From a3385dadcb0ffb53da32d2690c0ea8157e2419bd Mon Sep 17 00:00:00 2001
From: Gabe Black <gabeblack@google.com>
Date: Wed, 22 Aug 2018 16:49:22 -0700
Subject: base: If valgrind is available, tell it about Fiber stacks.

Valgrind can get confused when  switching stacks between different
Fibers. If valgrind (and its headers) are available, this change adds
calls to some hooks so valgrind knows where the new stacks are and
doesn't report a bunch of false positives.

Change-Id: I00aefe60372be6de7371dec29427d7182dbee7b6
Reviewed-on: https://gem5-review.googlesource.com/12227
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabeblack@google.com>
---
 SConstruct        |  8 ++++++--
 src/base/fiber.cc | 13 ++++++++++++-
 src/base/fiber.hh |  5 +++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/SConstruct b/SConstruct
index 5209aa6d4..79522e46f 100755
--- a/SConstruct
+++ b/SConstruct
@@ -783,6 +783,10 @@ main['HAVE_PROTOBUF'] = main['PROTOC'] and \
     conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
                             'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
 
+# Valgrind gets much less confused if you tell it when you're using
+# alternative stacks.
+main['HAVE_VALGRIND'] = conf.CheckCHeader('valgrind/valgrind.h')
+
 # If we have the compiler but not the library, print another warning.
 if main['PROTOC'] and not main['HAVE_PROTOBUF']:
     print(termcap.Yellow + termcap.Bold +
@@ -1012,8 +1016,8 @@ sticky_vars.AddVariables(
 # These variables get exported to #defines in config/*.hh (see src/SConscript).
 export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'TARGET_GPU_ISA',
                 'CP_ANNOTATE', 'USE_POSIX_CLOCK', 'USE_KVM', 'USE_TUNTAP',
-                'PROTOCOL', 'HAVE_PROTOBUF', 'HAVE_PERF_ATTR_EXCLUDE_HOST',
-                'USE_PNG']
+                'PROTOCOL', 'HAVE_PROTOBUF', 'HAVE_VALGRIND',
+                'HAVE_PERF_ATTR_EXCLUDE_HOST', 'USE_PNG']
 
 ###################################################
 #
diff --git a/src/base/fiber.cc b/src/base/fiber.cc
index f10f1fbfd..eac1d9394 100644
--- a/src/base/fiber.cc
+++ b/src/base/fiber.cc
@@ -29,6 +29,10 @@
 
 #include "base/fiber.hh"
 
+#if HAVE_VALGRIND
+#include <valgrind/valgrind.h>
+#endif
+
 #include <cerrno>
 #include <cstring>
 
@@ -71,7 +75,11 @@ Fiber::Fiber(size_t stack_size) :
     link(primaryFiber()),
     stack(stack_size ? new uint8_t[stack_size] : nullptr),
     stackSize(stack_size), started(false), _finished(false)
-{}
+{
+#if HAVE_VALGRIND
+    valgrindStackId = VALGRIND_STACK_REGISTER(stack, stack + stack_size);
+#endif
+}
 
 Fiber::Fiber(Fiber *link, size_t stack_size) :
     link(link), stack(stack_size ? new uint8_t[stack_size] : nullptr),
@@ -81,6 +89,9 @@ Fiber::Fiber(Fiber *link, size_t stack_size) :
 Fiber::~Fiber()
 {
     panic_if(stack && _currentFiber == this, "Fiber stack is in use.");
+#if HAVE_VALGRIND
+    VALGRIND_STACK_DEREGISTER(valgrindStackId);
+#endif
     delete [] stack;
 }
 
diff --git a/src/base/fiber.hh b/src/base/fiber.hh
index 5f7285b29..3d82075f0 100644
--- a/src/base/fiber.hh
+++ b/src/base/fiber.hh
@@ -44,6 +44,8 @@
 #include <cstddef>
 #include <cstdint>
 
+#include "config/have_valgrind.hh"
+
 /**
  * This class represents a fiber, which is a light weight sort of thread which
  * is cooperatively scheduled and runs sequentially with other fibers, swapping
@@ -106,6 +108,9 @@ class Fiber
     // The stack for this context, or a nullptr if allocated elsewhere.
     uint8_t *stack;
     size_t stackSize;
+#if HAVE_VALGRIND
+    unsigned valgrindStackId;
+#endif
 
     bool started;
     bool _finished;
-- 
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