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/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. */
  19void 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
  41static 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 */
  60void 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. */
  85static 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
 112void 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}
 128