root/arch/sparc/kernel/windows.c

DEFINITIONS

1. flush_user_windows
2. shift_window_buffer
3. synchronize_user_stack
4. copy_aligned_window
5. try_to_clear_window_buffer

   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. */
  20 void 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 
  42 static 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  */
  61 void 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. */
  86 static 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 
 113 void 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 }