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, 54 insertions, 0 deletions

diff --git a/arch/um/os-Linux/registers.c b/arch/um/os-Linux/registers.c
new file mode 100644
index 000000000000..9dc3fad9ea29
--- /dev/null
+++ b/arch/um/os-Linux/registers.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2004 PathScale, Inc
+ * Licensed under the GPL
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include "user.h"
+#include "sysdep/ptrace.h"
+
+/* This is set once at boot time and not changed thereafter */
+
+static unsigned long exec_regs[MAX_REG_NR];
+
+void init_thread_registers(union uml_pt_regs *to)
+{
+        memcpy(to->skas.regs, exec_regs, sizeof(to->skas.regs));
+}
+
+void save_registers(int pid, union uml_pt_regs *regs)
+{
+        int err;
+
+        err = ptrace(PTRACE_GETREGS, pid, 0, regs->skas.regs);
+        if(err < 0)
+                panic("save_registers - saving registers failed, errno = %d\n",
+                      errno);
+}
+
+void restore_registers(int pid, union uml_pt_regs *regs)
+{
+        int err;
+
+        err = ptrace(PTRACE_SETREGS, pid, 0, regs->skas.regs);
+        if(err < 0)
+                panic("restore_registers - saving registers failed, "
+                      "errno = %d\n", errno);
+}
+
+void init_registers(int pid)
+{
+        int err;
+
+        err = ptrace(PTRACE_GETREGS, pid, 0, exec_regs);
+        if(err)
+                panic("check_ptrace : PTRACE_GETREGS failed, errno = %d",
+                      errno);
+}
+
+void get_safe_registers(unsigned long *regs)
+{
+        memcpy(regs, exec_regs, sizeof(exec_regs));
+}