From 711f7a3009a1fe3ea93fcb45877569acc598c85f Mon Sep 17 00:00:00 2001
From: Sandipan Das <sandipan@linux.ibm.com>
Date: Mon, 5 Jul 2021 12:46:16 +0530
Subject: [PATCH] arch-power: Add clone support

This adds support for the clone() system call using
which multiple cpus can be utilized in SE mode. For
this change, it should be noted that Linux on Power
uses the CLONE_BACKWARDS argument order.

Change-Id: Iac91a7d110d9f7a133b8e102ac113f48a431a0d6
Signed-off-by: Kevin Joe <0keik0de@gmail.com>
Signed-off-by: Chetan Agarwal <chetanag35@gmail.com>
Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47579
Reviewed-by: Boris Shingarov <shingarov@labware.com>
Maintainer: Boris Shingarov <shingarov@labware.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/arch/power/linux/linux.hh       | 18 ++++++++++++++++++
 src/arch/power/linux/se_workload.cc |  2 +-
 src/arch/power/regs/int.hh          |  1 +
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/arch/power/linux/linux.hh b/src/arch/power/linux/linux.hh
index cdb1cda200..646d64271a 100644
--- a/src/arch/power/linux/linux.hh
+++ b/src/arch/power/linux/linux.hh
@@ -32,6 +32,9 @@
 
 #include <map>
 
+#include "arch/power/isa.hh"
+#include "arch/power/regs/int.hh"
+#include "cpu/thread_context.hh"
 #include "kern/linux/linux.hh"
 
 namespace gem5
@@ -214,6 +217,21 @@ class PowerLinux : public Linux
             return false;
         }
     }
+
+    static void
+    archClone(uint64_t flags,
+              Process *pp, Process *cp,
+              ThreadContext *ptc, ThreadContext *ctc,
+              uint64_t stack, uint64_t tls)
+    {
+        ctc->getIsaPtr()->copyRegsFrom(ptc);
+
+        if (flags & TGT_CLONE_SETTLS)
+            ctc->setIntReg(PowerISA::ThreadPointerReg, tls);
+
+        if (stack)
+            ctc->setIntReg(PowerISA::StackPointerReg, stack);
+    }
 };
 
 } // namespace gem5
diff --git a/src/arch/power/linux/se_workload.cc b/src/arch/power/linux/se_workload.cc
index 9d5f9de3b8..b49cb0b11b 100644
--- a/src/arch/power/linux/se_workload.cc
+++ b/src/arch/power/linux/se_workload.cc
@@ -227,7 +227,7 @@ SyscallDescTable<PowerISA::SEWorkload::SyscallABI> EmuLinux::syscallDescs = {
     { 117, "ipc" },
     { 118, "fsync" },
     { 119, "sigreturn" },
-    { 120, "clone" },
+    { 120, "clone", cloneBackwardsFunc<PowerLinux> },
     { 121, "setdomainname" },
     { 122, "uname", unameFunc },
     { 123, "modify_ldt" },
diff --git a/src/arch/power/regs/int.hh b/src/arch/power/regs/int.hh
index 891eaa16c6..95fbb8adf8 100644
--- a/src/arch/power/regs/int.hh
+++ b/src/arch/power/regs/int.hh
@@ -55,6 +55,7 @@ const int ArgumentReg4 = 7;
 const int ArgumentReg5 = 8;
 const int StackPointerReg = 1;
 const int TOCPointerReg = 2;
+const int ThreadPointerReg = 13;
 
 enum MiscIntRegNums
 {