File: /usr/src/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 #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. */
17 void flush_user_windows(void)
18 {
19 register int ctr asm("g5");
20
21 ctr = 0;
22 __asm__ __volatile__("
23 1:
24 ld [%%g6 + %2], %%g4
25 orcc %%g0, %%g4, %%g0
26 add %0, 1, %0
27 bne 1b
28 save %%sp, -64, %%sp
29 2:
30 subcc %0, 1, %0
31 bne 2b
32 restore %%g0, %%g0, %%g0"
33 : "=&r" (ctr)
34 : "0" (ctr),
35 "i" ((const unsigned long)(&(((struct task_struct *)0)->thread.uwinmask)))
36 : "g4", "cc");
37 }
38
39 static inline void shift_window_buffer(int first_win, int last_win, struct thread_struct *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 */
58 void synchronize_user_stack(void)
59 {
60 struct thread_struct *tp;
61 int window;
62
63 flush_user_windows();
64 tp = ¤t->thread;
65 if(!tp->w_saved)
66 return;
67
68 /* Ok, there is some dirty work to do. */
69 for(window = tp->w_saved - 1; window >= 0; window--) {
70 unsigned long sp = tp->rwbuf_stkptrs[window];
71
72 /* Ok, let it rip. */
73 if(copy_to_user((char *) sp, &tp->reg_window[window],
74 sizeof(struct reg_window)))
75 continue;
76
77 shift_window_buffer(window, tp->w_saved - 1, tp);
78 tp->w_saved--;
79 }
80 }
81
82 #if 0
83 /* An optimization. */
84 static inline void copy_aligned_window(void *dest, const void *src)
85 {
86 __asm__ __volatile__("ldd [%1], %%g2\n\t"
87 "ldd [%1 + 0x8], %%g4\n\t"
88 "std %%g2, [%0]\n\t"
89 "std %%g4, [%0 + 0x8]\n\t"
90 "ldd [%1 + 0x10], %%g2\n\t"
91 "ldd [%1 + 0x18], %%g4\n\t"
92 "std %%g2, [%0 + 0x10]\n\t"
93 "std %%g4, [%0 + 0x18]\n\t"
94 "ldd [%1 + 0x20], %%g2\n\t"
95 "ldd [%1 + 0x28], %%g4\n\t"
96 "std %%g2, [%0 + 0x20]\n\t"
97 "std %%g4, [%0 + 0x28]\n\t"
98 "ldd [%1 + 0x30], %%g2\n\t"
99 "ldd [%1 + 0x38], %%g4\n\t"
100 "std %%g2, [%0 + 0x30]\n\t"
101 "std %%g4, [%0 + 0x38]\n\t" : :
102 "r" (dest), "r" (src) :
103 "g2", "g3", "g4", "g5");
104 }
105 #endif
106
107 /* Try to push the windows in a threads window buffer to the
108 * user stack. Unaligned %sp's are not allowed here.
109 */
110
111 void try_to_clear_window_buffer(struct pt_regs *regs, int who)
112 {
113 struct thread_struct *tp;
114 int window;
115
116 lock_kernel();
117 flush_user_windows();
118 tp = ¤t->thread;
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 *) sp, &tp->reg_window[window], REGWIN_SZ))
124 do_exit(SIGILL);
125 }
126 tp->w_saved = 0;
127 unlock_kernel();
128 }
129