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
  13 #include <asm/uaccess.h>
  14
  15 /* Do save's until all user register windows are out of the cpu. */
  16 void flush_user_windows(void)
  17 {
  18         register int ctr asm("g5");
  19
  20         ctr = 0;
  21         __asm__ __volatile__(
  22                 "\n1:\n\t"
  23                 "ld     [%%g6 + %2], %%g4\n\t"
  24                 "orcc   %%g0, %%g4, %%g0\n\t"
  25                 "add    %0, 1, %0\n\t"
  26                 "bne    1b\n\t"
  27                 " save  %%sp, -64, %%sp\n"
  28                 "2:\n\t"
  29                 "subcc  %0, 1, %0\n\t"
  30                 "bne    2b\n\t"
  31                 " restore %%g0, %%g0, %%g0\n"
  32         : "=&r" (ctr)
  33         : "0" (ctr),
  34           "i" ((const unsigned long)TI_UWINMASK)
  35         : "g4", "cc");
  36 }
  37
  38 static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
  39 {
  40         int i;
  41
  42         for(i = first_win; i < last_win; i++) {
  43                 tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
  44                 memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
  45         }
  46 }
  47
  48 /* Place as many of the user's current register windows
  49  * on the stack that we can.  Even if the %sp is unaligned
  50  * we still copy the window there, the only case that we don't
  51  * succeed is if the %sp points to a bum mapping altogether.
  52  * setup_frame() and do_sigreturn() use this before shifting
  53  * the user stack around.  Future instruction and hardware
  54  * bug workaround routines will need this functionality as
  55  * well.
  56  */
  57 void synchronize_user_stack(void)
  58 {
  59         struct thread_info *tp = current_thread_info();
  60         int window;
  61
  62         flush_user_windows();
  63         if(!tp->w_saved)
  64                 return;
  65
  66         /* Ok, there is some dirty work to do. */
  67         for(window = tp->w_saved - 1; window >= 0; window--) {
  68                 unsigned long sp = tp->rwbuf_stkptrs[window];
  69
  70                 /* Ok, let it rip. */
  71                 if (copy_to_user((char __user *) sp, &tp->reg_window[window],
  72                                  sizeof(struct reg_window32)))
  73                         continue;
  74
  75                 shift_window_buffer(window, tp->w_saved - 1, tp);
  76                 tp->w_saved--;
  77         }
  78 }
  79
  80 #if 0
  81 /* An optimization. */
  82 static inline void copy_aligned_window(void *dest, const void *src)
  83 {
  84         __asm__ __volatile__("ldd [%1], %%g2\n\t"
  85                              "ldd [%1 + 0x8], %%g4\n\t"
  86                              "std %%g2, [%0]\n\t"
  87                              "std %%g4, [%0 + 0x8]\n\t"
  88                              "ldd [%1 + 0x10], %%g2\n\t"
  89                              "ldd [%1 + 0x18], %%g4\n\t"
  90                              "std %%g2, [%0 + 0x10]\n\t"
  91                              "std %%g4, [%0 + 0x18]\n\t"
  92                              "ldd [%1 + 0x20], %%g2\n\t"
  93                              "ldd [%1 + 0x28], %%g4\n\t"
  94                              "std %%g2, [%0 + 0x20]\n\t"
  95                              "std %%g4, [%0 + 0x28]\n\t"
  96                              "ldd [%1 + 0x30], %%g2\n\t"
  97                              "ldd [%1 + 0x38], %%g4\n\t"
  98                              "std %%g2, [%0 + 0x30]\n\t"
  99                              "std %%g4, [%0 + 0x38]\n\t" : :
 100                              "r" (dest), "r" (src) :
 101                              "g2", "g3", "g4", "g5");
 102 }
 103 #endif
 104
 105 /* Try to push the windows in a threads window buffer to the
 106  * user stack.  Unaligned %sp's are not allowed here.
 107  */
 108
 109 void try_to_clear_window_buffer(struct pt_regs *regs, int who)
 110 {
 111         struct thread_info *tp = current_thread_info();
 112         int window;
 113
 114         flush_user_windows();
 115         for(window = 0; window < tp->w_saved; window++) {
 116                 unsigned long sp = tp->rwbuf_stkptrs[window];
 117
 118                 if ((sp & 7) ||
 119                     copy_to_user((char __user *) sp, &tp->reg_window[window],
 120                                  sizeof(struct reg_window32)))
 121                         do_exit(SIGILL);
 122         }
 123         tp->w_saved = 0;
 124 }