gdb/x86: move have_ptrace_getfpxregs global into gdb/nat directory

The have_ptrace_getfpxregs global tracks whether GDB or gdbserver is
running on a kernel that supports the GETFPXREGS ptrace request.

Currently this global is declared twice (once in GDB and once in
gdbserver), I think it makes sense to move this global into the nat/
directory, and have a single declaration and definition.

While moving this variable I have converted it to a tribool, as that
was what it really was, if even used the same numbering as the tribool
enum (-1, 0, 1).  Where have_ptrace_getfpxregs was used I have updated
in the obvious way.

However, while making this change I noticed what I think is a bug in
x86_linux_nat_target::read_description and x86_linux_read_description,
both of these functions can be called multiple times, but in both
cases we only end up calling i386_linux_read_description the first
time through in the event that PTRACE_GETFPXREGS is not supported.
This is because initially have_ptrace_getfpxregs will be
TRIBOOL_UNKNOWN, but after the ptrace call fails we set
have_ptrace_getfpxregs to TRIBOOL_FALSE.  The next time we attempt to
read the target description we'll skip the ptrace call, and so skip
the call to i386_linux_read_description.

I've not tried to address this preexisting bug in this commit, this is
purely a refactor, there should be no user visible changes after this
commit.  In later commits I'll merge the gdbserver and GDB code
together into the nat/ directory, and after that I'll try to address
this bug.

Reviewed-By: Felix Willgerodt <felix.willgerodt@intel.com>

1 files changed, 5 insertions, 14 deletions

diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
index e8ef366..2d99a82 100644
--- a/gdbserver/linux-x86-low.cc
+++ b/gdbserver/linux-x86-low.cc
@@ -29,6 +29,8 @@
 
 #ifdef __x86_64__
 #include "nat/amd64-linux-siginfo.h"
+#else
+#include "nat/i386-linux.h"
 #endif
 
 #include "gdb_proc_service.h"
@@ -831,17 +833,6 @@ x86_target::low_siginfo_fixup (siginfo_t *ptrace, gdb_byte *inf, int direction)
 
 static int use_xml;
 
-/* Does the current host support the GETFPXREGS request?  The header
-   file may or may not define it, and even if it is defined, the
-   kernel will return EIO if it's running on a pre-SSE processor.  */
-int have_ptrace_getfpxregs =
-#ifdef HAVE_PTRACE_GETFPXREGS
-  -1
-#else
-  0
-#endif
-;
-
 /* Get Linux/x86 target description from running target.  */
 
 static const struct target_desc *
@@ -886,18 +877,18 @@ x86_linux_read_description (void)
     }
 
 #if !defined __x86_64__ && defined HAVE_PTRACE_GETFPXREGS
-  if (machine == EM_386 && have_ptrace_getfpxregs == -1)
+  if (machine == EM_386 && have_ptrace_getfpxregs == TRIBOOL_UNKNOWN)
     {
       elf_fpxregset_t fpxregs;
 
       if (ptrace (PTRACE_GETFPXREGS, tid, 0, (long) &fpxregs) < 0)
 	{
-	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getfpxregs = TRIBOOL_FALSE;
 	  have_ptrace_getregset = TRIBOOL_FALSE;
 	  return i386_linux_read_description (X86_XSTATE_X87);
 	}
       else
-	have_ptrace_getfpxregs = 1;
+	have_ptrace_getfpxregs = TRIBOOL_TRUE;
     }
 #endif