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/cacheflush.h>
  14 #include <asm/uaccess.h>
  15
  16 #include "kernel.h"
  17
  18 /* Do save's until all user register windows are out of the cpu. */
  19 void flush_user_windows(void)
  20 {
  21         register int ctr asm("g5");
  22
  23         ctr = 0;
  24         __asm__ __volatile__(
  25                 "\n1:\n\t"
  26                 "ld     [%%g6 + %2], %%g4\n\t"
  27                 "orcc   %%g0, %%g4, %%g0\n\t"
  28                 "add    %0, 1, %0\n\t"
  29                 "bne    1b\n\t"
  30                 " save  %%sp, -64, %%sp\n"
  31                 "2:\n\t"
  32                 "subcc  %0, 1, %0\n\t"
  33                 "bne    2b\n\t"
  34                 " restore %%g0, %%g0, %%g0\n"
  35         : "=&r" (ctr)
  36         : "0" (ctr),
  37           "i" ((const unsigned long)TI_UWINMASK)
  38         : "g4", "cc");
  39 }
  40
  41 static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
  42 {
  43         int i;
  44
  45         for(i = first_win; i < last_win; i++) {
  46                 tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
  47                 memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
  48         }
  49 }
  50
  51 /* Place as many of the user's current register windows
  52  * on the stack that we can.  Even if the %sp is unaligned
  53  * we still copy the window there, the only case that we don't
  54  * succeed is if the %sp points to a bum mapping altogether.
  55  * setup_frame() and do_sigreturn() use this before shifting
  56  * the user stack around.  Future instruction and hardware
  57  * bug workaround routines will need this functionality as
  58  * well.
  59  */
  60 void synchronize_user_stack(void)
  61 {
  62         struct thread_info *tp = current_thread_info();
  63         int window;
  64
  65         flush_user_windows();
  66         if(!tp->w_saved)
  67                 return;
  68
  69         /* Ok, there is some dirty work to do. */
  70         for(window = tp->w_saved - 1; window >= 0; window--) {
  71                 unsigned long sp = tp->rwbuf_stkptrs[window];
  72
  73                 /* Ok, let it rip. */
  74                 if (copy_to_user((char __user *) sp, &tp->reg_window[window],
  75                                  sizeof(struct reg_window32)))
  76                         continue;
  77
  78                 shift_window_buffer(window, tp->w_saved - 1, tp);
  79                 tp->w_saved--;
  80         }
  81 }
  82
  83 #if 0
  84 /* An optimization. */
  85 static inline void copy_aligned_window(void *dest, const void *src)
  86 {
  87         __asm__ __volatile__("ldd [%1], %%g2\n\t"
  88                              "ldd [%1 + 0x8], %%g4\n\t"
  89                              "std %%g2, [%0]\n\t"
  90                              "std %%g4, [%0 + 0x8]\n\t"
  91                              "ldd [%1 + 0x10], %%g2\n\t"
  92                              "ldd [%1 + 0x18], %%g4\n\t"
  93                              "std %%g2, [%0 + 0x10]\n\t"
  94                              "std %%g4, [%0 + 0x18]\n\t"
  95                              "ldd [%1 + 0x20], %%g2\n\t"
  96                              "ldd [%1 + 0x28], %%g4\n\t"
  97                              "std %%g2, [%0 + 0x20]\n\t"
  98                              "std %%g4, [%0 + 0x28]\n\t"
  99                              "ldd [%1 + 0x30], %%g2\n\t"
 100                              "ldd [%1 + 0x38], %%g4\n\t"
 101                              "std %%g2, [%0 + 0x30]\n\t"
 102                              "std %%g4, [%0 + 0x38]\n\t" : :
 103                              "r" (dest), "r" (src) :
 104                              "g2", "g3", "g4", "g5");
 105 }
 106 #endif
 107
 108 /* Try to push the windows in a threads window buffer to the
 109  * user stack.  Unaligned %sp's are not allowed here.
 110  */
 111
 112 void try_to_clear_window_buffer(struct pt_regs *regs, int who)
 113 {
 114         struct thread_info *tp = current_thread_info();
 115         int window;
 116
 117         flush_user_windows();
 118         for(window = 0; window < tp->w_saved; window++) {
 119                 unsigned long sp = tp->rwbuf_stkptrs[window];
 120
 121                 if ((sp & 7) ||
 122                     copy_to_user((char __user *) sp, &tp->reg_window[window],
 123                                  sizeof(struct reg_window32)))
 124                         do_exit(SIGILL);
 125         }
 126         tp->w_saved = 0;
 127 }