From e24d4b8659edda57906f48987e5b4714e581933f Mon Sep 17 00:00:00 2001
From: Maximilian Stein <m@steiny.biz>
Date: Thu, 11 Mar 2021 19:04:37 +0100
Subject: [PATCH] arch-x86: Add allocator for ACPI tables

This adds an allocator class to allocate memory linearly. It is intended
to be used by ACPI tables to dynamically request memory to write the
ACPI tables to.

Change-Id: I43c71d2b8e676f8ac0fd08b9468b00b6212d85b6
Signed-off-by: Maximilian Stein <m@steiny.biz>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42823
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/arch/x86/bios/acpi.cc | 14 ++++++++++++++
 src/arch/x86/bios/acpi.hh | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/arch/x86/bios/acpi.cc b/src/arch/x86/bios/acpi.cc
index 20cf088807..8cdcdac3f6 100644
--- a/src/arch/x86/bios/acpi.cc
+++ b/src/arch/x86/bios/acpi.cc
@@ -45,6 +45,20 @@
 #include "sim/byteswap.hh"
 #include "sim/sim_object.hh"
 
+Addr
+X86ISA::ACPI::LinearAllocator::alloc(std::size_t size, unsigned align)
+{
+    if (align) {
+        unsigned offset = next % align;
+        if (offset)
+            next += (align - offset);
+    }
+    Addr chunk = next;
+    next += size;
+    assert(0 == end || next <= end);
+    return chunk;
+}
+
 const char X86ISA::ACPI::RSDP::signature[] = "RSD PTR ";
 
 X86ISA::ACPI::RSDP::RSDP(const Params &p) : SimObject(p), oemID(p.oem_id),
diff --git a/src/arch/x86/bios/acpi.hh b/src/arch/x86/bios/acpi.hh
index bc6e2cd19e..6fe0f6e302 100644
--- a/src/arch/x86/bios/acpi.hh
+++ b/src/arch/x86/bios/acpi.hh
@@ -62,6 +62,24 @@ class RSDT;
 class XSDT;
 class SysDescTable;
 
+struct Allocator
+{
+    virtual Addr alloc(std::size_t size, unsigned align=1) = 0;
+};
+struct LinearAllocator : public Allocator
+{
+    LinearAllocator(Addr begin, Addr end=0) :
+        next(begin),
+        end(end)
+    {}
+
+    Addr alloc(std::size_t size, unsigned align) override;
+
+  protected:
+    Addr next;
+    Addr const end;
+};
+
 class RSDP : public SimObject
 {
   protected: