LXR linux/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. */
  16void 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
  38static 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 */
  57void 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. */
  82static 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
 109void 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}
 125