Black <gabeblack@google.com>
Date: Sun, 29 Mar 2020 03:14:50 -0700
Subject: [PATCH] mem: Support initializing a memory with an image file.

This is particularly useful for ROMs. It avoids forcing other components
of the simulation (the System object, the Workload object) from having
to know what ROMs exist, where they are, and what goes on them, and
leaves that to the config script.

Change-Id: Ibbcffffcb82e0d289f0b3942728c30b8f69d28ba
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27267
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/mem/AbstractMemory.py |  5 +++++
 src/mem/abstract_mem.cc   | 34 ++++++++++++++++++++++++++++++++++
 src/mem/abstract_mem.hh   |  2 ++
 3 files changed, 41 insertions(+)

diff --git a/src/mem/AbstractMemory.py b/src/mem/AbstractMemory.py
index 897e9e3cd..4c21d529c 100644
--- a/src/mem/AbstractMemory.py
+++ b/src/mem/AbstractMemory.py
@@ -64,3 +64,8 @@ class AbstractMemory(ClockedObject):
     # configuration information about the physical memory layout to
     # the kernel, e.g. using ATAG or ACPI
     conf_table_reported = Param.Bool(True, "Report to configuration table")
+
+    # Image file to load into this memory as its initial contents. This is
+    # particularly useful for ROMs.
+    image_file = Param.String('',
+            "Image to load into memory as its initial contents")
diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index b5412badf..aa800113b 100644
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -43,6 +43,8 @@
 #include <vector>
 
 #include "arch/locked_mem.hh"
+#include "base/loader/memory_image.hh"
+#include "base/loader/object_file.hh"
 #include "cpu/base.hh"
 #include "cpu/thread_context.hh"
 #include "debug/LLSC.hh"
@@ -66,6 +68,38 @@ AbstractMemory::AbstractMemory(const Params *p) :
              range.to_string());
 }
 
+void
+AbstractMemory::initState()
+{
+    ClockedObject::initState();
+
+    const auto &file = params()->image_file;
+    if (file == "")
+        return;
+
+    auto *object = createObjectFile(file, true);
+    fatal_if(!object, "%s: Could not load %s.", name(), file);
+
+    panic_if(!object->loadGlobalSymbols(debugSymbolTable),
+             "%s: Could not load symbols from %s.", name(), file);
+
+    MemoryImage image = object->buildImage();
+
+    AddrRange image_range(image.minAddr(), image.maxAddr());
+    if (!range.contains(image_range.start())) {
+        warn("%s: Moving image from %s to memory address range %s.",
+                name(), image_range.to_string(), range.to_string());
+        image = image.offset(range.start());
+        image_range = AddrRange(image.minAddr(), image.maxAddr());
+    }
+    panic_if(!image_range.isSubset(range), "%s: memory image %s doesn't fit.",
+             name(), file);
+
+    PortProxy proxy([this](PacketPtr pkt) { functionalAccess(pkt); }, size());
+
+    panic_if(!image.write(proxy), "%s: Unable to write image.");
+}
+
 void
 AbstractMemory::setBackingStore(uint8_t* pmem_addr)
 {
diff --git a/src/mem/abstract_mem.hh b/src/mem/abstract_mem.hh
index b1d54fdeb..616fd0e26 100644
--- a/src/mem/abstract_mem.hh
+++ b/src/mem/abstract_mem.hh
@@ -209,6 +209,8 @@ class AbstractMemory : public ClockedObject
     AbstractMemory(const Params* p);
     virtual ~AbstractMemory() {}
 
+    void initState() override;
+
     /**
      * See if this is a null memory that should never store data and
      * always return zero.
-- 
2.30.2