linux/arch/sparc/kernel/windows.c
<<
>>
Prefs
   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. */
  17void flush_user_windows(void)
  18{
  19        register int ctr asm("g5");
  20
  21        ctr = 0;
  22        __asm__ __volatile__(
  23                "\n1:\n\t"
  24                "ld     [%%g6 + %2], %%g4\n\t"
  25                "orcc   %%g0, %%g4, %%g0\n\t"
  26                "add    %0, 1, %0\n\t"
  27                "bne    1b\n\t"
  28                " save  %%sp, -64, %%sp\n"
  29                "2:\n\t"
  30                "subcc  %0, 1, %0\n\t"
  31                "bne    2b\n\t"
  32                " restore %%g0, %%g0, %%g0\n"
  33        : "=&r" (ctr)
  34        : "0" (ctr),
  35          "i" ((const unsigned long)TI_UWINMASK)
  36        : "g4", "cc");
  37}
  38
  39static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *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 */
  58void synchronize_user_stack(void)
  59{
  60        struct thread_info *tp = current_thread_info();
  61        int window;
  62
  63        flush_user_windows();
  64        if(!tp->w_saved)
  65                return;
  66
  67        /* Ok, there is some dirty work to do. */
  68        for(window = tp->w_saved - 1; window >= 0; window--) {
  69                unsigned long sp = tp->rwbuf_stkptrs[window];
  70
  71                /* Ok, let it rip. */
  72                if (copy_to_user((char __user *) sp, &tp->reg_window[window],
  73                                 sizeof(struct reg_window)))
  74                        continue;
  75
  76                shift_window_buffer(window, tp->w_saved - 1, tp);
  77                tp->w_saved--;
  78        }
  79}
  80
  81#if 0
  82/* An optimization. */
  83static inline void copy_aligned_window(void *dest, const void *src)
  84{
  85        __asm__ __volatile__("ldd [%1], %%g2\n\t"
  86                             "ldd [%1 + 0x8], %%g4\n\t"
  87                             "std %%g2, [%0]\n\t"
  88                             "std %%g4, [%0 + 0x8]\n\t"
  89                             "ldd [%1 + 0x10], %%g2\n\t"
  90                             "ldd [%1 + 0x18], %%g4\n\t"
  91                             "std %%g2, [%0 + 0x10]\n\t"
  92                             "std %%g4, [%0 + 0x18]\n\t"
  93                             "ldd [%1 + 0x20], %%g2\n\t"
  94                             "ldd [%1 + 0x28], %%g4\n\t"
  95                             "std %%g2, [%0 + 0x20]\n\t"
  96                             "std %%g4, [%0 + 0x28]\n\t"
  97                             "ldd [%1 + 0x30], %%g2\n\t"
  98                             "ldd [%1 + 0x38], %%g4\n\t"
  99                             "std %%g2, [%0 + 0x30]\n\t"
 100                             "std %%g4, [%0 + 0x38]\n\t" : :
 101                             "r" (dest), "r" (src) :
 102                             "g2", "g3", "g4", "g5");
 103}
 104#endif
 105
 106/* Try to push the windows in a threads window buffer to the
 107 * user stack.  Unaligned %sp's are not allowed here.
 108 */
 109
 110void try_to_clear_window_buffer(struct pt_regs *regs, int who)
 111{
 112        struct thread_info *tp = current_thread_info();
 113        int window;
 114
 115        lock_kernel();
 116        flush_user_windows();
 117        for(window = 0; window < tp->w_saved; window++) {
 118                unsigned long sp = tp->rwbuf_stkptrs[window];
 119
 120                if ((sp & 7) ||
 121                    copy_to_user((char __user *) sp, &tp->reg_window[window],
 122                                 sizeof(struct reg_window)))
 123                        do_exit(SIGILL);
 124        }
 125        tp->w_saved = 0;
 126        unlock_kernel();
 127}
 128