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>

8 files changed, 62 insertions, 46 deletions

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 3752bdf..277f878 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1397,7 +1397,6 @@ HFILES_NO_SRCDIR = \
 	hppa-tdep.h \
 	i386-bsd-nat.h \
 	i386-darwin-tdep.h \
-	i386-linux-nat.h \
 	i386-linux-tdep.h \
 	i386-tdep.h \
 	i387-tdep.h \
@@ -1594,6 +1593,7 @@ HFILES_NO_SRCDIR = \
 	nat/gdb_ptrace.h \
 	nat/gdb_thread_db.h \
 	nat/fork-inferior.h \
+	nat/i386-linux.h \
 	nat/linux-btrace.h \
 	nat/linux-namespaces.h \
 	nat/linux-nat.h \
diff --git a/gdb/configure.nat b/gdb/configure.nat
index 8b98511..25268bb 100644
--- a/gdb/configure.nat
+++ b/gdb/configure.nat
@@ -256,7 +256,7 @@ case ${gdb_host} in
 		NATDEPFILES="${NATDEPFILES} x86-nat.o nat/x86-dregs.o \
 		nat/x86-xstate.o \
 		i386-linux-nat.o x86-linux-nat.o nat/linux-btrace.o \
-		nat/x86-linux.o nat/x86-linux-dregs.o"
+		nat/x86-linux.o nat/x86-linux-dregs.o nat/i386-linux.o"
 		;;
 	    ia64)
 		# Host: Intel IA-64 running GNU/Linux
diff --git a/gdb/i386-linux-nat.c b/gdb/i386-linux-nat.c
index 7278dd9..bfe3fb8 100644
--- a/gdb/i386-linux-nat.c
+++ b/gdb/i386-linux-nat.c
@@ -26,7 +26,7 @@
 #include "gregset.h"
 #include "gdb_proc_service.h"
 
-#include "i386-linux-nat.h"
+#include "nat/i386-linux.h"
 #include "i387-tdep.h"
 #include "i386-tdep.h"
 #include "i386-linux-tdep.h"
@@ -80,22 +80,6 @@ int have_ptrace_getregs =
   0
 #endif
 ;
-
-/* 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.
-
-   My instinct is to attach this to some architecture- or
-   target-specific data structure, but really, a particular GDB
-   process can only run on top of one kernel at a time.  So it's okay
-   for this to be a simple variable.  */
-int have_ptrace_getfpxregs =
-#ifdef HAVE_PTRACE_GETFPXREGS
-  -1
-#else
-  0
-#endif
-;
 
 
 /* Accessing registers through the U area, one at a time.  */
@@ -388,14 +372,14 @@ fetch_fpxregs (struct regcache *regcache, int tid)
 {
   elf_fpxregset_t fpxregs;
 
-  if (! have_ptrace_getfpxregs)
+  if (have_ptrace_getfpxregs == TRIBOOL_FALSE)
     return 0;
 
   if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
     {
       if (errno == EIO)
 	{
-	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getfpxregs = TRIBOOL_FALSE;
 	  return 0;
 	}
 
@@ -415,14 +399,14 @@ store_fpxregs (const struct regcache *regcache, int tid, int regno)
 {
   elf_fpxregset_t fpxregs;
 
-  if (! have_ptrace_getfpxregs)
+  if (have_ptrace_getfpxregs == TRIBOOL_FALSE)
     return 0;
   
   if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
     {
       if (errno == EIO)
 	{
-	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getfpxregs = TRIBOOL_FALSE;
 	  return 0;
 	}
 
diff --git a/gdb/i386-linux-nat.h b/gdb/nat/i386-linux.c
index c3d32af..64605be 100644
--- a/gdb/i386-linux-nat.h
+++ b/gdb/nat/i386-linux.c
@@ -1,6 +1,6 @@
 /* Native-dependent code for GNU/Linux i386.
 
-   Copyright (C) 1999-2024 Free Software Foundation, Inc.
+   Copyright (C) 2024 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -17,10 +17,13 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifndef I386_LINUX_NAT_H
-#define I386_LINUX_NAT_H 1
-
-/* Does the current host support the GETFPXREGS request? */
-extern int have_ptrace_getfpxregs;
+#include "nat/i386-linux.h"
 
+/* See nat/i386-linux.h.  */
+tribool have_ptrace_getfpxregs =
+#ifdef HAVE_PTRACE_GETFPXREGS
+  TRIBOOL_UNKNOWN
+#else
+  TRIBOOL_FALSE
 #endif
+;
diff --git a/gdb/nat/i386-linux.h b/gdb/nat/i386-linux.h
new file mode 100644
index 0000000..c93626b
--- /dev/null
+++ b/gdb/nat/i386-linux.h
@@ -0,0 +1,37 @@
+/* Native-dependent code for GNU/Linux i386.
+
+   Copyright (C) 2024 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef NAT_I386_LINUX_H
+#define NAT_I386_LINUX_H
+
+/* Does the current host support the GETFPXREGS request?  The system header
+   file may or may not define it, but even if it is defined, the kernel
+   will return EIO if it's running on a pre-SSE processor.
+
+   Initially this will be TRIBOOL_UNKNOWN and should be changed to
+   TRIBOOL_FALSE if the ptrace call is attempted and fails or changed to
+   TRIBOOL_TRUE if the ptrace call is attempted and succeeds.
+
+   My instinct is to attach this to some architecture- or target-specific
+   data structure, but really, a particular GDB process can only run on top
+   of one kernel at a time.  So it's okay - for this to be a global
+   variable.  */
+extern tribool have_ptrace_getfpxregs;
+
+#endif /* NAT_I386_LINUX_H */
diff --git a/gdb/x86-linux-nat.c b/gdb/x86-linux-nat.c
index a3d8ffb..762151f 100644
--- a/gdb/x86-linux-nat.c
+++ b/gdb/x86-linux-nat.c
@@ -27,7 +27,7 @@
 
 #include "x86-nat.h"
 #ifndef __x86_64__
-#include "i386-linux-nat.h"
+#include "nat/i386-linux.h"
 #endif
 #include "x86-linux-nat.h"
 #include "i386-linux-tdep.h"
@@ -147,13 +147,13 @@ x86_linux_nat_target::read_description ()
       error (_("Can't debug 64-bit process with 32-bit GDB"));
   }
 #elif HAVE_PTRACE_GETFPXREGS
-  if (have_ptrace_getfpxregs == -1)
+  if (have_ptrace_getfpxregs == TRIBOOL_UNKNOWN)
     {
       elf_fpxregset_t fpxregs;
 
       if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
 	{
-	  have_ptrace_getfpxregs = 0;
+	  have_ptrace_getfpxregs = TRIBOOL_FALSE;
 	  have_ptrace_getregset = TRIBOOL_FALSE;
 	  return i386_linux_read_description (X86_XSTATE_X87_MASK);
 	}
diff --git a/gdbserver/configure.srv b/gdbserver/configure.srv
index 9e861a7..8e882d2 100644
--- a/gdbserver/configure.srv
+++ b/gdbserver/configure.srv
@@ -109,6 +109,7 @@ case "${gdbserver_host}" in
 			srv_tgtobj="${srv_tgtobj} nat/linux-btrace.o"
 			srv_tgtobj="${srv_tgtobj} nat/x86-linux.o"
 			srv_tgtobj="${srv_tgtobj} nat/x86-linux-dregs.o"
+			srv_tgtobj="${srv_tgtobj} nat/i386-linux.o"
 			srv_linux_usrregs=yes
 			srv_linux_regsets=yes
 			srv_linux_thread_db=yes
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