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, 1 insertions, 1 deletions

diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index 9fbf210..383052b 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -44,7 +44,7 @@ static unsigned long syscall_regs[MAX_REG_NR];
 
 static int __init init_syscall_regs(void)
 {
-	get_safe_registers(syscall_regs, NULL);
+	get_safe_registers(syscall_regs);
 	syscall_regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
 		((unsigned long) &batch_syscall_stub -
 		 (unsigned long) &__syscall_stub_start);