x86: unify chunks of kernel/process*.c

With x86-32 and -64 using the same mechanism for managing the
tss io permissions bitmap, large chunks of process*.c are
trivially unifyable, including:

 - exit_thread
 - flush_thread
 - __switch_to_xtra (along with tsc enable/disable)

and as bonus pickups:

 - sys_fork
 - sys_vfork

(Note: asmlinkage expands to empty on x86-64)

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 190 insertions, 1 deletions

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 87b69d4fac16..6afa5232dbb7 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -1,8 +1,8 @@
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
-#include <asm/idle.h>
 #include <linux/smp.h>
+#include <linux/prctl.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/module.h>
@@ -11,6 +11,9 @@
 #include <linux/ftrace.h>
 #include <asm/system.h>
 #include <asm/apic.h>
+#include <asm/idle.h>
+#include <asm/uaccess.h>
+#include <asm/i387.h>
 
 unsigned long idle_halt;
 EXPORT_SYMBOL(idle_halt);
@@ -56,6 +59,192 @@ void arch_task_cache_init(void)
 }
 
 /*
+ * Free current thread data structures etc..
+ */
+void exit_thread(void)
+{
+        struct task_struct *me = current;
+        struct thread_struct *t = &me->thread;
+
+        if (me->thread.io_bitmap_ptr) {
+                struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
+
+                kfree(t->io_bitmap_ptr);
+                t->io_bitmap_ptr = NULL;
+                clear_thread_flag(TIF_IO_BITMAP);
+                /*
+                 * Careful, clear this in the TSS too:
+                 */
+                memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
+                t->io_bitmap_max = 0;
+                put_cpu();
+        }
+
+        ds_exit_thread(current);
+}
+
+void flush_thread(void)
+{
+        struct task_struct *tsk = current;
+
+#ifdef CONFIG_X86_64
+        if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
+                clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
+                if (test_tsk_thread_flag(tsk, TIF_IA32)) {
+                        clear_tsk_thread_flag(tsk, TIF_IA32);
+                } else {
+                        set_tsk_thread_flag(tsk, TIF_IA32);
+                        current_thread_info()->status |= TS_COMPAT;
+                }
+        }
+#endif
+
+        clear_tsk_thread_flag(tsk, TIF_DEBUG);
+
+        tsk->thread.debugreg0 = 0;
+        tsk->thread.debugreg1 = 0;
+        tsk->thread.debugreg2 = 0;
+        tsk->thread.debugreg3 = 0;
+        tsk->thread.debugreg6 = 0;
+        tsk->thread.debugreg7 = 0;
+        memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
+        /*
+         * Forget coprocessor state..
+         */
+        tsk->fpu_counter = 0;
+        clear_fpu(tsk);
+        clear_used_math();
+}
+
+static void hard_disable_TSC(void)
+{
+        write_cr4(read_cr4() | X86_CR4_TSD);
+}
+
+void disable_TSC(void)
+{
+        preempt_disable();
+        if (!test_and_set_thread_flag(TIF_NOTSC))
+                /*
+                 * Must flip the CPU state synchronously with
+                 * TIF_NOTSC in the current running context.
+                 */
+                hard_disable_TSC();
+        preempt_enable();
+}
+
+static void hard_enable_TSC(void)
+{
+        write_cr4(read_cr4() & ~X86_CR4_TSD);
+}
+
+static void enable_TSC(void)
+{
+        preempt_disable();
+        if (test_and_clear_thread_flag(TIF_NOTSC))
+                /*
+                 * Must flip the CPU state synchronously with
+                 * TIF_NOTSC in the current running context.
+                 */
+                hard_enable_TSC();
+        preempt_enable();
+}
+
+int get_tsc_mode(unsigned long adr)
+{
+        unsigned int val;
+
+        if (test_thread_flag(TIF_NOTSC))
+                val = PR_TSC_SIGSEGV;
+        else
+                val = PR_TSC_ENABLE;
+
+        return put_user(val, (unsigned int __user *)adr);
+}
+
+int set_tsc_mode(unsigned int val)
+{
+        if (val == PR_TSC_SIGSEGV)
+                disable_TSC();
+        else if (val == PR_TSC_ENABLE)
+                enable_TSC();
+        else
+                return -EINVAL;
+
+        return 0;
+}
+
+void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
+                      struct tss_struct *tss)
+{
+        struct thread_struct *prev, *next;
+
+        prev = &prev_p->thread;
+        next = &next_p->thread;
+
+        if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
+            test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
+                ds_switch_to(prev_p, next_p);
+        else if (next->debugctlmsr != prev->debugctlmsr)
+                update_debugctlmsr(next->debugctlmsr);
+
+        if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
+                set_debugreg(next->debugreg0, 0);
+                set_debugreg(next->debugreg1, 1);
+                set_debugreg(next->debugreg2, 2);
+                set_debugreg(next->debugreg3, 3);
+                /* no 4 and 5 */
+                set_debugreg(next->debugreg6, 6);
+                set_debugreg(next->debugreg7, 7);
+        }
+
+        if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
+            test_tsk_thread_flag(next_p, TIF_NOTSC)) {
+                /* prev and next are different */
+                if (test_tsk_thread_flag(next_p, TIF_NOTSC))
+                        hard_disable_TSC();
+                else
+                        hard_enable_TSC();
+        }
+
+        if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
+                /*
+                 * Copy the relevant range of the IO bitmap.
+                 * Normally this is 128 bytes or less:
+                 */
+                memcpy(tss->io_bitmap, next->io_bitmap_ptr,
+                       max(prev->io_bitmap_max, next->io_bitmap_max));
+        } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
+                /*
+                 * Clear any possible leftover bits:
+                 */
+                memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
+        }
+}
+
+int sys_fork(struct pt_regs *regs)
+{
+        return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
+}
+
+/*
+ * This is trivial, and on the face of it looks like it
+ * could equally well be done in user mode.
+ *
+ * Not so, for quite unobvious reasons - register pressure.
+ * In user mode vfork() cannot have a stack frame, and if
+ * done by calling the "clone()" system call directly, you
+ * do not have enough call-clobbered registers to hold all
+ * the information you need.
+ */
+int sys_vfork(struct pt_regs *regs)
+{
+        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
+                       NULL, NULL);
+}
+
+
+/*
  * Idle related variables and functions
  */
 unsigned long boot_option_idle_override = 0;