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, 7 deletions

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index ba9af8d62055..db020d21f132 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -357,11 +357,10 @@ void userspace(union uml_pt_regs *regs)
 }
 
 static unsigned long thread_regs[MAX_REG_NR];
-static unsigned long thread_fp_regs[HOST_FP_SIZE];
 
 static int __init init_thread_regs(void)
 {
-        get_safe_registers(thread_regs, thread_fp_regs);
+        get_safe_registers(thread_regs);
         /* Set parent's instruction pointer to start of clone-stub */
         thread_regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
                                 (unsigned long) stub_clone_handler -
@@ -398,11 +397,6 @@ int copy_context_skas0(unsigned long new_stack, int pid)
                 panic("copy_context_skas0 : PTRACE_SETREGS failed, "
                       "pid = %d, errno = %d\n", pid, -err);
 
-        err = ptrace_setfpregs(pid, thread_fp_regs);
-        if(err < 0)
-                panic("copy_context_skas0 : PTRACE_SETFPREGS failed, "
-                      "pid = %d, errno = %d\n", pid, -err);
-
         /* set a well known return code for detection of child write failure */
         child_data->err = 12345678;