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