LXR linux/arch/sparc/kernel/windows.c

   1// SPDX-License-Identifier: GPL-2.0
   2/* windows.c: Routines to deal with register window management
   3 *            at the C-code level.
   4 *
   5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   6 */
   7
   8#include <linux/kernel.h>
   9#include <linux/sched.h>
  10#include <linux/string.h>
  11#include <linux/mm.h>
  12#include <linux/smp.h>
  13
  14#include <asm/cacheflush.h>
  15#include <linux/uaccess.h>
  16
  17#include "kernel.h"
  18
  19/* Do save's until all user register windows are out of the cpu. */
  20void flush_user_windows(void)
  21{
  22        register int ctr asm("g5");
  23
  24        ctr = 0;
  25        __asm__ __volatile__(
  26                "\n1:\n\t"
  27                "ld     [%%g6 + %2], %%g4\n\t"
  28                "orcc   %%g0, %%g4, %%g0\n\t"
  29                "add    %0, 1, %0\n\t"
  30                "bne    1b\n\t"
  31                " save  %%sp, -64, %%sp\n"
  32                "2:\n\t"
  33                "subcc  %0, 1, %0\n\t"
  34                "bne    2b\n\t"
  35                " restore %%g0, %%g0, %%g0\n"
  36        : "=&r" (ctr)
  37        : "0" (ctr),
  38          "i" ((const unsigned long)TI_UWINMASK)
  39        : "g4", "cc");
  40}
  41
  42static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
  43{
  44        int i;
  45
  46        for(i = first_win; i < last_win; i++) {
  47                tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
  48                memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
  49        }
  50}
  51
  52/* Place as many of the user's current register windows 
  53 * on the stack that we can.  Even if the %sp is unaligned
  54 * we still copy the window there, the only case that we don't
  55 * succeed is if the %sp points to a bum mapping altogether.
  56 * setup_frame() and do_sigreturn() use this before shifting
  57 * the user stack around.  Future instruction and hardware
  58 * bug workaround routines will need this functionality as
  59 * well.
  60 */
  61void synchronize_user_stack(void)
  62{
  63        struct thread_info *tp = current_thread_info();
  64        int window;
  65
  66        flush_user_windows();
  67        if(!tp->w_saved)
  68                return;
  69
  70        /* Ok, there is some dirty work to do. */
  71        for(window = tp->w_saved - 1; window >= 0; window--) {
  72                unsigned long sp = tp->rwbuf_stkptrs[window];
  73
  74                /* Ok, let it rip. */
  75                if (copy_to_user((char __user *) sp, &tp->reg_window[window],
  76                                 sizeof(struct reg_window32)))
  77                        continue;
  78
  79                shift_window_buffer(window, tp->w_saved - 1, tp);
  80                tp->w_saved--;
  81        }
  82}
  83
  84#if 0
  85/* An optimization. */
  86static inline void copy_aligned_window(void *dest, const void *src)
  87{
  88        __asm__ __volatile__("ldd [%1], %%g2\n\t"
  89                             "ldd [%1 + 0x8], %%g4\n\t"
  90                             "std %%g2, [%0]\n\t"
  91                             "std %%g4, [%0 + 0x8]\n\t"
  92                             "ldd [%1 + 0x10], %%g2\n\t"
  93                             "ldd [%1 + 0x18], %%g4\n\t"
  94                             "std %%g2, [%0 + 0x10]\n\t"
  95                             "std %%g4, [%0 + 0x18]\n\t"
  96                             "ldd [%1 + 0x20], %%g2\n\t"
  97                             "ldd [%1 + 0x28], %%g4\n\t"
  98                             "std %%g2, [%0 + 0x20]\n\t"
  99                             "std %%g4, [%0 + 0x28]\n\t"
 100                             "ldd [%1 + 0x30], %%g2\n\t"
 101                             "ldd [%1 + 0x38], %%g4\n\t"
 102                             "std %%g2, [%0 + 0x30]\n\t"
 103                             "std %%g4, [%0 + 0x38]\n\t" : :
 104                             "r" (dest), "r" (src) :
 105                             "g2", "g3", "g4", "g5");
 106}
 107#endif
 108
 109/* Try to push the windows in a threads window buffer to the
 110 * user stack.  Unaligned %sp's are not allowed here.
 111 */
 112
 113void try_to_clear_window_buffer(struct pt_regs *regs, int who)
 114{
 115        struct thread_info *tp = current_thread_info();
 116        int window;
 117
 118        flush_user_windows();
 119        for(window = 0; window < tp->w_saved; window++) {
 120                unsigned long sp = tp->rwbuf_stkptrs[window];
 121
 122                if ((sp & 7) ||
 123                    copy_to_user((char __user *) sp, &tp->reg_window[window],
 124                                 sizeof(struct reg_window32)))
 125                        do_exit(SIGILL);
 126        }
 127        tp->w_saved = 0;
 128}
 129