arch/sparc/kernel/windows.c

   1 /* windows.c: Routines to deal with register window management
   2  *            at the C-code level.
   3  *
   4  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/sched.h>
   9 #include <linux/string.h>
  10 #include <linux/mm.h>
  11 #include <linux/smp.h>
  12 #include <linux/smp_lock.h>
  13
  14 #include <asm/uaccess.h>
  15
  16 /* Do save's until all user register windows are out of the cpu. */
  17 void flush_user_windows(void)
  18 {
  19         register int ctr asm("g5");
  20
  21         ctr = 0;
  22         __asm__ __volatile__("
  23 1:
  24         ld      [%%g6 + %2], %%g4
  25         orcc    %%g0, %%g4, %%g0
  26         add     %0, 1, %0
  27         bne     1b
  28          save   %%sp, -64, %%sp
  29 2:
  30         subcc   %0, 1, %0
  31         bne     2b
  32          restore %%g0, %%g0, %%g0"
  33         : "=&r" (ctr)
  34         : "0" (ctr),
  35           "i" ((const unsigned long)(&(((struct task_struct *)0)->thread.uwinmask)))
  36         : "g4", "cc");
  37 }
  38
  39 static inline void shift_window_buffer(int first_win, int last_win, struct thread_struct *tp)
  40 {
  41         int i;
  42
  43         for(i = first_win; i < last_win; i++) {
  44                 tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
  45                 memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window));
  46         }
  47 }
  48
  49 /* Place as many of the user's current register windows
  50  * on the stack that we can.  Even if the %sp is unaligned
  51  * we still copy the window there, the only case that we don't
  52  * succeed is if the %sp points to a bum mapping altogether.
  53  * setup_frame() and do_sigreturn() use this before shifting
  54  * the user stack around.  Future instruction and hardware
  55  * bug workaround routines will need this functionality as
  56  * well.
  57  */
  58 void synchronize_user_stack(void)
  59 {
  60         struct thread_struct *tp;
  61         int window;
  62
  63         flush_user_windows();
  64         tp = &current->thread;
  65         if(!tp->w_saved)
  66                 return;
  67
  68         /* Ok, there is some dirty work to do. */
  69         for(window = tp->w_saved - 1; window >= 0; window--) {
  70                 unsigned long sp = tp->rwbuf_stkptrs[window];
  71
  72                 /* Ok, let it rip. */
  73                 if(copy_to_user((char *) sp, &tp->reg_window[window],
  74                                 sizeof(struct reg_window)))
  75                         continue;
  76
  77                 shift_window_buffer(window, tp->w_saved - 1, tp);
  78                 tp->w_saved--;
  79         }
  80 }
  81
  82 #if 0
  83 /* An optimization. */
  84 static inline void copy_aligned_window(void *dest, const void *src)
  85 {
  86         __asm__ __volatile__("ldd [%1], %%g2\n\t"
  87                              "ldd [%1 + 0x8], %%g4\n\t"
  88                              "std %%g2, [%0]\n\t"
  89                              "std %%g4, [%0 + 0x8]\n\t"
  90                              "ldd [%1 + 0x10], %%g2\n\t"
  91                              "ldd [%1 + 0x18], %%g4\n\t"
  92                              "std %%g2, [%0 + 0x10]\n\t"
  93                              "std %%g4, [%0 + 0x18]\n\t"
  94                              "ldd [%1 + 0x20], %%g2\n\t"
  95                              "ldd [%1 + 0x28], %%g4\n\t"
  96                              "std %%g2, [%0 + 0x20]\n\t"
  97                              "std %%g4, [%0 + 0x28]\n\t"
  98                              "ldd [%1 + 0x30], %%g2\n\t"
  99                              "ldd [%1 + 0x38], %%g4\n\t"
 100                              "std %%g2, [%0 + 0x30]\n\t"
 101                              "std %%g4, [%0 + 0x38]\n\t" : :
 102                              "r" (dest), "r" (src) :
 103                              "g2", "g3", "g4", "g5");
 104 }
 105 #endif
 106
 107 /* Try to push the windows in a threads window buffer to the
 108  * user stack.  Unaligned %sp's are not allowed here.
 109  */
 110
 111 void try_to_clear_window_buffer(struct pt_regs *regs, int who)
 112 {
 113         struct thread_struct *tp;
 114         int window;
 115
 116         lock_kernel();
 117         flush_user_windows();
 118         tp = &current->thread;
 119         for(window = 0; window < tp->w_saved; window++) {
 120                 unsigned long sp = tp->rwbuf_stkptrs[window];
 121
 122                 if((sp & 7) ||
 123                    copy_to_user((char *) sp, &tp->reg_window[window], REGWIN_SZ))
 124                         do_exit(SIGILL);
 125         }
 126         tp->w_saved = 0;
 127         unlock_kernel();
 128 }