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>

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index 2f8c79464015..f1bb58fe3207 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -4,8 +4,8 @@
 #
 
 obj-y = aio.o elf_aux.o execvp.o file.o helper.o irq.o main.o mem.o process.o \
-        sigio.o signal.o start_up.o time.o trap.o tty.o uaccess.o umid.o tls.o \
-        user_syms.o util.o drivers/ sys-$(SUBARCH)/
+        registers.o sigio.o signal.o start_up.o time.o trap.o tty.o uaccess.o \
+        umid.o tls.o user_syms.o util.o drivers/ sys-$(SUBARCH)/
 
 obj-$(CONFIG_MODE_SKAS) += skas/
 
@@ -16,8 +16,8 @@ obj-$(CONFIG_TTY_LOG) += tty_log.o
 user-objs-$(CONFIG_TTY_LOG) += tty_log.o
 
 USER_OBJS := $(user-objs-y) aio.o elf_aux.o execvp.o file.o helper.o irq.o \
-        main.o mem.o process.o sigio.o signal.o start_up.o time.o trap.o tty.o \
-        tls.o uaccess.o umid.o util.o
+        main.o mem.o process.o registers.o sigio.o signal.o start_up.o time.o \
+        trap.o tty.o tls.o uaccess.o umid.o util.o
 
 CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)