syscall_emul: move mmapGrowsDown() to LiveProcess

The mmapGrowsDown() method was a static method on the OperatingSystem
class (and derived classes), which worked OK for the templated syscall
emulation methods, but made it hard to access elsewhere.  This patch
moves the method to be a virtual function on the LiveProcess method,
where it can be overridden for specific platforms (for now, Alpha).

This patch also changes the value of mmapGrowsDown() from being false
by default and true only on X86Linux32 to being true by default and
false only on Alpha, which seems closer to reality (though in reality
most people use ASLR and this doesn't really matter anymore).

In the process, also got rid of the unused mmap_start field on
LiveProcess and OperatingSystem mmapGrowsUp variable.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/sim/process.hh b/src/sim/process.hh
index df007c9f2..72f789ec7 100644
--- a/src/sim/process.hh
+++ b/src/sim/process.hh
@@ -107,9 +107,13 @@ class Process : public SimObject
     Addr next_thread_stack_base;
 
     // Base of region for mmaps (when user doesn't specify an address).
-    Addr mmap_start;
     Addr mmap_end;
 
+    // Does mmap region grow upward or downward from mmap_end?  Most
+    // platforms grow downward, but a few (such as Alpha) grow upward
+    // instead, so they can override thie method to return false.
+    virtual bool mmapGrowsDown() const { return true; }
+
     // Base of region for nxm data
     Addr nxm_start;
     Addr nxm_end;