uml: stop saving process FP state

Throw out a lot of code dealing with saving and restoring floating-point
state.  In skas mode, where processes run in a restoring floating-point state
on kernel entry and exit is pointless.

This eliminates most of arch/um/os-Linux/sys-{i386,x86_64}/registers.c.  Most
of what remained is now arch-indpendent, and can be moved up to
arch/um/os-Linux/registers.c.  Both arches need the jmp_buf accessor
get_thread_reg, and i386 needs {save,restore}_fp_regs because it cheats during
sigreturn by getting the fp state using ptrace rather than copying it out of
the process sigcontext.

After this, it turns out that arch/um/include/skas/mode-skas.h is almost
completely unneeded.  The declarations in it are variables which either don't
exist or which don't have global scope.  The one exception is
kill_off_processes_skas.  If that's removed, this header can be deleted.

This uncovered a bug in user.h, which wasn't correctly making sure that a
size_t definition was available to both userspace and kernelspace files.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/include/os.h

@@ -307,6 +307,8 @@ extern int protect(struct mm_id * mm_idp, unsigned long addr,
 extern int is_skas_winch(int pid, int fd, void *data);
 extern int start_userspace(unsigned long stub_stack);
 extern int copy_context_skas0(unsigned long stack, int pid);
+extern void save_registers(int pid, union uml_pt_regs *regs);
+extern void restore_registers(int pid, union uml_pt_regs *regs);
 extern void userspace(union uml_pt_regs *regs);
 extern void map_stub_pages(int fd, unsigned long code,
 			   unsigned long data, unsigned long stack);

arch/um/include/registers.h

@@ -15,7 +15,7 @@ extern int restore_fp_registers(int pid, unsigned long *fp_regs);
 extern void save_registers(int pid, union uml_pt_regs *regs);
 extern void restore_registers(int pid, union uml_pt_regs *regs);
 extern void init_registers(int pid);
-extern void get_safe_registers(unsigned long * regs, unsigned long * fp_regs);
+extern void get_safe_registers(unsigned long *regs);
 extern unsigned long get_thread_reg(int reg, jmp_buf *buf);
 
 #endif

arch/um/include/skas/mode-skas.h

@@ -1,18 +1,11 @@
 /*
- * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
  * Licensed under the GPL
  */
 
 #ifndef __MODE_SKAS_H__
 #define __MODE_SKAS_H__
 
-#include <sysdep/ptrace.h>
-
-extern unsigned long exec_regs[];
-extern unsigned long exec_fp_regs[];
-extern unsigned long exec_fpx_regs[];
-extern int have_fpx_regs;
-
 extern void kill_off_processes_skas(void);
 
 #endif

arch/um/include/sysdep-i386/ptrace.h

@@ -219,14 +219,3 @@ struct syscall_args {
         CHOOSE_MODE((&(r)->tt.faultinfo), (&(r)->skas.faultinfo))
 
 #endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */

arch/um/include/user.h

@@ -14,10 +14,12 @@
  */
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
-/*
- * This will provide the size_t definition in both kernel and userspace builds
- */
+/* This is to get size_t */
+#ifdef __KERNEL__
 #include <linux/types.h>
+#else
+#include <stddef.h>
+#endif
 
 extern void panic(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));