uml: remove code made redundant by CHOOSE_MODE removal

This patch makes a number of simplifications enabled by the removal of
CHOOSE_MODE.  There were lots of functions that looked like

	int foo(args){
		foo_skas(args);
	}

The bodies of foo_skas are now folded into foo, and their declarations (and
sometimes entire header files) are deleted.

In addition, the union uml_pt_regs, which was a union between the tt and skas
register formats, is now a struct, with the tt-mode arm of the union being
removed.

It turns out that usr2_handler was unused, so it is gone.

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, 99 insertions, 21 deletions

diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 22ad46fd2c08..d3b9c62e73c7 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -43,8 +43,7 @@
 #include "frame_kern.h"
 #include "sigcontext.h"
 #include "os.h"
-#include "mode.h"
-#include "mode_kern.h"
+#include "skas.h"
 
 /* This is a per-cpu array.  A processor only modifies its entry and it only
  * cares about its entry, so it's OK if another processor is modifying its
@@ -54,7 +53,8 @@ struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
 
 static inline int external_pid(struct task_struct *task)
 {
-        return external_pid_skas(task);
+        /* FIXME: Need to look up userspace_pid by cpu */
+        return(userspace_pid[0]);
 }
 
 int pid_to_processor_id(int pid)
@@ -104,6 +104,8 @@ static inline void set_current(struct task_struct *task)
                 { external_pid(task), task });
 }
 
+extern void arch_switch_to(struct task_struct *from, struct task_struct *to);
+
 void *_switch_to(void *prev, void *next, void *last)
 {
         struct task_struct *from = prev;
@@ -114,7 +116,19 @@ void *_switch_to(void *prev, void *next, void *last)
 
         do {
                 current->thread.saved_task = NULL;
-                switch_to_skas(prev, next);
+
+                /* XXX need to check runqueues[cpu].idle */
+                if(current->pid == 0)
+                        switch_timers(0);
+
+                switch_threads(&from->thread.switch_buf,
+                               &to->thread.switch_buf);
+
+                arch_switch_to(current->thread.prev_sched, current);
+
+                if(current->pid == 0)
+                        switch_timers(1);
+
                 if(current->thread.saved_task)
                         show_regs(&(current->thread.regs));
                 next= current->thread.saved_task;
@@ -133,11 +147,6 @@ void interrupt_end(void)
                 do_signal();
 }
 
-void release_thread(struct task_struct *task)
-{
-        release_thread_skas(task);
-}
-
 void exit_thread(void)
 {
 }
@@ -147,27 +156,95 @@ void *get_current(void)
         return current;
 }
 
+extern void schedule_tail(struct task_struct *prev);
+
+/* This is called magically, by its address being stuffed in a jmp_buf
+ * and being longjmp-d to.
+ */
+void new_thread_handler(void)
+{
+        int (*fn)(void *), n;
+        void *arg;
+
+        if(current->thread.prev_sched != NULL)
+                schedule_tail(current->thread.prev_sched);
+        current->thread.prev_sched = NULL;
+
+        fn = current->thread.request.u.thread.proc;
+        arg = current->thread.request.u.thread.arg;
+
+        /* The return value is 1 if the kernel thread execs a process,
+         * 0 if it just exits
+         */
+        n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
+        if(n == 1){
+                /* Handle any immediate reschedules or signals */
+                interrupt_end();
+                userspace(&current->thread.regs.regs);
+        }
+        else do_exit(0);
+}
+
+/* Called magically, see new_thread_handler above */
+void fork_handler(void)
+{
+        force_flush_all();
+        if(current->thread.prev_sched == NULL)
+                panic("blech");
+
+        schedule_tail(current->thread.prev_sched);
+
+        /* XXX: if interrupt_end() calls schedule, this call to
+         * arch_switch_to isn't needed. We could want to apply this to
+         * improve performance. -bb */
+        arch_switch_to(current->thread.prev_sched, current);
+
+        current->thread.prev_sched = NULL;
+
+        /* Handle any immediate reschedules or signals */
+        interrupt_end();
+
+        userspace(&current->thread.regs.regs);
+}
+
 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
                 unsigned long stack_top, struct task_struct * p,
                 struct pt_regs *regs)
 {
-        int ret;
+        void (*handler)(void);
+        int ret = 0;
 
         p->thread = (struct thread_struct) INIT_THREAD;
-        ret = copy_thread_skas(nr, clone_flags, sp, stack_top, p, regs);
 
-        if (ret || !current->thread.forking)
-                goto out;
+        if(current->thread.forking){
+                memcpy(&p->thread.regs.regs, &regs->regs,
+                       sizeof(p->thread.regs.regs));
+                REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.regs, 0);
+                if(sp != 0)
+                        REGS_SP(p->thread.regs.regs.regs) = sp;
 
-        clear_flushed_tls(p);
+                handler = fork_handler;
 
-        /*
-         * Set a new TLS for the child thread?
-         */
-        if (clone_flags & CLONE_SETTLS)
-                ret = arch_copy_tls(p);
+                arch_copy_thread(&current->thread.arch, &p->thread.arch);
+        }
+        else {
+                init_thread_registers(&p->thread.regs.regs);
+                p->thread.request.u.thread = current->thread.request.u.thread;
+                handler = new_thread_handler;
+        }
+
+        new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
+
+        if (current->thread.forking) {
+                clear_flushed_tls(p);
+
+                /*
+                 * Set a new TLS for the child thread?
+                 */
+                if (clone_flags & CLONE_SETTLS)
+                        ret = arch_copy_tls(p);
+        }
 
-out:
         return ret;
 }
 
@@ -198,7 +275,8 @@ void default_idle(void)
 
 void cpu_idle(void)
 {
-        init_idle_skas();
+        cpu_tasks[current_thread->cpu].pid = os_getpid();
+        default_idle();
 }
 
 void *um_virt_to_phys(struct task_struct *task, unsigned long addr,