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

@@ -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']
 
 ###################################################
 #

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;
 }
 

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;